M
ODEL
SL900A V
ERSION
V_1.0
P
REPARED BY
H/W
D
ATE
2006.06.30
S
UBJECT
T
ECHNICAL
M
ANUAL
P
AGE
34/51
SL900A
T
ECHNICAL
M
ANUAL
9.3
Uplink Path (TX Path)
The purpose of the uplink path inside Baseband Front End is to sink TX symbols, one bit for each symbol,
from DSP, then perform GMSK modulation on them, then perform offset cancellation on I/Q digital signals out
of GMSK modulator, and finally control TX mixed-signal module to make D/A conversion on I/Q signals out of
GMSK Modulator with offset cancellation. Accordingly, the uplink path is composed of uplink parts of
Baseband Serial Ports, GSM Encryptor, GMSK Modulator and Offset Cancellation.
Figure 33. Block Diagram of TX Path
10.
Timing Generator
Timing is the most critical issue in GSM/GPRS applications. The TDMA timer provides a simple interface for
the MCU to program all the timing-related events for receive event control, transmit event control and the timing
adjustment.
In pause mode, the 13MHz reference clock may be switched off temporarily for the purpose of power saving
and the synchronization to the base-station is maintained by using a low power 32.768KHz crystal oscillator.
The 32.768KHz oscillator is not accurate and therefore it should be calibrated prior to entering pause mode.
Figure 34. The Block Diagram of TDMA Timer
.
Summary of Contents for SL900A
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