Quantization Efficiency

Quantization is a nonlinear process which generates additional frequency components (Thompson et al. 1986). This means that the signal is no longer band-limited, so the sampling theorem no longer holds. If a signal is sampled at the Nyquist frequency, information will be lost. Therefore, sampling faster than the Nyquist frequency results in detection of more of the signal and a lower signal-to-noise ratio [SNR]. Let  be the oversampling ratio and define

Then the following table gives values of  for a number of parameters.

quantization levels
2	0.64	0.74
3	0.81	0.89
4	0.88	0.94

The Very Large Array of 27 radio telescopes in Socorro, New Mexico uses three-level quantization at , so .

REFERENCES:

Thompson, A. R.; Moran, J. M.; and Swenson, G. W. Jr. Fig. 8.3 in Interferometry and Synthesis in Radio Astronomy. New York: Wiley, p. 220, 1986.