The%20Next%20Generation%20of%20Amateur%20Beacons%20for%20the%2021st%20Century

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The Next Generation of Amateur Beacons for the
21st Century

• Andy Talbot G4JNT / G8IMR
• www.scrbg.org/g4jnt

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What do we want beacons for ?

• Propagation Monitor
• Band openings, but theres nobody on!
• Is there anybody out there?
• Is the band dead?
• Receiver confidence check
• I cant hear anyone, is it working?
• Frequency Calibration
• Antenna and Bearing setup

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What do we have now

• HF Beacons
• IARU Beacon chain
• 14 - 28MHz, time sequenced
• Poor frequency stability / accuracy
• Others on dedicated frequencies gt14MHz
• VHF
• Hundreds around the world
• Simple crystal control, freq /- tens of ppm.

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Microwave Beacons

• Frequency calibration
• Dish and Bearing setup for /P operation
• Propagation Monitoring

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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

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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 ?

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Data Modes

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

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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

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Microwave Beacons

• 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

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

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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

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• 5MHz Automatic Propagation Monitor

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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

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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

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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

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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

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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

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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

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• Simple 10 Watt linear PA for HF beacons

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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)

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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

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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

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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

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• GB3VHF

GPS Disciplined Reference (12.8MHz)
GPS Module
DDS Source
PIC Controller
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A Few Ideas for the Future
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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

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Or Just Keep It Simple !!

• DFCWi
• Audio CW type tones,
• Equal length dot / dash on different freqs
• Third idle tone
• View on Spectrogram
• Listen !