R-15 (radar)
| File:R-15.jpg An R-15 unit in the nose of a TaH-27 Nissir. | |
| Country of origin |  Riysa |
|---|---|
| Introduced | 1998 |
| Type | Hybrid phased array radar |
| Frequency | 8-12 GHz |
| Diameter | 700 mm |
| Azimuth | ± 90° search ± 60° electronically and ± 30° mechanically |
| Elevation | ± 90° search ± 60° electronically and ± 30° mechanically |
| Power | ~7 kW peak |
The R-15 Fayrouz (Arabic: فيروز, English: Turquoise) is a Riysian multi-mode pulse-doppler radar, widely deployed on variants of the TaH-27 Nissir and TaH-29 Daqanoush light and medium fighters. Designed to replace the earlier R-10 and R-11 radars, the Fayrouz is currently the most numerous fighter radar in service in Riysa, despite the advent of more advanced radars in Riysian service.
Development
Design
The Fayrouz is a multi-mode planar phased array radar with an integrated IFF interrogator array, operating in the lower end of the X-band. For emitting its signal, it uses a single 7 kilowatt-class traveling wave tube transmitter, with a planar emitting array for significantly improved gain. Due to its phased array design, the radar can be electronically steered ± 60° degrees in azimuth and elevation, and is generally deployed on a mechanical mount allowing for an extra thirty degrees of freedom. Uniquely, the radar uses multiple independent receiver channels like an active phased array, despite using a central transmitter typical of passive phased arrays. This unique hybrid system is designed as such to combine high sensitivity and ECCM of AESAs, with the high resolution and power levels of traditional PESA radars. Radar operation and signal processing is digital and software-based, allowing for continued technical support and improvements in performance without changing out hardware components, as well as low probability of intercept modes. Three processing channels are used instead of the traditional two, with one being used as a guard channel for blanking out ECM in a sector. Total weight of a set is around 180 kilograms, with an MTBF of 350 hours. The entire set consists of 60 shop replaceable units and 6 line replaceable units, allowing for quick repair and easy maintenance.
Modes and Performance
Technical Characteristics
Beam width: 1.8°.
Arc scanned in 1 second: 70°.
Detection range of a fighter-sized (3m2) target in range-while-scan mode:
- Look-up mode:
- 160 kilometers frontal engagement (high PRF).
- 75 kilometers pursuit (rear) engagement (medium PRF).
- Look-down mode:
- 145 kilometers frontal engagement.
- 65 kilometers pursuit engagement.
Tracking and engagement range of a fighter-sized target:
- Look-up mode:
- 140 kilometers frontal engagement (high PRF).
- 65 kilometers pursuit (rear) engagement (medium PRF).
- Look-down mode:
- 120 kilometers frontal engagement.
- 55-60 kilometers pursuit engagement.
Rangefinding accuracy: No worse than 10 meters.
Azimuth accuracy: No worse than 1 milliradian.
Number of air-to-air targets tracked in track-while-scan mode: 24.
Number of air-to-air targets engaged at once: 4.
Detection range of ground targets in air-to-ground modes:
SAR resolution: 1 meter.
Air-to-Air Modes
Range-While-Scan - N (ن) - High and/or Medium PRF, all-aspect, look-up, look-down.
- Primary air-to-air search mode, covers selectable search area of ± 30°, ± 60°, or whole ± 90° in azimuth, and 1, 2, 4, or 6 bars in elevation. Displays range and azimuth/elevation data to pilot. Multiple sub-modes depending on engagement parameters.
- N/I (ن/ع) - High PRF mode to detect high-closure, typically frontal-aspect targets. Detects out to maximum range.
- N/M (ن/م) - Medium PRF mode to detect pursuit targets. Lower pule repetition frequency significantly reduces detection range.
- N/2 (ن/٢) - High and medium PRF interleaved mode for all-aspect detection. Frontal-aspect detection range is reduced by around 25%, rear-aspect stays the same, due to the switching of PRFs.
Velocity Search - S (س) - High PRF only, frontal aspect only, look-up, look-down.
- Similar to range-while-scan, estimates and displays velocity instead of range to the pilot. Provides 20-25% additional detection range against high-closure targets, but can not be used against low-closure or pursuit targets and can not calculate range. Same selectable search area as range-while-scan.
Track-While-Scan - T (ت) - High or medium PRF, all-aspect, look-up, look-down.
- Air-to-air combined search and engagement mode. Reduced and fixed search area of ± 35° in azimuth and 3 bars in elevation, or ± 15° in azimuth and 6 bars in elevation, though manually slewable across full azimuth and elevation range. Two sub-modes, can not use interleaved mode. In this mode, the radar can track up to 24 targets, providing full targeting information while still scanning for more contacts, with the computer being able to automatically select the 24 most important threats if desired by the pilot. Extra computational power necessary to operate this mode slightly reduces range relative to max detection range. From this mode, up to four targets can be selected for engagement.
- When a target is selected in this mode, it becomes the primary designated target. The TWS mode interleaves tracking of the primary target with regular scanning, providing tracking data similar to that of the single target track mode, but without noticeably changing the pulse repetition frequency or energy focused on the target, preventing the target from being alerted. Any targets designated after the primary one can also be engaged, but less information is provided and is given less priority.
- T/I (ت/ع) - High PRF mode to detect and engage high-closure frontal-aspect targets.
- T/M (ت/م) - Medium PRF mode to detect and engage pursuit targets.
Single Target Track - A (ا) - High PRF, all-aspect (primarily front), look-up, look-down.
- Special engagement and guidance mode, primarily used for guiding semi-active radar homing missiles. Provides significantly more information to prosecute an engagement, such as actual heading, and velocity. As the radar focuses all of its energy onto the target, it is much less like to lose it then with a TWS shot, at the expense of warning the target that it is under attack.
ECM Source Track - TTR (تتر) - N/A.
- Special mode for