@bkh I use xDrip+ and the software on the collector (watch, phone, tablet, whatever you’re using) can give raw sensor readings and refined by algorithm Bg readings.
So does the G5 transmitter send both the sensor data AND converted Bg numbers out over BLE?
@docslotnick - That is exactly what I am thinking. What possible reason could the Dexcom have to send both?
And if it DID send both, why would not the xdrip developers give you the option to see the Dexcom BG value? That would be trivial compared to the amount of work they do to get the xdrip computed BG value.
As @bkh stated, the CEO on the earnings call certainly said the algorithm resides on the G5 transmitter. But it still doesn’t make sense to me.
Yes, @Thomas, you found the description I was remembering. I vaguely recall he may have elaborated slightly in response to a question from one of the analysts.
@docslotnick, all I have is Kevin Sayers’s comments about moving the algorithm from the G4 receiver into the G5 transmitter. Perhaps looking at the xDrip+ collector code could reveal what xDrip+ receives from the transmitter, but I know nothing about it. I do know with Medtronic CGM I could see both the iSig (raw value) and the SG (sensor glucose as computed by the algorithm) but I wasn’t even aware that the Dexcom system provided something equivalent to the iSig (via xDrip+).
Does anyone know about watches and the G5? If you pair a watch with the G5 do you see a BG value right away? If so, then either the G5 transmitter is sending the computed BG, or it must be sending the sensor data plus the calibration data to the watch and the app in the watch is doing the 505 algorithm. I’d guess the former, but have no facts on this.
I put up a thread with the links for the Dexcom quarterly earnings calls if anybody is interested in poking through them:
@bkh - As of right now, there is no official Dexcom support for direct G5 Transmitter to Watch. All the data has to flow through the phone. Anything direct to watch is non-official. ie - Ask @docslotnick. lol.
@bkh Yes, I used the G5 with xDrip+ using a watch as the collector ( receiver). It continues to function even if the phone is out of range so the watch software must apply the xDrip+ algorithm.
Also, the same thing can be accomplished with the Dexcom G4 Share transmitter directly to a smartwatch with xDrip+. But with the regular G4 transmitter the Dexcom receiver must be an intermediary between the transmitter and a Bluetooth wixel.
All of this leads me to believe that the BLE signal coming out of the G4 Share and the G5 must contain both raw and calibrated values.
@docslotnick - What if the CEO was not technically correct and the G5 transmissions only contained raw values? Do you see anything that would contradict that possibility?
Nothing against CEOs but some of them tend to be a bit stronger on the financial side of things then the technical side of things.
Only suggestively: you can calibrate the G5 through one device, turn it off or put it out of range, and then pair a second device and receive BG data there without calibrating that second device. But I can’t rule out the possibility that the transmitter sends the calibration data together with raw sensor iSigs to the second device.
Agreed.
Still nothing conclusive.
@Thomas @bkh I just asked the xDrip+ developer what xDrip+ receives from the G5 sensor. Let’s see if I get an answer.
I am not sure if I can calibrate on the watch. I’ll try it tomorrow worth the phone out of range. If I can’t calibrate it without the phone in range then I doubt the watch is getting raw values.
Awesome !!!
I am not sure on that. By calibrate, I assume you mean enter a meter BG reading and have it uploaded to the transmitter. That is one function. But whether that means the watch receives the calibration data down from the transmitter and also receives the raw data and then puts it through its own algoritm on the watch to produce a BG value is perhaps not the same thing? ie - I can see where it would be possible not to be able to upload a meter BG reading for calibration purposes but still being able to download calibration data, raw data and process it through an algorithm. The two functionalities are not required to be tied together. But - just a guess.
@Thomas @bkh This is the answer I just got from jamorham, the xDrip+ developer:
If you're using it with xDrip then we use the raw sensor data and all the computation is done within the app. If you are using it with the official receiver or software then as far as I know the transmitter itself does the calculations and the final glucose number is what is transmitted
So it must be that the transmitter sends both computed and raw sensor data in the BLE bursts.
@docslotnick - I am always looking for the loophole.
lol
So in this, the developer confirms that he uses the raw signal. However he does not explicitly state that he sees a final BG number in the transmission. So, my skeptical self would still say it is possible the CEO was technically wrong and the transmitter only sends raw data.
Probably more of a pain then you would like to do but if you are up for it, would you mind asking the developer specifically if they are able to see actual computed BG data in the BLE transmissions (which they ignore)?
@Thomas My guess would be no, they can’t use it. I think if they could they would because they put an extraordinary amount of effort into the algorithm and calibration routines they use. (I’m talking about pages and pages of what looks like java, which I can’t decipher).
I know that this doesn’t answer the question at hand, but if he says “as far as I know” then that is likely to be as far as he knows. And I would bet he knows pretty far.
Maybe.
(I did read through the java code - thanks for posting it. I did my share of java programming. lol)
On the other hand, “as far as I know” could mean that he was not interested enough to look at the complete transmission feed? But he MIGHT be…
In any event - thanks for the info. Always interesting to get more information on how things work.
My extent of knowing how things work is—you just plug them in 
Dude - you are like the xdrip wizard. With a drill !!!
@Thomas Further answer from jamorham:
I was pretty surprised myself to first hear that the transmitter does the calculations as it seemed excessively complex. But when you look at their roadmap like having the transmitter be able to be calibrated from a pump or from a receiver and either to be present or not at any time it makes more sense.
Go have a look at the Gitter thread at jamorham/xDrip-plus. Some nuggets to be had.
Yeah - I had looked at the conversation when you mentioned it previously. I see you listed on there a lot.
Kinda hard to follow though as I am not sure how far back I should start reading but most seems to be talking about the xdrip and I don’t see much about the underlying device functionality which probably makes sense as the entire point of xdrip from what I gather is to replace that functionality.
Certainly one of the points. He did say that the reason xDrip doesn’t use or has not considered using the transmitter’ s calibrated data is that it would require upload of calibrations to the transmitter and that would shorten transmitter life.
That’s a good point. I don’t think a Dexcom G5 transmitter without the software time out would last 190+ days with the stock receiver.