xe1205 Semtech Corporation, xe1205 Datasheet - Page 17

• Manufacturer Part Number: xe1205
• Description: Low-power, High Link Budget Integrated Uhf Transceiver
• Manufacturer: Semtech Corporation

5.2.6
The lowest bandwidth for the base-band filter which can be selected by changing only a 2-bit word in the configuration
register is 10 kHz. However, as described in section 7.2.8, additional register settings allow this bandwidth to be further
reduced. This option allows the user to improve the selectivity of the receiver for very narrow-band applications.
Activating this option is advised for bit rates and frequency deviations not higher than 4.8 kbit/s and 5 kHz and if the LO
frequency of the receiver is well controlled, for instance by means of a very accurate crystal or the activation of an AFC.
The table below gives the sensitivity and the adjacent channel rejection for BR = 4.8 kbit/s and Df = 5 kHz for different
bandwidths.
Table 9 below gives the sensitivity and the adjacent channel rejection for BR = 1.2 kbit/s and Df = 2 kHz.
It can be seen from table 9 that this option also allows the sensitivity to be improved for very low bit rates and frequency
deviations.
© Semtech 2007
Bandwidth
Bandwidth
SSB
SSB
10 kHz
10 kHz
9 kHz
8 kHz
7 kHz
9 kHz
8 kHz
7 kHz
Additional narrowband filter bandwidths
TParam_Low _BW
TParam_Low _BW
Table 8: Performances of the receiver for very narrow bandwidths and 4.8 kbit/s
Table 9: Performances of the receiver for very narrow bandwidths and 1.2 kbit/s
0
1
1
1
0
1
1
1
TParam_Code_BW(8:0)
TParam_Code_BW(8:0)
139
160
185
X
139
160
185
X
17
(BER=0.1%)
Sensitivity
-117.5 dBm
-119.5 dBm
-115.5 dBm
(BER=0.1%)
Sensitivity
-116 dBm
-116 dBm
-115 dBm
-118 dBm
-119 dBm
RFS
RFS
Adjacent Channel Rejection
Adjacent Channel Rejection
(25 kHz offset single tone)
(25 kHz offset single tone)
ACR
ACR
18 dBc
23 dBc
28 dBc
33 dBc
20 dBc
25 dBc
30 dBc
35 dBc
XE1205
www.semtech.com