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The oscillator/transmitter circuit make RF pulse patterns and sends them out through the WXR antenna.
The oscillator circuits change the pulse width and the pulse repetition frequency (PRF) to make the RF pulse patterns for different selected ranges. The oscillator circuits can make RF pulse patterns for two different selected ranges at the same time. The transmitter circuits use the range from the left EFIS CP for the pulse pattern that transmits during the left-to-right antenna sweep. The pulse pattern made with the right EFIS CP range, transmits during the right-to-left antenna sweep.
If both range selections are the same, the RF pulse pattern is the same.
RF Transmit
The RF pulses go from the transmitter circuits through the duplexer. The duplexer connects the antenna to the transmitter during RF transmission. It also connects the antenna to the receiver circuits to get the return RF pulses. From the duplexer, the RF goes through the waveguide switch to the WXR antenna assembly.
RF Receive
The antenna receives the RF return signals. Then the RF goes through the waveguide switch, the duplexer, and to the receiver circuits. The receiver circuits process the return signals and send them to the CPU. The CPU uses the strength of the RF return signals to calculate the rate of rainfall and to make the WXR display data.
WXR Display Data
The CPU puts the WXR display data, system mode, and status data into the ARINC 453 format and sends it to the ARINC 453 transmitters. The 453 transmitters put the data on the high speed ARINC 453 DATA BUS 1 and DATA BUS 2. Each data bus sends the data for both the captain’s and first officer’s ND. Certain bits on the data word are set to define if the display data is to go on the captain’s or first officer’s ND.
System Status Data
The BITE module continuously gets system status data. The BITE module sends the system status data through the ARINC 429 input/output (I/O) and out on the MAINT DATA OUT data bus to the CMCF of both AIMS cabinets. The BITE module gets test start command from the CMCF of AIMS or the WXR CP.
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WXR SYSTEM -WXR RT FUNCTIONAL DESCRIPTION

Predictive Windshear
The predictive windshear (PWS) function is a seperate circuit card in each RT. The PWS card turns on the selected RT when certain conditions exist. PWS detection circuitry uses doppler radar returns with inertial reference and attitude data to calculate if a windshear alert exists. If an alert exists, the PWS card makes a symbol and sends it to WXR core processor. The core processor adds the windshear symbol to the WXR display.
The PWS card makes a hazard bus output that contains windshear alert data. This data goes to the ground proximity warning computer (GPWC) priority alert logic. The GPWC sends a discrete inhibit back to the PWS card if a higher alert exists. The PWS card also makes an inhibit discrete that changes TCAS resolution advisories to traffic advisories during a windshear alert.
The PWS card uses takeoff configuration arm signals from the warning electronic system (WES) to turn on the PWS function at takeoff. It also makes these outputs that go to WES:
*
Audio alert output

*
Windshear warning discrete.

The PWS card makes these discretes that go to OPAS:
*
PWS caution

*
PWS fail

* PWS warning.
The PWS card uses an input from the landing gear lever module in its alert logic circuit.
The PWS card uses an input from the air/ground relay for these logics:
*
Alert logic

*
PWS auto on/off logic.

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WXR SYSTEM -WXR RT FUNCTIONAL DESCRIPTION

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WXR SYSTEM -ANTENNA ASSEMBLY FUNCTIONAL DESCRIPTION

Antenna Control
The central processing unit (CPU) in the WXR RT controls and monitors the antenna operation.
Antenna Stabilization
The WXR RT uses attitude inputs from the ADIRS for antenna stabilization. The CPU uses the attitude inputs to calculate and command scan and elevation movements and sends them to the antenna for stabilization.
left/Right System Operation
The antenna assembly has two sets of electronics and two power supplies. When you select the left WXR RT, the left power supply in the antenna assembly gets 115v ac from the left WXR RTs power supply. When you select the right WXR RT, the right power supply in the antenna assembly gets 115v ac from the right WXR RT. The power supply sends 28v ac to their respective motor drive.
　
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