[sound clips]      ["waterfall" audio spectrums]      [mode descriptions]

 

Below are examples of sounds from digital radio modes on short wave. More info on most of these modes is provided further down on this page. These recordings can be used to test your digi-mode decoding software and receiver-PC interface.

This page uses HTML5 for playing audio. This is supported by modern browsers. Hence, it is not supported by Internet Explorer 8 and earlier versions. For older browsers, links are provided to the audio files in mp3, wav, and ogg format.


HELLSCHEIBER MODES

 

  Feld Hell

  Feld-Hell. Text: "The quick brown fox jumps over the lazy dog ..."

 Feld-Hell QSO: Weekly Sunday European Hell Net around 3580 kHz; 18 minutes. Recorded on 14-Sept-2008 by Bill, KA8VIT via this great web-SDR in The Netherlands. 

 Hell-72 "GL": character set (sorry, the sound of my machine is a little scratchy).

 Feld Hell: QSO with both start-stop and synchronous transmissions, recorded on 1-Mar-2010 around 7050 kHz

  Hell-80: synchronous mode (i.e., not start-stop)

  Hell-80: QSO in start-stop mode, recorded on 24-Jan-2011 (Part 1). Click here for a scan of the associated paper tape print-out.

  Hell-80: QSO in start-stop mode, recorded on 24-Jan-2011 (Final).

  Thomson Hellschreiber (see here): 2x entire character set. Can be printed with Feld-Hell (set to about 1250 Hz), or in Hell-FM105/254 mode (set to 1325 Hz "space" tone).

  Hell-FM/105.

  Hell-FM/245.

  Hell-PSK/105.

  Hell-PSK/245.

  C/MT Hell. Text appears in waterfall display.

  Duplo Hell.

 

For everything that is related to "Hellschreiber", see my Hellschreiber website.

 

FREQUENCY-SHIFT KEYING (FSK) MODES

 

  Radio Teletype (RTTY, "ritty"): 170 Hz shift, 45.45 Bd

  Radio Teletype (RTTY): 170 Hz shift, 50 Bd

  Radio Teletype (RTTY): 425 Hz shift, 50 Bd 

  Radio Teletype (RTTY): 850 Hz shift, 50 Bd

  SYNOP/SHIP: 450 Hz shift, 50 Bd; Weather synopsis data from station DDK9 (Germany) on 10100 kHz; recorded 5-Apr-2010.

  Telex Over Radio (TOR): PACTOR R 200 Bd

  Telex Over Radio (TOR): PACTOR2

  Telex Over Radio (TOR): Amateur PACTOR FEC (FEC = Foward Error Correction)

  Telex Over Radio (TOR): AMTOR ARQ (ARQ = Automatic Repeat Request)

  Telex Over Radio (TOR): AMTOR FEC

  Telex Over Radio (TOR): Amateur G-TOR; more info here.

  Telex Over Radio (TOR): Swedish ARQ

  Simplex Telex Over Radio (SITOR): SITOR-A ( = ARQ) = AMTOR

  Simplex Telex Over Radio (SITOR): SITOR-A Marker

  Simplex Telex Over Radio (SITOR): SITOR-B ( = FEC) = NAVTEX

  PACKET: AX25, 300 Bd; more info on this mode here and here.

  PACKET: AX25, 300 Bd; second example.

  Voice-Frequency RTTY (VFT): VFT; comprises 16 closely packed RTTY signal pairs.

  Voice-Frequency RTTY (VFT): VFT(US Air Force)

 

MULTI-FREQUENCY SHIFT KEYING (MFSK) MODES  (more info on these modes is here)

 

  MFSK8 (8 tones); text: "The quick brown fox jumps over the lazy dog ..."

  MFSK16 (16 tones); text: "The quick brown fox jumps over the lazy dog ..."

 MFSK16 (16 tones); second example.  

 MFSK16 (16 tones); amateur radio QSO.

 Olivia 125-4 (a spread-spectrum AFSK TOR FEC mode - more info here).

  Olivia 250-8

  Olivia 500-16

  Olivia 1000-32

  Olivia 2000-64

  Olivia 2000-128

  Contestia 4-250

  MT63-500

  MT63-1000.

  MT63-2000

  THROB-1

  THROB-2

  THROB-4

 THROBX-1  

 THROBX-2

 THROBX-4

  PICCOLO

  DominoEx-4

  DominoEx-8

  DominoEx-16

  JT65A

  ROS

  ARQ-M2 (Moore Code)

 

PHASE-SHIFT KEYING (PSK) MODES

 

  PSK31; more info here, here, and here.

  BPSK

 QPSK31  

 QPSK 15-tone AX25 SABM packet

 FSK31

  Amateur Clover, full-duplex

 

"MORSE CODE" CW

 

  CW, speed = 5 WMP

  CW, speed = 12 WMP

 CW, speed = 17 WMP  

 CW, speed = 21 WMP

 Coherent CW on MS25 and ET 1 calling CQ

 

ARRL/W1AW code practice files (various speeds).

 

PICTURE TRANSMISSION MODES (SSTV, NBTV)

 

  Slow-Scan Television (SSTV): Scotty1 format

  Slow-Scan Television (SSTV): Martin1 format

 Slow-Scan Television (SSTV): another example

 Slow-Scan Television (SSTV): another example

 Narrow-Band television (NBTV): sequence of 4 images

 

NBTV is originally from the 1920-1930s, still used today by a few amateurs; transmission has 10 kHz bandwidth. More info on this mode here and here.

 

DIGITAL VOICE MODES

 

  FDMDV

  D-STAR (Digital - Smart Technologies for Amateur Radio)

 AOR-DV

 MOTOTRBO (Motorola Digital Two-Way Radio, compatible with Digital Mobile Radio (DMR) Tier 2 standard)

 

Here is a presentation on this mode by ZS1AN.

 

WEATHER

 

  Weather Facsimile (WEFAX); recorded on 7878.1 kHz, USB, 120 lines/minute; weather station Offenbach/Germany.

  RTTY SYNOP weather report; 450 Hz shift, 50 Bd

 

 

AVIATION, NAVIGATION, GOVERNMENT, UTILITIES

 

  Non-Directional Beacon (NDB); these aviation navigation beacons are in the 190-1750 kHz frequency band (190-1535 kHz in the USA)

  DECCA: HF radio navigation system

 LORAN-C: long-range radio navigation system 

 Aircraft Communications Addressing & Reporting System (ACARS).

 GMDSS: Marine Selective Calling (SELCAL) system (presumed)

  Hyperbolic Radio Navigation  System

  ICAO Aeronautical Selective Calling (SELCAL)

  DCF77 time station signal

  Digital Voice scrambling (US government/militray)

  Differential-GPS: Minimum Shift Keying

  Differential-GPS: Quaternary Phase Shift Keying

  Link-11 network (NATO/military)

  Over-The-Horizon radar (OTHR); military

  SELCAL Link-Availability Sounder

  High-Frequency Active Auroral Research Program (HAARP)

 

DIGITAL BROADCAST (Long/Medium/Shortwave bands, AM)

 

  Digital radio Mondiale (DRM): IF sample of Radio Luxemburg, 6095 kHz

Digital Audio Broadcasting (DAB): sorry, no audio files yet... Primarily used in 175-220 MHz band

 

Links to other web-pages with radio sound samples

 
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DM780 (with waterfall images)

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KB9UKD

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EA2BAJ

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NB6Z

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other

 

IF YOUR BROWSER DOES NOT SUPPORT HTML5 AUDIO FOR MP3, WAV, OR OGG FILE FORMAT...

Below, you can select the same audio files as above, but use the audio player of your choice.

HELLSCHEIBER MODES

 

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Feld-Hell: .wav file, .mp3 file, .ogg file.

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Feld-Hell: .wav file, .mp3 file, .ogg file. Text: "The quick brown fox jumps over the lazy dog ..."

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Feld-Hell QSO: .wav file, .mp3 file, .ogg file. Weekly Sunday European Hell Net around 3580 kHz; 18 minutes. Recorded on 14-Sept-2008 by Bill, KA8VIT via this great web-SDR in The Netherlands.

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Hell-72 "GL": .wav file, .mp3 file, .ogg file (character set).

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Hell-80:  .wav file, .mp3 file, .ogg file. Sychronous mode (i.e., not start-stop).

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Hell-80:  .wav file, .mp3 file, .ogg file. Recording of a real Hell-80 transmissions (both start-stop and asynchronous mode). Recorded 1 March 2010 around 7050 kHz.

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Hell-80:  .wav file, .mp3 file, .ogg file. QSO, start-stop mode, 24-Jan-2011 - Part 1

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Hell-80:  .wav file, .mp3 file, .ogg file. QSO, start-stop mode, 24-Jan-2011 - Final.

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Thomson Hellschreiber: .wav file, .mp3 file, .ogg file (2x full character set); can be printed with Feld-Hell (set to about 1250 Hz), or in Hell FM105/254 mode (set to the 1325 Hz "space" tone).

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Hell-FM/105: .wav file, .mp3 file, .ogg file.

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Hell-FM/245: .wav file, .mp3 file, .ogg file.

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Hell-PSK/105: .wav file, .mp3 file, .ogg file.

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Hell-PSK/245: .wav file, .mp3 file, .ogg file.

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C/MT Hell: .wav file, .mp3 file, .ogg file (text appears in waterfall display)

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Duplo-Hell: .wav file, .mp3 file, .ogg file. 

 

FREQUENCY-SHIFT KEYING (FSK) MODES

 

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Radio Teletype (RTTY, "ritty"), 170 Hz shift, 45.45 Bd: .wav file, .mp3 file, .ogg file.

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Radio Teletype (RTTY), 170 Hz shift, 50 Bd: .wav file, .mp3 file, .ogg file.

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Radio Teletype (RTTY), 425 Hz shift, 50 Bd: .wav file, .mp3 file, .ogg file.

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Radio Teletype (RTTY), 850 Hz shift, 50 Bd: .wav file, .mp3 file, .ogg file.

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SYNOP/SHIP: 450 Hz shift, 50 Bd: .wav file, .mp3 file, .ogg file. Weather synopsis data from station DDK9 (Germany) on 10100 kHz; recorded 5-Apr-2010.

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Telex Over Radio (TOR), PACTOR R 200 Bd: .wav file, .mp3 file, .ogg file.

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Telex Over Radio (TOR), PACTOR2: .wav file, .mp3 file, .ogg file.

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Telex Over Radio (TOR), Amateur PACTOR FEC (FEC = Foward Error Correction): .wav file, .mp3 file, .ogg file.

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Telex Over Radio (TOR), AMTOR ARQ (ARQ = Automatic Repeat Request): .wav file, .mp3 file, .ogg file.

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Telex Over Radio (TOR), AMTOR FEC: .wav file, .mp3 file, .ogg file.

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Telex Over Radio (TOR), Amateur G-TOR: .wav file, .mp3 file, .ogg file. More info here.

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Telex Over Radio (TOR), Swedish ARQ: .wav file, .mp3 file, .ogg file.

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Simplex Telex Over Radio (SITOR), SITOR-A ( = ARQ) = AMTOR: .wav file, .mp3 file, .ogg file.

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Simplex Telex Over Radio (SITOR), SITOR-A Marker: .wav file, .mp3 file, .ogg file.

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Simplex Telex Over Radio (SITOR), SITOR-B ( = FEC) = NAVTEX: .wav file, .mp3 file, .ogg file.

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PACKET: AX25, 300 Bd: .wav file, .mp3 file, .ogg file. More info on this mode here and here.

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PACKET: AX25, 300 Bd, second example: .wav file, .mp3 file, .ogg file.

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Voice-Frequency RTTY (VFT), VFT: .wav file, .mp3 file, .ogg file. Comprises 16 closely packed RTTY signal pairs.

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Voice-Frequency RTTY (VFT), VFT(US Air Force): .wav file, .mp3 file, .ogg file.

 

MULTI-FREQUENCY-SHIFT KEYING (MFSK) MODES  (more info on these modes is here)

 

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MFSK8: .wav file, .mp3 file, .ogg file.

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MFSK16, "The quick brown fox...": .wav file, .mp3 file, .ogg file.

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MFSK16: .wav file, .mp3 file, .ogg file.

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MFSK16, QSO: .wav file, .mp3 file, .ogg file.

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Olivia 125-4: .wav file, .mp3 file, .ogg file. This is a spread-spectrum AFSK TOR FEC mode - more info here.

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Olivia 250-8: .wav file, .mp3 file, .ogg file.

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Olivia 500-16: .wav file, .mp3 file, .ogg file.

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Olivia 1000-32: .wav file, .mp3 file, .ogg file.

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Olivia 2000-64: .wav file, .mp3 file, .ogg file.

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Olivia 2000-128: .wav file, .mp3 file, .ogg file.

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Contestia 4-250: .wav file, .mp3 file, .ogg file.

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MT63-500: .wav file, .mp3 file, .ogg file.

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MT63-1000: .wav file, .mp3 file, .ogg file.

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MT63-2000: .wav file, .mp3 file, .ogg file.

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THROB-1: .wav file, .mp3 file, .ogg file.

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THROB-2: .wav file, .mp3 file, .ogg file.

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THROB-4: .wav file, .mp3 file, .ogg file.

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THROBX-1: .wav file, .mp3 file, .ogg file.

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THROBX-2: .wav file, .mp3 file, .ogg file.

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THROBX-4: .wav file, .mp3 file, .ogg file.

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PICCOLO: .wav file, .mp3 file, .ogg file.

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DominoEx-4: .wav file, .mp3 file, .ogg file.

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DominoEx-8: .wav file, .mp3 file, .ogg file.

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DominoEx-16: .wav file, .mp3 file, .ogg file.

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JT65A: .wav file, .mp3 file, .ogg file. More info on this mode is here.

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ROS: .wav file, .mp3 file, .ogg file. More info on this mode is here.

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ARQ-M" (Moore Code): .wav file, .mp3 file, .ogg file.

 

PHASE-SHIFT KEYING (PSK) MODES

 

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PSK31: .wav file, .mp3 file, .ogg file.

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BPSK31: .wav file, .mp3 file, .ogg file.

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QPSK31: .wav file, .mp3 file, .ogg file.

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QPSK, 15-tone AX25 SABM packet: .wav file, .mp3 file, .ogg file.

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FSK: .wav file, .mp3 file, .ogg file.

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Amateur CLOVER: .wav file, .mp3 file, .ogg file. Full duplex.

 

"MORSE CODE" CW

 

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CW "Morse", speed = 5 WPM: .wav file, .mp3 file, .ogg file.

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CW "Morse", speed = 12 WPM: .wav file, .mp3 file, .ogg file.

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CW "Morse", speed = 17 WPM: .wav file, .mp3 file, .ogg file.

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CW "Morse", speed = 21 WPM: .wav file, .mp3 file, .ogg file.

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Coherent CW: .wav file, .mp3 file, .ogg file.

 

ARRL/W1AW code practice files (various speeds).

 

PICTURE TRANSMISSION MODES (SSTV, NBTV)

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Slow-Scan Television (SSTV), Scotty1 format: .wav file, .mp3 file, .ogg file.

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Slow-Scan Television (SSTV), Martin1 format: .wav file, .mp3 file, .ogg file.

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Slow-Scan Television (SSTV), another example: .wav file, .mp3 file, .ogg file.

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Slow-Scan Television (SSTV), another example: .wav file, .mp3 file, .ogg file.

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Narrow Band Television (NBTV): .wav file, .mp3 file, .ogg file.

 

NBTV is originally from the 1920-1930s, still used today by a few amateurs; transmission has 10 kHz bandwidth. More info on this mode here and here.

 

DIGITAL VOICE MODES

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FDMDV: .wav file, .mp3 file, .ogg file.

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D-STAR (Digital - Smart Technologies for Amateur Radio): .wav file, .mp3 file, .ogg file.

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AOR-DV: .wav file, .mp3 file, .ogg file.

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MOTOTRBO: .wav file, .mp3 file, .ogg file; Motorola Digital Two-Way Radio, compatible with Digital Mobile Radio (DMR) Tier 2 standard)

Here is a presentation on this mode by ZS1AN.

WEATHER

 

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SYNOP RTTY, 450 Hz shift, 50 Bd: .wav file, .mp3 file, .ogg file.

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Weather facsimile (WEFAX): .wav file, .mp3 file, .ogg file. Recorded on 7878.1 kHz, USB, 120 lines/minute; weather station Offenbach/Germany)

 

AVIATION, NAVIGATION, GOVERNMENT, UTILITIES

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Non-Directional Beacon (NDB): .wav file, .mp3 file, .ogg file. Aeronautical navigation beacons in the 190-1750 kHz frequency band (190-1535 kHz in the USA).

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DECCA HF Radio Navigation System: .wav file, .mp3 file, .ogg file.

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LORAN-C Log Range Radio Navigation System: .wav file, .mp3 file, .ogg file.

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Aircraft Communications Addressing and Reporting System (ACARS): .wav file, .mp3 file, .ogg file.

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GMDSS Marine SELCAL System (TBC): .wav file, .mp3 file, .ogg file. Weather synopsis data from station DDK9 (Germany) on 10100 kHz; recorded 5-Apr-2010.

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Hyperbolic Radio Navigation System: .wav file, .mp3 file, .ogg file.

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ICAO Aeronautical SELCAL: .wav file, .mp3 file, .ogg file.

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DCF77 Time Station: .wav file, .mp3 file, .ogg file.

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Digital Voice Scrambling (US government/military): .wav file, .mp3 file, .ogg file.

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Differential GPS, Minimum Shift Keying: .wav file, .mp3 file, .ogg file.

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Differential GPS, Quaternary Phase Shift Keying: .wav file, .mp3 file, .ogg file. More info here.

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Link-11 Network (NATO/military): .wav file, .mp3 file, .ogg file.

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Over-The-Horizon Radar (OTHR; probably US military): .wav file, .mp3 file, .ogg file.

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SELSCAN Link Availability Sounder (presumed): .wav file, .mp3 file, .ogg file.

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High-Frequency Active Auroral Research Program (HAARP): .wav file, .mp3 file, .ogg file.

 

DIGITAL BROADCAST (Long/Medium/Shortwave bands, AM)

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Digital Radio Mondiale (RDM): .wav file, .mp3 file, .ogg file. IF sample of Radio Luxemburg, 6095 kHz

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Digital Audio Broadcast: sorry, no audio files yet. Primarily used in 175-220 MHz band

 

Links to other web-pages with radio sound samples

 
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DM780 (with waterfall images)

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KB9UKD

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EA2BAJ

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NB6Z

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other

- FFT spectra of the Hell modes are here-

audio spectrum with hellschreiber, MFSK, and RTTY signals
Audio spectrum, left to right: simultaneous Hellschreiber, MFSK, and RTTY signals

Feld Hell

 

Hell 72 GL (shifted to 900 Hz)

 

Hell 80 (shifted to 900 Hz)

 

Hell FM-105

 

Hell FM-245

 

Hell PSK-105

 

Hell PSK-245

 

Duplo Hell

 

C/MT Hell

 


Hell Thomson (shifted to 900 Hz)

 

RTTY 170 (shifted to 1000 Hz)

 

RTTY 425 (shifted to 1000 Hz)

 

RTTY 850 (shifted to 1000 Hz)

 

DominoEx-4

 

DominoEx-8

 

DominoEx-16

 

MT63-500

 

MT63-1000

 

MT63-2000

 

Olivia 125-4

 

Olivia 250-8

 

Olivia 500-16

 

Olivia 1000-32

 

Olivia 2000-64

 

Olivia 2000-128

 

JT65A

 

ROS

 

Throb-1

 

Throb-2

 

Throb-4

 

ThrobX-1

 

ThrobX-2

 

ThrobX-4

 


SSTV - Scotty1

 


Weather Fax
 


NBTV

 

FDMDV

TOR is an acronym for Teleprinting Over Radio. It is traditionally used to describe the three popular "error free" operating modes, AMTOR, PACTOR and G-TOR. The main method for error correction is from a technique called ARQ (automatic repeat request) which is sent by the receiving station to verify any missed data. Since they share the same method of transmission (FSK), they can be economically provided together in one TNC modem and easily operated with any modern radio transceiver. TOR methods that do not use the ARQ hand-shake can be easily operated with readily available software programs for personal computers. For these less complex modes, the TNC (terminal node controller) is replaced by an on-board sound card or out-board audio device. These modes may use redundancy or "human processing" to achieve a level of error correction.

AMTOR is an FSK mode that has been fading into history. While a robust mode, it only has 5 bits (as did its predecessor RTTY) and can not transfer extended ASCII or any binary data. With a set operating rate of 100 baud, it does not effectively compete with the speed and error correction of more modern ARQ modes. The non-ARQ version of this mode is known as FEC, and known as SITOR-B by the Marine Information services.

PACTOR is an FSK mode and is a standard on modern TNCs. It is designed with a combination of packet and Amtor Techniques. It is the most popular ARQ digital mode on amateur HF today. This mode is a major advancement over AMTOR, with its 200 baud operating rate, Huffman compression technique and true binary data transfer capability; more info here

G-TOR (Golay -TOR) is an FSK mode that offers a fast transfer rate compared to Pactor. It incorporates a data inter-leaving system that assists in minimizing the effects of atmospheric noise and has the ability to fix garbled data. G-tor tries to perform all transmissions at 300 baud but drops to 200 baud if difficulties are encountered and finally to 100 baud. (The protocol that brought back those good photos of Saturn and Jupiter from the Voyager space shots was devised by M.Golay and now adapted for ham radio use.)

PACTOR II is a robust and powerful PSK mode which operates well under varying conditions. It uses strong logic, automatic frequency tracking; it is DSP based and as much as 8 times faster then Pactor. Both PACTOR and PACTOR-2 use the same protocol handshake, making the modes compatible; more info here.

PACTOR-III is a proprietary mode used for message and traffic handling over an HF radio circuit. Use of Pactor-III protocol is limmitted for US hams and some other countries due to the very wide bandwidth of the Pactor-III signal. Presently digital signals that occupy the bandwidth of PCT-III are restricted to a few sub bands:
28.120-28.189 MHz, 24.925-24.930 MHz, 21.090-21.100 MHz, 18.105-18.110 MHz, 14.0950-14.0995 MHz, 14.1005-14.112 MHz, 10.140-10.150 MHz, 7.100-7.105 MHz, or 3.620-3.635 MHz.
Only the embedded hardware (modem) from the German company that owns the rights to this mode, is capable of operating Pactor-III.

CLOVER is a PSK mode which provides a full duplex simulation. It is well suited for HF operation (especially under good conditions), however, there are differences between CLOVER modems. The original modem was named CLOVER-I, the latest DSP based modem is named CLOVER-II. Clovers key characteristics are band-width efficiency with high error-corrected data rates. Clover adapts to conditions by constantly monitoring the received signal. Based on this monitoring, Clover determines the best modulation scheme to use; more info here

RTTY or "Radio Teletype" is a FSK mode that has been in use longer than any other digital mode (except for morse code). RTTY is a very simple technique which uses a five-bit code to represent all the letters of the alphabet, the numbers, some punctuation and some control characters. At 45 baud (typically) each bit is 1/45.45 seconds long, or 22 msec and corresponds to a typing speed of 60 WPM. There is no error correction provided in RTTY; noise and interference can have a seriously detrimental effect. Despite it's relative disadvantages, RTTY is still popular with die-hard operators; more info here

PSK31 is the first new digital mode to find popularity on HF bands in many years. It combines the advantages of a simple variable length text code with a narrow bandwidth phase-shift keying (PSK) signal using DSP techniques. This mode is designed for "real time" keyboard operation and at a 31 baud rate is only fast enough to keep up with the typical amateur typist. PSK31 enjoys great popularity on the HF bands today and is presently the standard for live keyboard communications. Most of the ASCII characters are supported. A second version having four (quad) phase shifts (QPSK) is available that provides Forward Error Correction (FEC) at the cost of reduced Signal to Noise ratio. Information on getting started with this mode and other sound card modes is available here .

HF PACKET radio is a FSK mode that is an adaption of the very popular Packet radio used on VHF FM ham radio. Although the HF version of Packet Radio has a much reduced bandwidth due to the noise levels associated with HF operation, it maintains the same protocols and ability to "node" many stations on one frequency. Even with the reduced bandwidth (300 baud rate), this mode is unreliable for general HF ham communications and is mainly used to pass routine traffic and data between areas where VHF repeaters maybe lacking.

HELLSCHREIBER is a method of sending and receiving text using facsimile technology. This mode has been around along time; the recent use of PC sound cards as DSP units has increased the interest in Hellschreiber. The single-tone version (Feld-Hell) is the method of choice for HF operation. It is an on-off keyed system with 122.5 dots/second, or about a 35 WPM text rate, with a narrow bandwidth (about 75 Hz). Text characters are "painted" on the screen, as apposed to being decoded and printed. A new "designer" flavor of this mode called FM HELL has some advantage for providing better quality print, at the expense of a greater duty cycle. As with other "fuzzy modes" it has the advantage of using the "human processor" for error correction.

MT63 is a new DSP based mode for sending keyboard text over paths that experience fading and interference from other signals. It is accomplished by a complex scheme to encode text in a matrix of 64 tones over time and frequency. This overkill method provides a "cushion" of error correction at the receiving end while still providing a 100 WPM rate. The wide bandwidth (1 kHz for the standard method) makes this mode less desirable on crowded ham bands such as 20 meters.  More info on this 64-tone mode here.

MFSK16 is an advancement to the THROB mode and encodes 16 tones. The PC sound card for DSP uses Fast Fourier Transform technology to decode the ASCII characters, and Constant Phase Frequency Shift Keying to send the coded signal. Continuous Forward Error Correction (FEC) sends all data twice with an interleaving technique to reduce errors from impulse noise and static crashes. A new improved Varicode is used to increase the efficiency of sending extended ASCII characters, making it possible to transfer short data files between stations under fair to good conditions. Similar to SSTV, small images can be transferred (typ. 170x128). The relatively wide bandwidth (316 Hz) for this mode allows higher baud rates (typing is about 42 WPM) and greater immunity to multi path phase shift. This mode is becoming a standard for reliable keyboard-to-keyboard operation and is available in several popular programs. (more info on this mode here)

THROB is yet another new DSP sound card mode that attempts to use Fast Fourier Transform technology (as used by waterfall displays) to decode a 5 tone signal. The THROB program is an attempt to push DSP into the area where other methods fail because of sensitivity or propagation difficulties and at the same time work at a reasonable speed. There are 1, 2, or 4 throbs per second, resulting in a text speed that is lower than other modes. Check the website of the THROB-author (G3PPT)his web site for the latest developments. (more info here)

OLIVIA is a new digital MFSK mode and it seems to be highly resistant to QSB (fading) and noise (QRM). It was created in 2005 by Pawel Jalocha (SP9VRC). Actually, it is a combination of MFSK and Forward Error Correction (FEC that is based on Walsh-functions. As with other modes, Olivia has several variants, each having a different bandwidth (from 500Hz to 2kHz) and different number of tones. Olivia can be very slow (in the order of 2-3 characters per second).  This mode can combine 4-256 tones (2n), with 250, 500, 1000, or 2000 Hz bandwidth. The prevailing standard setting is 32 tones and 1000 Hz with 31.25 baud. This allows ±125 Hz of mis-tuning. Standard frequencies are
7038.5, 14104.5, 14105.5, 14106.5, 14107.5, 14108.5 (calling frequency), 18102.5, 18103.5, 18104.5, 21129.5 kHz (for 1000 Hz AF; USB).

CONTESTIA was derived from OLIVIA by Nick Fedoseev (UT2UZ). It has yet to gain popularity...

NOTES:
Frequency-shift keying (FSK) shifts between two known states. Phase-shift keying (PSK) changes PHASE of a signal against some reference. FSK is sent by either shifting a carrier frequency (F1B) or modulating SSB with two shifting audio tones (AFSK). When sending PSK, a complex audio waveform is transmitted by SSB. Tracking is much more critical for PSK, thus requiring more frequency stability.

DSP (Digital Signal Processing) techniques use high speed processing to convert audio into digital coding, so that a program can manipulate the coded audio in ways not possible with traditional hardware filters. The 16 and 32 bit sound cards found in modern PCs provide this capability.

FUZZY MODES are those modes that allow the human eye/ear/brain to be used to its maximum potential. In order to do this, a number of rules are required, to ensure that any electronics or logic circuitry is not allowed to make decisions which may be less inspired than human decisions. Examples of potentially Fuzzy modes are Morse Code, HFFAX, SSTV and Hellschreiber. The rules are:
   1) The transmissions must be uncoded. (The signal is sent as a real-time language.)
   2) The receiver must not decide when data is present. (Untouched by any prior decisions.)
   3) The receiver must not decide what data is present. (It must be presented as received.)

The above mode descriptions are taken from NB6Z's web page on digital ham radio.

©2005-2010 F. Dörenberg N4SPP

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