Here is a chance to identify those strange
sounds you frequently hear chirping away on the short-wave bands
using the fine collection of sound files put together by David Crawford and collaborators.
There are many protocols for sending digital data over the air-waves. These include packet, pactor, clover, decca, selscan, Morse code, voice scrambling and various military protocols etc. etc.
When listening to the crowded short-wave radio bands it is is sometimes useful to be able to identify by ear which protocol is present. Decoders to unscramble many of these signals can be made or purchased; for example you may like to receive weather maps. Also amateur radio stations make use of several of these modes for general data exchange as well as slow scan TV.
An interesting collection of sounds, in"wav" files recorded from "on air", has been put together by David Crawford and collaborators at the WUN Digital Sounds Page, and is available for sampling directly from his site in the USA.
The Protocols and their Sounds available at the WUN Digital Sounds Page |
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| Aircraft Communications Addressing and Reporting System Digital Voice Scrambling (US govt/mil) ARQ-E3 96 baud ARQ-E3 200 baud idling Amateur CLOVER (presumed) DCF77 Time Station Signal DECCA HF Radio Navigation System Differential GPS, Minimum Shift Keying Differential GPS, Quarternary Phase Shift Keying GMDSS Marine SELCAL System (presumed) Hyperbolic Radio Navigation System ICAO Aeronautical SELCA> Link-11 Network (NATO mil) LORAN-C Long Range Radio Navigation System Morse Code |
Non-Directional Beacon Over-The-Horizon Radar (probably US mil) PACTOR 200 bau PACKET (AX.25) 300 baud Radioteletype (Baudot 50 baud) SELSCAN Link Availability Sounder (presumed) SITOR-A Telex-Over-Radio SITOR-A Telex-Over-Radio Marker SITOR-B Telex-Over-Radio (broadcast) Amateur Slow-Scan TV (Martin-1) Swedish ARQ Voice Frequency Telegraphy RTTY Voice Frequency Telegraphy RTTY (USAF) Weather Facimile |