Techniques for acquiring and tracking MIL-STD-181B signals

The paper examines the use of spectral estimation and maximum likelihood estimation techniques in acquiring and tracking current MIL-STD-188-181B UHF SATCOM waveforms. Digital signal processing (DSP)-based algorithms are presented that can acquire and track the carrier phase, carrier frequency offset, and symbol timing for the dual-h quaternary continuous phase modulated (CPM) waveforms. The algorithms are derived mathematically first, then using computer simulations. Performance is presented for various modulation rates, channel conditions, and different signal-to-noise ratio (SNR) levels. Several methods are then proposed to enhance the performance of these algorithms without requiring additional computational resources. The algorithms are easily configurable for different modulations and data rates, thus making them suitable for implementation in next generation software-defined UHF tactical radios.