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BU-353 Low Signal when starting in underground garage

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  • BU-353 Low Signal when starting in underground garage

    I have my system running CF3.1 with GMPC (it did the same with Destinator) and park in an underground garage (work or home), where it hibernates. When I resume, most of the time it either never gets enough satellites and locks or it takes a long time (at least 10 minutes), even if I get out of the garage before it finishes resuming. I'm guessing this issue has to do more with the state of the GPS when I hibernate the PC after entering the garage. It seems like this could be fixed possibly by a disable/enable of the GPS driver just like Xport does when it resumes. I have Xport running and this still occurs and the Xport GUI reports "Low signal". I have a GPS log from this morning when this occurred and can post it, but it doesn't look very helpful.

    Anybody have the same problem? Ideas?
    Carputer Progress:

    Re-do fabrication of screen [DONE]
    Add mini-USB and micro-USB power from M2-ATX [DONE]
    Teardown PC [100%]
    Add HDMI > VGA converter [0%]

  • #2
    the unit has an internal capacitor (battery) which keeps the sat info in memory... if you leave it for long..the capacitor will discharge and you will lose the info, thus the unit will have to re aquire it.. it can take up to 5 minutes or even more and of course it needs an open sky above to see the sats..

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    • #3
      Originally posted by Nomader View Post
      the unit has an internal capacitor (battery) which keeps the sat info in memory... if you leave it for long..the capacitor will discharge and you will lose the info, thus the unit will have to re aquire it.. it can take up to 5 minutes or even more and of course it needs an open sky above to see the sats..
      I don't have the same problems when I park outside...
      Carputer Progress:

      Re-do fabrication of screen [DONE]
      Add mini-USB and micro-USB power from M2-ATX [DONE]
      Teardown PC [100%]
      Add HDMI > VGA converter [0%]

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      • #4
        its just what happens when you complete loose all your satellite signal, it'll have to go through a cold startup, and it takes hella long. Unfortunately its a limitation of the gps, and there's not much we can do.

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        • #5
          Originally posted by Punky View Post
          its just what happens when you complete loose all your satellite signal, it'll have to go through a cold startup, and it takes hella long. Unfortunately its a limitation of the gps, and there's not much we can do.
          That's kinda what I was thinking was the problem. I just wonder if there is a way to reboot it or something once I am under a clear sky...
          Carputer Progress:

          Re-do fabrication of screen [DONE]
          Add mini-USB and micro-USB power from M2-ATX [DONE]
          Teardown PC [100%]
          Add HDMI > VGA converter [0%]

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          • #6
            I had this problem with my Garmin GPS 18 usb. It would lose signal completely in my garage (mounted inside the car). It would like 15min to reaquire signal, which was completely inacceptable (If I just parked outside with the carputer on, it would take 8-10 min, so moving, specially moving fast down the highway, made it to take longer to get usable signal).

            I then mounted outside the car, it takes about 5min, which is supposed to be normal. Same GPS, carputer, driver, everything, just mounted outside. It acquires much faster.
            Worklogs: 08 Sequoia Platinum Carputer (In Progress!)
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            07 Infiniti Fx35 (done!) & 06 Infiniti M35 (gone...)

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            • #7
              If I may make a suggestion which has worked for me. Get a LM7805 and wire it to only the power lines of the GPS and provide it power from a constant 12v source even when the pc is hibernated this should keep the GPS running and keep a lock.

              Hope this helps,
              yonu

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              • #8
                Originally posted by yonu View Post
                If I may make a suggestion which has worked for me. Get a LM7805 and wire it to only the power lines of the GPS and provide it power from a constant 12v source even when the pc is hibernated this should keep the GPS running and keep a lock.

                Hope this helps,
                yonu
                this works great if you're not underground. If you're underground (parking) for a long time, it will loose the lock anyway, and wait a while you'll still back to the same problem.

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                • #9
                  ok figured it was worth a shot. I don't have to worry about underground parking here. So wasn't sure if it could keep a lock if left on or not

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                  • #10
                    I was having this same problem. I figured out that if you go into the CF's Advanced Setting/Navigation, dont change anything, and simply then exit out of the settings (it will ask you to save the changes which of course you didnt make any, click Yes), the GPS then locks on immediately.
                    Its kind of a round-about way of doing it, but its better then waiting the 10-15 minutes before it reacquires the signal.
                    - scENFORCER

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                    • #11
                      If it's a cap issue, IMO that's design. It should be using novol else perm power.

                      But whereas some blame their mothers for pulling out web & payTV RJs or power - thus requiring setting up again - I see that as nothing short of a design fault.
                      (Cheapness maybe, but how many would scream if TVs etc lost their tuning after a reasonable power outage? It's ludicrous (IMO)!)

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                      • #12
                        That has nothing to do with power. Punky explained it correctly. After some time of not receiving a signal from any sats, it will reset to zero knowledge and begin a search which can take quite a long time. One idea would be to unplug it before entering the garage and plug it back in when you leave to make it pick back up with the saved state.

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                        • #13
                          I was going by Nomader....

                          I guess mine is smart. Without power or without an update, it just retains its last data.
                          I can't think of anything more sensible.

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                          • #14
                            You could also build a GPS retransmitter. Strictly speaking they're illegal, but I don't think anyone will notice if you use one underground... Just depends on how far away the nearest location is you could put a GPS antenna...

                            Aside from the antenna, the parts you need are mere pennies... (A bit of #26 AWG, #22 AWG (or thicker), a capacitor and a power supply)...
                            (See also http://www.bytethebullet.com/geocach...ng_antenna.htm and similar projects, or ready made from outlets like these: http://www.totalpda.co.uk/Carcomm/Ca...enna.7477.html)

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                            • #15
                              Originally posted by OldSpark View Post
                              I was going by Nomader....

                              I guess mine is smart. Without power or without an update, it just retains its last data.
                              I can't think of anything more sensible.
                              That's correct as well, as long as it's within probably 1-2 days. That's assuming it's powered off with a lock. When it powers back on, it will see that it's still on Earth in about the same spot that it remembers. But when it's been blinded for several minutes, it will reset and begin acquisition. If powered off before a lock, it won't save it's place so it will start back up at the beginning.

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