FT8 + CW + carrier

The FT8 + CW + carrier beacon program makes the RFzero capable of transmitting on any frequency from 10 kHz to 230 MHz running on the fundamental frequency. Above 230 MHz a harmonic frequency is used automatically taking the tone spacing into account.

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 FT8 part of the sequence the TX LED will flash at half the symbol rate, i.e. about 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.

Users

M0NYW

Jason, M0NYW, has built a 4 m personal beacon running 1 W on 70,093 MHz using the FT8 + CW + carrier program. The PA was designed by Rob, M0DTS, and uses an RD06HVF1. The PA saturates at 2,5 W and gives a stable 1 W.

Inside view of the beacon clearly showing the different units. Picture courtesy Jason, M0NYW.

ON0UCL

Pierre, ON4IV, is using an RFzero as driver for the ON0UCL beacon on 432,450 MHz. The beacon uses the third overtone from the RFzero which is then filtered and buffered before driving the 5 W PA into a Big Wheel antenna.

The 70 cm ON0ULC beacon. Picture courtesy Pierre, ON4IV.

PS8RF/B

Piraja, PS8RF, has put the PS8RF/B beacon on the air using FT8 + CW + carrier. The RFzero drives a Mitsubishi RA60H1317M power module to deliver 45 W. The RFzero will excite a PA of 160 W if needed. The beacon operates from the extreme north of Brazil in GI97HB on 144,434 MHz. The new beacon replaced an old CW beacon. The antenna is pointing to the EU continent.

The beacon ready for installation. Picture courtesy Piraja, PS8RF.

The beacon during the build. Picture courtesy Piraja, PS8RF.

The beacon sequence

When the GPS time is valid the beacon transmits FT8 for the first 12,6 s, then followed by a short break of 500 ms, then the call sign and locator is 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 the FT8 and just transmits CW and a fixed length 20 s carrier.

Display

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.

Please see the display page for more information.

LCD 16×2

The display shows the UTC seconds, the GPS status, the number of satellites and the HDOP.

Example of an LCD 16×2.

LCD 20×4

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.

Configuration

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) or the RFzero Manager (Windows)). Please connect the RFzero via a USB data 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.

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 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 pcf8574 ADDR

to set the I2C address of a PCF8574 series, if used, where ADDR is

  • 0: if not used
  • PCF8574 and PCK8574T: 0x20-0x27
  • PCF8574A: 0x38-0x3F

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 FT8 message, max 13 characters where space, ” “, is replaced with an underscore, “_”.

wr cw SPEED

to set the CW SPEED, i.e. duration in ms, 1 ms to 255 ms. 100 ms = 12 WPM/60 LPM.

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 10 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 gps 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.