Fldigi

Last updated

Fldigi
Developer(s) Dave Freese (W1HKJ), et al. [1]
Initial release2007
Stable release
4.1.19 / 24 June 2021;2 years ago (2021-06-24) [2]
Repository sourceforge.net/p/fldigi/fldigi/ci/master/tree/
Written in FLTK, C, C++
Operating system Windows, macOS, Linux, Android, FreeBSD [3]
Platform IA-32, x64, IA-64, armel, armhf, mips, mipsel, PowerPC, s390, s390x, SPARC, Raspberry Pi
Size About 6.5 MB
Available in7 languages
List of languages
English, Italian, Spanish, French, German, Polish, Dutch
Type Amateur radio and DSP
License GPL version 3.0
Website www.w1hkj.com OOjs UI icon edit-ltr-progressive.svg

Fldigi (short for Fast light digital) [4] is a free and open-source program which allows an ordinary computer's sound card to be used as a simple two-way data modem. The software is mostly used by amateur radio operators who connect the microphone and headphone connections of an amateur radio SSB or FM transceiver to the computer's headphone and microphone connections, respectively. [5] [6]

Contents

This interconnection creates a "sound card defined radio" whose available bandwidth is limited by the sound card's sample rate and the external radio's bandwidth.

Such communications are normally done on the shortwave amateur radio bands in modes such as PSK31, MFSK, RTTY, Olivia, and CW (Morse code). Increasingly, the software is also being used for data on VHF and UHF frequencies using faster modes such as 8-PSK.

Using this software, it is possible for amateur radio operators to communicate worldwide while using only a few watts of RF power.

Fldigi software is also used for amateur radio emergency communications when other communication systems fail due to natural disaster or power outage. Transfer of files, emails, and FEMA ICS forms are possible using inexpensive radio hardware. [7] [8] [9] [10]

Supported digital modes

Mode nameSpeeds supportedCustom modes
Morse code CW5–50 words-per-minuteYes
PSK 31, 63, 63F, 125, 250, 500, 1000No
FSQ2, 3, 4.5, 6No
IFKP [11] 0.5, 1.0, 2.0No
Contestia4/125, 4/250, 8/250, 4/500, 8/500, 16/500, 8/1000, 16/1000, 32/1000, 64/1000Yes
DominoEXMicro, 4, 5, 8, 11, 16, 22, 44, 88No
Hellschreiber Feld Hell, Slow Hell, Feld Hell X5, Feld Hell X9, FSK Hell, FSK Hell-105, Hell 80No
MFSK 4, 8, 11, 16, 22, 31, 32, 64, 64L, 128, 128LNo
MT63 500S, 1000S, 2000S, 500L, 1000L, 2000LNo
Navtex Navtex No
Olivia4/250, 8/250, 4/500, 8/500, 16/500, 8/1000, 16/1000, 32/1000, 64/2000Yes
QPSK 31, 63, 125, 250, 500No
8PSK 125, 250, 500, 1000, 125FL, 250FL, 125F, 250F, 500F, 1000F, 1200FNo
PSKR 125R, 250R, 500R, 1000RNo
RTTY 45.45/170, 50/170, 75/170, 75/850Yes
SYNOP SYNOP No
THORMicro, 4, 5, 8, 11, 16, 22, 25x4, 50x1, 50x2 100No
SITORB SitorBNo
Throb / ThrobX1, 2, 4   /   X1, X2, X4No
WEFAX IOC-576, [12] IOC288No
OFDM 500F, 750F, 3500No

Portability

Operating systems

Fldigi is based on the lightweight portable graphics library FLTK and the C/C++ language. Because of this, the software can run on many different operating systems such as:

Additionally, Fldigi is designed to compile and run on any POSIX compliant operating system that uses an X11 compatible window system / graphical user interface. [17]

Architectures

The Fldigi software is written in highly portable C/C++ and can be used on many CPU architectures, including:

Sound systems

Multiple sound systems are supported by Fldigi, allowing the program to abstract the sound card hardware across differing hardware and operating systems.

Features

The Fldigi Suite

The "Fldigi Suite" consists of the Fldigi modem and all extension programs released by the same development group. Most of these extensions add more capabilities to Fldigi such as verified file transfer and message passing. Interconnection between these programs and the Fldigi modem is made over TCP/IP port 7322. [22]

Some of the Suite are however standalone programs used for utility or testing purposes only, with no connection to the Fldigi main modem.

Flamp

Flamp implements the Amateur Multicast Protocol by Dave Freese, W1HKJ [23] and is a tool for connectionless transferring of files to multiple users simultaneously without requiring any existing infrastructure. The program breaks a given file into multiple smaller pieces, checksums each piece, then transmits each piece one or more times. When all parts are correctly received the sent file is re-assembled and can be saved by receiving stations. [24] This program is useful for multicasting files over lossy connections such as those found on High frequency (HF) or during emergency communications.

Flarq

Flarq implements the ARQ specification developed by Paul Schmidt, K9PS [25] to transfer emails, text files, images, and binary files over radio. This protocol is unicast and connection-based. The software seamlessly integrates with existing email clients such as Microsoft Outlook, Mozilla Thunderbird, and Sylpheed. [26]

Flmsg

Flmsg allows users to send, receive, edit, and create pre-formatted forms. Such a system speeds the flow of information during emergency communications. The software has a number of forms built-in including FEMA ICS forms, MARS reports & messages, Hospital ICS forms, Red Cross messages, IARU and NTS messages. [27]

Flwrap

Flwrap is a tool for the sending of files using a simplified drag and drop interface. Data compression is available also, which reduces data transfer times. [28]

FLNet

FLNet assists net control operators in keeping track of multiple stations during digital amateur radio nets. [29]

FLLog

FLLog is a logging software which keeps track of conversations between amateur radio operators in a database format known as ADIF. [30]

FLWkey

FLWkey is a simple interface to control an external piece of hardware called a Winkeyer. [31] This is a Morse code keyer which is adjustable via computer commands over USB. [32]

Flcluster

This is a telnet client to remote DX cluster servers, which is a real-time reporting of stations heard transmitting, and their frequencies. It does not connect to Fldigi. [33]

Flaa

Flaa is a control program for use with the RigExpert AA-xxxx series of antenna analyzers, and does not connect to Fldigi. [34]

Flrig

FLRig is a component of the FLDigi suite of applications that enables computer aided control of various radios using a serial or USB connection. [35]

Using FLRig in combination with FLDigi, events such as frequency, power level, receiver gain and audio gain may be adjusted from the computer automatically or by user intervention.

Test tools

The Fldigi development group also releases a number of open-source programs which assist in the testing, development, and comparison of different modes within Fldigi, such as LinSim, CompText, and CompTTY.

RSID

To identify the mode being transmitted a signal called an RSID, or Reed-Solomon Identifier, can be transmitted before the data. Using this identifier the receiving software can automatically switch to the proper mode for decoding. The assigning of these identifiers to new modes is coordinated to ensure inter-operation between programs. [36] Currently 7 sound card-digital-modem programs support this standard:

RSID operates by sending a short burst of a specific modulation before the data signal, which can be used to automatically identify over 272 digital modes. This burst consists of a 10.766 baud 16-tone MFSK modulation where 15 tones/symbols are sent. The burst occupies 172 Hz of bandwidth and lasts for 1.4 seconds. [36]

Software architecture

For simple keyboard-to-keyboard communication Fldigi can be operated using just the main window. For more complex uses or file transfer external programs can be attached to the internal TCP/UDP ports 7322 (ARQ), 7342 (KISS), and 7362 (XML-RPC).

The image below helps to illustrate the interconnections and signal-flow within the Fldigi architecture.

Fldigi softmodem flowchart FLdigi FLowchart.png
Fldigi softmodem flowchart

Community-provided extensions

Fldigi allows external programs to attach and send / receive data by connecting to port 7322/ARQ or 7342/KISS. When used this way, Fldigi and the computer's sound card are acting as a "softmodem" allowing text or data sent on one computer to be transferred using the wireless radio link in-between. Programs which have a history of use with Fldigi as the underlying modem include:

Awards and recognitions

Notable users

Disaster relief services

The software is also utilized by some organizations for both routine and disaster/emergency relief services.

Shortwave broadcasters

Following the successful tests by the Voice of America's VOA Radiogram program, international and government shortwave broadcasters began testing and experimenting with digital data over shortwave broadcast channels using the Fldigi software. [50] These tests led to regular weekly digital broadcasts by the broadcasters listed below.

MARS

The Fldigi suite of programs has become popular within the U.S. Army and U.S. Air Force Military Auxiliary Radio System. [56] [57]

Department of Homeland Security

Fldigi is being used in-testing as part of the Department of Homeland Security Shares program, which utilizes "existing HF radio resources of government, critical infrastructure, and disaster response organizations to coordinate and transmit emergency messages" [58] [59]

PSK Mail

Fldigi is used as the underlying modem for the PSKmail project. [37] PSK Mail allows users to retrieve and send normal emails over radio.

AirChat

In 2014, the group Anonymous released a communications tool named AirChat, which used Fldigi as the underlying modem. This provided a low speed yet reliable data connection using only moderate radio hardware. The AirChat software allows for anonymous transmissions of both encrypted and unencrypted messages over unencrypted channels. [60] [61] [62]

Decodeable broadcasts

The broadcasts listed below are transmitted on a regular schedule and can be decoded using Fldigi.

See also

Related Research Articles

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