Kenwood NXR-700H Service Manual

NXR-700H32This MPU controls the Flash Rom, two DSPs, the OCXOunit in the transmitter unit (X42-328) and the PLL circuit.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 base band limitation filter (root nyquist cosinefilter and 1/sinc filter).This signal is symbol-detected and bit-judged, and is thenconverted to NXDN data. Its frame timing is detected anddecoded for CAI (Common Air Interface: NXDN format) dataerror 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 ROMIC702EEPROMIC720DSPIC37CODEC ICIC4TEST/SPKRAOUT1~5DividerIC31Flash ROMIC17RS-232CIC705SDRAMIC704,707SRAMIC700Dsub25CN58OptionboardSWQ700Q702Beat shiftX70132.768kHzX70025.8048MHzRFcontrolMPUIC34RTC ICIC701SWQ4Q5Beat shiftX114.7456MHzSWQ704,Q705BeatshiftX70225MHzSWQ10,Q12BeatshiftX216.515072MHzModemcontrolMPUIC325RX DSPIC323Flash ROMIC314FRAMEIC302TX_VocoderDSPIC324BufferIC313PLL ICIC315CODEC ICIC309VCXO12.288MHzX300SWQ307Q308Beat shiftX30114.7456MHz19.2MHzOCXO controlBackupBA300UARTUARTShift register ICIC22Shift register ICIC1SR_CLKSR_DATASR_CLKSR_DATASTBShift register circuit (Display part)Refer to Fig. 27.STBSTB1Shift register(TX unit)STB_1DATAQSCIRCUIT DESCRIPTION / 电路说明该 MPU 控制 Flash Rom、两个 DSP、发射机单元 (X42-328)中的 OCXO 单元和 PLL 电路。它还监测外部电源电压。如果电压异常，它将停止系统。■ RX DSP(IC323)在 NXDN 模式中，从 ADC(IC312) 输入 RX DSP 的 IF 信号被限制为窄频带和超窄频带。因此，它将通过 IF 带限制频带。该信号由检波处理部分解调。制作的解调波通过基带限制滤波器 ( 根奈奎斯特余弦滤波器和 1/sinc 滤波器 )。该信号经过符号检测和位数判定，然后被转换成 NXDN 数据。其帧时序被检测和解码，用于 CAI( 公共空中接口 : NXDN 格式 )数据纠错。音频数据由 I C324 T X _ 声码器 D S P 进行声码器解码处理。然后，它被转换为 PCM 信号。它被音频编解码器 IC 的 DAC 部分 (IC309 AOUTL 端子 ) 模拟输出为音频信号。Fig. 25 Control circuit / 图 25 控制电路