The WSPR + CW beacon program makes the RFzero capable of transmitting on any frequency from 100 kHz to 200 MHz and beyond running on the fundamental frequency. The sequence can be either WSPR (2 min), WSPR + fast CW (2 min) or if the GPS is invalid the sequence will be slow CW + 20 s carrier (free running). It is also possible to append a “/B”to the CW part of the call sign.
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.
When transmitting the TX LED will flash at half the symbol rate, i.e. about 0,7 Hz.
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 to save power.
Chip, N6CA, has built a new 2 m WSPR beacon to operate from Hawaii using the call KH6HME/B. The power is 40 W (max) WSPR which is split between Southern Japan and the West coast of the US with seven element yagis.
The KH6HME/B RFzero inside a heavy duty box. Picture courtesy Chip, N6CA.
The beacon sequences
There are different sequences available
- WSPR only (2 min)
- If the GPS signal is invalid the beacon suspends the transmission.
- WSPR + CW (2 min)
- The CW has to be fast enough for the total sequence to complete in less than 118 seconds, otherwise the CW will overlap into the next time slot and there will be a long period of silence before the next WSPR transmission begins
- If the GPS is invalid the WSPR will be suspended and the sequence will be CW (call + locator) + carrier free running until the GPS becomes valid again. The speed of the CW will be half of that when the GPS is valid
The call used during the CW part of the sequence can be extend with /”B” if desired.
To setup the type of display used please use the “wr display” command. If you want to change what is shown on the display please edit the display.cpp file.
The display shows the UTC odd/even minute and seconds, the GPS status, the number of satellites and the HDOP.
Example of an LCD 16×2.
The display shows the GPS status, the number of satellites, the HDOP as a bar graph, the UTC, call sign and locator of the beacon and the frequency.
Example of an LCD 20×4.
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. Arduino IDE Serial Monitor, Termite Terminal (Windows), CuteCom (Linux) or Terminal (Mac OS)). Please connect the RFzero via a USB B cable to your computer 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 >.
Changes to the configuration does not take effect before leaving the configuration mode.
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 program for the specific default values.
wr t1 MODE
to set the T1 H/W mode where MODE is
- 0: Transformer (default)
- 1: Combiner
- 2: None
wr display MODE
to set the display mode where MODE is
- 0: None
- 1: LCD 16 characters and two lines, HD44780 interface
- 2: LCD 20 characters and four lines, HD44780 interface
- 3: LCD 16 characters and two lines, HD44780 via I2C PCF8574 interface
- 4: LCD 20 characters and four lines, HD44780 via I2C PCF8574 interface
- 5: Graphics display, ILI9341 SPI interface
- 6: Graphics display, ILI9488 SPI interface
wr bcn CALL
where CALL is the beacon call sign. The maximum length for WSPR Type 1 messages is six characters and it must include a number. The maximum length for WSPR Type 2 messages is ten characters and it must include a number. Please see the WSPR specification for more details about the message types.
wr loc LOCATOR
where LOCATOR is the locator up to eight characters, i.e. AA00AA00. But not all may be transmitted.
wr pwr POWER
where POWER is the total system power level in dBm, i.e. after further amplification and cable loss etc. The RFzero doesn’t change power. Only the values below are valid. If you can’t find an exact match pick the closest one.
- 0 dBm = 1 mW
- 3 dBm = 2 mW
- 7 dBm = 5 mW
- 10 dBm = 10 mW
- 13 dBm = 20 mW
- 17 dBm = 50 mW
- 20 dBm = 100 mW
- 23 dBm = 200 mW
- 27 dBm = 500 mW
- 30 dBm = 1 W
- 33 dBm = 2 W
- 37 dBm = 5 W
- 40 dBm = 10 W
- 43 dBm = 20 W
- 47 dBm = 50 W
- 50 dBm = 100 W
- 53 dBm = 200 W
- 57 dBm = 500 W
- 60 dBm = 1 kW
wr cw ONOFF
to turn on/off CW after the WSPR where ONOFF is
- 0: CW is off
- 1: CW is on
- 2: CW is on and “/B” is appended to the CW call sign
wr cw SPEED
to set the CW SPEED, i.e. duration in ms, 1 ms to 255 ms. 50 ms = 24 WPM/120 LPM when the GPS is valid. When the GPS is invalid the speed of the CW will automatically be half of that when the GPS is valid.
wr key STYLE
to set keying STYLE where 0: is on-off keying (OOK), or 1: for frequency shift keying (FSK).
wr freq FREQ
where FREQ is the nominal on-air 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 level LEVEL
where LEVEL is the drive strength current in the output stages. This effectively changes the output power by up to 10 dB, but varies somewhat with frequency. Valid LEVEL values are
- 0: 2 mA
- 1: 4 mA
- 2: 6 mA
- 3: 8 mA, default level
To read more about the drive strength current please consult the Si5351A datasheet.
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.
wr echo MODE
- 0: hide all NMEA strings
- 1: show the $GPGGA and $GPZDA NMEA strings
- 2: show the $GPGGA, $GPGLL, $GPGRS, $GPGSA, $GPGST, $GPGSV, $GPRMC, $GPVTG and $GPZDA NMEA strings
More commands are available so please enter a question mark (?) at the RFzero config> prompt to see them.
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