Abstract: The range of a weather radar systems (60) is automatically extended by incrementally increasing the pulse width (17) from transmitter (12) in response to detecion of excessive path attenuation determined by a comparator (32) comparing the level of actual attenuated return pulses (19) from a range correction accumulator (34) with a path attenuation compensation level selected by a computer (26). The bandwidth of the receiver (14), the value in an initial sensitivity time control value circuit (54), the value in a path attenuation compensation correction value circuit (62) and the path attenuation correction alert threshold are also selectively varied automatically in accordance with the incremental changes in the width of transmitted pulses (17).

Abstract: Disclosed is an alien radio ranging transmitter rejection technique utilizing random PRF to eliminate the possibility of lock-on between two coherent R/T units in close proximity. If one, or both, are utilizing the random PRF technique taught herein, the alien signal is rejected utilizing standard noise suppression techniques. The random PRF is selected utilizing noise or angle data computed from the received return signal and is thereafter utilized to designate which one of a set number of PRF delays is utilized on a substantially random basis.

Abstract: A ground clutter suppression technique is disclosed utilizing two parallel return signal processing paths, both utilizing linear-to-logarithmic conversion capability and one having a signal delay capability for one pulse repetition. The outputs are subtracted and are subsequently compared with a factor related to the root-mean-square (rms) of two deviation inputs, one input functionally related to apparatus limitations and one deviation input functionally related to antenna position (step between samples) for each signal received. The Doppler frequency standard deviation inputs are then summed rms and used to select an amplitude standard deviation which is compared with the amplitude difference between successive return signals. Thereafter, the logic decision output is operated on utilizing a digital filter to essentially eliminate ground clutter or small variance (PRF to PRf) return signals from the display.

Abstract: A system and technique is disclosed for estimating the real-time spectral width of radar returns to provide an indication of weather turbulence. The system includes a Doppler radar to provide the in-phase and quadrature phase signals from successive range returns which are digitized and converted to a phase angle prior to processing. Successive angular samples at the pulse repetition frequency are subtracted to provide a phase angle change. The phase angle change is filtered to determine an average angular mean which is then subtracted from new angular samples to determine the angular deviation. The angular deviation for each sample is in turn compared with a threshold to provide an output which is averaged over time to determine when the standard deviation of the samples exceeds a reference value. When the standard deviation of the samples exceeds that reference value, the spectral width is of a magnitude which indicates the presence of turbulence.