COMPONENT MAINTENANCE MANUAL
C17004
34-57-96
Page 25
COPYRIGHT
SEXTANT Avionique 1995
c
(3) Analog filtering
The GPS signals are received at the RF input on the HF PCB.
One or two frequencies can be received:
- L1 = 1575.42 MHz and eventually L2 = 1227.60 MHz.
(a) Single-frequency filtering
The L1 signal is filtered and matched before being applied to the
frequency conversion stage; CDEL1L2 signal is not used in this case.
(b) Double-frequency filtering
Each frequency is filtered and matched by a specific circuit, powered
by AFBL1 or AFBL2 voltage (+10V HF).
The selection between L1 or L2 is performed by a switching circuit
which receive CDEL1L2 signal.
This signal is sended by CPU PCB (when the specific software is
installed).
(4) Generation of the H1400 signal and HT100, HCAN clocks
(a) Local oscillator
This is a quartz oscillator which generates sinusoid signal H1400
(F = 1400 MHz), used by the frequency converter; this oscillator is
controlled by frequency synthesis circuit PLL1.
(b) PLL1 circuit
This is an AsGa integrated circuit which includes the elements
required for performing a phase locking loop.
It is made up mainly of a frequency division chain and a phase
comparator.
1
Frequency division
Sinusoid signal H1400 is applied to a divider by 14; the H100
signal thus obtained (100 MHz) is followed by a divider by 10,
the output of which (10 MHz) is applied to the V input of the
phase/frequency phase comparator.
OCT 15/01
© THALES AVIONICS
The document reference is online, please check the correspondence between the online documentation and the printed version.
