The Universal Radio M-450 Decoder is considered by many to be the "Cadillac" of standalone decoders. In addition to decoding and displaying CDCSS and CTCSS, it also decodes DTMF, ACARS, FEC-A, SITOR, NAVTEX, and many other code formats. This unit is available from time to time on auction sites. More info is here:
<www.universal-radio.com/catalog/decoders/0450.html> The technical details of CDCSS are found in Motorola Publication 6881106E83, entitled "Digital Private-Line Binary-Coded Squelch" and available from Motorola Parts (800-422-4210) for about $3. 73, Eric Lemmon WB6FLY
