Signaling Circuit; Compander Circuit; Gps Circuit - Kenwood NX-720 Service Manual

NX-720(G)/720

8. Signaling Circuit

8-1. Encode (QT/DQT/DTMF/2-tone/5-tone/MSK)
Each signaling data signal of the QT, DQT, DTMF, 2-tone,
5-tone and MSK is generated by the DSP circuit, super-
posed on a modulation signal and output from the ASIC
(IC507). Each deviation of the TX QT, DQT, DTMF, 2-tone,
5-tone and MSK tones are adjusted by changing the output
level of the DSP (IC502) and the resulting signal is routed to
the VCO and PLL.
8-2. Decode (QT/DQT/DTMF/2-tone/5-tone/MSK)
The audio signal is removed from the FM detection signal
sent to the DSP circuit and the resulting signal is decoded
by the DSP.

9. Compander Circuit

The term "compander" means compressor and expander.
The compander reduces noise by utilizing a compressor and
an expander. The DSP (IC502) performs this operation. The
Compander can be turned on or off using the FPU.
10. GPS Circuit (GPS model only)
The GPS information function can be used by setting it
through the FPU. The GPS signal of 1575.42MHz received
with the GPS active antenna (with a built-in LNA) is pro-
cessed by the GPS module (A801) and input to the ASIC
(IC507) through the UART port. The ASIC (IC507) processes
the GPS data (NMEA) and sends the resulting information to
the LCD.
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CIRCUIT DESCRIPTION