Connect Systems CS700, Руководство по обслуживанию

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DR6000-2/DR7000-2 Service Manual
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Frequency synthesizer consists of reference oscillator, voltage controlled oscillator (VCO),
programmable frequency divider (PFD), phase comparator and low pass filter (LPF).
RX VCO Unit consists of Q3 D1 D3 L13 C34 C38 C39 and C42.
TX VCO Unit consists of Q4 D2 D4 L14 C35 C41 C44 and C45,D5 is the modulation circuit of VCO.
IC607 (SKY72310) is PLL integrated circuit and contains programmable parametric frequency divider
(PPFD), programmable frequency divider (PFD), phase comparator and charge pump, etc.
Low pass filter consists of R5 R7 R9 R10 C12 C15 and C18.
Reference frequency is provided by X1 (TCXO, 16.8MHz).
Reference frequency of TCXO (Temperature-controlled Crystal Oscillator) is divided by PPFD in IC607
to produce reference frequency of 5kHz or 6.25kHz (controlled by MCU based on the set channel
frequency).
The oscillation frequency of VCO is compared with reference frequency to produce error signal after
divided by PFD in IC607. The error signal is filtered by low pass filter before changing the VCO
frequency to the set value in VCO (it is locking).
N=F
VCO
/F
R
N
：
Division Frequency
F
VCO
：
VCO Oscillation Frequency
F
R
：
Reference Frequency
Lock lost detection: When PLL is out of lock, IC pin4 will output low level signal to MCU
，
and then MCU
prohibit transmitter from transmitting with a warning tone.
Q8, the power filter, can provide PLL with more purified power to reduce the noise of frequency
synthesizer.
5.5 Base Band Processor
HR_C5000-1 (IC609) is a low power high performance base band processor supporting Tier 1 and
Tier 2 of the DMR protocol. it completes the entire physical layer and data link layer, and voice
processing part of the call control layer of DMR compliant with ETSI TS 102 361.