Khz Tx If Signal - Furuno FS-1575 Service Manual

Signal Name
CLK TX DDS / PLL IC clock signal
DATA TX Frequency data set to DDS / PLL IC
UNLOCK Unlock signal of PLL circuit
ST DDS TX Data set strobe signal to DDS
ST PLL TX Data set strobe signal to PLL
Detection signal of 36-kHz TX IF signal inputted to the TX board, which
IF CHK
is used to conduct self-tests
RF CHK Detection signal of TX output signal, which is used to conduct self-tests
5V, 15V Power supply voltage for circuit
ALC TX output power control signal, which is inputted from the TX FIL board
REF ADJ Controls a reference oscillation frequency of 36 MHz.
TX ON Activates the TX circuit.
TX PWR TX power data outputted from the T-CPU
Displays TX board version information when selecting [MENU] -> 9.
TX HW VER0, 1
SERVICE -> 5.TEST -> 1.VERSION.
OVEN 12V Unused

1. 36kHz TX IF signal

The 36-kHz TX IF signal is generated by modulating voice, DSC, and NBDP signals
with the DSP of the T-CPU board and converting the modulated signal to an analog
signal with CODEC. This signal varies in the frequency with the type of Emission.
• USB
: 34.5 kHz
• J2B (F1B) : 36.0 kHz
• A1A
: 36.0 kHz
2.0Vp-p
1.5
1.0
0.5
Fig. 7.2.2 SSB TX IF Input vs. Board Output Power Level
CONFIDENTIAL (internal use only)
This confidential document is used only by FURUNO authorized persons.
It is strictly prohibited to reproduce the document in whole or in part without prior written permission of FURUNO.
-60 -50 -40
AF OSC OUTPUT Level
7-10
7.2 Transmission Circuit
Table 7.2.1 Major Signals of TX Board
Function
SSB 12MHz
dBm
-30 -20