F800 CIRCUIT DESCRIPTION
6 (25)
Uppgjord (även faktaansvarig om annan) -
Prepared (also subject responsible if other)
Nr
-
No.
KL/ECS/S/LT Magnus Lindahl
ECS/S/LT-96:5044
Dokansv/Godk -
Doc respons/Approved
Kontr
-
Checked
Datum
-
Date
Rev
File
KI/ECS/S/LTC
1996-06-06
A
965044.DOC
Frequency generator
The frequency generator is implemented as a conventional phase locked loop
controlled synthesiser. In simplex versions of F800, one frequency generator produces
local oscillator signal for the receiver and also the transmitter carrier. In duplex
versions, one frequency generator is used for local oscillator and one frequency
generator is used to produce the transmitter carrier.
The following circuits are the major parts of the frequency generator used in simplex
versions:
#"
VCO, Voltage Controlled Oscillator.
#"
PLL, synthesiser circuit
#"
Prescaler
#"
Loop filter
#"
Crystal reference oscillator
#"
Buffer stage
#"
Output amplifiers
PLL
9 MHz
LOOP
Filter
VCO
1:1
Prescaler
40/41
[64/65]
TX Carrier
1st LO
Locking
Address
Data
Clock
Mod
Phase
Mod FM
Fig B: Frequency generator, principal diagram
In duplex versions two frequency generators are used. Both generators are built with
the same blocks as used in the simplex generator as indicated above.