P25 Phase 1

Widely deployed radio standard used in public safety and amateur radio.

Support includes decoding and synthesis of speech, display of all link control info, and the ability to save and replay .imb data files
ProVoice

EDACS Digital voice format used by public safety and amateur radio.

Support includes decoding and synthesis of speech and the ability to save and replay .imb data files.

Note: not enabled by default, use -fp to enable.
X2-TDMA

Two slot TDMA system currently being deployed by several public safety organizations. Based on the DMR standard with extensions for P25 style signaling.

Support includes decoding and synthesis of speech, display of all link control info, and the ability to save and replay .amb data files
DMR/MOTOTRBO

"Digital Mobile Radio" Eurpoean two slot TDMA standard. MOTOTRBO is a popular implementation of this standard.

Support includes decoding and synthesis of speech and the ability to save and replay .amb data files.
NXDN

Digital radio standard used by NEXEDGE and IDAS brands. Supports both 9600 baud (12.5 kHz) and 4800 baud (6.25 kHz) digital voice.

Support includes decoding and synthesis of speech and the ability to save and replay .amb data files.
D-STAR

Amateur radio digital voice standard

This is an earlier version of the AMBE codec than the one used by most of the protocols. Support for this was added by various developers.
Unsupported formats considered for future development:
P25 Phase 2

This is not yet a published standard. Full support is expected once the standard is published and there are systems operating to test against. Phase 2 will use a vocoder supported by mbelib.
OpenSKY

It is possible that the four slot version uses a vocoder supported by mbelib. The two slot version does not.
Supported demodulation optimizations:
C4FM

Continuous envelope 2 or 4 level FSK with relatively sharp transitions between symbols. Used by most P25 systems.

Optimizations include calibrating decision points only during sync, 4/10 sample window per symbol, and symbol edge timing calibration.
GFSK

Continuous envelope 2 or 4 level FSK with a narrower Gaussian/"raised cosine" filter that affects transitions between symbols. Used by DMR/MOTOTRBO, NXDN and many others. Noisy C4FM signals may be detected as GFSK

but this is ok, the optimization changes will help with noisy signals.

Optimizations are similar to C4FM except symbol transitions are only kept out of the middle 4 samples and only the middle two samples are used.
QPSK

Quadrature Phase Shift Keying (and variants) used in some P25 systems and all known X2-TDMA systems. May be advertised under the marketing term "LSM"

Optimizations include continuous decision point calibration, using middle two samples, and using the symbol midpoint "spike" for symbol timing.