Maxon Electronics Australia Pty. Ltd. MM-5500SU 用户手册
FCC Documentation
MM-5500SU CDMA 1X/EVDO Modem
MM-5500SU CDMA 1X/EVDO Modem
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Confidential and proprietary information.
This document is the sole and exclusive property of Maxon.
Not to be distributed or divulged without prior written agreement.
This document is the sole and exclusive property of Maxon.
Not to be distributed or divulged without prior written agreement.
9. Description of modulation system used
The CDMA Engine consists of MSM, baseband analog interface (RFT3100, S1M8656A) as
modulation system. The MSM integrates functions of a CDMA processing, a digital FM(DFM)
processing, CDMA subsystem in the MSM performs CDMA signal processing about CDMA
modulation / demodulation, viterbi
coding/decoding, interleaving/de-interleaving, and etc.
The CDMA baseband processor performs forward-link demodulation, time tracking and reverse-link
modulation for CDMA digital signals. The following figure shows a CDMA digital baseband processor
block diagram.
Figure 11. CDMA digital base-band block diagram
The modulator performs the orthogonal modulation, long code PN spreading and quadrature
spreading. The resulting data stream is then band limited with FIR filters and sent to the analog
base-band processor.
The RFT3100 Transmit Signal Path (shown in figure 8-2) accepts analog I and Q data from the MSM
and outputs modulated IF centered at 138.6 MHz to the RF transmitter. The RFT3100 transmit path
outputs a differential IF signal with spread spectrum modulation expending ±630KHz from the
transmit IF center frequency of 138.6 MHz.
The analog I and Q base-band components from the CDMA low-pass filters are mixed in quadrature
with un-modulated I and Q signals at 138.6 MHz. After mixing, the I and Q IF components are
summed and output differentially. The 138.6 MHz I and Q IF VCO signals are generated on the
RFT3100.