The Next Generation of Amateur Beacons for the

The Next Generation of Amateur Beacons for the st 21 Century Andy Talbot G 4 JNT / G 8 IMR www. scrbg. org/g 4 jnt

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

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

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

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

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 7 MHz Precise timed transmissions Single frequency on each band, worldwide ?

Data Modes PSK 31 or RTTY could carry information Propagation state, band openings Site telemetry Unique time signature confirms reception Time / Temperature / Pressure / ? ? ?

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 JT 65 Extended period of coherent carrier for very narrow band integration Timed PSK Automatic monitoring

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

Some Examples of nextgeneration beacons are already out there….

The 5 MHz beacon chain GB 3 RAL GB 3 WES GB 3 ORK 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 (G 3 PLX software) Sounder sequence

5 MHz Automatic Propagation Monitor

GB 3 SSS 1960 k. Hz / 3597 k. Hz Temporary beacon for winter transatlantic propagation tests. 1 Nov to end Jan 2007 on 1960 k. Hz NEW Nov 2007 – 2008 on 3597 k. Hz Sequence similar to the 5 MHz beacons Each 15 minutes, power steps, carrier PSK 31 message instead of sounder All waveforms generated by software CW Keying now has shaped rise time

GB 3 VHF 144. 43 MHz Wrotham, Kent GPS Controlled frequency and time JT 65, CW, 1 pps 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 GB 3 VHF

New GB 3 RAL VHF Beacons 40. 05 / 50. 05 / 60. 05 / 70. 05 MHz Non amateur bands for special propagation monitoring. All identical design – enhanced GB 3 VHF AD 9852 DDS GPS timed, every 15 minutes Master 250 MHz clock, GPS locked

Bell Hill Microwave Beacons Single site cluster of seven beacons for 2. 3 to 47 GHz and telemetry Tx on 70 MHz Evolutionary upgrades in capability So far, two are GPS locked with RTTY data message GB 3 SCF 3400. 90499999985 MHz GB 3 SCX 10368. 9050068 MHz Others will follow

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

Power Amplifier Power Steps, PSK 31 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

Simple 10 Watt linear PA for HF beacons

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 GB 3 VHF - additional crystal filter μWave beacons, lock crystal oscillator to DDS O/P Direct generation of most data modes Clock from standard frequency reference (10 MHz)

DDS Sources Older AD 9850 / 9851 Up to 30 MHz directly. FM / Phase modulation • But no AM Small and simple to use 32 bit frequency register -9 freq setting ~ 10 Internal x 6 PLL for clock AD 9852 / 9854 Up to 90 MHz directly Amplitude / phase / frequency changed in μs 48 Bit - 10 -14 Frequency setting X 4 – X 20 Internal clock PLL Even Faster devices eg. AD 9950

Controller Microcontroller eg. PIC Standard workhorse 16 F 84 or 16 F 628 has enough power for most controller tasks Re-programme the DDS in real time to generate data modes AD 9852 100μs to reprogramme (serial) PSK 31, JT 65, FSK 441 and RTTY demonstrated already. Accept external data / telemetry inputs

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

GB 3 VHF GPS Disciplined Reference (12. 8 MHz) GPS Module PIC Controller DDS Source

A Few Ideas for the Future

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 1805 1810 1815 1820 1825 1830 1835 JIC PEF MEB TOD PEF HYH TOD MEG 1801 1806 1811 1816 1821 1826 1831 1836 PUF HAR TAD ZUC JAH PIG MUG FAF 1802 1807 1812 1817 1822 1827 1832 1837 KIC CEG CAB FYF NAF WOJ HUD ZEH 1803 1808 1813 1818 1823 1828 1833 1838 FOF LUD HED NAC WEH RAG CYG WIF 1804 1809 1814 1819 1824 1829 1834 1839 WAC RYG MIB WEF CUF LEJ TAD NOH

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