8. New Technology Roots
Electromagnetic transducers had previously been shown to be capable of acting as pulse to achieve improved range resolution. Compression was achieved using pairs of transducers designed to produce or detect a burst with a linear frequency variation. An alternate approach, which is also easier to fabricate, is to impress a digital phase code on single frequency coils. One such code with good autocorrelation properties is the 13 bit Barker coder. Coils with this code were fabricated and evaluated. It will be shown that the operation of these devices is very similar to the coils with dispersive designs. The waveforms, compression ratio,and sidelobe levels to be expected from these devices are described.
Moran, T. J., "Digitally Coded Electromagnetic Transducers" (1978). Proceedings of the ARPA/AFML Review of Progress in Quantitative NDE, September 1976–June 1977. 60.