Digital control of an Encryptic broad-band radar application
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Date
2011-07-13
Authors
Raghavan, Vijaya Srinivasa
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Abstract
This project describes the digital control of a radar that is ideally insensitive to alien disturbance signals. The key factor in this project comprises the design and realisation of
a wide range of digital techniques combined into one digital controller consisting of
several elements.The project is divided into three major parts, namely,Transmitter, Channel and Receiver.Transmitter:
A radar control circuitry that generates binary noise with hidden codes has been
developed. A modulo-2 feedback shift register generates a pseudo-random sequence.
This sequence constitutes the binary noise. The codes [called Complementary Semi-
Barker codes] are generated by cascading 16-1 multiplexers. Control signals were
developed to establish a switch. The output of this switch transmits a signal consisting of the noise and the codes. The codes are known only to the sender. This makes it difficult for an intelligent target to distinguish between the codes and the binary noise.Consequently, this radar system is hard to influence.
Receiver:
The codes are matched using auto-correlation technique. In order to retrieve the matched
codes, they have to appear in an adder simultaneously. This calls for the introduction of a delay in the signal. A threshold voltage is set to clip off the undesired part of the retrieved signal. This resembles a traditional radar signal.
Channel:
A channel is introduced in the final stage to intrude on the output of the transmitter.
Disturbances in the form of additional pulses are introduced in order to investigate the sensitivity and robustness of the encryption technique.
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Digital communications