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Amateur Beacons for the 21 st Century

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Amateur Beacons for the 21 st Century. Andy Talbot G4JNT / G8IMR September 2010. What is a Beacon ?. A Transmitter at a Known Location That transmits a prestored message, With Limited Information Content, Continuously, or Periodically, On a Known Frequency, For reception by anyone.

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slide1
Amateur Beacons for the 21st Century

Andy Talbot G4JNT / G8IMR

September 2010

slide2
What is a Beacon ?
  • A Transmitter at a Known Location
    • That transmits a prestored message,
    • With Limited Information Content,
    • Continuously, or Periodically,
    • On a Known Frequency,
  • For reception by anyone
slide3
What do we want beacons for ?
  • Band openings, but there’s nobody on!
  • Is there anybody out there, is the band dead?
  • I can’t hear anyone, is it working?
  • Frequency Calibration
  • Antenna and Bearing setup
slide4
What do we have now
  • HF Beacons
    • IARU Beacon chain
    • 14 - 28MHz,
    • Five Frequencies
    • CW and Power Stepped Carrier
        • – 10 seconds
    • Time Sequenced
      • Poor frequency stability / accuracy
slide5
IBP Chain
  • Call Location 14.100 18.110 21.150 24.930 28.200 Operator
  • 4U1UN U- Nations 00:00 00:10 00:20 00:30 00:40 UNRC
  • VE8AT Canada 00:10 00:20 00:30 00:40 00:50 RAC/NARC
  • W6WX United States 00:20 00:30 00:40 00:50 01:00 NCDXF
  • KH6WO Hawaii 00:30 OFF 00:50 OFF 01:10 NOARG, HARC
  • ZL6B New Zealand 00:40 00:50 01:00 01:10 01:20 NZART
  • VK6RBPAustralia 00:50 01:00 01:10 01:20 01:30 WIA
  • JA2IGY Japan 01:00 01:10 01:20 01:30 01:40 JARL
  • RR9O Russia 01:10 01:20 01:30 01:40 01:50 SRR
  • VR2B Hong Kong 01:20 01:30 01:40 01:50 02:00 CRSA, HARTS
  • 4S7B Sri Lanka 01:30 01:40 01:50 02:00 02:10 RSSL
  • ZS6DN South Africa 01:40 01:50 02:00 02:10 02:20 ZS6DN
  • 5Z4B Kenya 01:50 02:00 02:10 02:20 02:30 ARSK
  • 4X6TU Israel 02:00 02:10 02:20 02:30 02:40 IARC
  • OH2B Finland 02:10 02:20 02:30 02:40 02:50 SRAL
  • CS3B Madeira 02:20 02:30 02:40 02:50 00:00 ARRM
  • LU4AA Argentina 02:30 02:40 02:50 00:00 00:10 RCA
  • OA4B Peru 02:40 02:50 00:00 00:10 00:20 RCP
  • YV5B Venezuela 02:50 00:00 00:10 00:20 00:30 RCV
slide6
What do we have now
  • Other HF Beacons
    • Majority on 28MHz for Propagation alerts
    • 5.29MHz for propagation tests
    • Generally banned below 7MHz
        • Apart from occasional specials
  • VHF
    • Hundreds around the world
    • Simple crystal control, freq +/- tens of ppm.
    • Carrier and CW – callsign and locator
slide7
Improvements
  • Design for Automatic Monitoing using PC / Soundcards
    • Narrow band
    • Want good frequency stability
  • Frequency Reuse
    • Time sequenced – helps QRM and regulatory issues
    • Simplifies auto-monitoring of multiple beacons
      • No Retuning
slide8
Next Generation HF
  • Frequency Stability
    • Aim for better than 10-7 at HF (+/-1 Hz)
    • TCXO or Ovened oscillator
  • Minimise frequency clutter
    • Time sequence - like the IARU chain
  • Change the rules to allow beacons below 7MHz
    • Let technolgy reduce the QRM by
      • Precisely timed transmissions
      • Single frequency on each band, worldwide ?
slide9
WSPR ??
    • Already Well Established
    • Reporting Website in place
    • Automated reports
  • How About a Network of WSPR Beacons ?
slide10
Data Modes
  • PSK31 or RTTY could carry information
    • Propagation state, band openings
    • Site telemetry
    • Unique time signature confirms reception
    • Time / Temperature / Pressure / ???
    • Status of other beacons
    • QSL / Report Checking
slide11
Next Generation VHF
  • Decent Frequency accuracy
    • Ovened crystal or GPS locked
    • Look for 10-9 accuracy (sub Hz) for auto search
  • Add weak signal data modes
    • JT65
    • Extended period of coherent carrier for very narrow band integration
    • PSK reversals for time-of-flight mewasurement
slide12
Microwave Beacons
  • Often Used when / Portable for :
    • Frequency calibration
    • Dish and Bearing setup
  • Propagation Monitoring
slide13
Microwave Beacons
  • Frequency accuracy even more important as
    • They are often used for calibration
  • We need a lot more μWave beacons to ensure everyone can hear at least one on each band
    • Personal beacons
    • Attended or unattended
    • Licensing easier at microwaves
slide14
What is needed – where shall we go?
  • Some Examples of next-generation beacons are already out there….
slide15
The 5MHz beacon chain
  • GB3RAL GB3WES GB3ORK transmit in sequence.
      • 1 minute every 15 GPS timed
  • Power steps over 54dB for audible S/N estimation
  • TCXO frequency control (few Hz)
  • The system was designed for automatic logging (G3PLX software)
  • Cover a complete sunspot cycle
slide17
GB3SSS 1.96MHz / 3.6MHz
  • Temporary beacon for winter transatlantic propagation tests from Poldhu
  • 1 Nov to end Jan 2007
  • Year later on 3.6MHz
  • Sequence similar to the 5MHz beacons
    • 1 / 15 minutes, power steps, carrier
  • PSK31 message – decoded in Canada
  • All waveforms generated in DDS chip
slide18
GB3VHF 144.43MHz Wrotham, Kent
  • GPS Controlled frequency and time
  • JT65, CW, 1pps PSK
  • Two minute repeat cycle
  • Generic beacon driver concept
    • Up to 16 thirty second time slots can each be allocated to different modes
slide19
GB3VHF

GPS Disciplined Reference (12.8MHz)

GPS Module

DDS Source

PIC Controller

slide20
GB3RAL VHF Chain
  • 40.05 50.05 60.05, 70.05MHz
  • Phase coherent from GPS Locked master reference
  • JT65, CW, 1pps PSK
  • Two minute repeat cycle
slide21
Bell Hill Microwave Beacons
  • Single site cluster of seven beacons for 2.3 to 47GHz and telemetry Tx on 70MHz
  • Evolutionary upgrades in capability
    • GB3SCS 2320.90503MHz JT4g GPS Locked
    • GB3SCF 3400.905000 MHz RTTY GPS Locked
    • GB3SCF 5760.905006MHz QRSS GPS Locked
    • GB3SCX 10368.9050068 MHz JT4g GPS Locked
    • GB3SCK 24048.905 MHz (CW only) OCXO
    • G8BKE/P 47.088905 GHz (CW only) OCXO
    • G4JNT/P 70.031MHz PSK31 Telemetry TCXO
slide24
Several parts already exist in current designs
    • Driver / oscillator (but freq may need stabilising)
    • Power Amplifier (+ filters)
    • Antenna
  • But several new modules will be needed
    • Agile Frequency Source
    • Controller / keyer
    • Timing – eg GPS
slide25
Power Amplifier
  • Power Steps, PSK31 etc need a linear PA
    • For low duty cycle time sequenced, simple class A or A/B MOSFET design is ideal
    • Broadband – so useable over multiple bands (beware filtering needs)
  • High duty cycle with no linear modes
    • Class C design is better suited.
    • Particularly at VHF / UHF
    • Frequency Multiplication
slide26
Frequency Source
  • Crystal oscillator
    • Single frequency, no data modes
    • Poor Frequency Stability
    • Use oven or clip-on heater
  • DDS

Directly useable at HF and low VHF

      • Spurii need cleaning up for higher frequencies
      • GB3VHF - additional crystal filter
      • μWave beacons, lock crystal oscillator to DDS O/P
    • Direct generation of most data modes
    • Clock from standard frequency reference (10MHz)
slide27
DDS Sources
  • Older AD9850 / 9851
    • Up to 30MHz directly.
    • FM / Phase modulation,
    • But no AM capability
    • Small and simple to use
    • 32 bit frequency register
    • ~ 10-9 freq setting
    • Internal x6 PLL for clock
  • AD9852 / 9854
    • Up to 90MHz directly
    • Amplitude / phase / frequency changed in μs
    • 48 Bit - 10-14 Frequency setting
    • X4 – X20 Internal clock PLL
  • Even Faster devices eg. AD9950
slide28
Controller
  • Simple CW Keyer
    • Tiny PIC
slide29
More Advanced Controller
  • Microcontroller eg. PIC
    • ‘Workhorse’ 16F628 has enough power for most controller tasks
  • Reprogramme a Direct Digital Synthesizer in real time to generate data modes
    • AD9852 100μs to reprogramme (serial)
    • PSK31, JT65, FSK441 and RTTY demonstrated already.
    • Accept external data / telemetry inputs
slide30
Timestamp the transmission with a unique code
  • Verifies correct reception at any given date / time.
  • Only the keeper knows the hashing key.
  • Simple to do in a PIC from the GPS data stream
  • Verifiable QSL – could this count as a one-way QSO !!!!
  • Alphanumeric code with pronounceable triads :-
    • 1800 JYC 1801 PUF 1802 KIC 1803 FOF 1804 WAC
    • 1805 PEF 1806 HAR 1807 CEG 1808 LUD 1809 RYG
    • 1810 MEB 1811 TAD 1812 CAB 1813 HED 1814 MIB
    • 1815 TOD 1816 ZUC 1817 FYF 1818 NAC 1819 WEF
  • May also have to send the minutes digit for correct time logging.
slide31
Repeater Beacons
  • Add a receiver and data decoding
  • Decode your callsign sent to it
  • Reply with acknowledgement and report
  • Who will be the first ?
slide32
Reverse Beacon
  • Instead of a Transmitter
  • Just a receiver with Internet Connection
    • You transmit to it
    • It reports to the web site, shows spectrum
  • There are a number of these at LF,
    • Ideal for antenna / transmitter tests
  • OR, phone up, transmit and listen
    • (Modest) premium rate phone number could finance it
slide33
And talking of Finance.....
  • Beacons Cost Money
  • Site Rental (Bell Hill £500 per year)
  • Electricity (Bell Hill 200 Watts 24/7)
  • Operators travelling Costs for maintenance
  • And, of course, the hardware itself
  • http://www.scrbg.org/donate/
  • Hamfest Stand
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