International Beacon Program - V2.0
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International Beacon Program - V2.0

The purpose of the NCDXF/IARU HF Beacon is to allow worldwide amateur radio operators to judge HF propagation at your location, for your local time. To use it, tune in the beacons, and if you can hear a beacon, you might be able to work some HF DX to that area of the world.

The v1.0 beacon equipment consists of a HF Vertical antenna, Kenwood TS50 transceiver, a Trimble Acutime GPS unit, and a custom controller built around a 8748 micro controller.

The network has been on the air for about 10 years. The current problem is the equipment is getting old, and dying. The original designers never expected the units to remain in the field 10 years.

HF V2.0 Beacon Network

The goal is to design a replacement equipment package that duplicates the existing features. There has been a lot of proposals for more features, other ways, etc. But, none of those proposing have been willing to put any work into it.

The aim is a practical design, with few or no new features.


Minimum Equipment

  • ICOM IC-7200 Transceiver
  • New TX Antenna
  • GPS
  • Switches
  • LCD
  • Rig Interface board
  • Power Supply
  • Filtering and isolation
  • Chassis

Additional possibilities


Each beacon transmits every three minutes, day and night.

A transmission consists of the callsign of the beacon sent at 22 words per minute followed by four one-second dashes. The callsign and the first dash are sent at 100 watts. The remaining dashes are sent at 10 watts, 1 watt and 100 milliwatts.

The beacons cycle thru the bands 14 Mhz, 18 MHz, 21 MHz, 24 MHz and 28 MHz.

Each station is given a specific time slot, such that only one frequency is needed (on 20m, it’s 14.100). The unit uses GPS to get an accurate time, to synchronize it’s timeslot. The beacon transmits on each band for ten seconds, once every three minutes.

  • Check switch for test sqeuence.
  • Monitor the GPS unit - get the current time of day, and monitor the 1PPS signal.
  • Compute the correct timeslot for the station
  • Check switches for band enable/disable.
  • Send commands via CI-V / CAT to the radio to select the frequency, and power level via commands
  • Send the callsign and long dashes in CW.

This table gives the minute and second of the start of the first transmission within the hour for each beacon on each frequency, and reports the status.

Test Mode

Below is the v1.0 test mode

The test sequence is used for adjusting the power levels and checking the keying waveforms. Control the power level and request either a string of dots or continual keying by using the switches which normally disable particular bands:

Effect Switch
100 watts 28 MHz
10 watts 24 MHz
1 watt 21 MHz
0.1 watt 18 MHz
Dits 14 MHz
Carrier 10 MHz

Equipment and Components Details

ICOM IC-7200 Transceiver

The ICOM IC-7200 transceiver offers CI-V commands for control of frequency, transmissions, and for monitoring.

For the CI-V commands see:

Statistics could also be gathered: for example, SWR could be measured.

New TX Antenna

There is likely no impact of antenna choice on this part of the v2.0 beacon project.


The GPS data stream will tell us the correct time of day. Once we know that, and our slot ID, we can just init a countdown register to our time slot.


The v1.0 system has the following switches:

  • Band Switches (6)
  • Test Switches (1 used, 3 reserved)

The band switches control which bands are used. v1.0 covers 5 bands with a 6th slot reserved for 10 MHz.

One test switch controls test mode, and in test mode, the band switches have other functions. Three other switches are reserved.


The v1.0 system has a single LED for showing GPS and other status.

Switching to a small LCD character display will make operation easier and will not greatly increase cost. An i2c LCD is probably the best choice.

There are combination switch/LCD I2C products that we can use and avoid the switch overloading by using screen feedback. For example,

Or we could use the Akafugu LCD backpack and use a separate mechanism for switches. This product has the advantage that it is mechanically easier to mount in case.


  • The Arduino Uno will be standard and remain easily understood for years.
  • The Arduino Leonardo has the advantage of a separate programming port and hardware TTL port for the GPS. Software TTL for CI-V rig control.
  • The Arduino Mega has the disadvantage of being off the Arduino main line, and users often have trouble with support for hardware and libraries.
  • The Arduino Yun is a combination of the Arduino Leonardo, a small Linux system running OpenWRT, and integrated Wifi connection, and an Ethernet connection.

Tentative Recommendations:

  • The Arduino Leonardo is probably the best choice for the non-network version
  • The Arduino Yun is the best choice for the connected version.

Interface Board

The interface board is an Arduino Shield. It has headers for connections to the IC-7200 CI-V TTL serial, IC-7200 CW line, GPS TTL serial, LCD, and possibly RTC.

Optional item: Network: WiFi or Ethernet for command & control, status

The sites are mostly hosted. If we had a USB connection to a local PC, then we could send the host a file to load new code on the controller, and we could also collect stats, etc.

If there is a network (WiFi or wired) we could also report the statistics, such as whether it's online, what the SWR is.

Optional item: Backup RTC with TXC

It might be nice to include a quartz crystal based time module, to keep it disciplined with the GPS, in case there is some loss of GPS signal.

Backup disciplined clock for use when GPS isn't available, for example, indoors.

Engineering Resources

  • Project Management: Kevin K6TD
  • Arduino system: Leigh WA5ZNU
  • Rig Control: Kevin K6TD
  • Beacon Event Loop: Leigh WA5ZNU
  • UX: ?
  • Systems Design: Kevin K6TD
  • Hardware Design: Kevin K6TD
  • Testing: ?

May 15, 2015

libraries used

SoftSerial AdaFruit_GPS EnableInterrupt LCDi2cNHD arduinomorse