MT63
MT63 is a mode for digital wireless communication and is mainly used by radio amateurs on shortwave . MT63 uses 64 tones spaced 15.625 Hz apart and in the range 0.5–1.5 kHz . 63 tones are used for data transmission , one is used for synchronization . Because of the relatively large bandwidth and its constant use, MT63 is reminiscent of frequency spreading . An MT63 signal sounds like increased noise and is extremely difficult to find on shortwave with very low field strengths .
MT63 is a forward error correction . In the event of transmission errors, the receiving station does not automatically request that the incorrectly transmitted information be retransmitted. MT63 therefore uses different methods in order to guarantee a highly secure transmission.
This is usually made more difficult by interference from other radio stations, atmospheric interference and temporal and selective fading . Amplitude-independent DBPSK modulation (differential bipolar phase shift keying) is used to increase the robustness against temporal fading . The temporal and spectral distribution of the information with high redundancy also leads to a high level of insensitivity to interference as well as temporal and selective fading. Since the information is in principle evenly distributed over 1 kHz and its transmission extends over a longer period of time, partial failures of the channel are irrelevant for transmission security.
The synchronization logic of MT63 allows a frequency tolerance of +/− 50 Hz. The coordination is therefore usually not critical.
Frequencies
The following frequencies are preferred frequencies or activity centers of MT63 in amateur radio :
| 80 m | Fashion |
|---|---|
| 3,590-3,600 kHz | USB |
| 40 m | Fashion |
| 7,038-7,040 kHz | USB |
| 30 m | Fashion |
| 10.135 kHz | USB |
| 20 m | Fashion |
| 14,130-14,135 MHz | USB |
| 14,147 MHz | USB |
| 14,348 MHz | USB |
| 15 m | Fashion |
| 21,130 MHz | USB |
| 21.148 MHz | USB |
| 10 m | Fashion |
| 28.130 MHz | USB |