Interference on Bluetooth devices

[atoz]

Wonder if others have had issues with interference with Bluetooth sensors eg heart rate monitor, cadence sensor etc? I used Wahoo Tickr as HRM and also their cadence sensor, with the Wahoo Element Bolt (v2) cycle computer.

I've found it's wise to turn off my Wahoo Bolt if calling in at a supermarket, even though the Bolt is on recording workout pause. Interference can sometimes stop or slow down the HRM signal. And as for cadence, I recorded a cadence of 466 rpm when calling into Morrisons not long ago. Entertaining, but useless.

I've had similar issues when negotiating long term roadworks locally. I know that devices compete for bandwidth. When these sources of interference are not present my Wahoo sensors and Bolt computer work well.

Has anyone else had similar issues?

Note: you get WiFi, Bluetooth and RFID devices in operation in supermarkets.

[Jdsk]

There's some discussion in the archives:
viewtopic.php?t=156532

With digital comms such as Bluetooth it's easy to explain degradation such as slow or failed communication. It's a lot harder to explain corruption of data.

Jonathan

[atoz]

Yes, I made those comments originally. I was hoping someone would know more than I do. I live in hopes...

[rareposter]

Note: you get WiFi, Bluetooth and RFID devices in operation in supermarkets.

I suspect the main cause of interference is (believe it or not) fluorescent lights - obviously supermarkets have lots of those and they're quite broad frequency.
Bluetooth (on devices like phones / computers) usually operates on a frequency hopping system where it'll flip between about 70 discrete frequencies several hundred times a second so any interference from other devices on the same frequency is very limited. The problem is that (eg) fluorescent tubes, microwaves etc are very broad spectrum so it'll tend to clog multiple frequencies. It's like a really basic form of jamming where if you throw enough electromagnetic interference across a wide enough range at something, chances are you'll manage to disrupt it at least partially.

I used to have a Polar HRM (back in the late 90's) that would record spurious data when underneath certain power lines. Modern ones are much better shielded and the tech is far superior so stuff like power lines, roadworks etc should have negligible effect most of the time.

Try resetting the devices and then pairing them again.

[Nearholmer]

Yes, probably something that produces a big mess across a broad spectrum, inducing currents in analogue links from sensors to “computer”. Possibly micro-arcing within a portable generator at the site of roadworks, because there’s often one chugging away feeding temporary traffic signals.

[ChrisF]

I think there are different issues here.

The data that is sent via Bluetooth will have data-checking built in. In other words, if the signal is strong enough it will receive the data correctly, with no 'false' readings. If the signal isn't strong enough it won't record incorrect data.

So for example in a supermarket the fluorescent lights and other electronic equipment may make the Bluetooth signal too weak (or relatively weak), so it may not receive reliable data - in which case your HRM lrecord zero (or - better - 'not avaliable').
So with the HRM I think the problem is with the sensor itself - it is picking up tiny electrical signals from your skin and amplifying them enough to count your heatbeats. That's where the electronic buzz in the supermarket will be affecting things - nothing to do with Bluetooth.

OTOH I'm baffled why your cadence sensor went beserk in a supermarket - did you take the bike in?

[atoz]

I think there are different issues here.

The data that is sent via Bluetooth will have data-checking built in. In other words, if the signal is strong enough it will receive the data correctly, with no 'false' readings. If the signal isn't strong enough it won't record incorrect data.

So for example in a supermarket the fluorescent lights and other electronic equipment may make the Bluetooth signal too weak (or relatively weak), so it may not receive reliable data - in which case your HRM lrecord zero (or - better - 'not avaliable').
So with the HRM I think the problem is with the sensor itself - it is picking up tiny electrical signals from your skin and amplifying them enough to count your heatbeats. That's where the electronic buzz in the supermarket will be affecting things - nothing to do with Bluetooth.

OTOH I'm baffled why your cadence sensor went beserk in a supermarket - did you take the bike in?

I didn't take the bike in, but of course I took the Bolt in, for obvious reasons. Makes you wonder if all the electronic interference screwed up the Bolt, rather than the sensors, but I'm no-one's idea of an expert, so basically I haven't a clue.

Interesting about the fluorescent lights. Hadn't considered this. Mind you, bluetooth headphones/earbuds seem less vulnerable. Up to recently I worked in an FE college where of course there were those type of lights, and other electrical sources of interference. But my cheapo JLab earbuds worked fine, as long as they weren't too far from the device they were connected to, of course. But those cycling sensors use Bluetooth LE, which is not the same as standard Bluetooth, as far as I understand these things.

[atoz]

Yes, probably something that produces a big mess across a broad spectrum, inducing currents in analogue links from sensors to “computer”. Possibly micro-arcing within a portable generator at the site of roadworks, because there’s often one chugging away feeding temporary traffic signals.

That makes a lot of sense, thanks for that. We've had a major traffiic roadworks project near where I live for months. If I don't go near those roadworks I rarely get problems with the Bolt and the sensors.

[atoz]

Hi all- thanks for all the useful suggestions and explanations.

Interestingly, my home electricity smart meter control display device uses sofware made by....Wahoo.Smart meter control units use Zigbee to communicate with these days. I take care to ensure that the Bolt is not near that device or the master meter panel when I come in from a ride.