A New FT8 with Rag Chew Abilities ( FT8CALL )

FT8 has taken over the airwaves as the digital communication mode for making QSOs over HF/VHF/UHF. The mode has been widely popular as the latest offering in K1JT’s WSJT-X application. FT8 stands on the shoulders of JT65, JT9, and WSPR modes for weak signal communication, but transmits much faster with only slightly reduced sensitivity.

While FT8 is an incredibly robust weak signal mode, it is designed heavily to take advantage of short band openings on HF/VHF/UHF and only offers a minimal QSO framework. However, many operators are using these weak signal qualities to make successful QSOs on the HF bands where other modes fail.

The idea with FT8Call is to take the robustness of FT8 mode and layer on a messaging and network protocol for weak signal communication on HF, similar to FSQ and Fldigi with a keyboard-to-keyboard interfac

Read more on the design inspiration here: https://github.com/jsherer/ft8call

For release announcements, join the FT8Call mailing list here: https://groups.io/g/ft8call

Notice

FT8Call is a derivative of the WSJT-X application, restructured and redesigned for keyboard-to-keyboard message passing. It is not supported by nor endorsed by the WSJT-X development group. While the WSJT-X group maintains copyright over the original work and code, FT8Call is a derivative work licensed under and in accordance with the terms of the GPLv3 license. Source code can be found in this public repository: https://bitbucket.org/widefido/wsjtx/

Install

FT8Call currently comes in a variety of builds.

Desktop Linux (64-bit x86_64, Ubuntu 18.04 AppImage) v0.4.2
Desktop Linux (64-bit x86_64, deb) v0.4.2
Desktop Linux (32-bit i386) v0.4.2: [not yet available]
Raspbian Stretch (armv7, AppImage) v0.4.2
Raspbian Stretch (armv7, deb) v0.4.2
Windows 10 (win32_64) v0.4.2
Mac OSX (x86_64) v0.4.2: [not yet available]

For the most up-to-date listing of build downloads, check the FT8Call release announcements and FT8Call Release Downloads Wiki. Of course, you are always free to take a look at the source code as well!

The application is distributed using the WSJT-X installer on Windows. For Linux, it is distributed as an AppImage, a single file executable that can be run portably on your Linux desktop or RaspberryPi, as well as a .deb. AppImage is an untraditional approach to distributing Linux software so if you’ve never dealt with an AppImage before, all you need to do is:

Download the AppImage for your platform
Set the AppImage file to be executable
Run the AppImage file
…
Profit!

NOTE: Until the general release of FT8Call, development versions will only carry a 10 day lifespan. After expiration, you’ll be required to upgrade to the latest version of the application.

Operation

If you’ve used Fldigi or WSJT-X before, you’ll feel right at home with FT8Call. The premise is that FT8Call changes the encoding structure of FT8 modulated messages, breaking up long freetext messages into multiple transmission frames / cycles.

Most operators testing the application can be found +/- 4-8kHz from the standard FT8 frequencies. It is essential to avoid the main FT8 frequencies, as that will cause confusion among WSJT-X operators. Here are some frequencies to use instead:

160m: 1.838 MHz // 2 kHz below FT8
80m: 3.580 MHz // 7 kHz above FT8
40m: 7.080 MHz // 6 kHz above FT8
30m: 10.130 MHz // 6 kHz below FT8
20m: 14.080 MHz // 6 kHz above FT8
17m: 18.104 MHz // 4 kHz above FT8u
15m: 21.080 MHz // 6 kHz above FT8
12m: 24.920 MHz // 5 kHz above FT8
10m: 28.080 MHz // 6 kHz above FT8
6m: 50.300 MHz // 13 kHz below FT8

You can use the mailing list Sked Chat or the Facebook group to schedule on other frequencies with test operators.

Band Activity

Band activity is displayed on the left. Callsigns you’ve heard CQing are on the right. Clicking either of those will move your RX/TX offset to that audio frequency (QSY).

There is a waterfall at the bottom of the screen to show you the signals in your audio passband.

Messages

The top yellow text box shows you messages that are either on the frequency offset you’re on or who have directed a message to you (they sent a message that included your callsign).

You type into the white box on the bottom to prepare a message for transmission. Normal FT8 character restrictions do not apply! The extended character set includes all printable uppercase ASCII (A-Z 0-9 Space ./?+-`~!@#$%^&*()_=[]\{}|;’:”,<>). The message structure is variable encoded, so the most common characters take the least amount of space, and special characters take longer to send.

As you type your message you’ll see the send button display the number of frames (15 second transmit cycles) it’ll take to send your complete message. All you have to do is click send (or hit enter) to start transmitting on the next interval. As each frame is transmitted one after the other, the button will update with the number of frames left.

Because of this special variable encoding, messages in FT8Call cannot be decoded by WSJT-X. The same is also true, WSJT-X messages will not be shown in FT8Call.

Messages come in two forms:

standard FT8Call free text messages
directed FT8Call messages

Standard Messages

Standard messages are freetext messages that do not start with a callsign or a directed command. These messages will only print at another’s station location if they align their receive offset within 10Hz of your transmit offset. This is operation similar to other keyboard-to-keyboard digital modes, like Olivia, RTTY, and PSK.

Directed Messages

Directed messages are special FT8Call transmissions that automatically prefix your message with your callsign, similar to how FSQCall operates. Directed messages are useful for communicating in that you do not have to include your callsign in your message, allowing you to use more of the transmission frame(s) for actual message text, as well as alerting the recipient that a message was sent to them. As long as you are in the same passband, you do not have to be on the same frequency offset to receive a directed message.

To send a directed message, all you need to do is include the callsign of the receiving station as the first word in the message. There is a special “ALLCALL” callsign that you can use to send the message to anybody who is able to receive your message. Some examples:

DR4CNK HELLO HOW ARE YOU JIM?
- Will be sent as: KN4CRD: DR4CNK HELLO HOW ARE YOU JIM? ⌁
ALLCALL HELLO NET PSE QSY 14300
- Will be sent as: KN4CRD: ALLCALL HELLO NET PSE QSY 14300 ⌁

You’ll notice a special character at the end of the message, ala ⌁. It is a symbol to indicate the End of Transmission, the last frame of the message has been transmitted with nothing else to follow. This means you get a visual indicator that the transmission is done and you can begin transmitting a reply.

There are special directed messages that you can send to stations to have them automatically reply if they have AUTO enabled. They are comprised in the form of [CALLSIGN][COMMAND].

Available commands:

? – What is my SNR?
@ – What is your QTH (station location)?
& – What is your QTC (station message)?
% – What is your station power?
$ – What stations are you hearing? (Top 4)
|message – Please ACK and retransmit the following message
- The message is retransmitted by the receiving station verbatim with the addition of “DE [CALLSIGN]” added to the end of the message…meaning you do not need to add it to your message.
!message – Please display this message in a alert dialog and ACK if acknowledged
#message – Please ACK if you receive this message in its entirety
AGN? – Have the station automatically retransmit their last message

Examples:

If I wanted to ask DR4CNK what his QTH was, I’d send:

DR4CNK@
- And he would respond with a directed message back to me: “DR4CNK: KN4CRD MY QTH IS SOUTH OF FRANCE”, automatically if AUTO reply is enabled.

You can also use “ALLCALL” with the “?” command and all stations that receive your message will respond on a random frequency offset, example:

ALLCALL?
- And all stations who heard your message would respond with your signal strength:
  “DR4CNK: KN4CRD SNR +21”

If I wanted to transmit a message to OH8STN through DR4CNK, I could use the retransmit command and send:

DR4CNK|OH8STN HELLO JULIAN!
- During retransmit, at each hop the originating sender’s call is appended to the message.
- The command above would be received by OH8STN, they would send an ACK back, then retransmit the message, like so:
  - My station sends:
    KN4CRD: DR4CNK|OH8STN HELLO JULIAN!
  - DR4 station acks and retransmits:
    DR4CNK: KN4CRD ACK
    DR4CNK: OH8STN HELLO JULIAN! DE KN4CRD

If I wanted to alert a message to LB9YH through OH8STN through DR4CNK, I could send:

DR4CNK|OH8STN|LB9YH!HEY KEN!

You can also mix and match standard and free text messages, but most of the time you won’t need to.

BCN – Beacons

There is an automated beacon that transmits on an interval once turned on (BCN button on the top right). This interval can be changed in the settings. There’s no protection against the beacon transmitting over a message you’re receiving, so you’ll have to keep an eye on it. All beacons are transmitted on your current frequency unless it is not free, in which case a random (unused) frequency free offset between 250Hz-1500Hz.

The intent of beaconing is not to report on propagation…it’s to help populate your heard list (on the right) so you know who’s likely to be reachable so you can try to make contact. You can’t work them if you can’t “hear” them.

AUTO – Automatic Replies

While auto is enabled, your software will automatically respond to directed queries, like “?”, “@”, and “&”. When auto is turned off, FT8Call will buffer responses in the send message textbox until you are ready to send the replies manually.

LOG

There’s a log button in the top right. You’ll have to fill out all of that information manually since the QSO is freetext and not automated.

SPOT

FT8Call will report callsigns you hear (or your callsign if heard by other stations) to PSKReporter.com under the “FT8CALL” mode.

MACRO

There are a few quick macro buttons for entering common messages. You can edit these in the settings window. Just be mindful that long macros will take a while to send.

Frequencies

If you want to transmit on a non-standard frequency (recommended) you can either modify the frequencies list in the settings, or you can type directly into the band dropdown box in the top left of the screen.

ips & Tricks

- An example QSO:
  - →KN4CRD: CQCQCQ EM73 ⌁
  - ←DR4CNK: KN4CRD SNR +01 GOOD SIGNAL ⌁
  - →KN4CRD: DR4CNK SNR -12 TU 4 FT8CALL RIG IS KX2 5W DIPOLE ⌁

←DR4CNK: KN4CRD RR -22 FB KX3 100W VERT ⌁

→KN4CRD: DR4CNK RR FB REALLY ENJOYING THE CHAT MODE WITH LONG MESSAGES. BUT HEY LET’S TRY A RELAY ⌁

… (and on, and on, if you want)

- →KN4CRD: DR4CNK 73 ⌁
- →KN4CRD: CQCQCQ EM73 ⌁
You do not need to include your callsign when initiating your directed replies. They will be prefixed to your message automatically.
You do not have to reply on the same frequency offset as the caller. But, if you’re calling another station off their frequency, you do need to include their callsign at the beginning of the the message so it is directed to them and will show up in their yellow directed activity window.
Directed messages pack as much data as standard FT8 frames. The following examples are all 1 transmit cycle long
- Example:
  - KN4CRD/P: CQCQCQ EM73 (1 transmit frame)
  - KN4CRD: ALLCALL? (1 transmit frame)
  - DR4CNK: KN4CRD SNR +15 (1 transmit frame)
  - DR4CNK: KN4CRD AGN? (1 transmit frame)
For replying to a station’s CQ, double click their call in the call activity window, then either choose a directed command or type a message to them:
- DR4CNK: KN4CRD SNR +12
- DR4CNK: KN4CRD YES
- DR4CNK: KN4CRD NO
- DR4CNK: KN4CRD RR
- DR4CNK: KN4CRD 73
- DR4CNK: KN4CRD HELLO MY FRIEND GREAT TO HEAR YOU!
You can send freetext at any time! That’s what FT8Call is for:
- HI JIM TU 4 CALL UR -12 INTO ATLANTA BTU DE KN4CRD (4 transmit frames)
It might be helpful to learn some of the morse code prosign/abbreviations and psk31 abbreviations:
- https://en.wikipedia.org/wiki/Prosigns_for_Morse_code
- http://www.hamblog.co.uk/common-psk31-abbreviations/
- Examples:
  - K – over
  - BTU – back to you
  - WX – weather
  - FB – fine business
  - HW? – how do you copy?
  - etc

Frequently Asked Questions

What are the random three (or six) characters at the end of my retransmit and alert commands?
- These are a checksum for the message added to ensure all of the message frames were delivered correctly before retransmitting / alerting. If received in its entirety by the receiving station, these checksums will not be displayed to them.
Beacons transmit back to back (30 seconds). Why? Is this normal?
- Yes. They currently transmit for 30 seconds to compensate for band fading.
- In the future, beacons that transmit for 30 seconds may be able to offer extra information during the beacon (things like compound callsigns, extra long grid locators for telemetry, station power, etc)
You said that all printable ASCII characters can be used. Do some take more space than others?
- Yes. The characters that are sent in the messages are variable encoded, ranging from 3 to 19 bits in length based on their probability of being used in a sentence. The most common characters take the least amount of space, allowing us to send more than 13 characters per transmission cycle on average.
- Example: Space and E are only 3 bits in length. You could send about 22 (!!) of them in a single transmission. Whereas a character like { is 14 bits in length, you could only send 4 of those. (But really, how frequently do you use that character?)
- Here are some examples of phrases that could be sent in one 15 second transmit cycle:
  - EEEEEEEEEEEEEEEEEEEEEEE (23 characters)
  - I HAVE EATEN A SHOE (19 characters)
  - WHICH WAY TO OHIO (17 characters)
  - NEVER HAVE I EVER (17 characters)
  - TU UR 599 INTO (14 characters)
  - Etc
How fast does FT8Call transmit?
- FT8Call uses the same 15-second transmission cycle as FT8. What is different is that due to the variable encoding of the characters, FT8Call can transmit up to 23 characters per transmission frame. For average sentences, FT8Call can pack words very tightly, at around 10-15WPM.
- Example:
  - “WE HOLD THESE TRUTHS TO BE SELF-EVIDENT THAT ALL MEN ARE CREATED EQUAL THAT THEY ARE ENDOWED BY THEIR CREATOR WITH CERTAIN UNALIENABLE RIGHTS THAT AMONG THESE ARE LIFE LIBERTY AND THE PURSUIT OF HAPPINESS.”
    - This phrase is 35 words. It would take 13 transmission cycles to send (3 minutes 15 seconds). That is just under 11 WPM.
  - CW has a neat way of calculating WPM, timing how long it takes to transmit the word PARIS. In FT8, PARIS is encoded into 24 bits (4.8 bits/character). Each transmission cycle can pack up to 69 character bits. That equates to about 11.5 WPM. (69/24=2.875 words / 15seconds * 4)