Frustrated with X2/G5 integration

I have my Dexcom data now showing on my Tandem X2 (which was easy to do.) I was thrilled with the idea of my Dexcom data showing on my pump so I didn’t have to have my phone with me, particularly when I exercise. But when I put my pump in a back pocket on my leggings or yoga pants, it fails to receive any Dexcom data. I called Tandem and they said my body is blocking the signal. Yet, when I put my iPhone in my back pocket, it never misses any data. What gives?


I agree this is frustrating. More so if you consider this is the first step towards the automated system which is planned to be delivered next year. (Although target dates always slip.)

Would you be able to go outside the range of other electronic devices and spend some time maybe 30~60 minutes and see if you get the same results? Including no phone. Just the Dexcom Transmitter and the Tandem X2. This would help to determine if the problem is related to signal interference from other devices or whether it is strictly the problem of the Bluetooth Low Energy (BLE) signal penetrating your body between the two devices.

Certainly one 30~60 minute “test” does not prove anything but it might give some limited observational data that might tend to lend some credence in one direction or the other.

There are plenty of online article related to BLE which both talk about interference from other electronic devices as well as interference trying to penetrate the human body.

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Thanks @Tim35. I did try the experiment you suggested and I did get the same results. What makes no sense to me is —since my iPhone can pick up the signal when it’s in my back pocket, why can’t the X2? It’s clearly not the signal then; it’s the receiver on the pump.

Yes, it is especially frustrating because it means I’ll have trouble with the automated system too.

I dance, so I really need to keep the pump in the small of my back while dancing. I guess I need to get an apple watch!

This is what performers use to carry the transmitter for wireless microphones. typically the pouch goes in the small of your back. It’s very stable and should be fine for dancing.{creative}%2C{keyword}&gclid=EAIaIQobChMInoLUxZWv1gIVgrfACh3cNQ3QEAQYBCABEgLoG_D_BwE&is=REG&m=Y&sku=403463

@Flem07 - This is a two-way transmission so potentially if the Apple iPhone and the Tandem X2 are not using the same power levels for the Bluetooth Low Energy (BLE) then it could make a difference. AFAIK there is an acceptable range of power output for BLE while still staying within the standards.

It would seem within the area of a possibility that Tandem choose to use lower BLE power so as to prevent the battery charge on the Pump from being depleted faster than it otherwise would have? Purely speculation as to that of course.

As you mentioned the Apple Watch, my understanding is the Apple Watch currently needs to piggyback off the Apple iPhone. This is how we have it configured and running currently on a Series 2 Apple Watch. I was a little confused on how to get the Dexcom G5 Transmitter to communicate directly with the Watch but I think (absolutely could be mistaken here) that Apple is releasing a major software update to the Watch tomorrow (Tuesday, Sept 19, 2017) that will allow direct communication between the Dexcom G5 transmitter and the Apple Watch without requiring the Apple iPhone to be involved. Although I am quite unsure if such a major update would require a new Dexcom App? I would tend to think so. In any event, I was planning on giving it a whirl and see if it works or perhaps I have totally misunderstood.

Similar to your thoughts on dancing, we had similar thoughts on the direct Dexcom G5 Transmitter to Apple Watch being very helpful for exercise in general when you may really not want to have the Phone itself on your person.

(Although the entire subject of the Watch clearly does nothing to help the Pump reliably get the cgm data which will obviously be critical for the Pump to ultimately be able to run in any sort of AUTO mode.)

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Thanks so much. However, it is the small of the back that is the issue. The X2 cannot read the Dexcom transmitter from the small of my back.

Right—therein lies the problem. A frustrating one.

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its just an elastic band and a pouch so you can wear it on the front or sides as well. It should also come with a shorter band that will wrap around your leg but that might be trickier

Tim- you’re absolutely correct about the update to the Apple watch OS4. Tim Cook specifically addressed Dexcom in his keynote speech this past summer confirming that the Dexcom transmitter will connect to the Apple watch without the iPhone. As far as a new app, I’m not sure how it will work. I guess we’ll see tomorrow. I never update the software on my Apple products right away, I learned my lesson the hard way with that God awful piece of crap iOS 8. Now, I usually wait a month to see if there are reports of major problems with the updates.

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I keep my X2 in my spibelt. I can’t even keep it on the other side of my stomach, which isn’t even fully blocked by my body.
I now keep it directly under the g5. Which now means that they hit each other when I bend over.
I get Good consistent signal this way though.

I’m having a similar issue with G5 and my iPad. Signal loss. I’m not sure if it’s because I closed the app sometimes but I usually have my iPad in a case over my shoulder or I’m reading it or is near me. I also can’t shut off the alerts to vibrate in the app on the iPad- there’s no seldtion for that in the app. So I have to keep an earphone in. I bought a cheap one and cut the end off but I’ve lost it already. I haven’t got a watch yet because of all these issues.

This is more than “frustrating.” It is one of several issues that are not disclosed until a Tandem tech rep asks the relevant questions.

Tonight, after yet another signal loss that seems permanent (i.e., > 6hours) -but only on the pump, not my Android app - and using a new transmitter and new X2G5 that were sent because of these and other problems (this not the first failed unit that Tanden had to replace), I was asked the following two questions (one from each rep, both reading from a list of questions related to BT signal loss):

  1. Do you have WiFi?
  2. Are you near metal?

I was shocked to the point of completely ruing my DME selection. WiFi is near ubiquitous (at least in NYC), but METAL? Even worse, when I pressed her to define “near,” the reply was…20 feet!!!

Not only is it nearly impossible to live in the predominantly post-industrial world to avoid metal within that radius…but when I pointed this out, as well as that the pump and phone both contained metal, the rep had no response.

Even more alarming, since most updates are likely to be software, this design will probably remain the base architecture for Tandem’s planned eventual closed loop artificial pancreas - which until tonight I had high hopes for - a device that would therefore require us to trust a device that is practically designed to fail as an AP.

I also wonder how these factors warranted an FDA approval.

I believe I have written about this before. The Dexcom uses Bluetooth Low Energy (BLE), which unfortunately operates at 2.4 GHz. By used BLE, the Dexcom can interface directy with things like smartphones, but the downside is that it has interference. One interference is with the 2.4 GHz wifi, and even if you have 5 GHz, your routers and wifi points will usually still be using 2.4 GHz because those protocols are so pervasive.

Another interference is with microwave ovens which use 2.45 GHz which is close enough that there will be interference.

As you note wifi is nearly ubiquitous, but fortunately BLE can operate in under significant interference. The two things to remember when minimizing this interference is that the closer the Tandem is to the Dexcom transmitter the higher the signal to noise ratio is and the less chance of a dropout. And also, sitting next to a wifi transmitter increases it’s signal and means more of a chance of dropout. wifi transmitters include not only routers, but laptops and even smartphones that have wifi engaged and are active transmitting.

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If your situation allows and if you can disable the 2.4 GHz transmission from your router and only run with the 5 GHz transmission, that is probably helpful.
You have no control over your neighbors, but as @Brian_BSC also points out:

Which also means the further away the wifi transmitter, the weaker the signal and less chance of interference. Which means your neighbors signals are (generally) not going to be as relevant as your own transmissions.

In our personal situation, disabling the 2.4 GHz wifi meant a lack of coverage in a remote portion of our house as the 5 GHz does not penetrate solid objects (thick brick walls as an example) as well as the 2.4 GHz signal. The best solution (for us) would be to run a wire to the other portion of the house and put a second wireless access point (WAP) up and run a second 5 GHz WAP transmission from there. (That is on my list of things to do.) In the meantime, I turned the 2.4 GHz wifi back on. In the wireless settings of the router, on the 2.4 GHz settings, I locked the channel width from Auto down to 20 MHz as well as locked the channel selection down to channel 11 (2.462 GHz). This does not eliminate interference but it is my opinion and experience that it likely does help the situation and shows no evidence of hurting the situation.

The microwave can not be helped. It is a beast. Only upside is it runs for (generally) very short periods of time. When the microwave is not actively running then it is also emitting no relevant transmissions and not a problem in this sense.

Baby monitors running at 2.4 GHz are also beasts and if you have one of these, I would strongly suggest to replace it with one which runs on an alternate frequency range. Some baby monitors will connect to your wifi so if have already optimized your wifi then the baby monitor will adjust to the wifi. Some baby monitors can run on 900 MHz which poses no issues for the BLE.

If you have a 2.4 GHz cordless phone, I would also suggest to replace that with a 1.9 GHz or 5.8 GHz cordless phone. I believe older phones ran at 900 MHz and if so - those are no problem. Probably not many of those left around. We run a 1.9 GHz cordless phone system.

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