Kenwood NXR-700 Service Manual

Also see for NEXEDGE NXR-700: Brochure Instruction manual Service manual Instruction manual Instruction manual

Contents

NXR-70021■ Modem control MPUModem control MPU (IC325) is 16-bit single chip micro-processor incorporating 256 kilobytes of ROM and 20 kilo-bytes of RAM.This MPU controls the Flash memory, two DSPs, theOCXO unit in the transmitter unit (X42-328) and the PLL cir-cuit.It also monitors the external power supply voltage. If thevoltage is abnormal, it stops the system.■ RX DSP (IC323)In NXDN mode, the IF signal input from the ADC (IC312)to the RX DSP is limited to a narrow band or a very narrowband. So, it passes through the IF band limitation band.This signal is demodulated by the wave detection pro-cessing part. The demodulated wave is made to passthrough the baseband limitation filter (root nyquist cosinefi lter and 1/sinc fi lter).This signal is symbol-detected and bit-judged, and isthen converted to NXDN data. Its frame timing is detectedand decoded for CAI (Common Air Interface: NXDN format)data error correction.Audio data is vocoder decode processed by the IC324TX_Vocoder_DSP. It is then converted into the PCM signal.It is analog-output as an audio signal by the DAC part of theAudio codec IC (IC309 AOUTL terminal).MainMPUIC703(CompactFlash)LAN ICIC719Flash memoryIC702EEPROMIC720DSPIC37CODEC ICIC4TEST/SPKRAOUT1~5DividerIC31Flash memoryIC17RS-232CIC705SDRAMIC704,707SRAMIC700Dsub25CN58OptionboardSWQ700Q702Beat shiftX70132.768kHzX70025.8048MHzRFcontrolMPUIC34RTC ICIC701SWQ4Q5Beat shiftX114.7456MHzSWQ704,Q705BeatshiftX70225MHzSWQ10,Q12BeatshiftX216.515072MHzModemcontrolMPUIC325RX DSPIC323Flash memoryIC314FRAMEIC302TX_VocoderDSPIC324BufferIC313CODEC ICIC309TCXO12.288MHzX300SWQ307Q308Beat shiftX30114.7456MHzOCXO controlBackupBA300UARTUARTShift register ICIC22Shift register ICIC1SR_CLKSR_DATASR_CLKSR_DATASTBShift register circuit (Display part)Refer to Fig. 27.STBSTB1Shift register(TX unit)STB_1DATAQSFig. 25 Control circuitCIRCUIT DESCRIPTION