Knowledge Base / PCIe GPS intermittent lock: antenna power and coax checks

PCIe GPS intermittent lock: antenna power and coax checks

Check the PCIe GPS card’s 5 V antenna supply, coax continuity, connector condition and sky visibility when satellite lock is intermittent.

Applies to: PCIe
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Antenna power and reception

The PCIe GPS card supplies 5 V DC to the active antenna through the coaxial cable. Use the supplied antenna or a compatible active antenna rated for that supply. The cable carries both the antenna power and the received satellite signal, so an open conductor, a short or a damaged connector can interrupt reception as well as power.

For intermittent lock, note whether the dropout follows cable movement or changes in satellite visibility. Check that connectors are fully seated and inspect their center contacts, shield connections and strain relief for damage or corrosion.

Check coax continuity with a multimeter

  1. Shut down the PC and remove power, then disconnect the coax from both the PCIe card and the antenna. Do not use continuity or resistance mode on a powered cable or while it is connected to either device. Test the cable section by itself, with in-line amplifiers, surge protectors and other accessories disconnected.
  2. Set the multimeter to continuity or resistance. Touch the probes together first to confirm the meter and leads work.
  3. Measure between the center conductor at one end and the center conductor at the other end. A sound conductor has continuity and a low, stable resistance appropriate to its length. An open reading indicates a broken conductor or connector.
  4. Measure between the outer connector shell/shield at each end. This path should also have continuity.
  5. Measure between the center conductor and outer shell. With the bare cable disconnected at both ends, this should be open. Continuity here indicates a short between the center conductor and shield.
  6. Gently flex the cable near each connector while watching the reading. A reading that changes between continuity and open points to an intermittent connection. Replace a damaged cable or connector.

A continuity test checks the DC path. It cannot establish acceptable RF loss or shielding performance, so a cable can pass this test and still impair GNSS reception.

Separate a cable fault from a reception problem

Reconnect a compatible antenna using a short, known-good coax cable and place it with an unobstructed sky view. If reception becomes stable, compare the installed cable length, connectors and accessories with the working setup. If the problem remains, check the antenna and its location before attributing the fault to the card.

Record the antenna model, cable type and length, continuity results and lock behavior for Masterclock Support if the problem persists. Do not short the powered antenna connector while probing or reconnecting it.

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Article ID: PCIe-GPS-002
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