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PMB 648 GPS module won't update — Parallax Forums

PMB 648 GPS module won't update

msg558msg558 Posts: 13
edited 2012-03-24 15:45 in Accessories
I've been using the PMB 648 GPS module for several weeks now and has been working fine up until recently. I brought it to my parents' house and the longitude and latitude that are output are still the same ones I was getting from my apartment 300 miles away.

Any ideas on how to make the thing update to my current location?

Comments

  • PublisonPublison Posts: 12,366
    edited 2012-03-17 08:54
    msg558 wrote: »
    I've been using the PMB 648 GPS module for several weeks now and has been working fine up until recently. I brought it to my parents' house and the longitude and latitude that are output are still the same ones I was getting from my apartment 300 miles away.

    Any ideas on how to make the thing update to my current location?

    Is the LED flashing or solid? It may take up to 10 minutes to get a good lock outside after moving it that distance.

    Jim
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2012-03-17 10:29
    $GPGLL has a Status character (A = OK, V = NG).

    Another guy recently posted he had trouble with another GPS (a '248?) and it took somewhere around that 10min. http://forums.parallax.com/showthread.php?138585-Gps-module-no-fix-status

    I've never had that trouble, despite having had them sitting in bags unpowered for a year in one case or in a breadboard in a box or something, they always got a lock in a few minutes at most.
  • msg558msg558 Posts: 13
    edited 2012-03-17 13:53
    It has been powered and sitting in the window for at least an hour and the LED is still blinking.
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2012-03-17 15:42
    OK, the GPS doesn't require intervention from a microcontroller, it does its thing independently; it gets a lock and knocks out the sentences it's set up for, some sentences it can knock out without a "valid" status.
    Assuming that it has proper power (no marginal battery voltage and that like), take it outdoors and see how that goes.
  • msg558msg558 Posts: 13
    edited 2012-03-22 17:41
    After coming back to my apartment, it received a lock within 5 minutes. Im going back to my parent's house this weekend so I'll give it another shot. Thanks for the help.
  • GordonMcCombGordonMcComb Posts: 3,366
    edited 2012-03-22 20:21
    You've never said if you're trying this outdoors or not. You could readily take it outdoors to see if the LED lock shows status.

    Look for sources of interference. Do your parents have old fashioned satellite TV? Does your dad wear a pacemaker? Is he (or your mom) a ham radio operator? Do they have a cell phone repeater in the house? Some of these are so badly made they generate wideband interference that can disrupt GPS reception. Taking the unit outdoors, away from the house, could answer a lot of questions. Look for high tension wires overhead. Though more rare, they can disrupt reception, too, especially the nasty 345 kV ones that criss-cross some parts of Texas.

    -- Gordon
  • msg558msg558 Posts: 13
    edited 2012-03-24 15:45
    Apparently the module was under-powered. After leaving it out in an open field for 20+ minutes it still did not get a lock when hooked up to 3.3V. Upon switching to 5V it got a lock within 3 minutes.
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