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The Next Generation of Amateur Beacons for the 21 st Century

Andy Talbot G4JNT / G8IMR www.scrbg.org/g4jnt. The Next Generation of Amateur Beacons for the 21 st Century. What do we want beacons for ?. Propagation Monitor Band openings, but there’s nobody on! Is there anybody out there? Is the band dead? Receiver confidence check

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The Next Generation of Amateur Beacons for the 21 st Century

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  1. Andy Talbot G4JNT / G8IMR www.scrbg.org/g4jnt The Next Generation of Amateur Beacons for the 21st Century

  2. What do we want beacons for ? • Propagation Monitor • Band openings, but there’s nobody on! • Is there anybody out there? • Is the band dead? • Receiver confidence check • I can’t hear anyone, is it working? • Frequency Calibration • Antenna and Bearing setup

  3. What do we have now • HF Beacons • IARU Beacon chain • 14 - 28MHz, time sequenced • Poor frequency stability / accuracy • Others on dedicated frequencies >14MHz • VHF • Hundreds around the world • Simple crystal control, freq +/- tens of ppm.

  4. Microwave Beacons • Frequency calibration • Dish and Bearing setup for /P operation • Propagation Monitoring

  5. Improvements • Automatic Monitoring using PC / Soundcards • Narrow band • Good frequency stability • Frequency Reuse • Time sequenced • Help QRM and regulatory issues • Simplifies auto-monitoring of multiple beacons • No Retuning

  6. 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 • Precise timed transmissions • Single frequency on each band, worldwide ?

  7. Data Modes • PSK31 or RTTY could carry information • Propagation state, band openings • Site telemetry • Unique time signature confirms reception • Time / Temperature / Pressure / ???

  8. Next Generation VHF • 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 • Timed PSK • Automatic monitoring

  9. Frequency accuracy is important Often used as calibration Aim for everyone to hear at least one on each band Personal beacons Attended or unattended Licensing easier at microwaves Microwave Beacons

  10. Some Examples of next-generation beacons are already out there….

  11. The 5MHz beacon chain • GB3RAL GB3WES GB3ORK transmit in sequence. Each is on for 1 minute every 15 • GPS timed • Power steps for audible S/N estimation • TCXO frequency control (few Hz) • The system was designed for automatic logging (G3PLX software) • Sounder sequence

  12. 5MHz Automatic Propagation Monitor

  13. GB3SSS 1960kHz / 3597kHz • Temporary beacon for winter transatlantic propagation tests. • 1 Nov to end Jan 2007 on 1960kHz • NEW Nov 2007 – 2008 on 3597kHz • Sequence similar to the 5MHz beacons • Each 15 minutes, power steps, carrier • PSK31 message instead of sounder • All waveforms generated by software • CW Keying now has shaped rise time

  14. 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 • RTTY message not used on GB3VHF

  15. New GB3RAL VHF Beacons • 40.05 / 50.05 / 60.05 / 70.05MHz • Non amateur bands for special propagation monitoring. • All identical design – enhanced GB3VHF • AD9852 DDS • GPS timed, every 15 minutes • Master 250MHz clock, GPS locked

  16. Bell Hill Microwave Beacons • Single site cluster of seven beacons for 2.3 to 47GHz and telemetry Tx on 70MHz • Evolutionary upgrades in capability • So far, two are GPS locked with RTTY data message • GB3SCF 3400.90499999985 MHz • GB3SCX 10368.9050068 MHz • Others will follow

  17. Beacon Hardware • Much already exists • Driver / oscillator (frequency may need stabilising) • Power Amplifier (+ filters etc) • Antenna • But several new modules are needed • Agile Frequency Source • Controller / keyer • Timing – eg GPS

  18. 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 • Probably need switched filters • High duty cycle with no linear modes • Class C design is better suited. • Particularly at VHF / UHF • Frequency Multiplication

  19. Simple 10 Watt linear PA for HF beacons

  20. Frequency Sources • 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)

  21. DDS Sources • Older AD9850 / 9851 • Up to 30MHz directly. • FM / Phase modulation • But no AM • 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

  22. Controller • Microcontroller eg. PIC • Standard workhorse 16F84 or 16F628 has enough power for most controller tasks • Re-programme the DDS in real time to generate data modes • AD9852 100μs to reprogramme (serial) • PSK31, JT65, FSK441 and RTTY demonstrated already. • Accept external data / telemetry inputs

  23. Timing • GPS module • Any version will give 1 PPS and timing data • NMEA or native binary • Jupiter Navman family have 10kHz output • Allows simple frequency locking using a synthesizer

  24. GPS Disciplined Reference (12.8MHz) • GB3VHF GPS Module DDS Source PIC Controller

  25. A Few Ideas for the Future

  26. Timestamp the transmission with a unique code • Verifies correct reception at any given date / time. • Only the keeper knows the hashing key, and can verify correct reception. • Simple to do in a PIC from the GPS data. • Alphanumeric code with pronounceable triads :- • 1800 JIC 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 • 1820 PEF 1821 JAH 1822 NAF 1823 WEH 1824 CUF • 1825 HYH 1826 PIG 1827 WOJ 1828 RAG 1829 LEJ • 1830 TOD 1831 MUG 1832 HUD 1833 CYG 1834 TAD • 1835 MEG 1836 FAF 1837 ZEH 1838 WIF 1839 NOH

  27. Or Just Keep It Simple !! • DFCWi • Audio CW type tones, • Equal length dot / dash on different freqs • Third idle tone • View on Spectrogram • Listen !

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