(11) A BITE/monitor The BITE/monitor provides the BITE power supply voltages to BITE functions and circuits, a power monitor for the detected transmitter output and an interconnect for various signals used throughout the transceiver.
**ON A/C 001-049, 101-105, 151-199,
B. Weather Radar Antenna (Ref. Fig. 008) The weather radar antenna is controlled in azimuth and elevation by the transceiver. The antenna movements are ensured by 2 DC motors and the angular positions are recopied by 2 or 4 synchros (2 for a single antenna and 4 for a dual antenna). The RF signal (transmitted or received) is conveyed by a wave guide between the antenna and the transceiver. Energization of the antenna is 115VAC/400 Hz through the transceiver.
R **ON A/C 051-099, 106-149, 201-299, 301-399, 401-499,
B. Weather Radar Antenna (Ref. Fig. 008A) The weather radar antenna is controlled in azimuth and elevation by the transceiver CPU. The binary control data are decoded and activate the antenna scan and elevation steeper motors through corresponding power circuits. The indication of these positions is sent to the CPU for comparison. The RF signal (transmitted or received) is conveyed by a wave guide between the antenna and the transceiver. Energization of the antenna is 115VAC/400 Hz through the transceiver.
**ON A/C ALL
C. Weather Radar Control Unit The gain and tilt potentiometric data are digitized by an 8-bit analog-to-digital converter. Moreover the different positions of the mode selector switch and the potentiometric data are formatted according to the ARINC 429 control word.
D. Weather Radar Wave Guide and Wave Guide Switch A wave guide assembly ensures the RF connection between the WR antenna drive and the WR transceiver mounting tray (connected to the wave guide switch). The wave guide assembly is made up of rigid and flexible parts which have a standard rectangular section (1 in. x 0.5 in.).
1EFF : ALL 1 34-41-00Page 38 1 1 Config-3 Aug 01/05 1 1 1CES 1
Weather Radar - Antenna
Figure 008
R 1EFF : 001-049, 101-105, 151-199, 1 34-41-00Page 39 1 1 Config-3 May 01/05 1 1 1CES 1
Weather Radar - Antenna
Figure 008A
R 1EFF : 051-099, 106-149, 201-299, 301-399, 1 34-41-00Page 40 1401-499, 1Config-3 Aug 01/05 1 1 1CES 1 The wave guide switch is integral with the mounting tray. It ensures switching of the RF signal from the antenna to the transceiver. Moreover control circuits recopy the wave guide switch position to avoid transmission on a closed wave guide.
R 1EFF : ALL 1 34-41-00Page 41 1 1 Config-3 May 01/05 1 1 1CES 1
7. Operation
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R **ON A/C 001-049, 101-105, 151-199,
A. Operation
(1) Weather Radar modes The weather radar system uses the principle of radio echoing. It works at a normal frequency of 9345 MHz. The peak power emitted is 125 W approx. The weather radar transceiver generates microwave energy in the form of electromagnetic pulses via an X-band wave guide to the antenna. When these pulses intercept an appropriate target, part of the energy is reflected back to the weather radar antenna then to the transceiver. For each case, the system uses a different mode of operation which allows to vary the scanning of the antenna, the timing of the pulses and the processing of the weather radar returns and of the predictive windshear events (if the function is activated). The electronics circuits of the transceiver measure the elapsed time between the transmission of the wave and the reception of the echo to determine the target distance (it takes around 12.36 microseconds for the electromagnetic wave to travel out and back for each nautical mile of target range). The angular position of the target is detected by the angular position of the antenna in its scanning in azimuth. As the quantity of energy reflected to the antenna is proportional to the target density, the different levels of atmospheric disturbances (see table 1 below) are shown on the displays by different colors. The detection of the turbulence areas are based on the Doppler phenomenon.
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