---
name: "fldigi"
section: "1"
platform: "linux"
package: "fldigi"
version: "4.2.06-1+deb13u1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/fldigi"
---

# fldigi(1)

digital modem program for hamradio operators

## NAME

fldigi - digital modem program for hamradio operators

## SYNOPSIS

**fldigi** \[*OPTIONS*\]

## DESCRIPTION

**Fldigi** is a cross-platform multi-modem program for most of the digital modes used by radio amateurs today: CW, PSK, MFSK, MT-63, RTTY, Hellschreiber, DominoEX, Olivia, THOR and Throb are all supported. It can also help calibrate a sound card to a time signal and do on-air frequency measurement tests. Fldigi features basic rig control, logging, and contest operation, “panoramic” PSK decoding, a PSK Reporter client, and remote control via XML-RPC.

## OPTIONS

Long options begin with two hyphens and are handled by fldigi. The option names may be abbreviated to any unambiguous substring, and the option argument may be separated from the name by a space or equals sign, as per [getopt(3)](/getopt/3.md).

Short options begin with a single hyphen and are passed directly to FLTK. They may be abbreviated only as indicated.

- **--config-dir** *DIRECTORY*

  Look for and store configuration files in directory *DIRECTORY*, which is created if it does not exist. Defaults to “$HOME/.fldigi”.

- **--rx-ipc-key** *KEY*

  Set the receive message queue key. May be given in hex if prefixed with “0x”. Defaults to “9876” or “0x2694”.

- **--tx-ipc-key** *KEY*

  Set the transmit message queue key. May be given in hex if prefixed with “0x”. Defaults to “6789” or “0x1a85”.

- **--arq-server-address** *HOSTNAME*

  Set the ARQ TCP server address. Defaults to “127.0.0.1”. *HOSTNAME* may be any *node name* string accepted by [getaddrinfo(3)](/getaddrinfo/3.md).

- **--arq-server-port** *PORT*

  Set the ARQ TCP server port. Defaults to “7322”. *PORT* may be any *service name* string accepted by [getaddrinfo(3)](/getaddrinfo/3.md).

**Note**\

The *--xmlrpc-\** options are only available if fldigi was built with XML-RPC support.

- **--xmlrpc-server-address** *HOSTNAME*

  Set the XML-RPC server address. Defaults to “127.0.0.1”.

- **--xmlrpc-server-port** *PORT*

  Set the XML-RPC server port. Defaults to “7362”.

- **--xmlrpc-allow** *REGEX*

  Allow only the methods whose names match *REGEX*. *REGEX* is a POSIX extended regular expression.

- **--xmlrpc-deny** *REGEX*

  Allow only the methods whose names do not match *REGEX*.

- **--xmlrpc-list**

  List all available XML-RPC methods and exit. May be preceded by the *--xmlrpc-allow* or *--xmlrpc-deny* options to verify their effect.

- **--cpu-speed-test**

  Perform the CPU speed test that is normally done when fldigi is run without an existing configuration directory. Results are shown in the event log and options may be changed to the recommended values for the measured CPU speed.

- **--noise**

  Unhide controls for adding noise to the transmitted signal.

- **--wfall-only**

  Hide all main window widgets except the menu bar and waterfall (with its associated controls). Meant to be used with external programs that control fldigi with XML-RPC.

- **--debug-level** *LEVEL*

  Set the event log verbosity. *LEVEL* is clamped to the range \[0,5\]; for *Quiet*, *Error*, *Warning*, *Info*, *Verbose* and *Debug*. Defaults to “3” (*Info*).

- **--version**

  Print version information and exit.

- **--build-info**

  Print build information and exit.

- **--help**

  Print options summary and exit.

### Standard FLTK options

- **-bg, -background** *COLOUR*

  Set the background colour.

- **-bg2, -background2** *COLOUR*

  Set the secondary (text) background colour.

- **-di, -display** *DISPLAY*

  Specifies the X server to connect to; see [X(7)](/X/7.md).

- **-dn, -dnd** or **-nodn, -nodnd**

  Enable or disable drag and drop copy and paste in text fields.

- **-fg, -foreground** *COLOUR*

  Set the foreground colour.

- **-g, -geometry** *GEOMETRY*

  Set the initial window size and position. **Fldigi may not honour this option**.

- **-i, -iconic**

  Start fldigi in iconified state. **Fldigi may not honour this option**.

- **-k, -kbd** or **-nok, -nokbd**

  Enable or disable visible keyboard focus in non-text widgets.

- **-na, -name** *CLASSNAME*

  Set the window class. Defaults to “Fldigi”.

- **-ti, -title** *WINDOWTITLE*

  Set the window title. Defaults to “fldigi - \<callsign\>”.

### Additional UI options

- **--font** *FONT\[:SIZE\]*

  Set the widget font and (optionally) size. Defaults to “sans:12”.

### Options useful to developers

**Note**\

The --benchmark-\* options are only enabled if fldigi was built (exclusively) for benchmarking and batch decoding.

- **--benchmark-modem** *ID*

  Specify the modem. Defaults to “25” (“BPSK31”).

- **--benchmark-frequency** *FREQ*

  Set the modem frequency in Hz. Defaults to “1000”.

- **--benchmark-afc** *BOOLEAN*

  Enable or disable modem AFC. Defaults to “false”.

- **--benchmark-squelch** *BOOLEAN*

  Enable or disable modem squelch. Defaults to “false”.

- **--benchmark-squelch-level** *LEVEL*

  Set the modem squelch level (1—100%). Defaults to “0.0”.

- **--benchmark-input** *INPUT*

  Specify the input. Must be a positive integer indicating the number of samples of silence to generate as the input, or, if fldigi was linked with libsndfile, the name of the input audio file. The filename must contain non-digit characters.

- **--benchmark-output** *FILE*

  Specify the output data file. Non-textual output (i.e. Hellschreiber or MFSK images) cannot be saved. Default: decoder output is discarded.

- **--benchmark-src-ratio** *RATIO*

  Specify the sample rate conversion ratio. Defaults to “1.0” (input is not resampled).

- **--benchmark-src-type** *TYPE*

  Set the sample rate conversion type. TYPE is an integer in the range \[0,4\]. Defaults to “2” (“Fastest SINC Interpolator”).

**Warning**\

**The following options should not be relied upon. They are listed here only for the sake of completeness, and may be replaced by GUI settings or removed altogether in a future version.**

- **--wfall-width** *WIDTH*

  Set the waterfall width.

- **--wfall-height** *HEIGHT*

  Set the waterfall height.

- **--window-width** *WIDTH*

  Set the minimum window width.

- **--window-height** *HEIGHT*

  Set the minimum window height.

- **--exit-after** *SECONDS*

  Run for approximately *SECONDS* seconds.

- **--frames-per-buffer** *FRAMES*

  Set frames per buffer option to *FRAMES* when creating PortAudio streams. Defaults to “0” (let PortAudio choose).

## ENVIRONMENT

Fldigi uses several environment variables, mainly set for child processes created by the \<EXEC\> macro and the notifier.

### General variables

FLDIGI\_BROWSER

The web browser to use for http and file URIs. Overrides $BROWSER and [xdg-open(1)](/xdg-open/1.md).

### Macro variables

The following variables are created in the environment of the child process that is forked by the *\<EXEC\>* macro. They are empty if values are not available.

FLDIGI\_RX\_IPC\_KEY

The receive message queue key.

FLDIGI\_TX\_IPC\_KEY

The transmit message queue key.

FLDIGI\_XMLRPC\_ADDRESS

The XML-RPC server address string.

FLDIGI\_XMLRPC\_PORT

The XML-RPC server port string.

FLDIGI\_ARQ\_ADDRESS

The ARQ server address string.

FLDIGI\_ARQ\_PORT

The ARQ server port string.

FLDIGI\_VERSION

The version string.

FLDIGI\_PID

The process ID of the parent fldigi process.

FLDIGI\_CONFIG\_DIR

The configuration directory.

FLDIGI\_MY\_CALL

The operator’s callsign.

FLDIGI\_MY\_NAME

The operator’s name.

FLDIGI\_MY\_LOCATOR

The operator’s IARU (Maidenhead) locator.

FLDIGI\_MODEM

The short modem name.

FLDIGI\_MODEM\_LONG\_NAME

The long modem name.

FLDIGI\_DIAL\_FREQUENCY

The rig (radio) frequency.

FLDIGI\_AUDIO\_FREQUENCY

The modem (audio) centre frequency.

FLDIGI\_FREQUENCY

The actual receive/transmit frequency, i.e. the sum of rig and modem frequencies taking into account the rig sideband.

FLDIGI\_LOG\_FREQUENCY

The text (frequency in MHz) contained in the *QSO Freq* log field.

FLDIGI\_LOG\_TIME\_ON

The text (QSO start time) contained in the (time) *On* log field.

FLDIGI\_LOG\_TIME\_OFF

The text (QSO end time) contained in the (time) *Off* log field.

FLDIGI\_LOG\_CALL

The text (other station’s callsign) contained in the *Call* log field.

FLDIGI\_LOG\_NAME

The text (other station’s name) contained in the *Name* log field.

FLDIGI\_LOG\_RST\_IN

The text (received RST) contained in the (RST) *In* log field.

FLDIGI\_LOG\_RST\_OUT

The text (sent RST) contained in the (RST) *Out* log field.

FLDIGI\_LOG\_QTH

The text (other station’s QTH) contained in the *QTH* log field.

FLDIGI\_LOG\_LOCATOR

The text (other station’s Maidenhead locator) contained in the *Loc* log field.

FLDIGI\_LOG\_NOTES

The text (free-form notes) contained in the *Notes* log field.

FLDIGI\_AZ

The text (azimuth in degrees to other station) contained in the *Az* log field.

### Notifier variables

The following variables are created in the environment of child processes created by the notifier.

FLDIGI\_NOTIFY\_STRi

These variables (i in \[0,9\]) contain substrings matched by capturing groups in the event’s regular expression. 0 contains the whole matched text.

FLDIGI\_NOTIFY\_STR\_NUM

The number of substrings available.

FLDIGI\_NOTIFY\_CALLSIGN

Builtin event types that match callsigns will place the callsign in this variable.

FLDIGI\_NOTIFY\_TEXT

The complete string that matched the event’s regular expression.

FLDIGI\_NOTIFY\_AUDIO\_FREQUENCY

The modem frequency.

FLDIGI\_NOTIFY\_EVENT

The event type.

FLDIGI\_NOTIFY\_COUNTRY

The station’s country name (for events of type "station heard twice").

### Debugging variables

The following variables are only used if fldigi was built with debugging support (*--enable-debug*), or they are only useful when debugging specific modules.

FLDIGI\_NO\_EXEC

If set, this variable disables glibc’s malloc debugging, which fldigi enables by default when built for debugging.

FLDIGI\_TRACE\_LOCKS

Traces *Fl::lock()* calls.

FLDIGI\_HAMLIB\_DEBUG

Initialises hamlib in debug mode.

## RESTRICTIONS

Fldigi is licensed under the GNU GPL, which grants you the right to run the program for any purpose (freedom 0). However, permission to use it for the transmission of radio signals can only be obtained from the communications authority of your country. When given, this permission almost always comes in the form of an amateur radio license.

If you do not have an amateur radio license you can still have fun using fldigi as a shortwave listener. One way to do so is by using the builtin PSK Reporter client to submit realtime spots of transmitting stations; see RESOURCES below. All you need is a computer, homebrew SDR receiver, and simple wire antenna!

## FILES

Various files and subdirectories are created in $HOME/.fldigi. Some of the most interesting ones are listed below.

fldigi\_def.xml

The main settings file.

fldigi.prefs

The “status” file. Stores window geometries, button states, current modem, current audio frequency, squelch level, and so on.

status\_log.txt

The event log.

macros/macros.mdf

The default macro file.

palettes/

This directory contains waterfall palettes.

scripts/

This directory is added to the PATH environment variable of the child process that runs \<EXEC\> macros.

logs/

This directory contains logged received and sent text (when such logging is enabled), including the default logbook database, logbook.adif.

images/

Received MFSK images are automatically saved in this directory.

freqanalysis.csv

This file is written by the frequency analysis modem. The fields are dial frequency, audio frequency, and offset. See documentation for details.

**Note**\

The following files are used if present. They must be downloaded and copied to ~/.fldigi/ by the user.

cty.dat

List of DXCC entities and callsign prefixes; used to display tooltips in the received text buffer, and also to auto-fill the Country, Locator and Azimuth log fields. Available at http://www.country-files.com/cty/.

lotw1.txt

List of known LOTW users (one callsign per line); used for the received text tooltips. Available at http://www.hb9bza.net/lotw/.

AGMemberList.txt or eqsl.txt

List of “Authenticity Guaranteed” eQSL users (one callsign per line); used for the received text tooltips. Available at http://www.eqsl.cc/QSLcard/Programming.cfm.

## EXAMPLES

fldigi --wfall-height 144 --font sans:11 -fg "#c0c0c0" -bg "#5f5f63" -bg2 "#19213b"

This is how the author of this document invokes fldigi.

fldigi --xmlrpc-deny "main.(tx\|tune\|run\_macro)"

Unregister XML-RPC methods that may transmit.

ssh -L 7362:localhost:7362 remote-host xvfb-run fldigi -display :99

Start fldigi on *remote-host* under a “fake” X server. (The [xvfb-run(1)](/xvfb-run/1.md) utility is available on Debian systems). The remote “headless” fldigi is then controlled via XML-RPC on port 7362, i.e from flrig, flamp etc.

fldigi --benchmark-input 480000 --benchmark-modem 1

Benchmark the DominoEX-4 modem with 480K audio samples.

fldigi --benchmark-input audio.wav --benchmark-modem 25 --benchmark-frequency 1500 --benchmark-afc 1 --benchmark-squelch 1 --benchmark-squelch-level 5.0 --benchmark-output out.txt

Read *audio.wav* (whose sample rate must be 8000Hz in this case) and decode BPSK-31 signals at 1500Hz. AFC is enabled and the squelch is set to 5%. Decoded text is saved to *out.txt*.

## BUGS

Yes.

## SEE ALSO

[fldigi-shell(1)](/fldigi-shell/1.md), [gmfsk(1)](/gmfsk/1.md), [gpsk31(1)](/gpsk31/1.md), [grig(1)](/grig/1.md), [rigctl(1)](/rigctl/1.md), [xlog(1)](/xlog/1.md), [getaddrinfo(3)](/getaddrinfo/3.md), [getopt(3)](/getopt/3.md), [regex(7)](/regex/7.md), [X(7)](/X/7.md)

## RESOURCES

Main web site: http://www.w1hkj.com/Fldigi.html

Sourceforge project page: http://sourceforge.net/projects/fldigi/

Wiki and bug tracker: https://fedorahosted.org/fldigi/

More information on MFSK16, DominoEX and other digital modes can be found at http://www.qsl.net/zl1bpu/ and http://www.w1hkj.com/FldigiHelp/Modes/index.htm

The PSK Automatic Propagation Reporter site can be found at http://www.pskreporter.info/

## AUTHORS

Fldigi was written by

• David Freese, W1HKJ.

• Stelios Bounanos, M0GLD.

• Leigh L. Klotz, Jr., WA5ZNU.

Fldigi also includes code written by others. Among them are

• Tomi Manninen, OH2BNS.

• Pawel Jalocha, SP9VRC.

• Hamish Moffatt, VK3SB.

This manual page was written by Stelios Bounanos \<sb\[at\]enotty(dot)net\>.

## COPYING

License GPLv3+: GNU GPL version 3 or later.