SM1211E915TOPIC Semtech, SM1211E915TOPIC Datasheet - Page 26

• Manufacturer Part Number: SM1211E915TOPIC
• Description: KIT PICTAIL EXT FOR SX1211
• Manufacturer: Semtech
• Type: Transceiver, UHFr

Specifications of SM1211E915TOPIC

• Frequency: 915MHz
• For Use With/related Products: SX1211
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Table 37 suggests filter settings in FSK mode, along with the corresponding passive filter bandwidth and the
accepted tolerance on the crystal reference.
The center frequency, fo, is always set to 100kHz. The following chart shows the receiver bandwidth when
changing RXParam_Butterfilt bits, whilst the polyphase filter is activated.
Table 38 suggests a few filter settings in OOK mode, along with the corresponding passive filter bandwidth and the
accepted tolerance on the crystal reference.
After filtering, the In-phase and Quadrature signals are amplified by a chain of 11 amplifiers, each with 6dB gain.
The outputs of these amplifiers are used to evaluate the Received Signal Strength (RSSI).
Whilst the RSSI resolution is 0.5 dB, the absolute accuracy is not expected to be better than +/- 3dB due to process
and external component variation. Higher accuracy whilst performing absolute RSSI measurements will require
additional calibration.
Rev 7 – Sept 2
ADVANCED COMMUNICATIONS & SENSING
3.4.6. Channel Filters Setting in OOK Mode
3.4.7. RSSI
nd
, 2008
3.4.7.1. Resolution and Accuracy
3.4.7.2. Acquisition Time
450
400
350
300
250
200
150
100
450
400
350
300
250
200
150
100
50
50
0
0
0
0
Figure 18: Butterworth Filter's Actual BW
Figure 19: Polyphase Filter's Actual BW
2
2
4
4
Butterworth Filter's BW, FSK
Polyphase Filter's BW, OOK
Page 26 of 92
Val (RXParam_ButterFilt) [d]
6
6
Val (RXParam_ButterFilt [d]
RXParam_PolypFilt="0011"
8
8
10
10
12
12
Actual
BW
Actual
BW
Theoretical
BW
14
14
Theoretical
BW
16
16
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SX1211