LG GB130kf750, Руководство по обслуживанию

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3.1.3 System Platform Application
X-GOLDTM102 was developed for very low cost Dual Band GSM/GPRS system solutions.
Here are some potential System Platform configurations that can be built with X-GOLDTM102
Solution:
3.1.4 GSM System Description
The X-GOLDTM102 is suited for mobile stations operating in the GSM850/900/1800/1900 bands.
In the receiver path the antenna input signal is converted to the baseband, filtered, and then
amplified to target level by the RF transceiver chip set. Two A-to-D converters generate two 6.5
Mbit/s data streams. The decimation and narrowband channel filtering is done by a digital
baseband filter in each path. The DSP performs:
1. The GMSK equalization of the received baseband signal (SAIC support available)
2. Viterbi channel decoding supported by an hardware accelerator.
The recovered digital speech data is fed into the speech decoder. The X-GOLDTM102 supports
fullrate, halfrate, enhanced fullrate and adaptive multirate speech CODEC algorithms.
The generated voice signal passes through a digital voiceband filter. The resulting 4 Mbit/s data
stream is D-to-A converted by a multi-bit-oversampling converter, postfiltered, and then amplified
by a programmable gain stage.
The output buffer can drive a handset ear-piece or an external audio amplifier, an additional output
driver for external loud speaker is implemented.
In the transmit direction the differential microphone signal is fed into a programmable gain amplifier.
The prefiltered and A-to-D converted voice signal forms a 2 Mbit/s data stream. The oversampled
voice signal passes a digital decimation filter.
The X-GOLDTM102 performs speech and channel encoding (including voice activity detection
(VAD) and discontinuous transmission (DTX)) and digital GMSK modulation.
In the RF transceiver part, the baseband signal modulates the RF carrier at the desired frequency
in the 850 MHz, 900 MHz, 1.8 GHz, and 1.9 GHz bands using an I/Q modulator. The
X-GOLDTM102 supports dual band applications.
Finally, an RF power module amplifies the RF transmit signal at the required power level. Using
software, the X-GOLDTM102 controls the gain of the power amplifier by predefined ramping curves
(16 words, 11 bits).