"Forcing" to use another com channel

[MenKuch]

Your Environment

• Uploader Version Number: 0.5.1
• Your Android Phone Model Name: Nexus 5
• Android Version Number (e.g. use 4.4 for 4.4.4): 6.0.1
• Network Connection at the time the issue occurred (Wi-Fi, Mobile): WiFi 5Ghz
• (if relevant) Nightscout website version (e.g. 0.8.4 Funnel cake, master / dev branch): 0.8.4

Brief Explanation of Issue

In my environment, there seems to be a lot of interference when communicating on channel 17. When operating on other channels, everything is working great - but as soon as the channel 17 is used, the range of the CNL <-> Pump communications is reduced to 30-50 centimeters.

This also affects Transmitter <-> Pump communications, sometimes leading to a sgv display of --- on the pump (not triggered by the uploader). The interference seems to come from WiFi networks from neighbors (I've switched mine to 5ghz just to be sure) not under my control. After 5-10 minutes, sgv values are again displayed on the pump.

If I understand the code to negotiate a channel correctly (negotiateChannel in MedtronicCnlReader.java), the pump decides which channel to use for communication (Excuse me if I am wrong, I am a Mac/iOS/Cocoa developer, don't have any experience with Android/Java at all).

My request: Would it be possible to "force" the pump to use a different com channel using the uploader? Or to never ever use a specific channel?

BTW, thanks for all your effort implementing the uploader - you certainly made the life of a lot of people much easier.

Severity Score

4 for me since it can lead to long periods of missed data on nightscout

[pazaan]

Unfortunately, this is not possible as far as I know. The pump chooses which channel to broadcast on. The CGM and the CNL are simply clients to the pump network (which is why they scan for the pump on all of the different channels in order to find it).

[MenKuch]

Thanks for your blazing fast response! Hope you don't mind if I am asking: Do you know any other way of getting the pump to use a different channel? Moving it out of range for example?

[Pogman]

There's a hacky way of sorta doing this that takes advantage of certain circumstances and a bugs.

Long story short... if you can build the Android code pull the develop-treatments branch, this has a way of encouraging a channel change if your on a channel you don't want.

In that branch open this file "MedtronicCnlIntentService.java" and change the channel number on lines 271 and 282 to the channel you want out of.

Note - that branch is depreciated from a development pov but it's 5.1++ and runs quite well.

[Pogman]

Also as I just remembered with v5.1

If your in a really noisy environment the sensor may be sending the sgv to the pump later then expected and there may be a radio clash going on extending the outage period. Also the recovery time that is supposed to happen after a lost sensor situation is a tad too short. This are being addressed for future versions.

[EllaGotemans]

I have a problem with signal between the pump minimed 640g and entiteit sensor. The signal is lost and cannot be recovered. I think surrounding noice? Any suggestions?

[MenKuch]

How long did you wait for the sensor to be found again?

I would do the following steps (from my own experience, do it at your own risk):

1) If you have any android phone with the uploader installed around connected to the contour nextlink meter, unplug the meter to make sure the android uploader is not interfering. Wait at least 15 minutes.

2) If possible, change your location (i.e. go to a different room) to make sure that a nearby WiFi is not interfering

3) Unplug the transmitter from the sensor (but leave the sensor in your skin so it is not wasted). Plug the transmitter in the tester and check if it is found by the pump. If NOT, plug the transmitter into the charging station and wait at least 15-20 minutes before trying again. You'll need to start the sensor again as a new sensor (and wait 2 hours). Please remember that it is not a new sensor, so you make sure to NOT use it longer than 6 days in total beginning at the day you put your sensor in your skin. Enlite sensors will become notoriously inaccurate for most persons when used longer than 6 days.

[EllaGotemans]

I have already plugged the wifi out in our house. Put all the phones on the wifi 5.0.

The pump searches for a while but after some time it stop. It also gives ‘go away from any electronic device’. But she was in her bed sleeping. The pump was really close to the transmitter.

The only option I had is to plug the transmitter in and out. Than it works fine for a few hours.

People of medtronic don’t know what to do anymore. I don’t know it either.

I really wan’t it to work because the pumpstop is great for my 6 year old daughter.

[Pogman]

It sound like you have a lost sensor issue. You should never need to unplug the transmitter and it should recover the link by itself.

If this is happening while in bed it is almost always due to the body obstructing the signal and closeness of the pump and sensor may not help if they are on each side of the body. It can be easy to have the sensor in an area that ends under the body depend on sleep positions etc. Try experimenting with different locations for the sensor on the body. Also try keeping the pump pinned to the side of bed near to the sensor and experiment with this location too.

[EllaGotemans]

The pump was on the same side the last time. I’m sure. Could the body cause this problem?

[Pogman]

The clue here is that this occurs while in bed and if it was something else it would be a constant issue all around your home. The radio frequency used is in the microwave band and the body blocks this completely. It helps to keep the pump close but a little bit away from the body while in bed and the sensor in a location that is mostly on the top while in sleeping position.

[EllaGotemans]

Ok we will try this!

Can the wifi be a cause of the problems?

[Pogman]

If WiFi was an issue it would be all around your home. It can cause intermittent noise where you may lose the sensor for a short period 10-15mins but this should be relatively rare and it would need to be a very saturated radio environment to happen often.

[Pogman]

Also make sure your using at least v0.6+ of the uploader, older versions have problems related to lost sensor recovery.

[EllaGotemans]

Ok thanks! The connection was also lost when she was in the livingroom and could not be restored.

Now I have looked at the places where the sensor was, It is a bit blue. So under the skin something went wrong? A vain instead of fat?

[pazaan]

@Pogman can this one be closed out now?

[Pogman]

Can be closed as it's not a app issue.