RV890 Won't Acquire Satellites

This has happened to us repeatedly with our two DriveSmart 50 LMTs, and the only fix has been to restore/reset the GPS from scratch. It's super annoying, even dangerous, when it happens midway on a long-distance trip... I mean I have literally yanked the GPS off the mount and flung it to the backseat out of frustration, and I am a peaceful person, but there you are.

The smoke could have blocked the signals from the satellites. It must have been as high as 40,000 feet or more, the height of the jet stream. Certainly Vermont was in one of the worst areas.

One more thing could have been done to improve reception of the signals as a test - remove the GPS from the vehicle - to see if it got a good fix.

I got the Driveluxe 51 to boot that way by placing it on the hood of the vehicle. I couldn't do it with the 890 since the powered mag mount is hard wired to the car. I got a low battery warning when I removed it from the mount since I had used it unpowered the previous day.

I suppose I should have tried booting the 890 outside the vehicle during one of my stops after the battery had recharged. By that time, I had given up fooling with it and just used the 51.

Strange.. a couple of days ago my DS65 could not find a satellite after stopping at a grocer. Drove home (< a mile) with it "searching".. nothing. Parked my vehicle then went out for another trip couple of hours later.. My DS65 booted up normally but no satellite. Ignored it while it searched.. nothing, and when I came home powered it down. Next morning manually started it.. all is normal and has been since. ????????

I have been lost twice in my life. Once while trying to find a place outside of Charlestown, IN and the other was looking for a church in VT where a buddy of mine was getting married when I was in the army at Ft. Devens, MA. Me and another buddy drove around looking for this church in Vermont for over 2 hours and we never did find the place. Of course, this was before we had even heard of a GPS and we were using paper maps along with directions from our buddy. Kind of reminds me of the Home Improvement episode where Tim the Tool Man was trying to drive to a wedding in Michigan.

I find it implausible that smoke would interfere but given my history of being wrong (which isn't necessary for this discussion!)...

Is smoke a conductor or consist of conductors? Graphite is a conductor. I infer that carbon smoke particles are too. Smoke though surely isn't a conductor because of the gaps between the particles.

Do the smoke particles come in sizes where they may resonate at GPS radio frequencies and thus become filters? I suppose that that may provide the answer. Maybe.

Any other ideas of what the mechanism may be?

We all know that rain can cause "fading" in RF propagation.

Being ignorant on the smoke and RF subject, I went looking, and found a couple of papers. I confess I did not read them more than a quick skim, but from that:

1. Yes, smoke can attenuate RF across quite a broad range of frequencies. Sometimes by enough to matter for terrestrial applications of interest
2. The effect is related to the water content of the smoke!

Getting back to GPS, the original system design only gives us about 10dB of margin by which the signal coming down from the satellite is successfully received by a typical receiver.
So we'd not need tremendous attenuation to have an effect.

So that moves me up from intense skepticism to "well, maybe, sometimes".

Here are links to the papers I found. Feel free to read them more carefully than I did and propose corrections to my comments.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2020...

https://digital.library.adelaide.edu.au/dspace/bitstream/244...

I'm glad that the first reference had a "plain language summary"! I appreciate the references.

Old GPS (called "block 1"??) seemed to work in spite of signal-to-noise ratios bordering on the impossible (minor exaggeration). Modern GPS I've read is "somewhat" better.

These days when I am interested in a topic, I commonly formulate a prompt and supply the identical text to Bard and to ChatGPT.

In this case I specifically asked whether wildfire smoke could give enough attenuation to harm GPS reception. Both of them gave an unequivocal Yes.

Yes, I have caught each making errors, occasionally howlers, but most of the time they don't make stuff up. So I strongly suspect that somewhere out there on the internet there is text posted which supports this.

So I'll further upgrade my initial intense skepticism to "Yes, sometimes". But I won't guess whether specific instances mentioned in this thread were smoke-induced.

If you have acquisition trouble, I suggest you drive your receiver to somewhere with an unusually unobstructed horizon, then having powered off your receiver take it out of the car and power it up with a clear view of the sky and leave it alone for some minutes. That gives your receiver a maximum number of satellites in many different directions to look for, and little trouble from multipath, signals bouncing around inside your car, and the like.

My .02 cents worth. Smoke has been covering the midwest/east/north east for many weeks now. That there hasn't been a general hue and cry about loss of GPS service lends me to believe that there is more to it than smoke.

ICBW.

When I lost my satellite connection the sky was pretty clear. And have had a proper connection when the sky was so obscured the sun would not shine through.. and/or so thick one could not see more than a couple of blocks. So.. kind of doubt smoke was responsible for my outage.

my gps wouldn't connect this morning and I am upwind of the fires