DRM Mode D
The digital test-card JPEG carried in a DRM MOT image service.
48,000 samples/s · 1 channel · 51.60 s
Generated by the SSTV 2.0 pinned transmitter library; PCM16 WAV verified by its writer.
DRM specification · DRM30
DRM Mode D
Severe delay spread and Doppler spread.
The most rugged DRM30 robustness mode, selected when long multipath and motion make A/B/C too fragile.
OFDM timing
| Parameter | Value |
|---|---|
| Useful symbol duration Tu | 9.3333 ms |
| Guard duration Tg | 7.3333 ms |
| Total symbol duration Ts | 16.6667 ms |
| Guard ratio Tg/Tu | 11/14 |
| Carrier spacing | 107.14 Hz |
| Transmission frame | 24 symbols / 400 ms |
| Nominal channel widths | 10, 20 kHz |
Very long guard ratio consumes capacity; useful when preserving a low-rate stream matters more than image or audio throughput.
Carrier ranges
| Occupancy | Bandwidth | Kmin | Kmax | Unused indices | Occupied positions |
|---|---|---|---|---|---|
| 3 | 10 kHz | -44 | 44 | 0 | 88 |
| 5 | 20 kHz | -43 | 135 | 0 | 178 |
2.0 input and image service
Select DRM Modes A-D. The reference waveform is 48 kHz mono real IF centred at 12 kHz, with 10 kHz spectrum occupancy. A conventional narrow voice filter can truncate this waveform; use a receiver or SDR path with enough bandwidth.
Synchronization identifies the waveform. FAC describes the multiplex; SDC describes services and stream allocation; MSC carries the application data. The image in this sample is an MOT object. FAC lock alone does not prove image recovery, and an audio-only broadcast may provide no image to display.
Lossless MOT image sample
The sample uses 64-QAM MSC, 4-QAM SDC and short interleaving at occupancy 3. The payload is a JPEG test card, not a recording of a broadcast station.