Rx sensitivity differs by 10dB between consecutive measurements I am observing unexpected behavior for one of our products using QN9083 BLE SoC. When I measure the device receiver sensitivity, I am seeing deltas up to 10dB between consecutive measurements. I am using a CMW100 in advertiser mode to perform measurement and the device is placed in a shielded RF box. Performing consecutive RxS measurements, without opening the box and/or changing device location, the device responds with up to 10dB difference (i.e., -91dBm and -81dBm) which is unexpected and never happened before. The behavior is random. I am looking for possible causes both hardware and software. Re: Rx sensitivity differs by 10dB between consecutive measurements Hello,
A variation of up to 10 dB between consecutive sensitivity measurements is not something we would normally expect.
Could you share the software/SDK version currently being used?
Also, can you clarify:
Does this occur on a single device or multiple products?
Have you seen the same behavior across different units?
Can the issue be reproduced on an NXP development board using the same measurement setup?
This information will help determine whether the issue is specific to the hardware, software, or test environment.
Best Regards,
Ricardo Re: Rx sensitivity differs by 10dB between consecutive measurements Hello thank you for getting back to me. Here are my answers: Could you share the software/SDK version currently being used? 5.0 based on 156414 (Controller Subsystem) and 156821 (Host Subsystem) Does this occur on a single device or multiple products? Same product. Never had the issue with different products. Have you seen the same behavior across different units? Yes but not consistently Can the issue be reproduced on an NXP development board using the same measurement setup? I will need a dev board with QN9083 and a FW that will set the chip on advertising Thank you, Re: Rx sensitivity differs by 10dB between consecutive measurements Additional info regarding BLE version: SDK 2.2.3 BLE 1.5.6 that supports BLE Core 5.0. Re: Rx sensitivity differs by 10dB between consecutive measurements @Ricardo_Zamora I ran measurements using QN9080-DK. Although I do not see 10dB discrepancy there is still 5dB fluctuation (see data below). What could cause this? furbani_0-1784214895282.pngfurbani_0-1784214895282.png Re: Rx sensitivity differs by 10dB between consecutive measurements Hi @Ricardo_Zamora did you get the chance to look into the data/answers I posted? Thank you. Re: Rx sensitivity differs by 10dB between consecutive measurements I measured the W236 FRDM boards to see how much variation there is in the radiated RSSI. It does vary as much as 4dB.
RomanPBudek_0-1789049903611.pngRomanPBudek_0-1789049903611.png RomanPBudek_1-1789049923585.pngRomanPBudek_1-1789049923585.png
Re: Rx sensitivity differs by 10dB between consecutive measurements @RomanPBudek Thank you for the update. What instrument did you use to perform the measurements? I'd like to ship one of our form factor devices if you could measure that one as well. Thank you Re: Rx sensitivity differs by 10dB between consecutive measurements It was NXP HCI black box software. I would be glad to compare to what was measured. I will email my address.
In the past, Rx sensitivity issues could be traced to probing issues on the test fixture. As the test fixture wears out, the probe pin could touch the plastic housing and inject static into the RF pin. That was resolved with grounding of the fixture. Let me see a few of these devices to see how they behave.
查看全文
