Kenwood TK-5400 Series Service Manual

Contents

13TK-5400CIRCUIT DESCRIPTION / SEMICONDUCTOR DATA7-7. DSPThe DSP circuit consists of a DSP (IC611), a codec(IC608), and an A/D converter (IC609) and processes thebase band signal. The DSP (IC611) operates on an externalclock of 12.288MHz (the same as the CPU), the I/O sectionoperates at 3.3V and the core section operates at 2.5V. TheDSP carries out the following processes:• C4FM modulation and demodulation• Analog FM modulation and demodulation• Vocoder (IMBE) processing between audio codec andmodulation/demodulation• CAI processing, such as error correction encoding• QT/DQT encoding/decoding• DTMF encoding• Compressor/expander processing• Transmit/receive audio filtering processing• VOX processing• Microphone amplifier AGC processing• Beep tone generation, audio mute processing• Modulation level processing8. Signaling Circuit8-1. Encode (QT/DQT/DTMF)Each signaling data signal of QT, DQT and DTMF is gen-erated by the DSP circuit, superposed on a modulation sig-nal and output from pin 16 of the codec IC (IC608).The modulation balance of the QT/DQT signal is adjustedby the D/A converter (IC605) and the resulting signal isrouted to the modulation input of the VCO (L702) and VCXO(X201).The DTMF deviation of the TX DTMF tone is adjusted bythe D/A converter (IC605) and the resulting signal is routedto VCO and VCXO. The RX DTMF tone is output from pin 15of the codec IC, passes through the receive audio signal sys-tem, and is output from the speaker.8-2. Decode (QT/DQT)The audio signal is removed from the FM detection signalsent to the DSP circuit and the resulting signal is decoded.9. Compander CircuitThe term “compander” means compressor and ex-pander. The compander reduces noise by utilizing a com-pressor and an expander.The TK-5400 contains DSP IC (IC611) to perform this op-eration. The TK-5400 compander can be turned on or offusing the FPU.2-bit Shiftregister22-bit ShiftregisterAddress decoder ControllatchReferencedividerLatchLatch2 2 2 2SMPhasedetectorSAAUX dividerLatchMain dividerPhasedetectorCOMP1481911Load signalsPumpbiasPumpcurrentsettingAmpAmp313171819516151224 7,106CLOCKDATASTROBERFin+RFin–REFin+REFin–AUXinTESTR SETV DDV DDCP20 PONPHPPHILOCKPHAGND GNDCP1. PLL : SA7026DH (TX-RX Unit IC204)1-1. Block Diagram1-2. Pin FunctionPin No. Pin Name Function1 LOCK Lock detect output2 TEST Test (should be either grounded orconnected to V DD )3 V DD Digital supply4 GND Digital ground5 RFin+ RF input to main divider6 RFin– RF input to main divider7 GND CP Charge pump ground8 PHP Main normal charge pump9 PHI Main integral charge pump10 GND CP Charge pump ground11 PHA Auxiliary charge pump output12 AUXin Input to auxiliary divider13 V DDCP Charge pump supply voltage14 R SET External resistor from this pin to groundsets the charge pump current15 REFin– Reference input16 REFin+ Reference input17 CLOCK Programming bus clock input18 DATA Programming bus data input19 STROBE Programming bus enable input20 PON Power down control