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CC11x1-Q1
SWRS076B – 11-07-22-013 - APRIL 2009 – REVISED APRIL 2010
The symbol encoding is shown in
3.12.2 Minimum Shift Keying
When using MSK [identical to offset QPSK with half-sine shaping (data coding may differ)], the complete
transmission (preamble, sync word, and payload) is MSK modulated. Phase shifts are performed with a
constant transition time. The fraction of a symbol period used to change the phase can be modified with
the DEVIATN.DEVIATION_M setting. This is equivalent to changing the shaping of the symbol. The MSK
modulation format implemented in CC11x1-Q1 inverts the sync word and data compared to, e.g., signal
generators.
3.12.3 Amplitude Modulation
CC11x1-Q1 supports two different forms of amplitude modulation: On-Off Keying (OOK) and Amplitude
Shift Keying (ASK).
OOK modulation simply turns on or off the PA to modulate 1 and 0 respectively.
The ASK variant supported by the CC11x1-Q1 allows programming of the modulation depth (the
difference between 1 and 0), and shaping of the pulse amplitude. Pulse shaping produces a more
bandwidth constrained output spectrum.
3.13 Received Signal Qualifiers and Link Quality Information
CC11x1-Q1 has several qualifiers that can be used to increase the likelihood that a valid sync word is
detected.
3.13.1 Sync Word Qualifier
If sync word detection in RX is enabled in register MDMCFG2, the CC11x1-Q1 does not start filling the RX
FIFO and performing the packet filtering described in
detected. The sync word qualifier mode is set by MDMCFG2.SYNC_MODE and is summarized in
Table
3-10. Carrier sense is described in
MDMCFG2.SYNC_MODE
38
Detailed Description
Table
3-9.
Table 3-9. Symbol Encoding for 2-FSK/GFSK
FORMAT
2-FSK/GFSK
Section
Table 3-10. Sync Word Qualifier Mode
000
No preamble/sync
001
15/16 sync word bits detected
010
16/16 sync word bits detected
011
30/32 sync word bits detected
100
No preamble/sync, carrier sense above threshold
101
15/16 + carrier sense above threshold
110
16/16 + carrier sense above threshold
111
30/32 + carrier sense above threshold
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Modulation
SYMBOL
CODING
0
– Deviation
1
+ Deviation
Section 3.11.3.3
3.13.4.
SYNC WORD QUALIFIER MODE
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before a valid sync word has been
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