The AN/SPS-48 is a three-dimensional (3D) FRESCAN (Frequency Scan) air search and weapons control radar to replace the SPS-39/42, which was unable to meet the long-range requirements of the Talos missile system. This radar is also more capable than the AN/SPS-52 and can support the longer-range Standard missiles. One of the SPS-48's major developments was its reduced weight, bulk and equipment complexity achieved by eliminating the SPS-39/42's mechanical stabilizer base.
A sinuous waveguide feed is located in the SPS-48's antenna array end plate. The end plate serves 76 linear arrays in the earlier variants, 95 in the SPS-48E. The antenna is stabilized up to 20 deg in two axes. Using changes in frequency to steer the beam in elevation, the radar stacks nine beams for a 6-deg elevation coverage. Earlier variants provide elevation coverage from 0 to 45 deg; the SPS-48E encompasses 0 to 65 deg. The FRESCAN technique gives the system increased range and a high data rate for high probability of hostile emission intercept. An anti-jamming mode is available and transmits the signal in a single beam for 27 microseconds; processing can compress the return to 3 microseconds. An Interrogation Friend or Foe (IFF) antenna is mounted on the right side of the antenna's top edge.
There are four versions of the SPS-48, A, C, D and E. The original SPS-48A sets were upgraded with Automatic Detection and Tracking (ADT) features and a Moving Target Indicator (MTI) capability, giving them multiple target detection and tracking capability. This modified version was then re-designated the SPS-48C.
The SPS-48D was an engineering development model of the SPS-48E that was tested in the destroyer MAHAN (DDG 42) in 1982-1983.
The latest version, the SPS-48E, is based on the SPS-48C, but has less than half of the components (126,000 as opposed to 280,000), making it more reliable and easier to maintain. The SPS-48E was designed as a direct replacement for the SPS-48C and all of its equipment can fit it the same space as that of the earlier radar, except for the antenna, which weighs 1,700 lbs (771 kg) more. The radar incorporates state-of-the-art Built-In Test (BIT) technology, automating routine system testing that had previously been done manually. This results in a longer Mean Time Between Failures (MTBF) and lower life cycle costs.
The SPS-48E is also better at resisting electronic countermeasures and at detecting and tracking small targets. The antenna produces much lower side lobes (-33 dB compared to the -23 dB of earlier variants) and is designed to withstand the most severe sea environment, including wind, rain and ice. Digital MTI is provided and is also being retrofitted to earlier SPS-48s. Like the Aegis SPY-1 radar, the SPS-48E has a "snap-on/snap-off" feature to control emissions that would attract anti-radar missiles. The -48E also doubles the effective radiated power, using a cross-field amplitron transmitter, while increasing receiver sensitivity.
| Weight (SPS-48C): | Antenna | 4,500 lb |
| Total System | 22,000 lb | |
| Dimensions: | Height | 17 ft |
| Width | 17 ft 6 in | |
| Band: |
S (2900-3100 MHz) |
|
| Gain: | 38.5 dB | |
| Pulse Repetition Frequency (PRF): | 1,250-2,000 | |
| Scan Rate: | 7.5 or 15 rpm | |
| Pulse: | Power | 2.2 MW |
| Length | 3 microsec | |
| Elevation: | SPS-48C | 45 deg |
| SPS-48E | 65 deg | |
| Maximum Altitude: | 100,000 ft | |
| Average Power: | SPS-48C | 15 kW |
| SPS-48E | 35 kW | |
| Bearing and Elevation Accuracy: | Range | 690 ft |
| Elevation | 1/6 deg | |
| Range: | 220 nm (253 mi) | |
| Low Angle Range: | 230 nm (265 mi) | |
| Resolution: | Range | 1,500 ft |
| Elevation | 2 deg | |
Source: janesonline.com, usni.com