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Problem with RFX2411N

bortolin

Hi all, i'm doing some beaconing experiments with my NRF51-DK, a RFX2411N-EVB and a HG2408U antenna. I'm using S110 with beaconing demo code, and nRF Connect app to measure signal strength. With the DK+external antenna (no RFX2411N-EVB) it works great and has a nice coverage, but problems start when i use the amplifier board (Transmit mode setup): signal is very strong in a radius of 20m circa, but as soon as I walk away a few meters the beacon becomes unreachable. It goes from ~-65dB to no signal at all.

What am I doing wrong?

I read in another question something about S132 and a mode for PA/LNA. Could I have a breif explanation of what should I do?

Thank You!

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    There does not seem to be much to go on, but if you are losing contact with the beacons as when the RSSI drops below -65 dBm-ish, I would consider other parameters than just the RSSI. As a signal metric, RSSI has the limitation that it only gives you information about the received signal power, not the quality per se. If the received signal has for example a bad SNR it may be that the receiver is unable to demodulate the signal even though it has a relatively high power. It is perfectly possible to have a high RSSI with an equally high noise, making it impossible to demodulate the signal.

    Can you measure the quality of the signal from your device with the PA? If that is OK, how is the RF environment you are testing in? Is it complex, with a lot of noise etc.? If both the beacon (with PA) and environment is OK, what about the receiver?

    On the nRF51, you would typically use VDD_PA (connected to C3 in the nRF51 DK) to know when the radio is in TX mode. You can optionally use the radio notification API and control a GPIO pin from software, but it will have less precise timing. (The S132 SoftDevice for the nRF52 has a PA/LNA control feature, but this does not exist in the S130 for the nRF51.)

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  • 0

    There does not seem to be much to go on, but if you are losing contact with the beacons as when the RSSI drops below -65 dBm-ish, I would consider other parameters than just the RSSI. As a signal metric, RSSI has the limitation that it only gives you information about the received signal power, not the quality per se. If the received signal has for example a bad SNR it may be that the receiver is unable to demodulate the signal even though it has a relatively high power. It is perfectly possible to have a high RSSI with an equally high noise, making it impossible to demodulate the signal.

    Can you measure the quality of the signal from your device with the PA? If that is OK, how is the RF environment you are testing in? Is it complex, with a lot of noise etc.? If both the beacon (with PA) and environment is OK, what about the receiver?

    On the nRF51, you would typically use VDD_PA (connected to C3 in the nRF51 DK) to know when the radio is in TX mode. You can optionally use the radio notification API and control a GPIO pin from software, but it will have less precise timing. (The S132 SoftDevice for the nRF52 has a PA/LNA control feature, but this does not exist in the S130 for the nRF51.)

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