Philips SPENDEX 40 Maintenance Manual page 26

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NATO CONFIDENTIAL
S P E N D E X 4 0 U A 8 2 5 1 / 0 0 A N D / O l L I M I T E D M A I N T E N A N C E M A N U A L
4 . 9 T i m i n g b o a r d
4 . 9 . 1 T i m e b a s e
The time base produces control and clock signals for the various
circuits on transmitting and receiving side, viz.:
- a 2400 Hz transmitting clock (TC);
- a 2400 Hz receiving clock (RC);
- the 300 Hz line out interrupt signal (CLOUT);
- the 300 Hz line in interrupt signal (CLIN);
- the 44.44 Hz new frame signal transmitting side (NFTN);
- the 44.44 Hz new frame signal receiving side (NFRN);
- an 8 kHz clock signal transmitting side;
- an 8 kHz clock signal receiving side.
The transmitting clock and the receiving clock have been synchronised
with the transmitting clock M0D114 and the receiving clock M0D115 of
the modem with the help of Phase Locked Loops (PLLs).
4 . 9 . 2 T i m e r s
The timing board is fitted with 2 timers, a timer long and a timer
short. The function of these timers is to measure intervals of time.
The timers are programmed by the comsec controller and produce an
interrupt signal when an interval of time has elapsed.
4 . 9 . 3 A l a r m a n d p o w e r - o n r e s e t c i r c u i t
This circuit produces a reset signal (RESET) when there is a
breakdown in the comsec controller, when the power supply is switched
on and when the power supply voltage becomes too low. The reset
signal is directed to the comsec controller and the vocoder
controller, which in their turn pass on the signal to several other
c i r c u i t s .
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NATO CONFIDENTIAL