Digital Modes Samples

Coming soon here is a page with as many samples that I can find of digital modulation, modes, protocols or weird noises captured over the air. Most of these samples have been recorded by me personally and hopefully can assist radio enthusiasts in identifying what they are hearing thru their scanner speaker. All samples are direct from discriminator and can be piped into programs such as DSD/DSD+ for decoding. WAV files in 48k/16bit are provided in the links after the player for your convenience. More information coming soon…

Commonly found in the 800MHz band on EDACS systems but was popular in Canada in conventional repeated mode in the 420MHz band. No software available to decode. Utilizes the AMBE vocoder from DVSI as well, but uses an unknown format. Currently being researched to add to DSD.


Also found in the 800MHz band on EDACS trunking systems. Is widely popular on the Florida State EDACS-IP system, also has been replacing the aging AEGIS talkgroups on the RACOM system. Not very popular in conventional mode due to P25 being released. Also uses IMBE vocoder from DVSI (7100X4400 format). Works well with DSD and DSD+


Probably the most popular digital voice/data format for public safety. Can be found on almost all bands VHF and up. This sample is C4FM (not simulcast), non-repeated. Gaining popularity in ham radio. P25 Phase 1 (FDMA) uses the IMBE vocoder from DVSI (7200X4400 format).  Works well with DSD and perfectly with DSD+

Digital voice going thru a repeater this time. You can hear the extra “padding” at the ends where the repeater is sending the “disconnect” data to tell the mobile radios to mute.


The first real commercial digital voice targeted at ham radio. Developed exclusively for Icom (utilizing the DVSI AMBE+ codec, ambe3600X2400 format) this PROPRIETARY voice format has similar characteristics to P25 Phase 2 voice.


  • DMR – MotoTRBO Voice: <coming soon>

Motorola – adapted variant of the popular DMR protocol. Has been adopted widely by many businesses and some public safety during the massive narrow-banding in 2012/2013. DMR allows for 2 slots in a TDMA system, this sample is data being sent between the base and subscriber units like GPS location, status etc. Found on VHF/UHF and 800. The DMR spec uses the AMBE vocoder from DVSI (3600X2450 format) and is very similar to DStar.


EDACS Wide trunking control channel. Few large systems remain, RACOM operates the largest privately-owned system in Iowa. State of Florida operates a massive EDACS-IP system that uses ProVoice exclusively. GFSK signalling, 9600 bits per second. Supports very fast channel access times, mobile data, voice, and telemetry.


Probably the most popular trunking format ever. The iconic sound of the Motorola 3600 control channel can be heard on VHF, UHF, 800 and 900MHz. More commonly referred to as TypeII, the same control channel format is also used for TypeI, TypeIIi and TypeII; as well as SmartZone and OmniLink systems. Supports data, digital voice (DVP/DES with ASTRO), analog encryption (DVP/DES), group calling and more. Used by public safety, commercial and utilities. 3600 baud data rate, wideband signalling. APCO-16 compliant.


Motorola-flavored P25 non-simulcast trunked control channel. 40 OSW (outbound status word) messages per second. This is the latest product being deployed for public safety. Supports a slew of features and uses digital voice exclusively. There is no analog backwards-compatibility with P25 systems. Decoding these can be tricky because of the C4FM encoding method. Discriminator taps on scanners strip away some of the signal needed for a solid decode, but acceptable results can be obtained with trail and error.


A popular format used by many public safety agencies for MDT data. May  be encrypted, decoding requires specialized hardware/software. Modulation is very similar to C4FM. There is also a 9600bps variant but most have been upgraded to the faster 19.2k.


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