comm.GMSKModulator & comm.GMSKDemodulator

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michael
michael on 2 Oct 2013
Hello all,
When using the comm.GMSKModulator & comm.GMSKDemodulator as their standard (i.e.modulator = comm.GMSKModulator; demodulator = comm.GMSKDemodulator; ) after the demodulation, the size of the output is the same as the input to the modulator. However, there are still missing some symbols: at the beginning i have 16 zeros but at the end, there are no additional symbols which are lost. How can I get those?
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Jose Marcelo Duarte
Jose Marcelo Duarte on 15 Jan 2021
The GMSK modulator has memory. Output sample value depends not only on current symbol value but also on some previous symbols too. Therefore, the GMSK modulator has a shift register memory with initial state being all zero. Therfore, dummy bits must be added at the end of the transmitt bit vector to push the last information bits through out this "shift register". The same thing is valid for the GMSK receiver.

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