DMR (Digital Mobile Radio) is a two-channel digital TDMA system for the transmission of voice and short text messages.

For voice the AMBE++ (or AMBE+2) codec by DVSI is used.  Data transmission accommodates 7-bit ASCII only.

To use the mode, set Offset to the frequency of the IF output of the receiver and select the correct Polarity. From Options use the Message Type menu to select an output method. If All Frames is selected, data and voice frames as well as all control frames will be displayed. Voice is output in real-time to the speaker. At the same time the latest voice session will be saved in a .wav-file in the default data output directory (see Default Data and Program Folders section). A “Bit Transparent” format is also available in “Message Type”, with this output format the decoded bits will be output before they are processed by the protocol interpreter. In this case no text or voice output is available. This format can be mainly used to analyse the bit stream when it deviates from the user data protocol.

The display parameter “Confidence” indicates the quality of decoding - a value above 95% indicates a very high decoding quality (low bit error rate), whereas a value below 85% indicates that decoding is unreliable. Minor center frequency deviations are automatically corrected. The value of the Carrier parameter is the center frequency after error correction - this value should remain close to the IF of the receiver.

Wavecom DMR decoder works with all equipments compatible to the ETSI standards, e.g., MOTOTRBO series from Motorola and Hytera DMR devices.

The current implementation complies with the ETSI DMR standard series:

Ø ETSI TS 102 361-1 V2.3.1 (2013-7)

Ø ETSI TS 102 361-2 V2.2.1 (2013-7)

Ø ETSI TS 102 361-3 V1.2.1 (2013-7) and

Ø ETSI TS 102 361-4 V1.6.1 (2014-6)

It covers all three layers of the DMR protocol stack:

Ø Layer 1: Air interface physical layer

Ø Layer 2: Air interface data link layer and

Ø Layer 3: Air interface call control layer.

Wavecom DMR decoder covers all three tier services:

Ø Tier 1: Direct mode

Ø Tier 2: Direct mode and base station communication

Ø Tier 3: Trunking protocol.

Decoding outputs (text, voice and service messages) from the two TDMA slots are sorted in two separate windows. The following two screen shots show a DMR data and voice transmission and real communication on a base station, respectively.

DMR decoding voice and data test messages.

DMR decoding of data messages.