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AS3932

Datasheet - Detailed Descr i p ti on

8.7 False Wake-up Register

The wake-up strategy in the AS3932 is based on 2 steps:

1. Frequency Detection: in this phase the frequency of the received signal is checked.

2. Pattern Correlation: here the pattern is demodulated and checked whether it corresponds to the valid one.

If there is a disturber or noise capable to overcome the first step (frequency detection) without producing a valid pattern, then a false wake-up call

happens.Each time this event is recognized a counter is incremented by one and the respective counter value is stored in a memory cell (false

wake-up register). Thus, the microcontroller can periodically look at the false wake-up register, to get a feeling how noisy the surrounding

environment is and can then react accordingly (e.g. reducing the gain of the LNA during frequency detection, set the AS3932 temporarily to

power down etc.), as shown in the Figure 20. The false wake-up counter is a useful tool to quickly adapt the system to any changes in the noise

environment and thus avoid false wake-up events.

Most wake-up receivers have to deal with environments that can rapidly change. By periodically monitoring the number of false wake-up events

it is possible to adapt the system setup to the actual characteristics of the environment and enables a better use of the full flexibility of AS3932.

1560

10.25

10.25

1488

10.75

10.75

1424

11.23

11.23

1364

11.73

11.73

1310

12.21

12.21

1260

12.69

12.69

1212

13.20

13.20

1170

13.67

13.67

1128

14.18

14.18

1092

14.65

14.65

1056

15.15

15.15

1024

15.62

15.62

Table 22. Preamble Requirements in Standard Mode, Scanning Mode and ON/OFF Mode

Bit rate (bit/s)

Maximum duration of the carrier burst in Standard

Mode and Scanning Mode (ms)

Maximum duration of the carrier burst in ON/OFF Mode

(ms)