Honeywell
COMPONENT MAINTENANCE MANUAL
PART NUMBER 964-0452
I.B.1516A
Mar 30/01
23-12-01
The Loop divider consists of D19, a predivider, whose division ratio can be var-
ied between 11:1 and 10:1, and D6, a synthesizer module, containing an A di-
vider, an N divider, a phase comparator, and an R divider.
The division ratios of D6 are set serially with 8 addressed 4-bit words, which are
processed in gate array, D99.
The predivider is switched from the A divider of the synthesizer module. The sig-
nal from predivider, D19, drives the A and N dividers. The frequency of the VCO
is divided by 11 A times and divided by 10 N-A times.
The entire division ratio M, therefore, is: 11 x A + 10 x (N–A) = 10 x N + A
The 1MHz reference frequency for loop 2 is supplied to the synthesizer module
via oscillator circuit L31/C89, and divided by 10 to obtain 100kHz in the R divider
of the synthesizer module.
The phase comparator, with subsequent integrator and amplifier, functions in
the same way as described for loop 1. The VCO is synchronized to M x 100kHz
with control voltage U-LOOP2.
4
DDS (digital direct synthesis)
A variable frequency is generated between 220kHz and 319.9kHz in 100Hz in-
crements with the 5MHz clock pulse in ICs, D99, D26, D24, and D23.
In addition, the setting of the loop 2 dividers is processed and output in gate ar-
ray, D99, and a strobe (STR7B) is decoded to store the VCO presetting in D25.
The registers with addresses 0 to 3 are loaded only when the transceiver is
switched on, the registers with addresses 4, 5, and 7 are loaded with each fre-
quency input.
With module select active (MS1 = LOW), the data of the module data bus are
loaded in the gate array registers according to the module addresses present
(MADR0, MADR1, MADR2) with the positive edge of the module write impulse
(MWR) (Ref. Fig. 12). The significance of the individual registers is:
Example:
A frequency of 15345.6kHz is set at the Control Display Unit (CDU).
R03, R02
Constant for N divider (39)
Value: 39MHz
R01
Constant for A divider (8)
Value: 800kHz
R14,R13
Constant for DDS (22)
Value: 220kHz
R12, R11,
R24, R23,
R22, R21
Constant for clock freq.
Value: 5MHz
R33, R32,
R31
Constant for R divider (A)
Value: 10
R44, R43,
R42, R41,
R54, R53
Value of the set frequency
+5kHz frequency offset.
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