1. A method to enhance Gaussian and Rayleigh sensitivity performance of Digital Audio
Broadcast receivers comprise the steps of:
evaluating Fast Fourier Transforms (FFT) at multiple positions of Orthogonal
Frequency Division Multiplexing (OFDM) symbols (100);
10 computing differential demodulation and subsequently combining post differential
demodulation subcarrier constellation symbols, wherein the steps are annexed to
the demodulator;
the channel impulse response peak estimator (101) retrieves the peak positions
(102, 103) of the channel impulse response;
15 samples in the cyclic prefix are dropped and a set of complex samples of length K
where K is the number of frequency subcarriers in the DAB transmission mode are
formed from the next K complex samples;
a subsequent step FFT of size K is (104, 105) evaluated to generate frequency
domain samples;
20 frequency domain samples of successive OFDM symbols (100) are differentially
demodulated Differential Quadrature Phase Shift Keying (DQPSK) to estimate the
subcarrier level Quadrature Phase Shift Keying (QPSK) symbols and the set of
complex samples are marked as r1k (109);
the second peak position in the channel impulse response is additionally utilized
25 and the K complex samples beginning from this peak position are collected;
FFT of size K (104, 105) is evaluated on this set of complex samples;
output frequency domain samples of successive OFDM symbols (100)
corresponding to this FFT are again differentially demodulated (DQPSK) to
estimate the second set of subcarrier level QPSK symbols r2k (110);
30 Subcarrier QPSK combination (108) is performed on r2k (110) and r1k (109); and
the resultant K complex samples (111) of the demodulator are then processed by
the channel splitter and subsequently, the channel decoded to retrieve the
information bit stream.
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5 2. The method to enhance Gaussian and Rayleigh sensitivity performance of Digital Audio
Broadcast receivers, as claimed in claim 1, wherein, the method can be extended by
utilizing more than two peaks from the channel impulse response and adding corresponding
computational blocks FFT, DQPSK (106, 107) and subcarrier QPSK combiner.
3. The method to enhance Gaussian and Rayleigh sensitivity performance of Digital Audio
10 Broadcast receivers, as claimed in claim 1, wherein, the method can also be generalized to
transmission schemes which involves OFDM and Differential Multi Phase Shift Keying
(DMPSK) instead of DQPSK.