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HiSeasNet Training Seatel Stabilized Antennas Series 9797, 4996, 4006, & 6006. HiSeasNet Training Agenda. Welcome & Introduction Basic Satellite Information Types of Satellite Orbits and Orbital Spacing Frequency Bands and Advantages Polarization Footprint Basics

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slide1

HiSeasNet Training

Seatel Stabilized Antennas

Series 9797, 4996, 4006, & 6006

hiseasnet training agenda
HiSeasNet Training Agenda

Welcome & Introduction

Basic Satellite Information

  • Types of Satellite Orbits and Orbital Spacing
  • Frequency Bands and Advantages
  • Polarization
  • Footprint Basics

System Block Diagrams

Basic Antenna Components Above Decks Equipment (ADE)

Basic Antenna Components Below Decks equipment (BDE)

Basic System Functions

Antenna Pointing, Targeting, and Tracking

Stabilization

Tracking

Searching

Installation

System Setup

Operation

Functional Testing

Troubleshooting and Repair

Lab Exercises

welcome introduction
Welcome & Introduction
  • • Welcome
  • • Introduction

Instructor

Students

  • • House-keeping
  • • Training Agenda
  • - 0900-1200 and 1300-1600 Daily
  • • Why you’re here
  • - Gain understanding of the installation, operation, maintenance and troubleshooting of the Seatel stabilized antenna system.
  • - What are the key points …
  • • Pointing/Targeting - Accurately driving the antenna to precise Azimuth and Elevation angles in three dimensional free space to be consistent with where the satellite signal is emanating from
  • • Stabilization - Maintaining the Azimuth and Elevation pointing angles while the ship is rolling, pitching and turning
  • • Tracking - Use of the received satellite signal level to continuously evaluate and optimize the pointing angles of the antenna for maximum signal level reception.
welcome introduction1
Welcome & Introduction
  • Definitions of relevant terms
  • Relative (REL) - Mechanical azimuth rotational position of the antenna relative to the Bow of the ship. When the antenna is pointed inline with the Bow of the ship the REL display should be 360.0/000.0. Range of display is 000.0-359.9.
  • Azimuth (AZ) -True Azimuth (requires Ships’ Gyro Compass input). the Azimuth pointing angle of the antenna relative to True North (North Pole of the Earth). When the antenna is pointed True North display will be 000.0, East at 090.0, South at 180.0 and West at 270.0. Range of display is 000.0-359.9, Up direction is CW rotation of the antenna.
  • Elevation (EL) - Elevation pointing angle of the antenna between Horizon (000.0) and Zenith (090.0).
  • Level (LV) - Pedestal Fore/Aft upright position relative to the Horizon. Level Sensor is a gravity reference to bring the Level Cage (fore/aft) aspect to “level". This input is used to stabilize Elevation.
  • Cross-Level (CL) - Pedestal Left/Right tilt position relative to the Horizon. Level Sensor is a gravity reference to bring the Level Cage (Left/Right) aspect to “level”. This input is used to stabilize The Left/Right Tilt of the antenna.
welcome introduction2
Welcome & Introduction
  • Definitions of other relevant terms
  • Roll - Tilting motion of the ship from side (Port) to side (Starboard).
  • Pitch - Tilting motion of the ship from Bow to Aft.
  • Yaw - Serpentine oscillation of the ship along a desired heading (steering badly)
  • Center of Gravity (C/G) - Center of gravity of the mass of the antenna. Azimuth, Elevation and Cross Level are aligned at the factory to be coincident within 0.003 inch.
  • Static Balance - Proper 3-dimensional balance of the antenna is critical to stabilization. When properly balanced the un-energized antenna can be pointed to any AZ/EL pointing position and it will remain pointed there when released.
  • Tangential Acceleration - G-Force exerted on the mass of the antenna as it swings through free space during ship motions.
welcome introduction3
Welcome & Introduction
  • Definitions of other relevant terms
  • SSPA - Solid State Power Amplifier. Part of the RF equipment mounted on the antenna. Provides the transmit power for the outbound signal
  • G/T - Gain over Temperature (degrees Kelvin) – also referred to as “figure of merit” a measure of the efficiency of the antenna reflector to provide gain (amplify) the desired signals
  • LNA - Low Noise Amplifier. This unit amplifies the C-Band frequencies with no frequency down conversion
  • LNB - Low Noise Block Downconverter. This unit amplifies the Ku-Band frequencies and then downconverts them to L-Band frequencies.
  • L-Band - The frequency range of 950 MHz to 1450 MHz
  • EIRP - Effective Radiated Isotropic Power – A measurement of power relative to an isotropic source
basic satellite information
Basic Satellite Information
  • The Satellite
  • Satellites are relay links (repeater) in space. They have very sophisticated antennas & RF equipment

They have highly focused Antenna Patterns (footprints)

They utilize up to 350 Watts per Transponder

  • Based on function and purpose, they can have Low, Medium, or geostationary orbits
  • They utilize either Linear or Circular polarization which requires the correctly polarized feed on the ship’s antenna
  • The ship must be in a strong enough area of the satellite’s footprint for antenna system to operate.
  • Satellites currently orbiting the earth represent a wide variety of sizes, shapes and capabilities, each having been designed for specific purposes.
  • Regardless of the type of signal, they are all relay devices, located in space to re-broadcast their signals to a much larger area than would be possible by local area (TV Station) transmissions.
  • The designed purpose dictates what type of orbit they are placed in, frequency band of operation, types of transmissions, power levels emitted and where their signal(s) are directed.
  • The different sizes and shapes vary widely, but all satellites have the same basic elements.
  • Stabilization, telemetry equipment, and boosters are all used to keep the satellite oriented properly in its' specific orbital position.
  • Solar panels and batteries are used to power the transmit and receive RF equipment and telemetry systems which are used to track & control the satellites' position.
types of satellite orbits
Types of Satellite Orbits
  • LEO (Low Earth Orbit)
    • 500 to 1000 miles above the earth
  • MEO (Medium Earth Orbits)
    • 8000 miles above the earth
  • GEO (Geostationary Earth Orbit)
    • 22,753.2 miles above the earth

MEO

LEO

GEO

types of satellite orbits1
Types of Satellite Orbits
  • Orbits
  • Satellites are launched using a variety of multi-stage rockets to get them up to a Transfer Orbit, where they can be maneuvered to the correct final orbit position. The most common orbits are:
  • Exploratory - These satellites are the "Deep Space" satellites which are launched for Scientific purposes such as to explore Mars, Venus and other planets or even solar systems
  • Polar Orbit - Low, or Medium, Earth Orbits (LEO/MEO) are orbits that are parallel to the earth’s axis. From a location on the earth’s surface these satellites appear to rise from a point on the horizon, pass across some portion of the sky descending to an opposite point on the horizon.

How many "passes" of a satellite over a specific location in a 24 hour period depends on the Number of satellites in orbit, their Altitude of orbit and the specific location on the earth’s surface. Examples of present services are Global Positioning System (GPS) and SAR-Sat (Search And Rescue) and GlobalStar Satellite Phone & Data services.

types of satellite orbits2
Types of Satellite Orbits
  • Clarke Orbit
  • Named after the famous Science Fiction writer, Arthur C. Clarke, who first envisioned its' potential for global communications usage in 1945.
  • If a satellite is positioned 22,753 Statute Miles above the Equator, its' rotational speed will match that of the earth and, therefore, appear to remain in a fixed position when viewed from the earth’s surface. These satellites are referred to as "Geo-Synchronous" or "Geo-Stationary".
  • Many serve a wide variety of communications services including telephone, data, radio and television. These are the satellites that Seatel antenna systems are most commonly used with.
  • They are all in orbit over the Equator (0 degrees Latitude) and so are usually referred to by their "longitudinal" position as often as by their name.
  • Starting from 0 degrees longitude increasing in degrees East or West to 180. At these two points a satellite could be called 0.0 degrees East or West, or 180 degrees East or West respectively.
  • It is also acceptable to refer to all satellites as some number of degrees EAST, ranging from 0.0-359.9 (this would mean that satellite 270.0E would be the same as the one called 90.0W ).
satellite orbital spacing
Satellite Orbital Spacing
  • Orbital Spacing
  • In the simplest form 3 satellites would be required to provide global coverage, with each satellite illuminating about 42% of the earth’s surface.
  • As time has past, the number of satellites in Geosynchronous orbit has increased to the present population of more than 130 satellites.
  • The satellite positions are regulated by multi-national organizations which use illumination area, frequency allocation and polarity usage to plan satellite positioning (for each type of services) in such a way as to provide for the greatest number of satellites possible without interfering with each other.
  • Good planning and co-operation is the only way that the goal of having the satellites be only 2 degrees apart in longitudinal position is possible.
basic satellite information1
Basic Satellite Information
  • RF Equipment
  • The satellite has redundant Receive and Transmit equipment capable of operating in its' assigned frequency band(s).
  • It also has switching equipment to direct selected transponder outputs to a particular antenna.
  • Technological advances in microwave devices = the use of a greater number of frequency bands possible.
  • Better control of bandwidth used by each transponder = more transponder channels within each frequency band.
  • Some bands have even been split into multiple sub-bands because they are (now) being used so efficiently.
  • Some of the new hybrid satellites have 32 transponders which are capable of transmitting C and Ku Band simultaneously at high power levels (150-250 Watts).
basic satellite information2
Basic Satellite Information
  • The Antenna
  • Today’s' sophisticated satellite antenna designs provide highly focused illumination patterns (footprints).
  • Some illumination patterns are shaped to fit the geographic area of coverage.
  • Focusing and shaping the beam concentrates the transmitted energy into the footprint of the desired area of coverage without wasting any of it elsewhere.
  • This increases the overall receive level (Effective Isotropic Radiated Power -EIRP) throughout the footprint pattern, allowing smaller (lower gain) dishes to be used in receive only systems.
  • It also reduces the Gain over Temperature (G/T), requirements for TX/RX systems, allowing them to operate with smaller dishes and/or lower transmit power levels.
  • Some of these antennas provide very wide coverage allowing them to receive from, or transmit to, an area equal to about 40% of the earth’s surface (global)
basic satellite information3
Basic Satellite Information

The Relay Link

The satellite itself is a relay device, receiving and re-transmitting signals.

Transmitted signals originate from an Earth Station, or in special cases, another satellite.

These UPLINK signals are received at the satellite on one frequency, routed to the on-board conversion & transmission equipment and are then transmitted as the DOWNLINK at a different frequency.

The received and transmitted signals may use the same antenna and be using the same area of coverage (footprint) or the signals may be received from one area (on an antenna pointed to that area) and transmitted on a different antenna to a different coverage area. This may be done in a single UP-DOWN link (single “hop”), or multiple UP-DOWN links (double “hop”).

  • The "Earth Station", can be fixed or mobile. A fixed station is one which does not move (stationary position) and a mobile station is one which is capable of changing position (ie.. a news van, or a HiSeasNet ship).
intelsat 701 pacific region c band
Intelsat 701 - Pacific Region C-Band
  • Intelsat 701
  • Located at longitude 180 West (or East)
  • Provides C-Band coverage for HiSeasNet ships
intelsat 707 atlantic region c band
Intelsat 707 - Atlantic Region C-Band
  • Intelsat 707
  • Located at longitude 307 degrees East (53 degrees West)
  • Provides C-Band coverage for HiSeasNet ships
satmex 5 beam 1 ku band
Satmex 5 - Beam 1 Ku-Band
  • Satmex 5 Beam 1
  • Satellite provides Ku-Band service for HiSeasNet ships
  • Beam 1 covers Continental U.S. (including Pacific & Atlantic coasts), Mexico, and Gulf of Mexico
  • Located at longitude of 116.8 degrees West (or 243.2 East)
  • Shows EIRP Footprint contours (in dbW)
satmex 5 beam 2 ku band
Satmex 5 - Beam 2 Ku-Band
  • Satmex 5
  • Satellite provides Ku-Band service for HiSeasNet ships
  • Beam 2 covers Continental U.S. (including Pacific & Atlantic coasts), Mexico, and Gulf of Mexico, Caribbean Sea, majority of South America
  • Located at longitude of 116.8 degrees West (or 243.2 East)
  • Shows EIRP Footprint contours (in dbW)
satellite frequency bands
Satellite Frequency Bands

Frequency Bands

  • A wide band of frequencies is shown in the next slide.

It is important to note that frequencies used by other Electronic Systems may interfere with the Satellite System. CB, TV UHF & VHF and especially Navigational RADARS are examples of sources of interference.

The next slide gives Uplink and Downlink frequencies of the Satellite Bands.

Note that several Sub-Bands maybe in use within what is commonly called C & Ku bands.

Certain sub-band usage may be restricted to a given geographic area in an effort to extend the maximum number of satellite signals in that area while minimizing interference.

standard satellite frequency bands
Standard Satellite Frequency Bands
  • BANDUPLINK FREQDOWNLINK FREQ

(GHz)(GHz)

  • S-Band 5.925-6.055 2.535-2.655
  • C-Band 5.725-6.425 3.700-4.200

6.425-7.075 4.500-4.800

  • X-Band 7.900-8.400 7.200-7.750
  • Ku-Band 12.75-13.25 10.700-12.700

14.00-14.25 12.500-12.750

14.00-14.50 10.950-12.200

17.30-18.10 11.700-12.500

17.30-17.80 12.200-12.750

  • Ka-Band 27.00-43.00 18.300-22.200
geostationary satellites
Geostationary Satellites

Rain Fade

Rain Fade is the common term for Rain Attenuation. This attenuation (or signal strength loss) is caused by the absorption of the satellite signals by heavy rain.

Below is a chart that shows typical attenuation based on rain rate with the subject antenna set to a 30 degree elevation angle

satellite frequency advantages
Satellite Frequency Advantages

C-Band Frequencies

Advantages

Wide Footprint Coverage

Minor Effect From Rain (Rain Fade)

Disadvantages

Requires Larger Antennas

Requires Larger SSPA

Effected by Terrestrial Interference (TI)

Difficult to obtain a Tx License

Ku-Band Frequencies

Advantages

Requires Smaller Antennas

Requires Smaller SSPA

Easy to Obtain a Tx License

Disadvantages

Effect by Rain (Rain Fade)

Smaller Footprint

satellite frequency polarization
Satellite Frequency Polarization
  • Frequency Polarization

Frequency polarization is a technique designed to increase the capacity of the satellite transmission frequency.

In linear cross polarization schemes, half of a satellite’s transponders transmit their signals to earth in vertically polarized mode; the other half of the satellite’s transponders transmit their signals in horizontally polarized mode.

Although the two sets of frequencies overlap, they are 90 degree out of phase, and will not interfere with each other.

For both satellites and earth stations the normal configuration is to transmit in one polarization and receive in the opposite polarization.

satellite polarization linear and circular
Satellite Polarization - Linear and Circular

Linear & Circular Waves

Electro-Magnetic transmissions are comprised of

Electric and Magnetic fields, which are inherently 90

degrees apart in phase, and are called "E field" and

"H field" respectively. These transmissions are

referred to by the orientation of their Electric field.

In a purely Vertical Linear wave the "E" field would be perfectly vertical. A Horizontal waves' "E" field is rotated exactly 90 degrees from the Vertical wave. In Circular transmissions the "E" field spins/rotates and is described by the direction, Right or Left handed, the "E" field is spinning as you view the wave. Right handed transmission must be received using Left handed polarization of the feed. A Teflon Dielectric wedge is usually placed in the OMT at a precise angular position to allow pick-off probes to "capture this signal for insertion into the C-Band waveguide Signal flow inside the rectangular waveguide section is oriented with the "E" field across the narrow dimension of the waveguide.

satellite frequencies and transponders

Rx (MHz)

11720

11760

11800

11840

11880

11920

11960

12000

12040

12080

12120

12160

Tran.

1

3

5

7

9

11

13

15

17

19

21

23

V

Rx (MHz)

11740

11780

11820

11860

11900

11940

11980

12020

12060

12100

12140

12180

Tran.

2

4

6

8

10

12

14

16

18

20

22

24

H

Tx (MHz)

14020

14060

14100

14140

14180

14220

14260

14300

14340

14380

14420

14460

Tran.

1

3

5

7

9

11

13

15

17

19

21

23

H

Tx (MHz)

14040

14080

14120

14160

14200

14240

14280

14320

14360

14400

14440

14480

Tran.

2

4

6

8

10

12

14

16

18

20

22

24

V

Satellite Frequencies and Transponders
  • Transponder
  • Block of frequency on a satellite. Typical bandwidth is 40MHz per transponder (36MHz usable - 2 MHz of guard band on each side). Some Ku-Band transponder are 54MHz & 72MHz.

Typical Ku-Band Transponder

geostationary satellites1
Geostationary Satellites
  • SUMMARY
  • Satellites are relay devices, re-broadcasting to a large area.
  • They operate in a variety of frequency bands and have highly sophisticated antennas which allow the transmitted energy to be aimed and focused very accurately.
  • They are in Geo-Synchronous Orbit over the Equator, therefore, appear to remain in a fixed position when viewed from the earth’s surface.
  • Because they are all at 0 degrees Latitude (Equator) they are commonly referred to by their Longitudinal position.
  • It is common for a satellite to alternate transponder polarities to use the inherent attenuation between Horizontal and Vertical (or Right & Left handed Circular) transmissions to prevent interference of one channel to another, and for adjacent satellites to reverse their transponder polarities.
  • Other Electronic Systems may interfere with your Satellite System (CB, TV UHF & VHF and especially Navigational RADARS).
  • Satellite signals are typically focused, and aimed, at the populated land mass areas of the globe.
satellite footprint basics
Satellite Footprint Basics
  • Transmit power, beam-width, frequency band and polarization mode are all important factors of the signal transmitted by the satellite. The ship’s location within the footprint, the overall gain of the system, blockages and atmospheric conditions are the primary factors in the system’s ability to receive the signals from a desired satellite.
  • Transmit Power

Transmit power output from some satellites is as little as 8 Watts per transponder and some newer satellites are capable of 350 Watt transmission. The higher the transmitted power level, the stronger the receive signal will be at any point within the footprint.

Transmitted Beam Width

A fixed amount of power is being transmitted into the footprint area. The larger the area is (wider beam width), the lower the received signal level will be at any given point within that footprint. The smaller (narrower beam width) the footprint area is, the higher the received signal level will be at any point within it.

Frequency Band and Polarization Type

The frequency of the transmission is not as important as the power level or beam-width, but lower

frequencies offer a slightly better atmospheric penetration (less attenuation). Circular polarization also offers better penetration of fog and rain (over linear transmissions).

satellite footprint basics1
Satellite Footprint Basics

Location

The signal level of a given footprint is always strongest in the center, decaying (basically in concentric rings) out to the fringes. However, these concentric rings are not necessarily uniform rings or circles. The further out from center beam each contour is, the lower the signal level is along its' circumference.

Because of this, the ship’s position is very important. This position may not even be in a footprint area, and even when the ship is in a footprint the antenna may not be receiving enough signal level for the DAC or the modem to be able to process it properly.

Be very careful in trying to interpret satellite footprint charts, because they are a mathematically generated pattern (based on the antennas' performance before launch) overlaid on pictorial locations of earth. Also keep in mind that a given satellite can have multiple footprints, with some transponder signals in one but NOT in another.

In any given satellite footprint, atmospherics change through the day causing all the transponder signal levels to change accordingly.

Finally, the signal levels may vary from one transponder to another.

system gain
System Gain

System Gain

  • The overall gain of the Seatel antenna system determines its ability to receive enough signal for the DAC and Comtech modem to process it into usable data.
  • The System Gain is determined by the size and type of the reflector, the type and proper alignment of the feedhorn, Noise Figure rating of the Low Noise Converters (LNB or LNA), the RF receive equipment, the DAC and Modem receiver specs and all of the loss factors (primarily cables and splitters).

This is of paramount importance when trying to receive weaker signals (when in "fringe" areas of the footprint, especially from satellites transmitting low power or wide beam patterns).

System Gain determines how far from beam center the "fringe area" is. The easiest way to determine the actual system performance is to observe where signals from a variety of satellites are lost, note that location and signal level from the footprint charts for those satellites.

This will show what the value of the weakest signal level your system performance allows, therefore, which level satellite footprint contour is the “fringe area” for the system.

satellite beam footprint patterns
Satellite Beam (Footprint) Patterns

Satellite Beam Patterns

  • The beam pattern of the signal transmitted by the satellite is a function of the antenna being used.
  • The pattern is based on the antennas' radiated field pattern when it was tested prior to launch.
  • A given amount of power spread over a wide area, such as a Global beam covering 42% of the earth’s surface, makes the signal level very weak at all locations within that area.
  • A Hemi-beam only covers about 20% of the earth’s surface and would have signal levels at least 3dB higher (half the area equals twice the effective power) throughout its' coverage.
  • Area beams cover about 10%, doubling the power again (another 3dB higher) over a Global beam and Spot beams may be as little as 2% (another 6 dB higher).
system block diagram basic system components
System Block DiagramBasic System Components
  • The following pages show typical TX/RX System Block Diagrams for the three equipment configurations in the HighSeasNet network. They show the Basic System Components which include:
  • Above Deck Equipment (ADE)
  • Below Decks Equipment (BDE)
basic system components above decks equipment ade2
Basic System ComponentsAbove Decks Equipment (ADE)
  • The Radome Assembly - Provides for the mechanical mounting and environmental protection of the antenna assembly.
  • The Support Assembly - Mechanical support for the antenna. Rigidly attached to the ship via the Base Frame, therefore, provides the antenna a mechanical reference to the bow-line of the ship.
  • AZ Spindle/Stabilization Section - (Also called the Azimuth Canister), Provides UNLIMITED Azimuth rotation, Lateral and Vertical shock isolation, AC Power and Dual Coaxial signal paths.
  • Equipment Frame, RF Equipment and the Antenna Section form the “Stabilized Mass” of the antenna.
  • Level cage is attached to the equipment frame and contains the Rate sensors (3) and Tilt sensor. Level cage is ONLY driven to initialize or change the ELEVATION angle of the dish.
basic system components above decks equipment ade3
Basic System ComponentsAbove Decks Equipment (ADE)
  • 28VDC Pedestal power supply has voltage select/fuse block which must be set correctly.
  • Pedestal Control Unit (PCU) initializes the antenna pedestal, is solely responsible for stabilization and carries out commands sent by the ACU.
  • Pedestal multiplexer (MUX) - 9600 baud asynchronous FSK modem. Converts RS-422 to RF and RF to RS-422 to provide for ACU-PCU communications (Pedestal M&C) across the coaxial path between the ADE & BDE.
  • A second MUX is provided on TX/RX systems for communication with the RF Equipment (Radio M&C).
basic system components above decks equipment ade5
Basic System ComponentsAbove Decks Equipment (ADE)
  • Antenna Section
  • Reflector - The Gain & Efficiency of the dish is directly related to; the Size of reflector (in square centimeters), Type of reflecting surface (all 97 antenna systems use solid, precision reflectors with very accurate Parabolic curve) and the Focal type of the reflector
  • Direct Focus - Feed and Scalar block receive signal from the dish. Feed, Scalar and Struts cause some interfere with the transmitted main beam and side-lobe pattern. Does not provide full Illumination of the dish surface and the illumination is not evenly distributed (strongest in the center and weak at the outer edges of the dish) therefore reflections off the scalar and struts represent a “peak” signal loss.
  • Offset - Dish shape is a cutout of a section of an axis symmetric parabola. Feed and Struts are out of the signal path (to the dish) so they do not interfere with receive or transmit pattern.
  • Cassegrain - Overall dimension from the dish to the far side of the Sub-Reflector is shorter (more compact). Sub-Reflector more evenly distributes illumination of the dish so that the signal path blockage of the sub-reflector represents a low “average” signal loss.
basic system components above decks equipment ade6
Basic System ComponentsAbove Decks Equipment (ADE)
  • Feed Assembly -Refer to the next slide for the appropriate TVRO or TX/RX feed drawing.
  • Scalar Plate - Improves the receive gain of the feed as much as 3dB by recovering stray receive energy and focuses transmit energy to improve illumination of the dish surface.
  • OMT (Orthogonal Mode Transition) - Transition from an Orthogonal Mode chamber to standard Waveguide flanges appropriate for the frequency of usage. Must be designed specifically for the frequency of operation, f/D ratio of the dish, and polarization mode (Linear and/or Circular) that will be used.
  • Polarization Angle (PolAng) motor - Polarity of the 24 VDC applied to the DC motor determines the direction of rotation. Rotates the OMT to optimize its’ Linear (electrical) angle to match that of the desired satellite .
  • Waveguide Filters

Band Pass Filters - Passes only the desired band of frequencies, attenuating others (Radar Filter).

Transmit Reject Filter - Passes the desired receive band and specifically rejects the transmit band.

Receive Reject Filter - Passes the desired transmit band and specifically rejects the receive band

  • LNAs, LNBs, and LNCs

Low Noise Amplifiers (RF), Low Noise Block (down) Converters (500 MHz band-pass output, or more) and Low Noise Converters (36 MHz band-pass output for 70 MHz systems).

slide48

The basic functions of the front panel keys, display and LEDs are:

DISPLAY - 20 character x 2-line display of all menu display, entry, control and status windows.

AUX1 - Toggles Tracking ON/OFF, regardless of which displayed menu location you are currently in.

AUX2 - No current operator function.

Main Menu Display & Entry Keys:

SHIP - Accesses the SHIP menus to display, enter or edit current Ships’ Latitude, Longitude and gyro compass Heading information.

SAT - Accesses the SAT menus to display, enter or edit current Satellite Longitude, Threshold, Satellite ID, Tracking Receiver settings, Network ID and current signal level being received (AGC).

ANTENNA - Accesses the ANTENNA menus to display, enter or edit current Azimuth, Elevation & Relative antenna position and Polarization setting. Current signal level being received (AGC) and Conscan tracking signals are also displayed in some of the sub-menu screens.

MODE - Accesses control of Tracking band & ON/OFF selection, Searching ON/OFF selection, Error status and Remote Auxiliary value. Provides access to the Setup Parameters and Remote Command, Remote Monitor, & Remote Tilt

KEY PAD - Used to key in numeric values in all entry menus.

NUMBERS - Key in numeric value of desired entry. May be used in conjunction with the Decimal Point. DECIMAL POINT - Used with the Numbers to enter whole and tenths of degrees or MHz & KHz to enter tuning frequency.

C Key - Clear an incorrect numeric entry. Special Keys - UP/DOWN Arrows - Steps the selected entry UP or DOWN one increment per sequential key-press or rapidly increments the selected entry when pressed & held. Affects all Numeric entries and is used to toggle Tracking ON/OFF, turn Searching ON or to clear the Error display.

below decks equipment bde dac 97 antenna controller
Below Decks Equipment (BDE) – DAC-97 Antenna Controller
  • DAC Main Menu Display & Entry Keys (continued)

N/S/E/W - Toggles North/South Latitude entry, East/West Longitude entry, Tracking Receiver Input selection and Polarization mode (depends on POL TYPE parameter setting). It is used when making numeric entries to cause them to become negative values. When in MODE menus the N/S/E/W key steps the display back UP to the previous sub-menu.

  • ENTER - Enters the value that has been keyed in.
  • Status LEDs
  • TRACKING - (Green LED) ON indicates that the ACU is Tracking a satellite signal whose AGC value is greater than the Threshold value. The ACU is actively issuing small azimuth & elevation position adjustments to the antenna to optimize the signal level (AGC). If the system was Searching, SEARCH will go OFF when TRACKING turns ON.

Blinking - indicates that the satellite signal AGC value is less than the Threshold value, and the ACU is counting down the “SEARCH DELAY” (seconds). If the AGC does not rise above the Threshold before the count-down is completed, the ACU will automatically start, or continue, a SEARCH to acquire a signal that is greater than Threshold.

When SEARCH is ON, TRACKING will be OFF.

OFF - indicates that Tracking is OFF. This may be due to the operator turning Tracking OFF intentionally or that Tracking was pre-empted by SEARCH.

below decks equipment bde dac 97 antenna controller1
Below Decks Equipment (BDE) – DAC-97 Antenna Controller
  • SEARCHING - (Green LED) - ON indicates that the ACU is Searching for a satellite signal whose AGC value is greater than the Threshold value. When a satellite signal is found SEARCH will go OFF and TRACKING will come ON. If an adequate satellite signal is not found during the Search, SEARCH will blink as the antenna re-targets to the desired satellite. If an adequate satellite signal is still not found, then TRACKING will begin flashing (count-down) until the next SEARCH is automatically started.
  • Blinking - This indicates that the antenna is TARGETING to the calculated Azimuth & Elevation positions of the desired satellite (SAT). When the antenna arrives at the calculated position SEARCH will go OFF. If an adequate satellite signal is found at the targeted position Tracking will commence. If an adequate satellite signal is not found at the targeted position, TRACKING will begin blinking (see above) until the next SEARCH is automatically started.
  • OFF - This indicates that SEARCH is OFF. This may be due to the operator turning Search OFF intentionally or that Tracking has pre-empted SEARCH.
  • UNWRAP - (Red LED) Not used on these systems, this LED should never be ON.
  • ERROR - (Red LED) - ON indicates that one, or more, discrete system errors have occurred. Use the MODE button to view the error code or use DacRemP to view the error information.
  • OFF – This indicates that no errors have occurred.
  • RESET - Resets the processors inside the ACU. This does NOT reset the antenna pedestal
basic system components below decks equipment bde2
Basic System ComponentsBelow Decks Equipment (BDE)

Seatel DAC-2200 Front and Rear Panels

FRONT PANEL

Status indicator 6 LEDs to indicate Tracking, Searching, Target, Power, Initializing, and Error

Alpha Numeric Display 2 line 20 character Alpha Numeric

Next Button Cycles Display between Ship, Satellite, Antenna, and Status

4-Position Keypad Cycles Cursor Up, Down, Left, Right

Enter Button

Reset Button

Controls: AC Power On / Off

basic system components below decks equipment bde3
Basic System ComponentsBelow Decks Equipment (BDE)
  • Seatel DAC-2200 Front and Rear Panels

Rear Panel Connectors

J1 “Gyro Compass” 25 pin female D-Subminiature

J2 “NMEA” RS-422 Serial I/O 9 pin male D-Subminiature

J3 “M&C” RS-422 Serial I/O 9 pin female D-Subminiature

J4A “Antenna” Control 9 pin male D-Subminiature

J4B RF and Pedestal DC Power Type “BNC” female

J6 “RF IN” Tracking Receiver Type “F” female

IF Input

J7 “RF OUT Tracking Receiver Type “F” female

IF Output

AC Input Power IEC receptacle with power cord

Ethernet Connector Standard

basic system components
Basic System Components
  • Satellite Reference Mode
  • The ships gyro compass input to the ACU may be accurate and stable in static conditions and yet may NOT be accurate or stable enough in some underway dynamic conditions. If there is no gyro compass or if the input is corrupt, not stable or not consistently accurate the tracking errors will become large enough to cause the antenna to be miss-pointed off satellite.
  • Satellite Reference Mode will uncouple the gyro reference from the azimuth rate sensor control loop. When operating in Satellite Reference Mode changes in ships gyro reading will not directly affect the azimuth control loop.
  • The Pedestal Control Unit will stabilize the antenna based entirely on the azimuth rate sensor loop and the tracking information from DishScan (or ConScan). This will keep the azimuth rate sensor position from eventually drifting away at a rate faster than the tracking loop can correct by using the tracking errors to regulate the rate sensor bias.
  • Satellite Reference Mode can be used as a diagnostic mode to determine if tracking errors are caused by faulty gyro inputs.
  • Satellite Reference Mode MUST be used when:

No Gyro Compass is available

Frequent or constant ACU Error Code 0001 (Gyro Compass has failed)

Gyro Compass output is NMEA heading

Flux Gate Compass is being used

GPS Satellite Compass is being used

basic system functions
Basic System Functions
  • • Antenna Control Unit (DAC)- Master, controls the antenna through the PCU

Interface with Ships Gyro Compass

Interface for GPS input

Interface with computer to Monitor and Control the ACU

Controls Pointing and Targeting of the antenna

Controls Tracking

  • • Pedestal Control Unit (PCU) - Remote

Initializes the antenna pedestal

Reads sensors

Controls Motors

Controls Stabilization of the antenna

Takes pointing and tracking direction from the ACU

  • • ACU<->PCU Control Signals - Pedestal M&C

ACU RS422 input/output via the Pedestal MUX (TX = 1.1MHz, RX = 1.5MHz)

PCU RS422 input/output via the Base MUX (RX = 1.1MHz, TX = 1.5MHz)

Base and Pedestal MUXes are mirror tuned

antenna pointing targeting and tracking
Antenna Pointing, Targeting, and Tracking
  • Antenna Pointing - This is the process of accurately pointing the antenna to a specific angular position (satellite location), in 3-dimensional free space. This process is controlled by the Antenna Control Unit (DAC). It requires that the antenna is capable of moving in all three axes (Azimuth, Elevation, and Cross Level).
  • Satellite Targeting - This process is the beginning of a search for the satellite by the antenna. The Antenna Controller (DAC), has calculated the 3 dimensional location of the satellite based on the GPS, GYRO, HDG, Sat Long and is now moving the antenna to point at that location.
  • Satellite Tracking –This is the process of the ACU actively optimizing the pointing of the dish for maximum signal reception. This process is accomplished by continuously making small movements of the dish while monitoring the level of the received signal. Evaluation of this information is used to continuously make minor pointing corrections to keep the signal level “peaked” as part of normal operation.
antenna stabilization
Antenna Stabilization
  • Antenna Initialization - Every time the antenna is energized (or commanded to re-initialize), the PCU initializes the antenna in the following phases. Each phase must complete properly for the antenna to function properly.
  • Level Cage Activates - Level Cage is driven CCW, issuing extra steps to assure that the cage is driven all the way to the mechanical stop. Then the Level Cage will be driven exactly 45.0 degrees CW. The Level Cage should now be in a level position relative to the radome floor
  • Elevation axis activates - Input from the LV axis of the tilt sensor (inside the Level Cage) is used to drive the Elevation of the antenna to 45.0 degrees (brings the tilt sensor LV axis to level)
  • Cross-Level axis activates - Input from the CL axis of the tilt sensor (inside the Level Cage) is used to drive the Cross-Level (tilt) of the antenna to level (brings the Cross-Level Beam, and the tilt sensor CL axis to level).
  • Azimuth axis activates - Antenna drives in azimuth until the “Home Flag” signal is produced. This signal is produced by a Home Switch hitting a cam (9797 antennas), or by a Hall Effect sensor in close proximity to a magnet (4006 & 6006 antennas).

This completes the phases of antenna initialization. At this time the antenna elevation should be 45.0 degrees and Relative azimuth should be at be at home flag (home switch engaged on the home flag cam).

antenna stabilization1
Antenna Stabilization

Inertia – actually provides 98 percent of stabilization. Inertia is affected by:

1. Antenna balance Loose cables will affect antenna balance. In extreme situations, an out of balance antenna will cause pedestal errors.

2. Bearing drag Bearings in the Elevation, Cross-Level, and Azimuth axes can fail and would have to be replaced. Failed (or failing) bearings will cause a pedestal error on the DAC

3. Mechanical binding Worn or failing belts and motors will affect performance and usually cause drag to the antenna movements. This drag will cause pedestal errors

4. Cable restrictions Loose cables and/or worn springs can cause unexpected or

or spring action movement of the antenna in rough weather conditions. These movements will cause pedestal errors

antenna stabilization2
Antenna Stabilization

Components of Stabilization

  • Level Cage

Rate Sensors (3)

Azimuth, Level and Cross-Level

2.50VDC +/- 100mV (NOM) output when the rate sensor is NOT being rotated.

Right-Hand Rule device - Right-hand (CW) rotation causes the voltage output to increase. Left-hand (CCW) rotation causes the voltage output to decrease.

Tilt Sensor

AC voltage signal applied to each axis of the device is demodulated into DC Voltage. Conductivity of probes directly proportional to amount of conductive liquid coverage of the probes (acting like a potentiometer, with the center probe representing the wiper) 2.50VDC (NOM) into the A-D circuit in the PCU when the tilt sensor is level.

  • Level Cage Stepper Motor - Drives the level cage ONLY to initialize or change Elevation position. Elevation display is based on steps issued by the PCU, no positive feedback is provided.
antenna stabilization cont
Antenna Stabilization (cont)
  • Servo Amp/Motor Controllers - Commutates and controls the Brush-Less DC motors.
  • BLDC Motors (Torque Motors) - Hall sensor feedback to the Servo Amp/Motor Controller enable it to commutate with the motor.
  • Azimuth Encoder - Digital output into PCU “Relative” position counter. Position counter is pre-set by the home switch once each revolution of the antenna.
  • Home Switch - Cam on the azimuth driven sprocket contacts Home Switch once each revolution of the antenna. This input to the PCU pre-sets the Relative position counter (to the Home Flag Offset value stored in NVRam).
antenna stabilization6
Antenna Stabilization

Antenna balance

1. Reduces the load on the motors and increases longevity

2. Helps maintain nominal current flow through Servo Amplifier/Motor Controllers and reduces wear.

3. Responsible for 75% of the stability of the antenna - Top/bottom balancing

Front/rear balancing

Left/Right balancing

  • • Balancing Lab
antenna tracking
Antenna - Tracking
  • Antenna Tracking - (Tracking of the satellite) - Fine adjustments to the pointing of the antenna to optimize the received signal level (AGC is monitored by the ACU). Tracking is controlled by the ACU.
  • ConScan - (Conical Scanning)

Uses a bore-sight shift of the signal entry into the throat of the OMT.

Provides a 75-300 RPM sampling of signal level on the four quadrants of the dish to provide intelligent tracking.

Provides the Timing marks of bore-sight location relative to the four quadrants of the dish (up, down, left & right).

Conscan controller receives timing marks from the feed (dish quadrant location of the feed eccentricity) and the AGC level from the IF signal in the DAC. It compares these timing marks to the AGC level in real time

- If dish is mis-pointed the signal level will be high in one, or two, quadrants and pointing can be adjusted

- If dish is properly pointed, the AGC level will be equal in all four quadrants

- The DAC EL STEP SIZE, AZ STEP SIZE, and STEP INTEGRAL must all be set to zero “0” for ConScan to be operational

antenna tracking1
Antenna - Tracking
  • DishScan Operation
  • DishScan -This system is a variation of Conical scanning, which continuously drives the antenna in a very small diameter circle at 60 RPM. The received signal is evaluated throughout each full circle rotation of the antenna to determine where the strongest signal level is and will issue the appropriate Azimuth and/or Elevation steps to the antenna, as needed, 60 times per minute.

When The DAC is in the AZIMUTH or ELEVATION entry menu, the DishScan commands (2, 4, 6 or 8) will be visible in the lower left corner of the display.

Antenna Movement 2 = DOWN

4 = LEFT

6 = RIGHT

8 = UP.

When Tracking is turned OFF, these commands indicate the movement direction that is needed, but the commands will not be issued to the antenna to actually re-position it. Tracking must be turned ON to keep the antenna peaked on the satellite.

antenna tracking2
Antenna - Tracking
  • DishScan (continued)
  • If the antenna is already perfectly pointed, the signal received (AGC level) throughout each full circle will be equal. If the dish is slightly mis-pointed, a portion of the circle movement will have higher signal level than the rest of the circle. DishScan will then issue a step in Azimuth, and/or Elevation, to move the antenna in the direction of the stronger signal.
  • [EXAMPLE: If the dish is mis-pointed slightly to the LEFT of the satellite peak; as DishScan drives the antenna through one circle rotation it will evaluate that the signal is slightly higher to the RIGHT, therefore, a RIGHT (Azimuth UP) step will be issued to the antenna].
  • The internal tracking receiver settings must be set correctly and the EL STEP SIZE, AZ STEP SIZE and STEP INTEGRAL parameters must all be set to 0000 for DishScan to operate properly.
antenna tracking3
Antenna - Tracking
  • Antenna TrackingTest
  • The best way to test tracking (regardless of which tracking mode is being used) is to test each of the 4 quadrants (UP, DOWN, LEFT & RIGHT of peak signal AZ/EL pointing). This will confirm that regardless the tracking mode (Conscan or Dishscan) being used drives the antenna back to peak satellite signal level .
  • 1. Confirm tracking is on and record maximum AGC level on DAC front panel
  • 2. Turn off tracking, and manually mis-point the antenna in one quadrant
  • 3. Confirm that antenna is off peak signal by viewing reduced AGC level
  • 4. Turn tacking back on and verify that the antenna automatically returns to peak

signal level (peak AGC level)

  • 5. Repeat steps 1, 2, & 3 for the other three quadrants.
antenna tracking4
Antenna Tracking
  • Antenna Tracking (cont.)
  • AGC - The internal tuner card of the DAC provides a DC voltage output that is directly proportional to the level of the satellite signal input. The receiver output will be positive (voltage increases as satellite signal level increases) between 0.00-5.00 VDC.
  • This output is converted from the analog voltage to a digital value by an A/D converter on the DAC-97 Main PCB. 30-40 digital counts of AGC is approximately 1dB of satellite signal. Satellite IF signal is provided into the internal tuner card of the DAC-97 or DAC 2200 using the BNC or “F” connectors mounted in the rear panel.
  • Receiver selection and tuning is set by pressing the SAT key 4 times to the RCVR menu. The input is selected by pressing the NS/EW key until the appropriate input is selected. Selections are Ext AGC (external connection to the Terminal Mounting Strip), INA (TVRO receiver F connector input “A”), INB (TVRO receiver F connector input “B”) or IF (70/140 MHz SCPC BNC connector input).
  • For the HiSeasNet systems, the correct selection is the “IF”. Enter the correct IF frequency supplied by the HiSeasNet Technical Team.
  • EXAMPLE: For the IF frequency of 64.800 MHz, press the numbers “68” then press ENTER. Next press decimal point “.” and then “800” and then ENTER
antenna tracking5
Antenna Tracking
  • Antenna Tracking - Cont.
  • -AGC vs Pointing - As the antenna is moved
  • (in either AZ or EL) through a satellite, from an
  • “off satellite” position, through “peak satellite”
  • reception to an opposite “off satellite” position, the AGC
  • value on the DAC will be seen to change. At an
  • “off satellite” position, the AGC value will be at or near
  • the noise floor and below the Threshold value. The AGC
  • value will then rise rapidly to a peak value as the antenna
  • moves through the satellite signal, and then fall rapidly
  • back to a level at or near the value of the noise floor.
  • If the antenna position vs. AGC value was plotted on a
  • Graph, it would look similar to the graph at the right.
  • Note the following:
  • AGC value equal or near to the background noise level when at an “off satellite” position.
  • Peak AGC level when antenna is “Peaked” on satellite signal.
  • AGC delta (difference in AGC value between off satellite and peak satellite). Note that this has a direct relationship to the C/N of the satellite signal. (30-40 counts of AGC = approx. 1dB of signal strength.
  • 4. Relationship to Threshold .
antenna searching
Antenna Searching

Searching Operation

A search pattern will automatically be initiated when AGC falls below the current Threshold setting (indicates that satellite signal has been lost).

The search, it’s pattern dimensions and timing are determined

by the SETUP searching parameters SEARCH INC, SEARCH

LIMIT and SEARCH DELAY. Search is also affected by the

Threshold and the internal receiver settings under the Satellite

menu. Search is conducted in a two-axis pattern consisting

of alternate movements in azimuth and elevation (forming an

expanding square). The size and direction of the movements

are increased and reversed every other time resulting in an

increasing spiral pattern as shown.

A Search can be initiated manually by selecting the Status - Searching menu and pressing the UP key. While in the Searching window, pressing the DOWN key will stop a search. Search is terminated automatically when the AGC level exceeds the threshold value.

installation
Installation
  • Location - Site Survey Considerations

Check for potential blockage from mast, stack or other structures

Check for sources of other RF interference (radar)

  • Above Deck installation

Assemble radome base frame. Connect all parts using supplied hardware. Once all parts are connected, torque all hardware.

Assemble lower half of the radome

Connect all radome panels to each other and to the radome base. Leave hardware loose. This will leave an open space between the panel seams. Once all lower panels are interconnected, apply silicone to one seam, and tighten all hardware. Repeat for all remaining seams.

Assemble upper half of the radome

Connect all radome panels to each other. (Be sure to elevate bottom edge of panels off the ground using wood blocks from the shipping crates). Leave all hardware loose to create open space between all panel seams. Once all panels are connected, one person will be inside the radome. This person will apply silicone to each seam and then tighten hardware.

installation1
Installation
  • Place top circular panel in opening at top of radome, apply silicone and tighten hardware. Lift one edge of assembled radome to supply access for the assembler to exit.
  • Assemble reflector assembly (dish, feed and struts)

Lift antenna pedestal into lower radome half

Locktite and tighten all hardware.

Lift and attach reflector and RF equipment

Lift radome top half onto lower half

Attach lifting sling to top half of radome at 4 equidistant points.

Lift top half of radome onto bottom half and align bolt holes

Loosely Install bolts and nuts-Leave open space between radome halves using available spacers.

Apply silicone between the radome halves and tighten hardware.

installation2
Installation
  • Attach Radome to ship

Lift completed radome assembly to mounting location on ship

Bolt or weld radome base legs to ship as determined by ship’s captain or other authorized personnel.

  • Wiring

Install, route and terminate 110 VAC power wires to antenna pedestal breaker box.

Install, route, and terminate the 220 VAC power wires to the air conditioner unit.

Install, route and terminate IF cables inside the radome at the IFL interface panel.

  • Below Deck Installation

Install the ACU and interface panel in the equipment rack

Terminate all power and signal cables to ACU and tie wrap in place

  • Confirm Antenna control connections

IF cables – confirm they are connected inside the radome and at the below decks interface panel

Ship’s gyro and NMEA signals – confirm they are being receive by the DAC

Optional remote Radio M&C Terminal or personal computer (PCDAC and/or DacRemP)

Install and connect other BDE equipment. (MUX, router, etc..)

system setup
SystemSetup
  • After the physical installation of the Above Decks Equipment (antenna & radome) and the Below Decks Equipment (DAC, Modem, Mux) is complete, the system setup can begin. The setup includes the following
  • Above Deck Equipment (Antenna)

Check antenna freedom of motion

Check all cable connections

Check antenna balance

  • Energize antenna – Apply AC power to the antenna and confirm the initialization process is completed correctly. Note the mechanical position of reflector pointing when at home switch to calculate Home Flag Offset

Home Flag Offset (HFO) = (( Mech/360) x 255)

  • Below Deck Equipment – Apply power to the DAC. Confirm that the LCD screen first shows the DAC model and firmware version and then shows the PCU configuration and firmware version. Then go to the Setup window and program the DAC parameters
dac setup parameters
DAC Setup Parameters
  • Setup Parameters – These parameter values can be accessed and changed either through the DAC front panel (using the MODE button to enter the SETUP screens) or by using RemDacP.
  • Most of the factory default values should not need to be changed but a complete review of all parameter settings is required.
  • Brief descriptions of the parameters follow.
system setup1
System Setup
  • Antenna Control Unit (DAC) Setup Parameters
  • Mode Button - Displays Setup Parameter Displays and is Password protected area. These parameters establish how the system will behave by enabling/disabling hardware and software options. The DAC Setup Parameters are:
  • EL TRIM - Used to adjust the displayed elevation value when “ON satellite” peak to agree with mathematically calculated value. Trim value entered is the number of tenths (positive or negative) required to correct the “on satellite” elevation. NSEW key is used to toggle the entry to negative value. Should be re-evaluated every time the antenna is re-balanced. Azimuth and Elevation trim values must be set correctly for targeting to be accurate.
  • AZ TRIM - Used to adjust the displayed azimuth value when “ON Satellite” peak to agree with mathematically calculated value. Does not affect REL azimuth reading. Trim value is entered as the number of tenths (positive or negative) required to correct the “ON satellite” true azimuth. NSEW key is used to toggle the entry to negative value. Azimuth and Elevation trim values must be set correctly for targeting to be accurate Increase number to increase the resultant azimuth display.
system setup2
System Setup
  • DAC Setup Parameters (continued)
  • AUTO THRES – DAC sets threshold value of AGC counts above the average noise floor. Auto threshold programming code runs whenever the antenna is targeting or searching, integrating the average AGC over the past 6 seconds.

When the AGC rises faster than the auto-threshold can adjust, the sum (THRSH=“average AGC” plus “auto thrsh”) is saved as the current Threshold for the system.

Threshold is the value stored in RAM that the processor uses as a minimum acceptable AGC. When AGC falls below THRES the ACU will wait for “search delay” amount of time and then initiate a search. Units are in A/D counts, approximately 30 counts/dB (default setting is 128). A setting of 0 disables auto threshold.

  • EL STEP SIZE - Sets elevation sensitivity in Conscan/Dishscan mode, acts as a divider to determine how many of the elevation commands from the Conscan controller are actually sent through the PCU to the elevation motor.

A zero value sends all Conscan/Dishscan elevation commands through, each increment greater than zero divides by two (a setting of 3 would divide the number of commands actually sent to the motor by 8). Range is 0-255 steps. The value must be entered in the DAC field twice within 3 seconds to be accepted.

system setup3
System Setup
  • DAC Parameters (continued)
  • AZ STEP SIZE - Sets azimuth sensitivity in Conscan/Dishscan mode, acting as a divider to determine how many of the azimuth commands from the Conscan controller are actually sent through the PCU to the azimuth motor.

A zero value sends all Conscan azimuth commands through, each increment greater than zero divides by two (a setting of 3 would divide the number of commands actually sent to the motor by 8). Range is 0-255 steps. The value must be entered in the DAC field twice within 3 seconds to be accepted.

  • STEP INTEGRAL - Conscan/Dishscan setting is 0000 (zero). Any non-zero value disables Conscan/Dishscan.
  • SEARCH INC - Sets size of search pattern increment. Units are in pedestal step resolution (1/24 degree). The suggested setting is equal to 1/2 the 3dB beamwidth (factory default). Range is 0-255 steps.
  • SEARCH LIMIT - Sets the overall peak to peak size of the search pattern. Units are in pedestal step resolution. Range is 0-255 steps. After optimizing Targeting you may want to reduce the Search Limit size to help prevent tracking onto an adjacent satellite.
  • SEARCH DELAY - Time delay (in seconds) until a search begins after the AGC value drops below threshold. Range is 0-255 seconds, 0000 disables automatic search.
system setup4
System Setup
  • STEP DELAY / SWEEP INC - Step Delay should always be set to factory default. Sweep Increment should be set to 0000 unless GYRO TYPE is set to 0000 (No Gyro/Heading input NOT available). When Gyro Type is set to 0000, the Sweep Increment set the azimuth sweep rate during the linear azimuth search.
  • SYSTEM TYPE - List of functional options each having a numerical value. Enter the sum of the desired options.
  • GYRO TYPE - Select the appropriate type of gyro compass input (also depends on the synchro adapter installed on the main PCB).
  • POLANG TYPE - List of functions each having a numerical value. Enter the sum of the desired functions based on desired displays AND the capabilities of the feed installed on the antenna.
  • POL OFFSET - Used to optimize the linear polarization angle of the feed while in Auto-Pol mode.
  • POL SCALE - 90 degree 24V PolAng pot motion scale factor
system setup5
System Setup
  • AZ LIMIT 1 - Lower Relative AZ limit for pattern blockage mapping (DAC-03 & DAC 2200 have 3 zones instead of only 1)
  • AZ LIMIT 2 - Upper Relative AZ limit for pattern blockage mapping (DAC-03 & DAC 2200 have 3 zones instead of only 1)
  • TX POLARITY - Selects TX polarity override. 0=no TX polarity override, 2=Vertical TX polarity and 4=Horizontal TX polarity. When switching from 2-4, or4-2, feed will drive exactly 90 degrees.
  • SAVE NEW PARAMETERS - Press the UP Arrow key and then the ENTER key to save/write recent changes to NVRam. Press AUX2 and CLEAR simultaneously to access this function directly from any other mode.
  • REMOTE COMMAND WINDOW - Used to enter diagnostic commands
  • REMOTE MONITOR WINDOW - Used to monitor some diagnostic command results
  • REMOTE TILTWINDOW- Used to adjust the level cage after replacement ONLY if it is not level after antenna is initialized.
operation
Operation

Target satellite

Verify Manual operation and control of antenna & peak on satellite

Confirm that antenna moves to calculated satellite location and begins an automatic search upon issuing a Target command.

Optimize the system

Adjust PolAng (if required only used on Linear Polarized systems)

Program/Confirm DAC Internal tuner frequency (Satellite IF frequency)

Confirm proper operation of Dishscan – check parameters and personally view antenna motion

Adjust AZ & EL Trim Values

Program Home Flag Offset (HFO) if required

Final checkout - May be helpful to have an assistant with a 2-way radio

Confirm antenna finds satellite after Trim & HFO adjustments are programmed

Evaluate auto-threshold value - Is Peak AGC value at least 50 – 100 counts above Threshold??

Verifying Tracking - Perform Four quadrant tracking test

Observe the antenna to ensure it remains stable and tracks a satellite (while under way if possible).

Make sure no fasteners or radome hardware have come loose and that radome is sealed properly

Clean up the radome interior.

functional testing
Functional Testing
  • Above deck equipment

Check antenna freedom of motion – no binding or friction

Check feed alignment – feed struts are tight and secure

Check antenna balance

  • Energize antenna and view initialization sequence. Confirm process is completed correctly. Also note mechanical position of reflector pointing when antenna is at the mechanical home switch to calculate the Home Flag Offset

Below deck equipment

Set/Confirm all parameters on ACU

Check System type

Tracking parameters

Confirm Gyro Type

Home flag offset – if required

Confirm Gyro compass Heading and DAC Heading are the same

Vessel position (automatic if GPS input is used)

Confirm and save Internal tuner selection and tuning frequency

Verify Correct satellite longitude is entered in DAC

functional testing1
Functional Testing
  • Functional testing - Check each function to assure proper operation, ACU Power is" ON”, and Verify ACU/PCU communications

Ships Heading - Confirm Initial setting and subsequent updating of the heading correctly follows the ships gyro compass.

LAT/LONG - Verify manual entry and automatic GPS updates to the DAC from the ship’s Gyrocompass system.

Internal tuner selection and frequency – Confirm DAC tracking frequency is set to the carrier specified by HiSeasNet Technical Team. Never use the TX IF frequency.

AZ Drive - Step, slew and target AZ to verify proper drive performance.

EL Drive - Step, slew and target EL to verify proper drive performance.

Feed polarization - Verify that polarization of the feed is operating properly in manual and/or automatic modes. (Used only on Linear Polarized satellites)

functional testing2
Functional Testing
  • Satellite Targeting - Verify that antenna is driven to within +/- 1.0 degrees of the satellite position (evaluate and set AZ & EL Trim values as needed to assure targeting is within this spec).
  • Satellite Search - Verify that the delay, increment and limit parameters are set for the best performance. These values will be initially specified by HiSeasNet Customer Support but can be adjusted based on particular satellite
  • AGC performance - Verify that the AGC level is proportional to the satellite signal level as the antenna is stepped from “OFF” satellite, through peak satellite signal to “OFF” satellite without being clipped off.
  • Side-Lobe Presence - High side-lobes on specific satellite may require auto threshold value to be set differently.
  • Tracking Setup - Band selection, stepsizes and step integration (may involve system type setting also).
functional testing3
Functional Testing
  • Functional testing (cont)

Optimize all other BDE Components as required

Verify proper antenna stabilization during ship motion, using any of the following;

On satellite performance

Remote Commands & monitoring

PC diagnostic programs

  • Commissioning - Commissioning the system includes accomplishing all of the functional testing above plus verifying that all of the other BDE equipment operates properly.
  • TVRO Systems - Test all TVRO receivers, modulators, Standards Converters, combiner/amplifiers and Television sets have good receive signal and verify proper programming services are received at each Integrated Receiver Decoder (IRD).
  • TX/RX Systems - Test Modem, multiplexer and other equipment for proper services.

Accomplish testing and commissioning as required with the satellite operator(i.e. side lobe testing and optimizing cross-pol isolation (optimizing polarization).

Set final TX & RX signal levels with HiSeasNet Technical Team and Satellite Operator.

troubleshooting and repair antenna system
Troubleshooting and Repair Antenna System
  • Required Test equipment

Voltmeter (for checking Ac & DC power)

Spectrum analyzer (if available) to view satellite reception and station TX carrier

Test Cables (coaxial)

Computer with Seatel Diagnostic Software & Hyper Terminal software ( for communications with the DAC and RF equipment)

System block diagram (Test Points) – Refer to Antenna & DAC Installation manuals

  • Check Component functions

ADE components – Radome, Base, Air Conditioner, IFL Cables for damage or unusual circumstances.

Pedestal components – power off antenna and manually move antenna in all three planes (AZ, LV, CL). Check for binding, or any resistance. Antenna should move freely in all directions. Check all belts for wear.

Stabilization components – Check/Confirm antenna Balance. Look for loose coaxial or other cables and secure them as required. Check Level Cage and motor for free movement.

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Troubleshooting and Repair Antenna System
  • RF (Radio) equipment - Check Converter window for Power and Alarm LEDs. Use Hyper Terminal to Check/Confirm parameter settings. For BUC systems check Comtech modem for BUC parameters. Troubleshoot and Clear all error conditions.
  • Below Deck Equipment (BDE) Components
  • Antenna Control Unit – Check DAC front panel for alarms and confirm all parameter settings. Use DacRemP to query the PCU and to check Sat Ref, Dishscan & Error Status. Also check coax cable connections, RX Splitter, Comtech Modem, Multiplexer, Computer and other ancillary equipment.
  • Comm Errors & Dishscan Errors – Check DAC error screen for Communication Errors (left bank of numbers), and System Errors (right bank of numbers). Continuous increase of Comm Errors indicates loss of signal and possible failure of Rotary Joint, RF modems (either Pedestal or Base), or IFL cable problem.
  • GPS & GYRO Signals – Verify that the DAC shows correct values for LAT, LONG, and HDG. Confirm that DAC is being updated by ship’s systems. Wrong numbers or no updates indicate loss of signal from ship’s systems.
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Troubleshooting and Repair Antenna System
  • DAC AGC & Threshold Levels – Check both parameters on DAC front panel and confirm both values are greater then 1000. Values of 500 or less indicate possible problem with LNA/LNB or IFL cable connection.
  • IF signal ADE-BDE - Low AGC and Threshold values indicate possible DAC tuner card failure, an IFL cable connector problem or possible LNA/LNB failure.
  • Pedestal & Radio M&C signals (ADE  BDE) - Continuous Comm Errors or System Errors that won’t clear indicate possible failure of Rotary Joint, RF modems (Pedestal or Base) or IFL cable problem.
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Troubleshooting and Repair Antenna System
  • Isolate the problem
  • Determine where the problem is (or isn’t)

Ask why the system is doing what it is doing and what might cause that problem

Use parts from the spare parts kits to substitute as required or directed

  • Diagnostics Tools

Use of remote commands & remote monitoring in the DAC-97 & DAC-2200 to assist in isolation of the faulty unit or component.

Use of computer diagnostic tests (PCDAC and DacRemP) to record functions to assist in isolation of the faulty unit or component.

PC Computer (PCDAC & DacRemP)

Remote Monitor & Control - Controls & Monitors the antenna through the ACU. Can be used on Series 96, 97, and 06 series antennas.

Tests include diagnostic tests (for Series 96, 97, and 06 antennas ) and Dishscan setup and operation

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Troubleshooting and Repair Antenna System

PCDAC & DacRemPChart Recording

  • Both programs provide diagnostic charts - These charts will record, or display, a strip chart recording of system performance. Azimuth, Elevation, Rel. Azimuth, Heading, Heading plus REL and Signal (AGC), are recorded once per second.

One full screen of recorder data is 2 mins. Only 4 of these values are displayed on screen, but all are being recorded and all will be displayed in Excel format.

In normal operation Signal level should always remain high and steady, so a falling signal level would indicate a problem.

Azimuth & Elevation should stay at the same values (in short term view) requiring many hours to significantly change.

Azimuth equals Heading plus Relative, so (in the short term) as Heading goes UP Relative MUST go DOWN the same amount (equal and opposite to what Heading does).

lab exercises
Lab Exercises
  • Optimize targeting using AZ & EL Trims
  • Calibrate Relative Antenna position
  • Calculate the Home Flag Offset (HFO)
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Lab Exercises – Optimizing Targeting with AZ & EL Trims

Optimizing Targeting

  • The easiest method to determine what amount of AZ & EL Trim is required is to first confirm that all the Ship & Satellite settings are correct on the DAC. Then target the desired satellite, immediately turn Tracking OFF and record the Antenna Azimuth and Elevation positions. These are the positions calculated by the DAC based on the “Ship” & “Satellite” settings (Calculated Position).
  • Turn Tracking back ON, and allow the antenna to “Search” for the targeted satellite. Confirm that the antenna has acquired and peaks up on the satellite that you targeted (check AGC level). Now record the Antenna Azimuth and Elevation positions while peaked on satellite (Peak Position).
  • Subtract the Peak Positions from the Calculated Positions to determine the amount of Trim (+/-) required
  • Re-target the satellite several times to verify that targeting is now driving the antenna to a position that is within +/- 1.0 degrees of where the satellite signal is located.
  • EXAMPLE: The DAC targets the satellite to an Elevation position of 30.0 degrees and an Azimuth position of 180.2 (Calculated). Peak signal strength (AGC level) of the satellite is found at 31.5 degrees and Peak Azimuth is 178.0. You should enter an EL TRIM value of -1.5 and an AZ TRIM of +2.2.
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Lab Exercises – Calibrate Relative Antenna position
  • Home Flag Offset
  • Calibrating Relative Antenna Position (Home Flag Offset)
  • During initialization, azimuth drives the CW antenna until the Home Switch is contacted, which “presets” the relative position counter to the value stored in the Home Flag Offset. This assures that the encoder input increments/decrements from this initialization value so that the encoder does not have to be precision aligned.
  • The Home Switch is a micro switch with a roller arm which is actuated by cam mounted on the azimuth driven sprocket, or it is a hall sensor which is actuated by a magnet mounted on the azimuth driven sprocket, which produces the “Home Flag” signal.
  • The Home Flag Offset is a value saved in NVRam (Non-Volatile RAM) in the PCU. This value is the relative position of the antenna when the home switch is engaged. Presetting the counter to this value assures that when the antenna is pointed in-line with the bow of the ship the counter will read 000.0 Relative (360.0 = 000.0).
  • In most cases when the antenna stops at the home flag, it will be pointed in-line with the Bow of the ship. In these cases Home Flag the Offset (HFO) should be set to zero. When “Optimizing Targeting” small variations (up to +/- 10.0 degrees) in Azimuth can be corrected using the AZ TRIM.
  • Large variations in Azimuth position indicate that the Relative position is incorrect and should be “calibrated” using
  • the correct HFO value instead of an Azimuth Trim offset. This is especially true if sector blockage mapping is used.
  • If the antenna stops at the home flag, but it is NOT pointed in-line with the Bow of the ship, it is important to assure that the antennas actual position (relative to the bow of the ship) is the value that gets “preset” into the Relative position counter. By saving the antennas actual Relative position when at the home flag into HFO, you have
  • calibrated the antenna to the ship.
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Lab Exercises – Home Flag Offset (HFO)

Calculate the HFO:

  • If Targeting has been optimized by entering a large value of AZ TRIM (> +/-10 degrees), first verify that the antenna can repeatably target a desired satellite (within +/- 1.0 degrees). Then use the AZ TRIM value to calculate the value of HFO. Then set the AZ Trim back to zero “0”.
  • Convert the AZ TRIM value to the nearest whole degree (round up or down as needed). The calculated HFO value is also rounded to the nearest whole number.
  • If AZ TRIM was a plus value: HFO = (TRIM / 360) x 255
  • Example: AZ TRIM was 0200 (+ 20 degrees). HFO = (20/360) x 255 = (0.0556) x 255 = 14.16 so round the number to 14.
  • If AZ TRIM was a negative value: HFO = ((360-TRIM) / 360)) x 255
  • Example: AZ TRIM = -0450 (minus 45 degrees). HFO = ((360 - 45) / 360)) x 255 = (315 / 360) x 255 = 0.875 x 255 = 223.125 so round the number to 223.
  • .
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Lab Exercises – Home Flag Offset (HFO)

Calculate the HFO (continued)

  • If Targeting has NOT been optimized, allow the antenna to initialize to its home flag position. Visually compare the antennas pointing to the bow-line of the ship (parallel to the Bow). Note the antennas position relative to the Bow.
  • If the antenna appears to be very close to being parallel with the bow, the HFO will probably not be needed and you can proceed with Optimizing Targeting. If it is NOT close, initialization was driving the azimuth CW, so note if the antenna appears to have stopped before it got to the Bow or if it went past the Bow. It may be able to be determined (or guessed), how many degrees the antenna is from the bow after initialization.
  • If the satellite cannot be found by Targeting, turn tracking off and manually set the Elevation to the calculated value. Next manually move the antenna in Azimuth until the satellite is found. Turn tracking on and allow the DAC to automatically peak the antenna. Record these Az & El values and calculate the Azimuth difference in degrees. Then calculate the HFO.
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Lab Exercises – Home Flag Offset (HFO)
  • If the antenna stopped before it got to the bow-line
  • When the antenna initially targets a satellite, it will also stop prior to the satellite position. This means that it will have to be driven UP in Azimuth to actually find the satellite.
  • Using the same basic procedure as in the Optimizing Targeting procedure, target the satellite and record the “Calculated” Azimuth position that the antenna was driven to. Drive UP until the satellite is found, confirm it is the correct satellite, and allow tracking to peak the antenna position. Record the “Peak” Azimuth position. Subtract the “Peak” position from the “Calculated” position to determine the number of degrees of AZ TRIM that would be required.
  • Example: In this new installation, the desired satellite is Targeted and the Calculated Azimuth of 180.5 is recorded. The antenna is driven UP until the desired satellite is found at a Peak Azimuth of 227.0 degrees. Subtract the Peak value from the Calculated value and the difference is -46.5 degrees.
  • Therefore the actual Relative position that needs to be preset into the counter when the antenna is at the Home Flag is 313.5.
  • HFO = ((360-46.5) / 360)) x 255 = (313.5 / 360) x 255 = 0.87 x 255 = 222.06 so round down to 222.
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Lab Exercises – Home Flag Offset (HFO)

If the antenna went past the bow-line

  • When the antenna initially targets a satellite, it will also go past the satellite position, so that it will need to be driven DOWN in Azimuth to actually find the satellite.
  • Using the same basic procedure as in the Optimizing Targeting procedure, target the satellite and record the “Calculated” Azimuth position that the antenna was driven to. Drive DOWN until the satellite is found, confirm it is the correct satellite and allow tracking to peak the antenna position.
  • Record the “Peak” Azimuth position. Subtract the “Peak” position from the “Calculated” position to determine the number of degrees of AZ TRIM that would be required. Refer to the calculations above to determine the HFO required for use for this antenna.
  • Example: In this new installation, the desired satellite is Targeted, and the Calculated Azimuth of 180.0 is recorded. The antenna is driven DOWN and the desired satellite is found at a Peak Azimuth of 90.0 degrees. Subtract Peak value from the Calculated value and the difference is +90.0 degrees.
  • Therefore the actual Relative position that needs to be preset into the counter when the antenna is at the Home Flag is 90.0.
  • HFO = ((90.0) / 360)) x 255 = 0.25 x 255 = 63.75 so round up to 64.