TRANSCEIVER 800 MHz MTP700 Portable Radio / Detailed Service Manual 4.2 - 7
Transmitter Path
When the radio is transmitting (see Figure 4.2-3), the microphone audio is sent to the
GCAP3 (CODEC). The CODEC performs 13-bit analog-to-digital conversion and the dig-
ital signal is routed to the DSP (part of RedCap2). The DSP performs coding, Error Cor-
rection and
modulation. From the DSP, the signal is sent to the WPIC.
Figure 4.2-3 Transmit Path - Block Diagram
In the WPIC, the digital baseband I & Q signals are converted into corresponding analog
signals. These signals are also filtered. From the WPIC, I & Q signals are injected to the
LNODCT. In the LNODCT the data is mixed with RF signal.
From the differential output of the LNODCT the modulated RF signal is injected to the
Balun-Filter, that transforms the differential input into single output, and then it is routed to
the antenna via the Antenna Switch.
The feedback signal is used for power control.
GCAP
REDCAP2
WPIC LNODCT Balun-Filter Attenuator
Attenuator
RF PA
-3dB
0dB
32dB
-6dB
-0.2dB
-0.8dB
Antenna
Switch
Harmonic
Filter
Figure 3 Transmit Path Block Diagram
Power at Antenna:30dBm + 2dB
Mic
From Tx PLL
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