AN/SPS-50
History
The AN/SPS-50 was an higher frequency development of the SPS-49 prototype. It was designed to replace the AN/SPS-6 and AN/SPS-12 radars, but failed the operational evaluation. This was likely done in the late 1960's.
Used on
This radar system never reached operational status.
Affiliated systems
Part description
Both sides and a front view are drawn of the 'regular' SPS-49 radar antenna. A side and a front view are drawn of the planar SPS-49 antenna. The drawing is based on limited references so might be inaccurate.
See also
From Norman Friedman, Naval Radar: This system was essentially the prototype SPS-49 modified to exploit the next step up in frequency, about 23 rather than 33cm, or the 1215-1400mc/s band. Had it not failed operational evaluation, it would have replaced the SPS-6 and -12 series.
SPS-50 was designed to detect a 1m2 target at up to 250nm and 150,000ft, up to a maximum elevation angle of 20°. To overcome the minimum range limitation inherent in pulse-compression radars, it had three modes: long pulse (125 microseconds, compressed to 2.5), medium (2 microseconds) and short (0.2 microseconds), with PRFs matching those of SPS-49. The beam was 2-2.4° x 9.5°.
In the short-range mode (short pulse), minimum range was 500yds and maximum 25nm, timed to take advantage of the normal radar dead time, thus allowing normal long-range operation without degradation of maximum range. The short pulse was generated by a separate impulse generator, and bypassed the compression/expansion system. Another innovation was a medium-range (2-microsecond) mode, with a maximum range of 63nm, intended to improve sub-clutter visibility (SCV) at medium ranges. To achieve sufficient dead time to accommodate this mode, the original trigger logic had to be re-designed and maximum range in the long-range mode reduced to 180nm.
Signal-processing included coherent MTI. Processing options were MTR (Moving Target Resolver), AMTI (Area Moving Target Indicator), LIN (Linear), LOG (Logarithmic), SHT RNG (Short Range), and MTI (Medium Range). In the MTR mode, successive pulses were added together before compression, with doppler information extracted during pulse-compression. This type of processing also eliminated jamming signals. In AMTR, signals with the same bearing and range from scan to scan were eliminated; those with sufficient radial velocity (about 150 kts) moved far enough from scan to scan to escape their previously recorded positions. Finally there was a Jamming Direction-Finder (JDF) circuit.
Compared to SPS-49, SPS-50 incorporated a fast-switching klystron modulator in which all tubes were replaced by transistors, as well as modified internal logic. As evaluated, SPS-50 was considered unreliable, with fault location extremely difficult. The short-range mode was considered unneccessary, particularly in view of the complications it imposed.
