SX1210 SEMTECH [Semtech Corporation], SX1210 Datasheet - Page 45

• Manufacturer Part Number: SX1210
• Description: Ultra-Low Power Integrated UHF Receiver
• Manufacturer: SEMTECH [Semtech Corporation]

Two techniques are supported by the SX1210 packet handler: Manchester decoding and data whitening. Please
note that only one of the two methods should be enabled at a time.
Manchester decoding is enabled by setting bit PKTParam_Manchester_on and can only be used in Packet mode.
The NRZ data to Manchester codes ‘1’ as “10” and ‘0’ as “01”.
In this case, the maximum chip rate is the maximum bit rate given in the specifications section and the actual bit
rate is half the chip rate.
Manchester decoding is only applied to the payload and CRC checksum while preamble and Sync word are kept
NRZ. However, the chip rate from preamble to CRC is the same and defined by MCParam_BR (Chip Rate = Bit
Rate NRZ = 2 x Bit Rate Manchester).
Manchester decoding is thus made transparent for the user, who still retrieves NRZ data from the FIFO.
Another technique called whitening or scrambling is widely used for randomizing the user data before radio
transmission. The data is whitened using a random sequence on the Tx side and de-whitened on the SX1210 (Rx
side) using the same sequence. Comparing to Manchester technique it has the advantage of keeping NRZ datarate
i.e. actual bit rate is not halved.
SX1210 supported whitening algorithm is given in Figure 38. This figure provides you with the random sequence to
be X-ORed with the actual payload.
The de-whitening process is enabled by setting bit PKTParam_Whitening_on. The data is de-whitened by the
SX1210 receiver side by XORing with the same random sequence as the Tx.
Payload de-whitening is thus made transparent for the user, who still retrieves NRZ data from the FIFO.
Rev 2– Sept 8
ADV
RF chips @ BR
User/NRZ bits
Manchester OFF
User/NRZ bits
Manchester ON
ANCED COMMUNICATIONS & SENSING
data input
5.5.5. DC-Free Data Mechanisms
th
, 2008
X
5.5.5.1. Manchester Decoding
5.5.5.2. Data Dewhitening
15
...
...
...
X
14
1
1
1
1/BR
1
1
1
X
13
...Sync
1
1
1
0
0
0
X
Figure 37: Manchester Decoding
Figure 36: CRC Implementation
12
1
1
1
CRC Polynomial =X
0
0
0
0
0
0
Page 45 of 73
X
1
1
11
1
0
0
* * *
1/BR
0
0
16
0
+ X
1
1
12
X
5
+ X
0
0
Payload...
5
+ 1
0
1
1
1
1
X
1
4
0
0
* * *
1
1
1
www.semtech.com
0
0
SX1210
X
...
...
...
0
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