CC1100ERGPR datasheet(39/97 Pages) TI

39 / 97 page

CC1100E

SWRS082

Page 39 of 92

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

the

pulse

amplitude.

Pulse

shaping

produces

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

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

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

set

MDMCFG2.SYNC_MODE

and is summarized in

Table 28. Carrier sense in Table 28 is

described in Section 17.4.

MDMCFG2.

SYNC_MODE

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

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

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

the

PKTSTATUS

when the received signal exceeds the PQT.

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