воскресенье, 20 февраля 2011 г.

SA update to version v Universal MFSK demodulator

SA update to version v

In this update, the pilot version of the general-purpose/universal demodulator MFSK is realized.

The demodulator supports to 256 levels (frequencies) of various MFSK signals. As an example: obtaining of a bit stream from the records Packet AX.25 and APCO-25 it is shown on the picture above. As FSK-2 it is special case of MFSK, the current extension of the module doesn't influence the previous possibilities, but only expands them.

Please pay attention on the allocation of levels of demodulation. The first and last levels, aren't restricted by the markers! Their area is stretched behind their limits, as it is shown below.

The bit stream can be presented in two variants.

The first variant is the symbol representation of levels recoded by default. In this case, the internal map of codings is used. 32 characters are supported standardly. It is favourable for using for FSK-2, MFSK-4,8,16 etc., that is, for rather few-channeled MFSK modes.

The second - obtaining/recieveing of the stream in the form of HEX-byte. Bytes in this case are partitioned/devided by the symbol-separator "x" (the Latin character "X" on the lower register).

As, the bit stream implies further processing anyway, we have refused an inverse mode. There is no big sense in an inverse mode, as an inverse can be received in any exterior viewer. Besides, we are planning to create our own special viewer of a bit streams.

Below you may view the practical example of operation of general-purpose/universal MFSK demodulator on the signal South African Navy.

Good luck!