Transcript The Next Generation of Amateur Beacons

The Next Generation of
Amateur Beacons for the
st
21 Century
Andy Talbot G4JNT / G8IMR
www.scrbg.org/g4jnt
What do we want beacons for ?
Propagation
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Band openings, but there’s nobody on!
Is there anybody out there?
Is the band dead?
Receiver
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Monitor
confidence check
I can’t hear anyone, is it working?
Frequency Calibration
Antenna and Bearing setup
What do we have now
 HF
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Beacons
IARU Beacon chain
• 14 - 28MHz, time sequenced
• Poor frequency stability / accuracy
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Others on dedicated frequencies >14MHz
 VHF
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Hundreds around the world
Simple crystal control, freq +/- tens of ppm.
Microwave Beacons
 Frequency
 Dish
calibration
and Bearing setup for /P operation
 Propagation
Monitoring
Improvements
 Automatic
Monitoring using PC /
Soundcards
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Narrow band
Good frequency stability
 Frequency
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Reuse
Time sequenced
• Help QRM and regulatory issues
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Simplifies auto-monitoring of multiple beacons
• No Retuning
Next Generation HF
 Frequency
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Aim for better than 10-7 at HF (+/-1 Hz)
TCXO or Ovened oscillator
 Minimise
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Stability
frequency clutter
Time sequence - like the IARU chain
 Change
the rules to allow beacons below
7MHz
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Precise timed transmissions
Single frequency on each band, worldwide ?
Data Modes
 PSK31
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or RTTY could carry information
Propagation state, band openings
Site telemetry
Unique time signature confirms reception
Time / Temperature / Pressure / ???
Next Generation VHF
 Frequency
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Ovened crystal or GPS locked
Look for 10-9 accuracy (sub Hz) for auto
search
 Add
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accuracy
weak signal data modes
JT65
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
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Some Examples of nextgeneration beacons are
already out there….
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
5MHz Automatic Propagation Monitor
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
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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
GB3VHF 144.43MHz
Wrotham, Kent
 GPS
Controlled frequency and time
 JT65, CW, 1pps PSK
 Two minute repeat cycle
 Generic beacon driver concept
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Up to 16 thirty second time slots can each be
allocated to different modes
RTTY message not used on GB3VHF
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
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GB3SCF 3400.90499999985 MHz
GB3SCX 10368.9050068 MHz
Others will follow
Beacon Hardware
 Much
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Driver / oscillator (frequency may need stabilising)
Power Amplifier (+ filters etc)
Antenna
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already exists
several new modules are needed
Agile Frequency Source
Controller / keyer
Timing – eg GPS
Power Amplifier
 Power
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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
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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
Frequency Sources
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Crystal oscillator
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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
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Direct generation of most data modes
Clock from standard frequency reference (10MHz)
DDS Sources
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Older AD9850 / 9851
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AD9852 / 9854
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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
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
Controller
 Microcontroller
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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
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AD9852 100μs to reprogramme (serial)
PSK31, JT65, FSK441 and RTTY
demonstrated already.
Accept external data / telemetry inputs
Timing
 GPS
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module
Any version will give 1 PPS and timing data
NMEA or native binary
 Jupiter
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Navman family have 10kHz output
Allows simple frequency locking using a
synthesizer
 GB3VHF
GPS Disciplined
Reference (12.8MHz)
GPS Module
PIC Controller
DDS Source
A Few Ideas for the
Future
Timestamp the transmission with a
unique code
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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.
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Alphanumeric code with pronounceable triads :-
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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
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Audio CW type tones,
• Equal length dot / dash on different freqs
• Third idle tone
View on Spectrogram
Listen !