missing ADV events while scanning

RE: missing ADV events while scanning

Joakim Jakobsen — Fri, 25 Jun 2021 15:12:25 GMT

The BLE spec requires a jitter in the advertising interval. I.e. there is a random extra time delay of 10ms added to each advertising interval. This is to avoid situations where a peripheral and a central device with the exact same advertising- and scan interval never hear each other. Hence, with a scan window equal to the advertising interval you might actually still miss the advertising packet.

If you have a scan window that is exactly as long as the advertising interval then it comes down to the scan interval. With short intervals you will find your device fast, and with long intervals it might take some time. However, I guess that statistically you will need to have your radio on for an equal amount of time.

RE: missing ADV events while scanning

kizhimon — Wed, 16 Jun 2021 10:59:55 GMT

they are kept close by, less than 30 cm. But sometimes the interval changes to one beacon/2 minute. I am advertising on all 3 channels. Is there a chance that, the scanner misses the beacon when it switches the channel (37->38->39) while scanning ?

RE: missing ADV events while scanning

Joakim Jakobsen — Fri, 04 Jun 2021 10:17:36 GMT

Ok, then you should be able to receive it.

Do you know how many times you miss the broadcast from the beacon?

What is the distance between the two?

Br,
Joakim

RE: missing ADV events while scanning

kizhimon — Tue, 01 Jun 2021 12:57:14 GMT

I send beacon every 1 second from one device, but there can be many other beacons in surrounding

RE: missing ADV events while scanning

Joakim Jakobsen — Tue, 01 Jun 2021 10:11:49 GMT

Hi.

How many beacons are you trying to capture the adv. from?

How are the adv. interval set up for the beacons?

If there are several beacons, there might be some collisions causing the scanner to miss some events.

[quote user=""]will connecting an antenna to nrf52 DK board (as given below) help it to receive all the ADV events.[/quote]

As long as the beacons aren't far away and range isn't an issue, I don't think the antenna would increase the amount of adv. received.