BPSK Based Super Regenerative Receiver

Abstract

The Super Regenerative Receiver was invented by Armstrong in 1922 [1]. It is used in various applications such as sensor networks, short distance telemetry, home automation, biomedicine, remotely controlled systems, etc., because of its simplicity and low power design. In the classical super regenerative receiver, the RF oscillations obtained at the output of the oscillator is applied to a non-linear detector followed by a low pass filter. Hence the demodulation capabilities of the super regenerative receiver was restricted to amplitude modulation or on off keying (OOK) signals. The challenge is to use the super regenerative architecture to demodulate phase modulated signals which are more robust to interference compared to OOK signals and still maintaining the low power, low cost features of the receiver. The principle of super regenerative receiver is based on the theory of quenching, where a quench oscillator causes repeated build up and decay of oscillations and the oscillations are maximum at the zero crossing where the quench signal goes towards the positive half cycle. Any phase errors in the quench signal directly affects the phase detection performance. Thus it is also important to maintain synchronization between the quench signal and the carrier. In digital communications, packet arrival instants are generally random and unknown at the receiver. The payload of the packet can be successfully demodulated if the start time of the payload is known at the receiver. Thus the objective of this thesis is threefold. Firstly the super regenerative architecture for demodulating BPSK signals is presented and an analyses based on performance and power is done. Secondly a method for synchronizing the quench signal to the carrier is presented and the effects of jitter on the detection performance is analysed. Thirdly, the procedure for preamble detection is presented and its performance is analysed.