The Digital Sounds Library

Click on each link for a sound example.

  1. Motorola Type II Trunked System Control Channel  This 3600 baud channel is used to tell mobile/portable radios which voice frequency to use.  The sound here is the same for Type I newer, and all flavors of Type II, except networked systems.  Try 851 and 869 MHz.

  2. Motorola Type I Trunked System Control Channel  This 3600 baud channel is used to tell mobile/portable radios which voice frequency to use.  Try 851-869 MHz.

  3. Motorola Networked Trunking Control Channel  This 3600 baud channel is used to tell mobile/portable radios which voice frequency to use.  Networked, or "SmartZone" systems use Type II-style IDs, which can span across many distinct transmitter sites over a wide area.  Try 851 and 869 MHz.
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  4. Motorola ASTRO APCO-25 Trunking Control Channel  This 9600 baud channel is used to tell mobile/portable radios which voice frequency to use.  ASTRO is a digital/analog voice trunked radio system. APCO-25 makes it industry standards compliant for smooth interaction with neighboring systems.

  5. Motorola ASTRO APCO-25 IMBE Digital Audio (Trunked)

  6. Motorola ASTRO VCELP Digital Audio

  7. Ericsson EDACS Trunked System Control Channel

  8. Ericsson EDACS Narrowband Trunked System

  9. Ericsson EDACS Transmission Post-Amble

  10. Ericsson EDACS "GE-Gingle" Post-Amble

  11. Motorola MDC4800 MDT Protocol - 4.8k Baud  (Milwaukee PD MDTs at 858.2625 MHz)

  12. Motorola RD-LAP MDT Protocol - 9.6k Baud

  13. Motorola RD-LAP MDT Protocol - 19.2k Baud

  14. Motorola OTAR (Over-the-Air-Rekeying)  Used for DES encryption re-keying of radios.

  15. GE/Ericsson GE-STAR Signaling Protocol  For signaling, emergency, status, etc.

  16. Motorola MODAT Signaling Protocol  For signaling, emergency, status, etc.

  17. RTTY - 45 baud  Radio Teletype (RTTY) sends text as 5 bit characters with no error correction.  45 baud is the amateur standard.  Try around 14.075 MHz SSB.

  18. RTTY - 75 baud  Same as above, except faster at 75 baud.  Commonly used in weather data transfer.  Try 10.536 MHz SSB.

  19. SITOR-A/AMTOR ARQ  Amateur Teletype Over Radio (AMTOR) in Automatic Repeat Request mode sends data in a two frequency mode, one for sending and one for receiving an acknowledge.  The brief pause you hear in this sample is where the receiving station sends the acknowledge burst.

  20. SITOR-B/AMTOR FEC - 100 baud  Amateur Teletype Over Radio (AMTOR), in this case, using Forward Error Correctio (FEC) mode.  Identical format used in Simplex Teletype Over Radio (SITOR), and Navigational Telex (NAVTEX).  Try 14.070 MHz SSB, 6.330 MHz SSB, and 518 kHz SSB.

  21. ROU-FEC - 164.5/218.3 baud  Roumanian FEC

  22. SSTV  Slow Scan Television (SSTV) carries images one frame at a time by using a frequency shift for each pixel.  Try 14.230 MHz SSB.  Check out this pic I received directly from the Mir spacecraft on 145.985 MHz.

  23. WEFAX  Weather Fax (WEFAX) is used to send weather maps and photos primarily to ships at sea and operates similarly to SSTV.  Try 8.080 MHz SSB.

  24. Packet - 300 baud  Amateur packet radio sends data in bursts at 300 baud, and waits for an acknowledge packet from the other end before sending the next packet.  Try 14.105 MHz SSB.

  25. Packet - 1200 baud  Same as above, except faster at 1200 bps.  Try 145.03 MHz NFM.

  26. POCSAG - 512 baud  Post Office Code Standarisation Advisory Group (POCSAG), a paging format originating in the U.K.

  27. POCSAG - 1200 baud  Same as above, only faster at 1200 bps.

  28. POCSAG - 2400 baud  Same as above, only faster yet at 2400 bps.

  29. Golay  Named after a mathematician, Golay is a 600 baud paging signal developed by Motorola.  Motorola DPL uses the same format.  It is a 23 bit repeated word sent at a 134.5 Hz rate.

  30. FLEX  Another paging format.  A great explanation of this mode can be found at this link.

  31. ERMES  European Radio Message System (ERMES) is a 6250 baud paging format used in Europe (France, Hungary, and Malaysia) in the 169 MHz band.  A great explanation of this mode can be found at this link

  32. ARDIS/MDC4800 at 854.8375 MHz  ARDIS is a packet switched data network for two-way data transfer that operates in the 851-866 MHz or 935-941 MHz range.  In Southeastern Wisconsin, it can be heard on 855.8375 and 854.8375 MHz base (and 45 MHz below for mobiles).  A great explanation of this mode can be found at this link.

  33. Mobitex (RAM data service) - Submitted by a U.K. monitor. This format is used in the US between 935 and 940 MHz and in Europe and is similar in use to ARDIS. RAM is a company providing mobile data service over the mobitex protocol.

  34. Paknet data service - Submitted by a U.K. monitor. This is another British commercial data system which operates around 164 MHz. It uses the X.25 protocol system.

  35. Cognito data service - Submitted by a U.K. monitor. This is another British commercial data system which operates around 178 MHz.

  36. GSM digital cellular - Global System for Mobile. Submitted by a U.K. monitor. This form of digital voice transmission is very common in North America, Europe, and the Middle East. Try 890-915 MHz. A great explanation of this mode can be found in this paper.

  37. ARDIS/MDC4800 at 854.8375 MHz  ARDIS is a packet switched data network for two-way data transfer that operates in the 851-866 MHz or 935-941 MHz range.  In Southeastern Wisconsin, it can be heard on 855.8375 and 854.8375 MHz base (and 45 MHz below for mobiles).  A great explanation of this mode can be found at this link.

  38. Mobitex (RAM data service) - Submitted by a U.K. monitor. This format is used in the US between 935 and 940 MHz and in Europe and is similar in use to ARDIS. RAM is a company providing mobile data service over the mobitex protocol.

  39. Cellular Control Channel - This channel tells cell phones what channel to use for voice, and other information. These can be found in the 879-881 MHz range.

  40. ARDIS/MDC4800 at 854.8375 MHz  ARDIS is a packet switched data network for two-way data transfer that operates in the 851-866 MHz or 935-941 MHz range.  In Southeastern Wisconsin, it can be heard on 855.8375 and 854.8375 MHz base (and 45 MHz below for mobiles).  A great explanation of this mode can be found at this link.

  41. Mobitex (RAM data service) - Submitted by a U.K. monitor. This format is used in the US between 935 and 940 MHz and in Europe and is similar in use to ARDIS. RAM is a company providing mobile data service over the mobitex protocol.

  42. EFJ LTR Trunking Control subaudible - Submitted by Bruce in Colorado. This subaudible tone sequence is used to tell mobile radios which voice frequency to use. You will need a set of HEADPHONES or speakers/amplifier with plenty of bass response to hear anything as these tones are "SUBAUDIBLE". The audible tones you hear is just a telephone ring. Try between 851 and 869 MHz.

  43. ARDIS/MDC4800 at 854.8375 MHz  ARDIS is a packet switched data network for two-way data transfer that operates in the 851-866 MHz or 935-941 MHz range.  In Southeastern Wisconsin, it can be heard on 855.8375 and 854.8375 MHz base (and 45 MHz below for mobiles).  A great explanation of this mode can be found at this link.

  44. Mobitex (RAM data service) - Submitted by a U.K. monitor. This format is used in the US between 935 and 940 MHz and in Europe and is similar in use to ARDIS. RAM is a company providing mobile data service over the mobitex protocol.

  45. MPT 1327 Trunking Control Channel - Submitted by a U.K. monitor. This format is very common in European countries, Australia, and South Africa. This channel is used to tell mobile radios which voice frequency to use. Decoder software can be acquired here.
  46. MPT1317 - A data format found in the UK on 86.5875 MHz. It is a variant of MPT1327.

  47. ARDIS/MDC4800 at 854.8375 MHz  ARDIS is a packet switched data network for two-way data transfer that operates in the 851-866 MHz or 935-941 MHz range.  In Southeastern Wisconsin, it can be heard on 855.8375 and 854.8375 MHz base (and 45 MHz below for mobiles).  A great explanation of this mode can be found at this link.

  48. Mobitex (RAM data service) - Submitted by a U.K. monitor. This format is used in the US between 935 and 940 MHz and in Europe and is similar in use to ARDIS. RAM is a company providing mobile data service over the mobitex protocol.

  49. Motorola iDen (Nextel) - A digital modulation scheme used by the Nextel digital cellular system. Found on 851-869 freqs throughout the US.

  50. ARDIS/MDC4800 at 854.8375 MHz  ARDIS is a packet switched data network for two-way data transfer that operates in the 851-866 MHz or 935-941 MHz range.  In Southeastern Wisconsin, it can be heard on 855.8375 and 854.8375 MHz base (and 45 MHz below for mobiles).  A great explanation of this mode can be found at this link.

  51. Mobitex (RAM data service) - Submitted by a U.K. monitor. This format is used in the US between 935 and 940 MHz and in Europe and is similar in use to ARDIS. RAM is a company providing mobile data service over the mobitex protocol.

  52. ACARS - Aircraft Communications And Reporting System is used to transmit aircraft waypoint, temperature, performance, and other data between to and from the ground station. Try 131.55 MHz AM. A great explanation of this mode can be found at this link.

  53. ARDIS/MDC4800 at 854.8375 MHz  ARDIS is a packet switched data network for two-way data transfer that operates in the 851-866 MHz or 935-941 MHz range.  In Southeastern Wisconsin, it can be heard on 855.8375 and 854.8375 MHz base (and 45 MHz below for mobiles).  A great explanation of this mode can be found at this link.

  54. Mobitex (RAM data service) - Submitted by a U.K. monitor. This format is used in the US between 935 and 940 MHz and in Europe and is similar in use to ARDIS. RAM is a company providing mobile data service over the mobitex protocol.

  55. Supervisory Control And Data Acquisition (SCADA)  Technically this isn't a mode, but a semi-generic term for a data acquistion means.  Some of possible data protocols are SC-1801, Harris 5000/6000/XA-21, Telegyr 8979, TRW-9550, and PERT 26/31.  This particular signal is heard in the Milwaukee, WI area.  It is a wide signal spanning 952.250 thru 952.750 MHz with this audio being recorded from the center of 952.500 MHz WFM.  My Percon Spectrum database shows a listing for 952.50625 MHz for Wisconsin Electric Power Company.  I have observed directional 900 MHz antennas in use at various utility shacks, so I suppose it could be monitoring or control telemetry from these.  This mystery was solved thanks to a contact at WEPCO.

  56. ARDIS/MDC4800 at 854.8375 MHz  ARDIS is a packet switched data network for two-way data transfer that operates in the 851-866 MHz or 935-941 MHz range.  In Southeastern Wisconsin, it can be heard on 855.8375 and 854.8375 MHz base (and 45 MHz below for mobiles).  A great explanation of this mode can be found at this link.

  57. Mobitex (RAM data service) - Submitted by a U.K. monitor. This format is used in the US between 935 and 940 MHz and in Europe and is similar in use to ARDIS. RAM is a company providing mobile data service over the mobitex protocol.

  58. SSR - Secondary Surveillance Radar is used to transmit an aircraft's ID number and altitude to ground controllers. It is otherwise known as a transponder and the transmissions are referred to as "squawks". Aircraft squawk on 1090 MHz when interrogated by ground radar. Listen in SSB or AM mode.

  59. EAS - Emergency Alert System is the new tone sequence you will be hearing to replace the EBS annoying tone. These new tones will be used on commercial and NWS radio stations and carry location-specific emergency messages. Try your local broadcast station or the NWS in the 162.4-162.55 MHz range during a test or real emergency.

  60. Motorola FLEX 3200 Baud[3200flex.wav - MISSING]

  61. Motorola FLEX 1600 Baud[1600flex.wav - MISSING]

  62. Motorola MDC-1200 Signaling Protocol (Signaling, Emergency, Status, etc.)[mdc1200.wav - MISSING]

  63. FedEx and Dallas PD/Fire Unid MDT Data[dpdfedex.wav - MISSING]


    64. Knowledge is Power

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