AN3213 datasheet(51/64 Pages) STMICROELECTRONICS

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AN3213

Application ideas

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Figure 48.

Scheme of principle for switched three-phase architecture

8.2

Received signal strength indication (RSSI)

In many application fields, measuring the strength of the incoming signal is useful to:

●

Evaluate the SNR (signal-to-noise ratio) at the node

●

Choose the best routing through the network (if repeaters are allowed).

As explained in References 1 and 2, the ST7570 embeds estimators for signal-to-noise ratio

(SNR0, SNR1) values. These estimators are calculated during valid packet reception on

each S-FSK spectrum frequency f0 and f1. The values are notified to the external host

during each data indication message (References 2). In order to evaluate the robustness of

ST7570 embedded estimators, the setup represented in Figure 33 has been adopted and all

the estimator values extracted from received packets have been compared to the values

measured by the spectrum analyzer.

Figure 49, 50, 51 and 52 show the error bars with standard deviation for SNR0 and SNR1

values, compared to the measured values for 1200 and 2400 baud.

AN3213 Datasheet(PDF) 51 Page - STMicroelectronics