Abstract: Techniques for measuring the carrier to noise ratio (CNR) in a received digital signal are disclosed. The methods can operate on a received digital signal, such as a layered modulation signal used in a satellite television system. The CNR measurement can be made at the output of a carrier recovery loop or a timing recovery loop in a demodulator. Alternately, the CNR measurement can be made when the received signal is digitized in an analog to digital (A/D) converter at base-band by the demodulator.

Abstract: An inverse synthetic array radar (ISAR) system provides for improving the resolution of an ISAR image by providing compensation for non-uniformity in the magnitude of the angular velocity of a rotating target as the target rotates to generate the synthetic-aperture-angle, and enables use of a larger synthetic-aperture angle, without compromising ISAR image quality with respect to smear. The preferred embodiment records sampled data signals to generate a collected-data matrix indexed in each of two dimensions on the basis of uniform increments of time, and performs data processing to produce a translated data matrix indexed in a dimension on the basis of uniform increments of synthetic-aperture angle. Further processing of the translated data matrix produces data in a buffer for controlling a display device for the ISAR image.