This post is older than 2 years and might not be relevant anymore
More Info: Consider searching for newer posts

PHY coded and Coexistence

Hello,

I'm testing PHY coding (for long range), I'm pretty surprise from what I get when I scan the RSSI of bluetooth channels (with Nordic app).

This is my set up:

image description

M1 is the central, S1 is the peripheral sending 1ko/s. (with uart exemple) I use softdevice 140 V5 alpha.2

M3 is the RSSI scanner connected to "Nordic app RSSI Viewer" Here are the results I get for phy= 1mbps (Short Range) and for phy=125kbps (coded-Long Range):

  1. Short Range image description
  2. Long Range image description

Can you explain me why the long Range mode trash all Bluetooth channels ? this is one link (S1-M1) so my data received is what I expected (1ko/s) but when I use 10 links, the data rate drops dramatically.

Regards,

-Damien

Parents
  • (1/2) Thank you for your answer Martin,

    1. From what I see, the RSSI spikes seems to have a 10MHz spacing. And It looks like there're at least 4-5 spikes at the same time and all of them are shifting over the time. I see spikes on 2440MHz + 2450MHz + 2460MHz + 2470MHz (at the same moment) shifting to 2439MHz + 2449MHz + 2459MHz + 2469MHz then to 2438MHZ + 2448MHz + 2458MHz + 2468MHz ... So the total RSSI activity looks like to be 40-50MHz wide and shifting (to the left), and it looks like to be periodic of 2 seconds.
    2. The previous results were on nrf52840pdk V0.91 : https://ibb.co/jKXonw, on V0,92 it seems that this "wave" is larger: https://ibb.co/b7nzCw. and this is for V0.93 : https://ibb.co/nf8NXw (looks a bit better)
    3. Sorry it's koctet/s (french I guess) = kBytes/s
    4. yes, I'm damien5606, I created a new topic because I thought It was different
Reply
  • (1/2) Thank you for your answer Martin,

    1. From what I see, the RSSI spikes seems to have a 10MHz spacing. And It looks like there're at least 4-5 spikes at the same time and all of them are shifting over the time. I see spikes on 2440MHz + 2450MHz + 2460MHz + 2470MHz (at the same moment) shifting to 2439MHz + 2449MHz + 2459MHz + 2469MHz then to 2438MHZ + 2448MHz + 2458MHz + 2468MHz ... So the total RSSI activity looks like to be 40-50MHz wide and shifting (to the left), and it looks like to be periodic of 2 seconds.
    2. The previous results were on nrf52840pdk V0.91 : https://ibb.co/jKXonw, on V0,92 it seems that this "wave" is larger: https://ibb.co/b7nzCw. and this is for V0.93 : https://ibb.co/nf8NXw (looks a bit better)
    3. Sorry it's koctet/s (french I guess) = kBytes/s
    4. yes, I'm damien5606, I created a new topic because I thought It was different
Children
No Data
Related