Description of the radar set, tactical-technical characteristics
Figure 1: AN/SPS-3, Drawing of the antenna unit
U.S. Naval Research Laboratory
|frequency:||9 003 … 9 168 MHz, and
9 345 … 9 405 MHz
|pulse repetition time (PRT):|
|pulse repetition frequency (PRF):||3000 or 1500 Hz|
|pulsewidth (τ):||0.25, 0.33 or 1.33 µs|
|peak power:||2×200 kW|
|instrumented range:||25 NM (≙ 46 km)|
|hits per scan:|
The AN/SPS-3 was an early post-WWII, short range, X-Band naval radar for use on destroyers and larger vessels. It was a hemispherical search radar and utilizes two rapid scanning pencil-type antenna beams, each covering a 40-degree elevation angle sector and full 360-degree azimuth. Slightly different frequencies are used for the two beams (frequency diversity). Each beam had its own transmitter, receiver and waveguide system, but only one antenna system, using a dual Foster Scanner, was required.
The modulator was of the hydrogen thyratron type and was capable of pulsing both magnetrons simultaneously by use of a special dual type pulse transformer. The magnetrons were types 4J50 and 4J78. A so called synchroscope unit (combined synchronisator and display) containing a 5-inch cathode ray tube and associated circuits was capable of presenting video, trigger, modulator pulse, and STC voltages, as well as functioning as an A-scope with 1/2, 5 and 25 miles sweeps.
It was installed as a pre-production prototype (XN-1) on the USS Northampton CLC-1 in 1954. After this one installation the AN/SPS-3 program was cancelled.