Fm Radio Interface; Rf Description; Receiver (Rx); Transmitter (Tx) - Nokia RM-529 Service Manual

RM-529; RM-530; RM-584
System Module
The BTHFM module is powered by VBAT and the regulated voltage VIO. For audio applications the Bluetooth
has a PCM data bus. In addition an UART (universal asynchronous receiver/transmitter) is used for data
communication and controls.
Bluetooth shares the antenna with WLAN.
For Bluetooth interface, see the System module block diagram in

FM radio interface

The FM radio system is controlled by RAPU via the I2C bus. EM ASIC delivers the needed voltages and the clock
reference (32.768kHz SleepClk). EM ASIC also processes the analog audio.
The FM receiver fully supports reception over US/European (87.5MHz to 108MHz) FM band. The FM receiver
comprises an RF receiver with fully integrated VCO, a stereo FM demodulator and an RDS demodulator.
A headset accessory is used as an external antenna. The headset is connected to the AV connector.
The FM radio is physically integrated with Bluetooth in the BTHFM module ASIC, but from a functional point
of view the FM radio and Bluetooth have nothing in common.
For FM radio interface, see the System module block diagram in

RF description

Receiver (RX)

An analogue signal is received by the phone's antenna. The signal is converted to a digital signal and is then
transferred further to the baseband (e.g. to the earpiece).
The receiver functions are implemented in the RF ASIC.
Signals with different frequencies take different paths, therefore being handled by different components.
The principle of GSM and WCDMA is the same.

Transmitter (TX)

The digital baseband signal (e.g. from the microphone) is converted to an analogue signal, which is then
amplified and transmitted from the antenna. The frequency of this signal can be tuned to match the bandwith
of the system in use (e.g. GSM900).
The transmitter functions are implemented in the RF ASIC.
Even though the GSM and WCDMA signals are sent via different components, the principle of the transmission
is the same.
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Phone description (page
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6–5).
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