The Syncronized Beacon Project (SBP) example program makes the RFzero capable of transmitting on any frequency from 100 kHz to 200 MHz and beyond running on the fundamental frequency. However, the SBP concept is a 50 MHz time multiplexed beacon system. The system consists of three 10 x 1 kHz allocations, i.e. one 10 kHz allocation per IARU Region, and five time slots per frequency. Thus in total there are 150 frequency-time slots.
The RFzero example program be be used as either an exclusive SBP beacon or during the non SBP transmission it may be used on another frequency transmitting PI4 + CW + Carrier.
A four lines and 20 characters LCD can be connected showing the UTC minutes and seconds, the GPS status, the beacon call sign and locator and the kHz part of the current frequency.
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. It is also possible to wait for the GPS to be valid before starting to transmit.
During the PI4 part of the sequence the TX LED will flash at half the symbol rate, i.e. 3 Hz, during the CW part of the sequence the TX LED will flash with the CW and during the carrier part of the sequence the TX LED will be constantly lit.
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.
A PA can be controlled on/off on D7, i.e. off during no transmission periods to save power.
The beacon sequence
When the GPS time is valid the beacon transmits PI4 for the first 24 1/3 s, then followed by a short break of 2/3 s, then the call sign and locator are sent in CW followed by a short break of 500 ms and then a carrier until the full minute. Then the sequence repeats again.
If the GPS signal is invalid the beacon suspends transmitting on the SBP frequency. If the beacon is configured to also transmit on another non-SBP frequency the PI4 part is suspended and the beacon just transmits CW and a fixed length 20 s carrier on this non SBP-frequency.
The LCD (4×20) shows the kHz part of the transmitted frequency, the UTC minutes and seconds, the beacon call sign and locator, the GPS status, the number of satellites and the HDOP.
The PA line is, for the time being, for inspiration only showing the PA voltage, current and power and SWR. Implementing PA and SWR monitoring functions is very beacon specific. We will be more than happy to make a generic solution when we have receive d input from a handful of different implementations.
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.
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
to see the configuration that will be used after exiting the configuration mode.
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 loc LOCATOR
where LOCATOR is the locator up to eight characters, i.e. AA00AA00.
wr mgm MESSAGE
where MESSAGE is the PI4 message, max eight characters where space, ” “, is replaced with an underscore, “_”.
wr freq FREQ
where FREQUENCY is the nominal beacon frequency in Hz from 100 kHz and up.
wr sbp mode MODE
where the MODE controls if the beacon is exclusively used for SBP or a mix of both SBP and normal where 0: SBP only and 1: mixed.
wr sbp mask MASK
where the MASK is the SBP/normal beacon time slot transmission mask where 0: is normal beacon and 1: is SBP beacon. Input must be in hex, e.g. to configure the beacon to transmit as SBP in the first time slot, i.e. 00001
wr sbp mask 01
Example of some bit masks to hex
- 00001 = 01
- 00010 = 02
- 00100 = 04
- 00101 = 05
- 01000 = 08
- 10000 = 10
- 10011 = 13
It is possible to transmit in more than one SBP time slot, e.g. to transmit in the first, middle and last time slots 10101 = 15
wr sbp mask 15
wr sbp call CALL
where CALL is the beacon SBP call sign, max 15 characters. This may be different form the normal call sign and if identical please add “/S” to the end of the call sign, e.g. OZ0RF/S, to identify as a SBP and normal frequency beacon.
wr sbp mgm MESSAGE
where MESSAGE is the PI4 message, max eight characters where space, ” “, is replaced with an underscore, “_”. This may be different from the normal call sign. If the call signs are identical please add “/S” to the end of the SBP call sign, e.g. OZ0RF/S.
wr sbp freq FREQ
where FREQUENCY is the SBP beacon frequency in Hz from 100 kHz and up.
wr warmup SECONDS
where SECONDS is the number of seconds to wait for the RFzero to warm up.
wr wait ONOFF
to turn on or off waiting for the GPS to be valid before transmitting where ONOFF is either 0: for off/don’t wait for the GPS to be valid, or 1: for on/wait for the GPS to be valid.
More commands are available so please enter a question mark (?) at the RFzero config> prompt to see them.