TDA5230 Datasheet, PDF (79/186 Pages) Infineon Technologies AG – Universal Low Power ASK/FSK Single Conversion Multi-Channel Image-Reject Receiver

TDA523x
2.4.9 Digital Receiver
Functional Description
The functionality of the Digital Receiver (DigRX) is divided into three consecutive data
processing stages: the Data Filter, the Clock and Data Recovery and the Framer
Synchronization Unit. The architecture of the Digital Receiver is optimized for processing
Manchester-coded data streams. The figure below shows all the symbol combinations.
Digital 0 and 1 are coded with the change of the amplitude in the middle of the symbol
period. The Code Violations (CV) M (mark) and S (space), are coded as low/high signal
levels. Generally, the Digital Receiver can handle one single CV following four valid
Manchester-coded data bits
0
1
S
M
Figure 37
1st 2nd
Chip Chip
1st 2nd
Chip Chip
Manchester Code
1st 2nd
Chip Chip
1st 2nd
Chip Chip
The basic structure of a telegram frame is shown in the figure below. The protocol starts
with RUNIN. The RUNIN with the minimum length of four manchester coded symbols is
used for internal filter setting and frequency adjustment. The TSI (Telegram Start
Identifier), which is used as framing word, follows the RUNIN sequence. The payload
contains the effective data. The length of the valid payload data is defined as the length
itself or additional criteria (e.g. loss of Sync).
RUNIN
TSI
Figure 38 Frame
PAYLOAD
2.4.9.1 Synchronization Search Time and Inter-Frame Time
Two important system parameters will be described in this chapter: the Synchronization
Search Time Out (SYSRCT0) and the Inter-Frame Time. The processing sequence of a
telegram is shown below.
Data Sheet
75
Version 4.0, 2007-06-01