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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
Seatel Stabilized Antennas
Series 9797, 4996, 4006, & 6006
Welcome & Introduction
Basic Satellite Information
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
Troubleshooting and Repair
They have highly focused Antenna Patterns (footprints)
They utilize up to 350 Watts per Transponder
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.
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”).
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.
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
Wide Footprint Coverage
Minor Effect From Rain (Rain Fade)
Requires Larger Antennas
Requires Larger SSPA
Effected by Terrestrial Interference (TI)
Difficult to obtain a Tx License
Requires Smaller Antennas
Requires Smaller SSPA
Easy to Obtain a Tx License
Effect by Rain (Rain Fade)
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.
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.
VSatellite Frequencies and Transponders
Typical Ku-Band Transponder
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).
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.
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 Patterns
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
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).
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.
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.
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.
Seatel DAC-2200 Front and Rear Panels
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
Controls: AC Power On / Off
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
J7 “RF OUT Tracking Receiver Type “F” female
AC Input Power IEC receptacle with power cord
Ethernet Connector Standard
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
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
Initializes the antenna pedestal
Controls Stabilization of the antenna
Takes pointing and tracking direction from the ACU
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
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).
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
Components of Stabilization
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.
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.
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
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
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.
signal level (peak AGC level)
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.
Check for potential blockage from mast, stack or other structures
Check for sources of other RF interference (radar)
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.
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.
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.
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.
Install the ACU and interface panel in the equipment rack
Terminate all power and signal cables to ACU and tie wrap in place
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..)
Check antenna freedom of motion
Check all cable connections
Check antenna balance
Home Flag Offset (HFO) = (( Mech/360) x 255)
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.
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.
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.
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.
Check antenna freedom of motion – no binding or friction
Check feed alignment – feed struts are tight and secure
Check antenna balance
Below deck equipment
Set/Confirm all parameters on ACU
Check System type
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
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)
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
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.
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
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.
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
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
PCDAC & DacRemPChart Recording
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).
Calculate the HFO:
Calculate the HFO (continued)
If the antenna went past the bow-line