FLY DS 110, Руководство по обслуживанию

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DS 110 Service menu
2 RF
2.1 RF Overview
RF part mainly consists of transceiver AD6548 (adopts program of near-zero IF receiver,
supporting the EGSM / DCS and 26M Crystal as the clock input, integrated clock buffer, LO
VCO and TX VCO and regulator, only need for external connections of VBAT / AVDD),
PARPF88143B (it supports EGSM / DCS and integrated automatic power control and
transceiver switch).
AD6548
Baseband Chip
GSM RF and BB interface diagram
Transceiver (AD6548) with the RF modulation and demodulation functions contains IF
frequency synthesizer and VCO RF, which is part of the core component of the RF. PA has a
major role in amplification of modulation signal, and it must be controllable and the
speed should meet the GSM agreement.
2.2 Transmit
TX is composed of the modulation loop, power amplifier and antenna switch. PLL is
mainly in the internal AD6548, I / Q signal first enters into the AD6548, after entering the
PLL the signal is modulated to RF, and then it outputs from the chip to PA, converts into
electromagnetic energy through antenna by the antenna switch after enlarged.
PA:
This part adopts voltage control to achieve and its role is to amplify the signal power in
accordance with the requirements. It is divided to two different power levels through
VRAMP signal. The transmit signal of GSM is 5 to 19, power is from 3.2MW to 2W while
DCS is 0 ~ 15, power from 1MW ~ 1W. PA is time-sharing work controlled by TX-EN chip,
the output power of PA is controlled by VRAMP (APC) through the
voltage. PA is intermittent work, by the BS to achieve the choice of frequency bands.
2.3 Receive
Antenna RX – AD6548 (RX_VCO mixer) - band-pass - Amplification - filter - Amplification -
RX_VCO mixer - CPU
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