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I am developing an embedded system that performs GPS and Wifi operation with separate modules for each and two SMA connectors to connect the respective antennas. Once it is being installed, is there a way I can identify whether the antennas are connected properly or the cable I am using is broken? As I am writing the diagnostic software, it would be great if I could include this case so as to identify wrong installations.

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  • \$\begingroup\$ The following has an example of GSM antenna detection that may be useful telit.com/module/infopool/download.php?id=901. Some GPS modules already have it built it. \$\endgroup\$ – PeterJ Apr 24 '13 at 2:04
  • \$\begingroup\$ Wi-Fi connections usually use SMA-RP (reverse polarity) connections. Can you use -RP for the Wifi and normal SMA for the GPS connection? \$\endgroup\$ – markrages Apr 24 '13 at 3:24
  • \$\begingroup\$ Yeah I could,but how does that help? \$\endgroup\$ – Elsa Adams Apr 24 '13 at 18:52
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For GPS receivers in particular, many of them use an "active" antenna that has a built-in preamp, and requires typically 3.3V or 5.0V at a few 10s of mA of DC power fed down the coax. Some GPS receiver modules actually monitor the amount of current being drawn by the antenna and can alert you if it is either too low (cable open) or too high (cable shorted).

Other GPS modules don't monitor the current themselves, but they do have a separate power input specifically for antenna power, to which you can add your own monitor circuit.

Unfortunately, WiFi antennas are usually passive, so the same technique can't be used there.

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I am sure somebody with more knowledge about antennas will have a more elegant solution, but you could put these antennas on a sub-board if this is your own design, and then see if the sub board is plugged in (ie. simply closing two pins on the connector to the sub-board). This will add more parts and cost though.

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  • \$\begingroup\$ could you please explain what you mean by closing two pins on the connector? \$\endgroup\$ – Elsa Adams Apr 23 '13 at 23:41
  • \$\begingroup\$ Think of it like a jumper. Jumper closed, sub-board (with antenna) plugged in correctly. Jumper open, not plugged in. \$\endgroup\$ – Alex Apr 25 '13 at 0:18

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