The Collins WRT-701X Receiver-transmitter functions as a component of the WXR-700X Weather Radar System. The solid state Color Weather Radar System operates in the X-band frequency range. The WXR-700X provides weather information to assist in hazardous weather condition detection and avoidance. Ground mapping capability provides an aid to navigation. The WRT-701X radiates 85 watts of peak power at 9.33 GHz (150 watts on FLW capable units) then receives reflected return signals from precipitation, ground terrain, or aircraft targets depending upon the mode of operation selected. Receive circuits then process the return signals into display video. In addition to normal weather detection, the WRT-701X can detect turbulence and wind shear events. The Pulse Repetition Frequency varies from 180 Pulses Per Second (PPS) in Weather Mode to 1440 PPS during Turbulence Detection getting as high as 9000 PPS on FLW capable units. The WRT-701X receiver-transmitter units with FLW capability are capable of recording three wind shear events that will be stored within the unit in the magnitude-velocity deviation data (MVD) log. The MVD log will not overwrite a logged wind shear event. Once three wind shear events have been recorded no new events will be recorded. The range selections vary from 5 to 320 nmi with 5 nmi increments.

The WRT-701X was designed for operation in an unpressurized environment and should be fitted in the right hand under the deck area. The WRT-701X should only be installed using the WMT-701X/702X RT mount. Using another manufacturers R/T mount may result in the loss of the fuse resistor in the 28 V keep-alive circuit. The WRT-701X has been designed and tested for mounting on a horizontal surface in to an equipment rack conforming to ARINC 600-B with forced air cooling. The WMA-702X/701X software program allows the WRT-701X to step the antenna flat plate in quarter degree increments for pointing accuracy while actual antenna movements are microstepped for smoother position movement. A Weather Radar Antenna receives in-phase and quadrature step signals from the WRT-701X in both the scan and elevation axes. The microcontroller computes the microstep positions and outputs them to the motor drive circuitry. The scan rate is a constant forty-five degrees per second. The elevation rate is dependent on the attitude correction required. The elevation movement is filtered to provide a smoother and less audible operation. The end of scan is decelerated and accelerated to soften turnaround thump. Movement of the antenna is smoothed by microstep positioning of the antenna stepper motors in both the scan and elevation axes. The antenna returns the in-phase and quadrature incremental monitor signals for the scan and elevation axes to the WRT-701X along with the left/right and up/down zero monitor signals. The CPU manages the incremental monitors for fault monitoring and reporting to the WRT-701X. The WRT-701X uses these monitor signals to detect faults in the antenna positioning.