Advertisement packet loss in Coded PHY vs 1 Mb PHY

[Kcecil]

Using the following:

Rigado BMD-360 nRF52811 development board.

Softdevice S140 7.0.1

SDK 16.0

Using two development boards inches apart, one development board sends a single advertising event every 12 seconds.  The other development board is continuously scanning (interval and window = 7s).  The packets have 30 bytes of data including a sequence number.  I calculated packet loss based on the missing sequence numbers.

Sending and scanning using the 1 MB/s PHY, in a test of approx. 20 minutes  I get 100% reception of packets.

Sending and scanning using the Coded PHY, in the same test I get ~43% reception of packets, ~57% packet loss.

Is this expected behavior, or could I be configuring something wrong when advertising using Coded PHY?

Another behavior I've seen is for the above condition using the Coded PHY to have a repeating pattern of receiving 3 and missing 2.

[Simonr]

Hi Kurtis

When you're increasing the scan interval and scan window, that also increases the time of how long you scan on each channel, so that might cause the packet loss you're seeing. See the picture below for reference (note that this is for "regular" BLE scanning, but it should be similar for Coded PHY as well AFAIK):

The only other thing I can think of is that your custom HW's antenna layout isn't optimal, and that causes the radio to drift and lose more packets when it is scanning for a longer amount of time. 

Best regards,

Simon