CC1100ERGPR Datasheet, PDF (39/97 Pages) Texas Instruments – Low-Power Sub-GHz RF Transceiver

CC1100E
16.3 Amplitude Modulation
The CC1100E supports two different forms of
amplitude modulation: On-Off Keying (OOK)
and Amplitude Shift Keying (ASK).
OOK modulation simply turns the PA on or off
to modulate ones and zeros respectively.
The ASK variant supported by the CC1100E
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.
When using OOK/ASK, the AGC settings from
the SmartRF^® Studio [8] preferred FSK/MSK
settings are not optimum. DN022 [15] give
guidelines on how to find optimum OOK/ASK
settings from the preferred settings in
SmartRF^® Studio [8]. The DEVIATN register
setting has no effect in either TX or RX when
using OOK/ASK.
17 Received Signal Qualifiers and Link Quality Information
The CC1100E has several qualifiers that can be
used to increase the likelihood that a valid
sync word is detected:
 Sync Word Qualifier
 Preamble Quality Threshold
 RSSI
 Carrier Sense
 Clear Channel Assessment
 Link Quality Indicator
17.1 Sync Word Qualifier
If sync word detection in RX is enabled in the
MDMCFG2 register, the CC1100E will not start
filling the RX FIFO and perform the packet
filtering described in Section 15.3 before a
valid sync word has been detected. The sync
word qualifier mode is set by
MDMCFG2.SYNC_MODE and is summarized in
Table 28. Carrier sense in Table 28 is
described in Section 17.4.
MDMCFG2.
Sync Word Qualifier Mode
SYNC_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
Table 28: Sync Word Qualifier Mode
17.2 Preamble Quality Threshold (PQT)
The Preamble Quality Threshold (PQT) sync
word qualifier adds the requirement that the
received sync word must be preceded with a
preamble with a quality above the
programmed threshold.
Another use of the preamble quality threshold
is as a qualifier for the optional RX termination
timer. See Section 19.7 on page 49 for details.
The preamble quality estimator increases an
internal counter by one each time a bit is
received that is different from the previous bit,
and decreases the counter by eight each time
a bit is received that is the same as the last bit.
The threshold is configured with the register
field PKTCTRL1.PQT. A threshold of 4∙PQT for
this counter is used to gate sync word
detection. By setting the value to zero, the
preamble quality qualifier of the sync word is
disabled.
A “Preamble Quality Reached” signal can be
observed on one of the GDO pins by setting
IOCFGx.GDOx_CFG=8. It is also possible to
determine if preamble quality is reached by
checking the PQT_REACHED bit in the
PKTSTATUS register. This signal / bit asserts
when the received signal exceeds the PQT.
SWRS082
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