Abstract
Tamed frequency modulation (TFM) is a spectrally
efficient constant amplitude continuous phase modulation
(CPM) scheme which can be simply realized by using a
frequency modulator (FM). In the implementation the
modulation index of TFM is calibrated to have a nominal
value of 0.5, but due to temperature variations it can
drift causing time varying phase jitter. In this paper we
present novel algorithms and performance results to
measure and control the modulation index in a coherent
receiver based on the joint reduced state sequence
detector (RSSD) and per-survivor processing (PSP) carrier
phase estimation. The modulation index estimator measures
phase transitions in the receiver and derives estimates
by comparing the result to the coding rule of the TFM
signal. The estimator has acquisition and tracking
ability, and the current estimate can be used to replace
the nominal index value. Our simulation results show that
the proposed coherent receiver with the novel modulation
index estimator has less than 1 dB performance
degradation compared to around 4.5 dB exploiting only the
PSP carrier phase estimation.
Original language | English |
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Pages (from-to) | 61-71 |
Number of pages | 11 |
Journal | Physical Communication |
Volume | 10 |
DOIs | |
Publication status | Published - 2014 |
MoE publication type | A1 Journal article-refereed |
Keywords
- continuous phase modulation
- demodulation
- frequency modulation
- parameter estimation
- viterbi alhorithm