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Thread: Hacking a Holux GM-210 for external antenna (doesn't work)

  1. #1
    Newbie mpquattro's Avatar
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    Hacking a Holux GM-210 for external antenna (doesn't work)

    I recently purchased and installed a Hirschmann GPS 2400 antenna (GSM, GPS, 802.11) and, like others, wanted to attempt to use my existing USB GPS receiver (Holux GM-210) with it. I had thought of getting a re-radiating antenna, but wasn's sold on the idea yet. I had read of others trying to solder a pigtail in place of the internal antenna with no success. I figured excessive heat had destroyed sensitive parts and I really wanted to solder an SMA connerctor in place of the original antenna, so that i could connect it to my GPS 2400. What follows is a step-by-step descrioption of taking apart the Holux GM-210. (spoiler.... no it didn't work, but I was able to restore functionality by reversing what I did, I think this is still useful information)

    1. The case is not screwed together. There is nothing under the magnets. To open it up, I just inserted a small flathead screwdriver in the groove on the side and pryed it open. There are 4 little plastic clips and sealing glue that hold it together, 2 of the clips ended up breaking for me. It also won't be waterproof after this (unless you glue it again) (sorry for this blurry image, just to show there's nothing under the magnet)



    2. Once opened you see the antenna.It is adhesed to the metal ground plane, and the easiest way to get it off is by desoldering where the metal shield is soldered to the board. BE CAREFUL, too much heat will damage IC's. I used a 15W iron.




    3. Once the ground shield is off, you can see the wire for the antenna. Desolder the center wire, and then gently pry off the antenna.


    Again, sorry for the blurry image below


    4. Then Desolder the antenna wire.



    5. I drilled holes for the SMA connector



    6. And soldered the SMA connector in place. This thing is VERY secure.




    7. Solder on the antenna wire.



    8. Solder the ground shield back onto the board. (Test if you want)



    9. Then I drilled a (horribly ugly) hole in the top of the GM-210 case

    10. Then I reassembled the whole thing and put on my SMA-FME adapter




    To my dismay I could not get a lock on the satellites. The LED stayed green, and never started to blink. I downloaded GPS viewer and SIRFdemo to try to diagnose the problem, but couldn't get a reading. The device still showed up as "Holux USB GPS device" (or something like that) in my device manager, so I was still hopefull. I then tried to solder the original antenna (with improvised ground plane) to the end of a FME-pigtail. Also didn't work at first. Then it started to sporadically read satellites in GPS viewer. I tried connecting it to the GPS 2400 antenna, and nothing. Then I got frustrated and decided the Holux probably doesn't like the GPS 2400 antenna, probably not designed to power an external antenna (dunno if that makes sense). So undid everything I had just done, removed the SMA connector and resoldered the original antenna in its factory position. Then I went to test it, and it was glitchy at first, but after about 10 minutes of switching between softwares, it started to get a lock.

    The only difference now is that when being used in DeLorme Street Atlas I now occasionally get a 3-D DGPS lock where as before it would only get 2-D or 3-D locks (still get both of those). A quick reading of the help file shows that "a WAAS enabled device will give a 3-D DGPS lock". I'm not sure if it is good that I now get this when before I didn't, but I don't really care.

    Hope this helps someone who wants to open up their Holux GM-210

  2. #2
    Variable Bitrate slimmegane's Avatar
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    I've already think to make this hack to an USB GPS but i've think probably the USb GPS don't get any power to an external antenna, I now have the confirmation, I think that the problem is that.

    Thanks.
    --------------------------------
    ITALIANI: DISPONIBILI MODULI OEM GPS:

    http://www.mp3car.com/vbulletin/show...214#post639214
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  3. #3
    Newbie mpquattro's Avatar
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    Quote Originally Posted by slimmegane
    I've already think to make this hack to an USB GPS but i've think probably the USb GPS don't get any power to an external antenna, I now have the confirmation, I think that the problem is that.
    yeah, I came to the same conclusion, especially after noticing that the original antenna looked very similar to this passive antenna.
    http://www.laipac.com/ant_GLP1_P1P_eng.htm

    patching in 5v to the antenna through a DC injector might be possible but with OEM boards being so cheap it just doesn't make fiscal sense.

    My axiom sandpiperII board is being shipped as we speak. $19.99 + $5s&h. Really now, my sma-fme male adapter alone was 9.99.

    gotta love this place
    -------------
    lilliput 629, EPIA M10K, 256m, 40gig, dvd, travla C134, CarNetix CNX-P1260, holux gm210, bluetooth dongle, USB audio dongle, ovislink WL-5480USB WLAN adapter, Hirschmann GPS-2400 cell/gps/802.11 antenna, SonyEricsson T616

  4. #4
    Variable Bitrate slimmegane's Avatar
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    SandpiperII, good, I've one, 9 sat linked is more for my zone! Only whit this GPS I've see 9 sat!

    Bye.
    --------------------------------
    ITALIANI: DISPONIBILI MODULI OEM GPS:

    http://www.mp3car.com/vbulletin/show...214#post639214
    --------------------------------

  5. #5
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    What kind of antenna is in the GPS 2400? Your Holux should work fine with an external passive antenna, such as a patch. There must be something wrong with your wiring. Are you using 50ohm coax? How long is your cable? Remember, the longer the cable, the longer the loss. Even connectors cause .5-1dB loss.

    I don't know the specs of your antenna, but if it really purports to handle cellular and wifi as well, it's can't possibly give you as high gain as an antenna that's optimized specifically for GPS frequencies.

  6. #6
    Newbie mpquattro's Avatar
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    Quote Originally Posted by lincomatic
    What kind of antenna is in the GPS 2400?
    The GPS 2400 is three antennas in one housing; GPS, WLAN, and quad-band cellular.

    Check out the website with the specs
    http://products.hirschmann.com//inde...,maid=0,view=1

    I'm assuming since it has a current draw of 30mA and needs a supply of 3-5VDC that it is not a passive antenna.

    Once I get my SandpiperII installed I'll play around some more with the Holux. I'll keep y'all posted.
    -------------
    lilliput 629, EPIA M10K, 256m, 40gig, dvd, travla C134, CarNetix CNX-P1260, holux gm210, bluetooth dongle, USB audio dongle, ovislink WL-5480USB WLAN adapter, Hirschmann GPS-2400 cell/gps/802.11 antenna, SonyEricsson T616

  7. #7
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    Quote Originally Posted by mpquattro
    The GPS 2400 is three antennas in one housing; GPS, WLAN, and quad-band cellular.

    Check out the website with the specs
    http://products.hirschmann.com//inde...,maid=0,view=1

    I'm assuming since it has a current draw of 30mA and needs a supply of 3-5VDC that it is not a passive antenna.

    Once I get my SandpiperII installed I'll play around some more with the Holux. I'll keep y'all posted.
    Yeah, it's strange... it says the voltage is "external fed," but there's no mention of where to connect the power. In any case, you guys are right... that's why this antenna won't work.... the USB GPS won't power it.

  8. #8
    Variable Bitrate markland556's Avatar
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    so does anyone have an idea on how to hook up the gps 2400 antenna to that gps yet??? or what gps systems will work with it??
    96' Mercedes Benz C36 -Matte Black-
    Status..::... {##------}25%~~ back to planning

  9. #9
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    I'm trying to do the same thing and i found this.

    "active antennas amplify the signal to get past the loss in the extra wiring; with a little bit of hacking, you can add an external active gps antenna to just about any GPS unit. Find out how in today's How-To."
    http://www.engadget.com/2006/03/28/h...l-gps-antenna/

    Anyone ever try this or find another solution?

  10. #10
    Newbie mpquattro's Avatar
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    Quote Originally Posted by ACompGeek
    I'm trying to do the same thing and i found this.

    " you can add an external active gps antenna to just about any GPS unit. Find out how in today's How-To."
    http://www.engadget.com/2006/03/28/h...l-gps-antenna/

    Anyone ever try this or find another solution?
    Nice Find, when I've got some more time on my hands (read "in a couple of weeks") I'll give this a try. My Holux is currently sitting collecting dust on my desk, might as well put it to good use.

    My sandpiper is in, running on iGuidance now, a dream....
    -------------
    lilliput 629, EPIA M10K, 256m, 40gig, dvd, travla C134, CarNetix CNX-P1260, holux gm210, bluetooth dongle, USB audio dongle, ovislink WL-5480USB WLAN adapter, Hirschmann GPS-2400 cell/gps/802.11 antenna, SonyEricsson T616

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