| 摘要 |
PURPOSE: A frequency converter using an in-phase/quadra-phase baseband signal in an RFU(Radio Frequency Unit) for a CDMA(Code Division Multiple Access) BTS(Base Transceiver Station) is provided to improve transmission efficiency using a low frequency by using a transmission signal with a DSP(Digital Signal Processor) block as a baseband signal with 0-165KHz bands. CONSTITUTION: An orthogonal modulator(60) raises a frequency of an in-phase/quadra-phase baseband signal transmitted from a DSP and generates a transmitting signal. An orthogonal demodulator receives an IF(Intermediate Frequency) signal of a receiving signal, lowers a frequency of the IF signal, and generates an in-phase/quadra-phase baseband signal. The orthogonal modulator(60) processes the in-phase/quadra-phase baseband signal according to a direct conversion method and generated the transmitting signal. The orthogonal modulator(60) inserts the in-phase/quadra-phase baseband signal into a carrier wave with 869-894MHz bands, directly cross-modulates the carrier wave, and generates the transmitting signal.
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