AN3213 datasheet(40/64 Pages) STMICROELECTRONICS

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ST7570 demonstration board description

AN3213

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Doc ID 17429 Rev 1

Figure 34 represents the BER vs. SNR curve in the presence of white noise for both 1200

bps and 2400 bps at 50 Hz in these conditions.

Figure 34.

Measured BER vs. SNR curve (typical), white noise

7.2.4

NBI tests

In order to test the demonstration board immunity to a narrow-band interferer (NBI), the

method described in the IEC61334-5-1 standard has been followed (References 5). It

requires a sine wave interferer at a 20 kHz < fN < 95 kHz frequency to be applied at the

receiving device. Setting an rms interferer level equal to SN and an rms signal level equal to

SS, the BER of the receiving device must be lower than 10-5 with SN/SS < 30 dB.

The waveform generator has been used to provide the sine wave signal, whereas a second

demonstration board was generating packet traffic compliant with IEC61334-5-1 at PHY

layer (standard preamble and SSD sequence followed by a random payload) (References

5).

Table 7 shows the parameters setting the test conditions. Both signal and noise levels have

been measured through a spectrum analyzer with differential probe. The resolution

bandwidth RBW was equal to 100 Hz.

The test returned a BER value lower than 10-5 for all the interferer frequencies, proving that

the demonstration board is compliant with IEC 61334-5-1 requirements on narrowband

interferer tests.

Table 7.

Narrow-band interferer immunity test settings

Parameter

Value

Received signal level

69.5 dBµV rms

Received NBI level

100.0 dBµV rms

Signal bandwidth

2400 Hz

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