General Information
Digital Mobile Radio (DMR) is a digital modem with 12.5 kHz channel spacing and TDMA based protocol described in the ETSI technical standards.
TS 102 398: General Design
TS 102 361:
Part 1: DMR Air Interface (AI) protocol
Part 2: DMR voice and generic services and facilities
Part 3: DMR Data protocol
Part 4: DMR trunking protocol
TS 102 362: Conformance Testing
Usage:
§ Category 1: Individuals and industries with low requirements, small-scale applications.
§ Category 2: Industries with high demands on business-critical large-scale communication.
Mode Details
|
|
Item |
Value |
|
Standard |
Duplex method |
FDD or TDD |
|
|
Modulation |
FSK |
|
|
Number of tones |
4 |
|
|
Tone spacing (Hz) |
1296 |
|
|
Symbol rate (Bd) |
4800 |
|
Demodulator Settings |
Demodulator |
FSK 2, 3, 4 discr. |
|
|
Symbol rate (Bd) |
4800 |
|
|
SR tolerance (Bd) |
10 |
|
|
Modulation order |
4 |
|
|
Shift (Hz) |
4080 |
|
|
Shift tolerance (Hz) |
0 |
|
|
Modem type |
Synchronous |
|
|
Min. burst length (s) |
0.015 |
|
|
Max. burst length (s) |
0.045 |
|
|
Min. pause length (s) |
0.015 |
|
Features |
Demodulation |
yes |
|
|
Recognition |
yes |
|
|
Decoding, Binary Data / Voice Data |
Yes, under development |
|
|
Automatic Polarity Adjustment |
no |
|
|
Combination with other modems (modem list) |
yes |
|
Vocoder
|
The DVSI AMBE+2™ vocoder is based on Multi-Band Excitation (MBE), i.e. a frequency domain approach. Main characteristics are: § Very low bit rate 2450 bps (voice) + 1150 bps (FEC) = 3600 bps § Very high voice quality at very low bit rate. § Robust to strong background noise and to PMR/LMR channel § Moderate complexity, easy to implement on a low-cost DSP § Language indepdendent § 20ms voice frame and FEC optimized for PMR/LMR applications |
not included |
|
Tuning |
The tuning frequency is 240 Hz below the center peak | |
Table 6: DMR