International Beacon Project

(Please note that this example program will not run without a GPS antenna)

The International Beacon Project (IBP) example program makes the RFzero capable of transmitting CW on five predefined HF frequencies (14,100 MHz, 18,110 MHz, 21,150 MHz 24,930 MHz and 28,200 MHz).

A 16 characters and two lines LCD can be connected showing the UTC minutes and seconds and GPS data.

The configuration is done via the USB port. It is possible to wait for the RFzero to warm up for up to 255 s before starting to transmit.

During the CW part of the sequence the TX LED will flash and during power steps it will be lit for 1 s.

When GPS signals are received the PPS LED flashes ones per second and when the status of the GPS signal is valid the Valid LED is lit. Then the program waits for the right minute and seconds to arrive before transmitting.

The ULN2803A is used to identify the band, D4 to D0, for controlling an external filter bank and the power steps, D7 to D5.

The beacon sequence

When the GPS time is valid the beacon transmits once on each band once every three minutes. The transmission consists of the call sign of the beacon sent at 22 words per minute followed by four one-second dashes.

At the end of each 10 second transmission, the beacon steps to the next higher band and the next beacon in the sequence begins transmitting.

If the GPS signal is invalid the beacon suspends transmitting until the GPS becomes valid again. This is to prevent the beacon of being out of sync and transmit on top of the other beacons.


The display is a LCD (16×2) that shows the UTC seconds, the GPS status, the number of satellites and the HDOP.

If you want to change what is shown on the display please edit the Display_Update() function and in the // Prepare LCD section in the setup() function in the IBP.ino file.


The configuration of the program is done via the USB port, 9600 Baud, 8 bits, no parity and one stop bit, using a terminal program (e.g. Termite Terminal (Windows), CuteCom (Linux) or Terminal (Mac OS)). Please connect the RFzero via a USB B cable to your compute and connect the terminal program to the right COM port in the terminal program. The RFzero identifies itself as an Arduino Zero (Windows Device Manager).

If you don’t see the RFzero> or RFzero config> prompts please press the enter key. When you want to execute a command you don’t have to enter the prompt but only the command and parameters after the >.

All input to the RFzero must be in lowercase.

To enter the configuration mode please enter   config   at the RFzero> prompt, i.e.

RFzero> config

To see the available commands please enter   ?   at the RFzero config> prompt, i.e.

RFzero config> ?

To leave the configuration mode please enter   exit   at the RFzero config> prompt, i.e.

RFzero config> exit

When in configuration mode, i.e. when you see the RFzero config> prompt, the most frequent commands are

rd cfg

to see the configuration that will be used after exiting the configuration mode.

wr defaults

to set most of parameters to their default values. Please see the actual example program for the specific default values.

wr bcn CALL

where CALL is the beacon call sign, max 15 characters.

wr ibp MIN SEC

where the MIN and SEC are the fundamental IBP transmission minute and seconds.

wr warmup SECONDS

where SECONDS is the number of seconds to wait for the RFzero to warm up.

More commands are available so please enter a question mark (?) at the RFzero config> prompt to see them.