• Advanced Doppler-based turbulence and weather detection for faster, better quality weather analysis
• Solid-state transmitter provides higher reliability (no magnetron burnout) and allows optimum pulse width for all ranges and modes
• Supersensitive coherent receiver architecture with bandwidth optimized for each transmitter pulse width
• Virtually eliminates personnel radiation hazard of conventional radars
• Ground clutter suppression mode enhances weather returns by minimizing ground returns using Doppler processing
• Dual control capability that gives independently selectable range, mode and tilt for pilot and copilot
• Auto tilt reduces pilot workload by automatically readjusting antenna tilt after a range or altitude change
• Automatic picture rotation capable during aircraft turns keeps a clear weather picture at all times; no waiting for a scan update
• Path Attenuation and Correction (PAC) accurately displays weather behind intervening storms warns of attenuated areas (radar shadow)
• Sector scan provides rapid picture updates by reducing scan angle to ± 30°

Unprecedented radar performance is now available with the Collins TWR-850/ WXR-840/WXR-800 Weather Radar Systems. State-of-the-art electronic and computer technologies provide operational convenience and features previously available only to large air transport aircraft. Now, the small size and light weight of the TWR-850/WXR-840/WXR-800 makes these radars the choice for the rest of the turbine-powered fleet. In addition, the solid-state transmitter improves reliability and eliminates one of the most troublesome components of conventional weather radar - the magnetron vacuum tube.

In addition to the expected function of detecting precipitation, the TWR-850 also detects accompanying turbulence by using Doppler frequency shift. This technological advancement is made possible by the availability of transmitters with extremely high frequency stability and powerful digital signal processing capabilities.

The sensor portion of the TWR-850/WXR-840/WXR-800 system is a single unit comprising an integrated receiver, transmitter, antenna and processing circuitry. This entire unit weighs less than 24 pounds and mounts in the aircraft radome.

Weather radar system control is via the WXP-850/WXP-840/WXP-800 Weather Radar Control Panel or the DCP-2000 Display Control Panel installed in the flight deck. As an option on the WXP-840/WXP-850, two such panels can be installed, providing each pilot independent control of the radar picture.

The weather radar picture can be displayed on the Electronic Flight Instrument System (EFIS) multifunction or adaptive flight display in a four-color (green, yellow, red, magenta) format. The magenta color indicates areas of very heavy rainfall rates of two inches per hour or greater. In addition, Path Attenuation Compensation (PAC) alert indicates areas of radar shadow due to signal attenuation caused by intervening areas of precipitation.

The system is fully digital and requires a minimum of interconnecting wires. Standard ARINC 429 interfaces are used for control information and digital altitude inputs while radar data is transmitted from the sensor unit via digital ARINC 453 buses. The system will also accept conventional analog altitude signals for antenna stabilization.

The maximum display range of 300 nautical miles provides long-range viewing capability. Avoidance range, a calculated performance measurement, is even greater than the 300 mile display range with an 18-inch flat-plate antenna. The minimum full-scale display range of five nautical miles provides an expanded view that pilots will find particularly convenient in terminal areas.

The TWR-850 provides the safety-enhancing features of turbulence detection, heavy rainfall rate emphasis and indications of areas of radar attenuation (radar shadow). Picture interpretation and pilot workload are reduced with the selectable ground clutter suppression mode.

The optional capabilities of the TWR-850/WXR-840 include dual-mode operation that allows each pilot to select mode, range and tilt settings independently.

A feature of Collins solid-state radar is the automatic rotation of the picture while the aircraft is turned. No longer are the details lost as the picture is recreated with each scan. Instead, the picture is rotated in synchronization with the aircraft turn if the radar display is also capable of this function.

Auto tilt (TWR-850/WXR-840 only) is an additional feature designed to decrease workload. During altitude or range changes, it automatically maintains the antenna tilt angle to the approximate angle desired by the pilot based on the previous selected tilt settings. Pilots will also appreciate the sector scan (not included on WXR-800) of ±30° for providing rapid updates at critical times.

The TWR-850/WXR-840/WXR-800 also provides gain settings both above and below the calibrated position. Three steps in each direction with each step and provide approximately six dB of gain change that result in a total range of ±18 dB (two color levels) from the calibrated position.

The all solid-state RTA-8XX receiver/transmitter/antenna/processor assembly is the central item of the TWR-850/WXR-840/WXR-800 system. This unit mounts on the forward bulkhead in the place where, traditionally, only the radar antenna was installed. Mounted on the forward portion of this unit is the flat plate antenna. Directly behind the antenna is the RF assembly that consists of a solid-state transmitter and the receiver. No waveguide is required due to packaging. This eliminates the nuisance of installing and pressurizing the waveguide and, most importantly, the signal loss associated with waveguides.

The receiver/transmitter/antenna moves as a single unit as the system scans. This assembly is mounted on a drive mechanism that contains the motors and gears for the scan and tilt process.

The drive assembly is attached to the base, a cylindrical unit 15 inches in diameter and less than two inches deep. The base contains power supplies and the processing circuits which perform the signal processing required to obtain detailed information from the signals returned from the targets. Increased speed and decreased size of digital processing devices make it possible to provide this sophisticated signal processing in such a small unit.

Control of all weather radar functions is performed through the WXP-850, WXP-840 and WXP-800 Weather Radar Control Panels, associated with the TWR-850/WXR-840/WXR-800 systems or the DCP-2000 Display Control Panel. All provide rotary, push button and push-pull switches for the pilot and also contains circuitry required to process the radar data from the sensor unit and output it for use by the display system.