sniffer

[MK Chen]

I use Nodic sniffer nRF_Sniffer_200_beta3 to capture BLE Mesh packets, but found one strange scenario:

1 if set channel filter 37, 38, 39, can capture 3 packets in channel 37, 38 and 39 once pressed light button.

2 if set channel filter 37, can capture 3 packets also, all in channel 37, once pressed light button, as following screen shot

my question is why light profile  will change TX channel,  if changing sniffer setting?

Thanks

MK

[David Edwin]

1. What do you mean by " if set channel filter 37", is this a setting that you do in Wireshark.
Can you clarify. (I not not see a change in the Adv Hop settings in both images)

2. I noticed that you are sniffing all packets but not packets from a specific device so be aware that packets from multiple devices will be in the sniffer trace. Is this your intention. Typically I would prefer to specify a device that is being sniffer and capture all packets from that device.

Please comment
David

[MK Chen]

Hi David,

Thanks for your reply.

yes, means setting in Wireshark.

Sorry, I have sent wrong screen shot, amend following:

I means BLE-Mesh TX channel will be affected by Wireshark.

[David Edwin]

I think we need to set the Adv Hop to  37,37,37 to set it to channel 37 

[MK Chen]

my question is BLE advertiser channels should not affect by sniffier channel setting.

sniffer can capture one packet if advertiser channel is set 37 only, but should not capture 3 packets in channel 37.

[David Edwin]

I see 3 packets in the screenshot but I do not see the time between the packets. The PC timestamp that you have shown is the timestamp of the packet arriving at the PC. This is not the on air timestamp.
You will have to use the packet delta time to get the on air timestamp.

Send the pcap file and I will mark the timestamp for you.

You are very likely looking at 3 separate advertising events, i.e. 9 packets transmitted over 3 channels and the sniffer is seeing 3 of the 9 packets on one channel.

Once you look at the timeline with the delta time between packets on air, you will see if the packets are from the same advertising event or from different events.

[MK Chen]

I will capture .pcap file.

I have thought the possibility of 9 packets, but I never capture more than 3 packets if turn on 37, 38 and 39 channels. 

Thanks 

[MK Chen]

Hi David,

attached .pcap file for you to study what is wrong?

Thanks

MKChannels_37_38_39.pcapngChannels_38.pcapngChannels_39.pcapngChannels_37.pcapng