Hi,
Scenario:
Two nRF52832DK boards on a table, approx 20 cm from each other, +4dBm output power.
Payload length is ~60bytes.
Running at 1Mbps gives me less than 0.1% PER, running at 2Mbps gives about 25% PER. (everything else kept identical)
Is this expected, or is there something at play here?
Nope, no WiFi or anything else... Spectrum is almost empty here... the same difference regardless of what channel I'm using....
And at that distance, if anything would affect the reception to a large extent it would probably be receiver saturation in that case.... But it that case, why such a difference between 1Mbps and 2Mbps...
Sorry I referenced throughput. Most people test PER in respect to throughput. This is a requirement during ETSI testing and often is brought up in this forum.
What you are describing then is really lost packets and not PER since you are counting the number of received packets and not a ratio of CRC good vs. CRC bad packets. With your test setup it would be impossible to tell the difference between packet not sent, packet sent but not received (ie, lost) and packet received but bad and CRC error. You should improve the robustness of your test method by including counters on both ends and not just assuming the timing works out. Also on the receiver you should catalog CRC good vs. CRC bad events.
Another thought is in the mode you are testing you can do BLE2Mbps and Nordic Proprietary 2Mbps. The options show up in the enumerations for the mode register. There are minor differences in the gaussian indices for the GFSK and I believe that is it. It would be interesting if there was a difference.
Finally, even though you are convinced it is RF quiet in your local you should try outside of the ISM band just to be sure. The nRF52 operates from 2360 to 2500 MHz.
There are a lot of discussions on PER testing on this blog. Here are some good links: devzone.nordicsemi.com/.../ And a link to DTM PER testing: infocenter.nordicsemi.com/index.jsp
Please post back your final conclusion on the issue. It would be interesting to know what caused the problem.
Sorry I referenced throughput. Most people test PER in respect to throughput. This is a requirement during ETSI testing and often is brought up in this forum.
What you are describing then is really lost packets and not PER since you are counting the number of received packets and not a ratio of CRC good vs. CRC bad packets. With your test setup it would be impossible to tell the difference between packet not sent, packet sent but not received (ie, lost) and packet received but bad and CRC error. You should improve the robustness of your test method by including counters on both ends and not just assuming the timing works out. Also on the receiver you should catalog CRC good vs. CRC bad events.
Another thought is in the mode you are testing you can do BLE2Mbps and Nordic Proprietary 2Mbps. The options show up in the enumerations for the mode register. There are minor differences in the gaussian indices for the GFSK and I believe that is it. It would be interesting if there was a difference.
Finally, even though you are convinced it is RF quiet in your local you should try outside of the ISM band just to be sure. The nRF52 operates from 2360 to 2500 MHz.
There are a lot of discussions on PER testing on this blog. Here are some good links: devzone.nordicsemi.com/.../ And a link to DTM PER testing: infocenter.nordicsemi.com/index.jsp
Please post back your final conclusion on the issue. It would be interesting to know what caused the problem.
