AN4494

Sensitivity test

9.5.2

Two BlueNRG boards

In this case, the previous procedure changes in the following way:

1.

Connect the RF input/output of both boards, DUT and tester, by using a variable

attenuator.

2.

Start Rx on DUT: HCI_LE_RECEIVER_TEST

3.

Make the Tx board send packets: HCI_LE_TRANSMITTER_TEST, with the length of

test data: 0x25

4.

Stop test on Tx board: HCI_LE_TEST_END

5.

Send a further command to determine the number of packets sent by the Tx board:

HAL_LE_TX_TEST_PACKET_NUMBER

6.

Stop test on DUT: HCI_LE_TEST_END

This will return Y as the number of received packets. PER is 1-Y/X.

If PER is below 0.308 (30.8%), go back to step b and increase the value of the attenuation.

If PER goes above 0.308, then the level of power received by the DUT in the previous test

is the sensitivity of the receiver. It is very important to measure correctly or estimate the

power received by the DUT (e.g. by the use of a tone instead of a modulated signal).

Moreover, in order to reduce the level of the signal received over-the-air by the DUT, the

BlueNRG Tester should use the minimum output power. Performing the measurements

inside an anechoic chamber will also give more accurate results.

9.6

Expected results

The expected value should be a few dBm from the value reported in the datasheet. If it is

not, the reason could be related to the matching network.

9.7

Note

Since the sensitivity test is very time-consuming, ST can provide specific software for both

hardware configurations in order to implement an automatic procedure.

9.8

Other

N/A.

DocID026361 Rev 3

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