Tamed frequency modulation detection analysis with NEC receivers

Abstract

Various PSK modulations as well as minimum shift keying (MSK) have achieved great improvements in the signal-to-noise ratio by utilising the nonredundant error correction (NEC) technique. The cost for this improvement is neither an increase in bandwidth nor an increase in transmission power, but some extra complexity in the receiver. The receiver is only equipped with a bank of differential detectors and a simple error detection/correction circuit, whose complexity depends on the correction capability that the transmit–receive system must have. Here, it is proved that it is possible to differentially detect correlative, nonsymmetric continuous-phase frequency modulations such as tamed frequency modulation (TFM) with NEC receivers. TFM has not been used as much as MSK until now owing to its generation difficulties, but its main advantages of constant envelope and of very high spectrum efficiency make it a perfect candidate to work upon. Hence, TFM is first contaminated with additive white Gaussian noise and is subsequently detected through a single-error-correcting NEC receiver. Both the theoretical analysis and the computer simulations show that substantial error probability reduction is achieved over differentially detected TFM systems.