XE1203 ETC1 [List of Unclassifed Manufacturers], XE1203 Datasheet - Page 11

• Manufacturer Part Number: XE1203
• Description: Low-Power, integrated UHF transceiver
• Manufacturer: ETC1 [List of Unclassifed Manufacturers]

4.1.6
The Barker decoder is an alternative to the bit synchronizer for a fixed data rate of 1154 bps. The barker block is
selected in receiver mode when RTParam_Barker is high. In transmission, the information data at a bit rate of 1154
bps is spread using an 11 bits barker code. The result is a bit stream at 12.7 Kilo chips per second (Kcps), which is
applied to the frequency synthesizer. At the receiver part, the signal is demodulated using the FSK demodulator (at
12.7 Kcps) and fed to the Barker decoder that provides a information data stream (1154 bps) and a synchronized
clock to sample it.
The following figure describes the coding/decoding process.
In reception mode, the chip provides a clock (DCLK) to a microcontroller. The data can be sampled at the rising
edge of the clock. When using the barker coding decoding process, DCLK is used to detect the sync acquisition. If
there is no valid data, DCLK remains high. The first falling edge of the clock means that the sync acquisition phase
is reached and the data has became available. The next figure shows the data exchange during the reception
mode.
11
Barker decoder
information data
1154 bps
FSK DEMODULATOR
BARKER ENCODER
11 bit barker code
Demodulated chips with some
Figure 3. Data encoding decoding channel.
chip rate = 12.7 Kcps
residual jitter.
encoded information
chip rate = 12.7 Kcps
12.7 Kcps
data out (information recovered)
dclk = 1.145 KHz
data rate = 1.145 Kbps
BARKER DECODER
11 bit barker code
data
DCLK
MODULATOR
FSK
Data Sheet
XE1203
D0308-214