Analog binary programmable transversal filter

The objective of this program is to develop a programmable CCD (Charge-Coupled Device) circuit capable of correlating a variety of binary-coded waveforms. This analog-binary correlator will store a binary waveform as a reference, and will then compare newly arriving signals to the reference waveform. In general, the signal will be a binary code that has been corrupted in the transmission channel so that upon arrival at the receiver, it really has an analog character (i.e., the amplitude varies continuously). Analog-binary correlation techniques have an important advantage over purely digital approaches. If the analog signal is directly compared to the reference, only a single correlation channel is required, whereas a digital correlator requires a separate channel for each bit of resolution in the analog-to-digital converter. Thus, a reduction in parts count, with attendant improvements in size, cost and reliability, is realized with the CCD correlator. The correlator is an important device because correlation of binary waveforms is a function widely used in spread spectrum systems, which offer important advantages for military communications and radar applications. Spread spectrum advantages include jam resistance, reduced detectability and improved signal-to-noise ratio for given transmitter power. Thus, the device whose design is described here should be broadly useful in military systems.