(5)
The QAR records the data on four tracks with tape marks being used as file seperators. The tape marks are BEGINNING OF TAPE (BOT), END OF TAPE (EOT), LOAD POINT (LP) and END WRITING (EW). The cartridge drive is controlled by DFDAMU during normal operation (reading, writing and searching). The QAR is completely automatic in all operation other than loading and ejection of the cartridge.
D. TAPE
(1) The tape normal recording time is 14 hours with a tape speed XX inches per second. The cartridge has 4 tracks.
3. Operation (Fig. 2)
GUN 051 ú
31-35-00
ú ú 07 Page 3 ú Jan 28/02
QUICK ACCESS RECORDER
Quick Access Recorder Schematic
Figure 2
A
757
MAINTENANCE MANUAL
GUN 051 ú
31-35-00
ú ú 06 Page 4 ú Jan 28/02
A10240
A
757
MAINTENANCE MANUAL
A. Functional Description
(1)
The QAR receives data from DFDAU. The data is received by a B1-Polar circuit which interfaces with the C.P.U. Once the C.P.U. interprets the data it is transmitted to the data formatter circuit. This then sends the data to the cartridge. The data status circuit sends out signals to the DFDAU to indicate if the QAR is in normal operation or in the fail mode.
(2)
When the data is received, it is formatted into blocks. These are a preamble, a cyclic redundancy check character (CRCC) and post amble which are added before being written to tape. Read-after write error detection and automatic rewrite procedures are used to check transmission to tape accuracy. If writing is terminated and the data is incomplete, a tape mark is written followed by an end of track erase gap.
(3)
A write operation is initiated by inserting a blank cartridge in the QAR.
(4)
Reading of data is initiated by specifying the GMT reference for the required data.
(5)
The tape drive assembly has a single servo controller capstan with optical tachometer for speed control. This allows for a system free of mechanical clutches or belts. Accurate cartridge position is insured due to a three point suspension by which the cartridge is locked in place.
(6)
Data is read from the tape in blocks. After the preamble and postamble are removed the data is checked against CRCC. If correct it is also removed and the data is output to the DFDAU.
GUN 051 ú
31-35-00
ú ú 03 Page 5 ú Jan 28/01
A
757
FAULT ISOLATION/MAINT MANUAL
AIRPLANE CONDITION MONITORING SYSTEM
COMPONENT FIG. 102 SHT QTY ACCESS/AREA REFERENCE
RECORDER - QUICK ACCESS, M10387 DIGITAL FLIGHT DATA ACQUISITION MANAGEMENT UNIT - (31-31-00/101) FLIGHT RECORDER DC, C578 ACMS, C4459 CIRCUIT BREAKERS -FLIGHT RECORDER AC, C561 -------- 1 1 1 1 119BL MAIN EQUIP CTR, E3-3 11J34 FLT COMPT, P11 11J7 11J8 31-35-01* * *
中国航空网 www.aero.cn
航空翻译 www.aviation.cn
本文链接地址：757 AMM 飞机维护手册 仪表 CHAPTER 31 - INSTRUMENTS 2(7)
