I found a little workaround for when no numbers show up on my Dex, even though it is within range of my sensor, so I thought I'd share (I searched and did not see anything like this already posted here).
Occasionally, for no apparent reason, I get the "Out of Range Antenna" icon in the upper right of my Dex, even though my Dex is within range (usually it's in my pants pocket). There is no number because of this apparent disconnect, however I found a way to get at the current number:
1. Click the OK button
2. Arrow down to "Enter BG" and hit OK again as if you are entering a new BG number
The number shown by default there when you do this is your current BG number!
3. Hit the RED button on the right to exit (DO NOT hit OK or it will actually enter this BG number for you as if you pin pricked to get it, and you don't want to do that here)
A moment or two upon exiting and going back to the graph, the normal antenna appears in the lower right, and the number shown you via the workaround is shown in the upper right as your current BG level.
This seems to work every time for me, though YMMV.
I thank everybody sharing their personal experiences.
From a technical perspective; these transceiver technologies are compact IC based and they have two issues with interferor's.
a) the interfering equipment is on your same frequency and high enough power to jam.
b) the interfering equipment simply high enough power regardless of frequency to overwhelm receiver and its rejection capability and overwhelm it. I believe many cases are like this.
One time was real nasty when I was in my dentist's offfice ( been there a number of times without incident) and my receiver went out of range. It did not connect till I walked out of this medical building and hopped into my car - metal and it immediately re-connected. Diathermy machine - RF heater, this was medical building.
I have had so many cases sitting in my condo with my unit 1 to 2 feet away as others here have noticed and seen it disconnect for no apparent reason. It would not re-connect till I went outside across street and it immediatly re-connected.
I have a small solid state RF meter that I have scanned my condo(5 unit set of a townhouse building unit) and have caught burglar alarms, servers presence. Without about $ 12K of RF spectrum analyzer and directional antenna - tracking the nuisance factor is extremely diffficult.
Checking the 400 megahertz band on web for uses and I see military has some equipment and channels in or very near to 400 megahertz band that is also used by low energy medical non licenced connection equipment used for insulin pumps, Dexcom, etc.
I really belive these links should have encryption with user supplied key as well as more robust reporting on connection status and interference. Presence status reporting is totally shameless and next to none.
The funny part is that sitting in my car driving for 5 hours up in backwoods - Bishop California, drving across LA, result in far less disconnects and issues than living in my condo in Camarillo.
Last Sunday, on day 7 of operation after week of running stable, I see my Dexcom at 7:00 am read crazy readings - drops to 100 and flatlines and then later goes to the dred ???. I walk outside it reconnects and starts back up with great readings and I let it run for an hour. I then do a stop and restart to get a few days more and sensor goes ???. Woud not clear till stopped and restarted.
I left same sensor in and drove off site for 2 hours in the back weeds of here in some local mountain canyons and sensor completes a restart without incident and starts backup reading fine. I go back to my condo and the sensor drops out again after awhile with ???.
I did get it to clear and come back on with rational readings; but decided to swap in a new sensor.
Maybe I need to line the inside of my condo with fine copper mesh to block the nonsense.
Thanks for the detailed analysis jim. I'm an engineer myself and enjoy learning more about these sort of issues at a deeper scientific level.
Hey, it worked! Thanks Michael ;)
THis issue of no numbers and the dreaded ??? gets more curious:
This story gets more curious, the more I delve into.
I was finding in last months, that the appearance that my sensors were dropping out due to failing exactly 7 days - mostly ??? !
the more I checked , I found that no, sensors were still functioning correctly as long as I got out of my condo a 100 feet and found receiver would recover after about 30 minutes and then accurate readings would come back on . As long as I stayed out of my condo, receiver and old sensor started working fine again.
I also found that while in my condo when the fun erupted - readings dropped to 100 at speeds that body cannot do, if I walked out of condo, and got away from my condo, I would see the following:
a) receiver would go to ???. Antenna status would disconnect and then reconnect.
b) While out of condo, I would cause a disconnect of receiver and then let it recover and stayed away till back up.
c) amazingly now 3 weeks later and multi-times , I have repeated this nonsense and recovered the sensor/receiver pair and got accurate readings.
d) after recovery, during this interval of interference in my condo, as long as I kept my receiver in my car trunk/ refrigerator and took out when I left my condo, there was no problems with it on old timed out sensor(restarted)
I find this all very unacceptable, intolerable.
My sense is that:
Some interfering RF signal close by in my unit was emitting sufficient power to override my sensor/transmitter pair.
Some how my receiver was loading incorrect erroneous data causing drop to 100. I would see the antenna staus on receiver suddenly disconnect for no known reason and if I walked outside away from unit, it would re-connect properly and run.
When I walked out of my condo and got far enough away from interferer, my receiver would see valid restored reading of my transmitter that was way different from previous garbage loaded in my condo and declared the sensor bad ???.
Staying out of range of interferor, allowed the receiver to recover and then go back and display correct data. ( About 1/2 hour.)
Is this acceptable - no!
One thing driving me nuts is why this crap goes on in my 6 unit condo site while in fact out of here, performance is actually fine for a rf linked device, outside up by condo lot swimming pool, in car, driving around, in the mountains around here near the beach.
I have even walked around my 6 set townhouse-condo building with an excellent rf field meter set and find that looking out from our building set, I see little and mostly quiet, but looking into our building set I see high energy leakage that shouldn't be there.
The other curiosity was that if I caught a fast drop just as it started by walking out, receiver sensor pair would immediately recover back to path it had been on and continue fine with no ??? . I would also see an antenna status change although receiver had been within 2 feet.
I do not know how the rest of you good folks cope with this kind of grief?