Amateur Beacons for the
st
21 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
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
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
IBP Chain

Call

4U1UN U- Nations
VE8AT Canada
W6WX United States
KH6WOHawaii
ZL6B New Zealand
VK6RBPAustralia
JA2IGY Japan
RR9O Russia
VR2B Hong Kong
4S7B Sri Lanka
ZS6DN South Africa
5Z4B Kenya
4X6TU Israel
OH2B Finland
CS3B Madeira
LU4AA Argentina
OA4B Peru
YV5B Venezuela
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Location
14.100
18.110
21.150
24.930
28.200
Operator
00:00
00:10
00:20
00:30
00:40
00:50
01:00
01:10
01:20
01:30
01:40
01:50
02:00
02:10
02:20
02:30
02:40
02:50
00:10
00:20
00:30
OFF
00:50
01:00
01:10
01:20
01:30
01:40
01:50
02:00
02:10
02:20
02:30
02:40
02:50
00:00
00:20
00:30
00:40
00:50
01:00
01:10
01:20
01:30
01:40
01:50
02:00
02:10
02:20
02:30
02:40
02:50
00:00
00:10
00:30
00:40
00:50
OFF
01:10
01:20
01:30
01:40
01:50
02:00
02:10
02:20
02:30
02:40
02:50
00:00
00:10
00:20
00:40
00:50
01:00
01:10
01:20
01:30
01:40
01:50
02:00
02:10
02:20
02:30
02:40
02:50
00:00
00:10
00:20
00:30
UNRC
RAC/NARC
NCDXF
NOARG, HARC
NZART
WIA
JARL
SRR
CRSA, HARTS
RSSL
ZS6DN
ARSK
IARC
SRAL
ARRM
RCA
RCP
RCV
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
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
Next Generation HF
 Frequency


Aim for better than 10-7 at HF (+/-1 Hz)
TCXO or Ovened oscillator
 Minimise

Stability
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 ?
WSPR ??

• Already Well Established
• Reporting Website in place
• Automated reports
How About a Network of WSPR
Beacons ?
Data Modes
 PSK31

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
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

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
Next Generation VHF
 Decent


Ovened crystal or GPS locked
Look for 10-9 accuracy (sub Hz) for auto
search
 Add



Frequency accuracy
weak signal data modes
JT65
Extended period of coherent carrier for
very narrow band integration
PSK reversals for time-of-flight
mewasurement
Microwave Beacons
 Often
Used when / Portable for :

Frequency calibration

Dish and Bearing setup
 Propagation
Monitoring
Microwave Beacons
 Frequency

accuracy even more important as
They are often used for calibration
need a lot more μWave beacons to
ensure everyone can hear at least one on
each band
 We



Personal beacons
Attended or unattended
Licensing easier at microwaves
 What
is needed – where shall we go?
 Some
Examples of next-generation
beacons are already out there….
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
5MHz Automatic Propagation Monitor
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
message – decoded in Canada
 All waveforms generated in DDS chip
 PSK31
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
 GB3VHF
GPS Disciplined
Reference (12.8MHz)
GPS Module
PIC Controller
DDS Source
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
Bell Hill Microwave Beacons


Single site cluster of seven beacons for 2.3 to 47GHz
and telemetry Tx on 70MHz
Evolutionary upgrades in capability

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GB3SCS
GB3SCF
GB3SCF
GB3SCX
GB3SCK
G8BKE/P
G4JNT/P
2320.90503MHz JT4g
3400.905000 MHz RTTY
5760.905006MHz QRSS
10368.9050068 MHz JT4g
24048.905 MHz (CW only)
47.088905 GHz (CW only)
70.031MHz PSK31 Telemetry
GPS Locked
GPS Locked
GPS Locked
GPS Locked
OCXO
OCXO
TCXO
Bell Hill Microwave Beacons
Beacon Hardware

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
Power Amplifier
 Power


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



Steps, PSK31 etc need a linear PA
duty cycle with no linear modes
Class C design is better suited.
Particularly at VHF / UHF
Frequency Multiplication
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)
DDS Sources

Older AD9850 / 9851

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
AD9852 / 9854

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
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
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
 Simple

CW Keyer
Tiny PIC
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
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 :-


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1800
1805
1810
1815
JYC
PEF
MEB
TOD
1801
1806
1811
1816
PUF
HAR
TAD
ZUC
1802
1807
1812
1817
KIC
CEG
CAB
FYF
1803
1808
1813
1818
FOF
LUD
HED
NAC
1804
1809
1814
1819
WAC
RYG
MIB
WEF
May also have to send the minutes digit for correct time
logging.
Repeater Beacons
 Add
a receiver and data decoding
 Decode your callsign sent to it
 Reply with acknowledgement and report
 Who
will be the first ?
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

Ideal for antenna / transmitter tests
 OR,

are a number of these at LF,
phone up, transmit and listen
(Modest) premium rate phone number could
finance it
And talking of Finance.....
 Beacons
 Site
Cost Money
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
Questions ?