Adding Aftermarket Internal GPS to the CF-28

Discussion in 'Panasonic' started by Toughbook, Nov 19, 2007.

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  1. AircooledT1

    AircooledT1 Newbie

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    Here's my latest and greatest issue. The link doesn't work and I'm unsure how to plug this sucker from the Geohelix antenna to the MMCX input in the GPS engine.
     
  2. Toughbook

    Toughbook Drop and Give Me 20!

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    You will need a right angle MMCX connector with the center conductor of the MMCX going to the center of the Sarantel antenna. The ground lead can go to either pad beside the center lead on the antenna base.

    Can you fab this up or need help?
     
  3. AircooledT1

    AircooledT1 Newbie

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    I'm trying to fab this together myself just so I can say I've done it :)

    When I bought my laptop, it came with a Cellular card and a 90 degree MMCX antenna connected to it, but it's only about 10" long and I'm assuming the cable needs to connect directly from the GPS to the antenna (meaning I need a new, longer MMCX cable); and judging by your response I just strip the end and solder it directly to the antenna? Also, as I'm reading to the requirements of this antenna, it's saying it needs a 50 ohm resistor in line going to the GPS, for some reason that doesn't strike me as right, but maybe it is?

    (Page 4, SL1204)
    http://www.sparkfun.com/datasheets/GPS/SL1206_SL1204 Electrical_Guide_v10.pdf

    Also, obviously the antenna has two grounds, should I connect them together, is it common to leave one open? Last question, is there a proper grounding spot that's better than another because I was figuring I'll just ground it directly to the chassis.

    Thanks!
     
  4. Toughbook

    Toughbook Drop and Give Me 20!

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    I don't think that is the Sarantel antenna that I used to use....
     
  5. AircooledT1

    AircooledT1 Newbie

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    For anybody else, the wiring from the GPS to the Antenna is very easy (come to find out). Your quickest bet is to buy a 90 degree MMCX connector long enough to reach where your mounting your antenna (I'm doing it in place of the old stocker, I think 30 inch long was reported).

    The EM408 to the SL1204 requires no grounding or power from an external source, meaning you plug the MMCX end directly into the GPS engine and the other end you cut off and solder to the Antenna. There are MULTIPLE parts to this wire though.

    Outside layer 1 - Insulation
    Outside layer 2 - Braided wire (ground)
    Inside layer 1 - Insulation
    Inside layer 2 - TRL

    Outside layer 2 is what you ground the SL1204 with: either gnd1 or gnd2, I went ahead and connected it to gnd1 and threw a second wire around so gnd2 could be connected to it. This is probably overkill, might not be recommended, but I love grounds and it worked for me.

    Inside layer 2 is what you solder to the TRL: very small gauge, I hate twisting around the wire strippers but had to in order to properly cut the braided wire on top, just be careful that if you do the same you don't drag the wire strippers across the TRL wire because it's a solid strand wire (meaning if damaged, it can break when you flex it/if you flex it too much).

    I soldered up those 3 points (2 ground and 1 TRL) and I'm getting 4 sats inside a rather tall building.

    Last note: on the MMCX connector itself (on the wire), it is VERY easy to bend the little TRL connection there in the middle. Feel the wire in, do NOT force it or you may be spending a little time with a fine needle trying to bend it back.

    Edit:
    http://en.wikipedia.org/wiki/File:RG-59.jpg
    Picture of the type of wire I'm talking about (pictured is a normal Coaxial, but the MMCX is the same thing only smaller).
     
  6. ohlip

    ohlip Toughbook Modder

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    Here is another way of integrating the EM408 GPS engine receiver to CF-28 toughbook without RIM board or daughterboard.

    I know its an old machine but recently, one of our member on NBR refer a friend to me to do a wi-fi and Gps integration to his machine. He had three unit of CF-29STJ......which has all have 1.0Ghz cpu and with complete caddy and harddrive. In return, he just need one with all the mention stuff and I will keep the two as payment. All of this unit has max. out ram of 768Mb. Now! as you all know that all gps aftermarket installation on cf-28 uses a Rim Board or a daughterboard as we speak. I don't have those stuff. Instead I managed to installed it Using just a 40pin Flat cable ribbon soldered to a round cable to interface with EM408 module. Another thing is that I don't have a bump out casing or Sarantel antena to finished the job. What I have done is taking out one of the rubber bumper to a damaged traveling laugage bag which is ready to throw out on the landfill, Lol..Below is the pin out for those who are still interested on modding a cf-28 with EM408.

    Using CN(A) 50pin connector on CF-28 toughbook

    EM408--------------------------CN(A)pin

    1.0(enable/dis.)-----------------40-41
    2.0(Ground)---------------------37GPS In,38-39
    3.0(Rx)--------------------------28
    4.0(Tx)--------------------------27
    5.0(Vcc)------------------------40-41 ( you can short pin1 and pin5 of Em 408 and then connect to pin40-41 of CN(A)



    Here a couple of pictures for your reference:
     

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  7. toughasnails

    toughasnails Toughbook Moderator Moderator

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