GPS receives lots of satellites, but doesn't get fixes

W9MDOW9MDO
in General Chat

Hi all, I saw another post with a similar issue, and it can be solved the same way mine is, by starting over with a fresh install. I've had it happen maybe 6 times in the past few months. It seems to be related to having the radio power interrupted without a proper shutdown, and I guess some corruption has happened. When it's working, the radio is very reliable, and I had a stretch of 3 weeks without any issues.

Any thoughts?

Thanks very much.

73, Chuck W9MDO

Comments

  • PowernumptyPowernumpty
    edited February 2021

    Hi Chuck,

    That is really unusual, I've had Kiwi's run for months solidly at one boot (years in total use) without any corruption.

    Describe what power supply you are using, the measured voltage and ideally a picture of the barrel connector?

    The supply needs to be solid 5-5.25V all the time at the PCB connector, so good solid regulation on the PSU, decent conductors and well made (5.5mm/2.1mm) connector are a must to avoid the voltage sag you may have suffered from.

    After looking at barrel connectors recently I realised they rely on some pretty poor engineering to make a contact. Barrels used on laptops have spring loaded contacts but on lower current supplies it is just "hope and alignment". If the connector is even slightly over size on the inner dimension it reduces the contact area or pressure significantly.


    --OK--

    Once your RaspiSDR is back online I noticed it is a clone so the barrel stuff does not count.

    Personally I'd make sure you are running a Geniune PSU for the version you have, take extra care to cool the CPU and take it offline for a month. (just a hunch)

    73 Stu

  • W9MDOW9MDO

    Hi Stu,

    Thanks for your comments. The power supply can supply up to 12 amps at 5.25V, and I have measured the 5.25V on the board: https://www.amazon.com/gp/product/B08HN6JK7N

    73, Chuck

  • PowernumptyPowernumpty
    edited February 2021

    OK I'll double down on the use a genuine PI PSU. Those USB things normally have some current limiting and device sensing but little capacitance, momentary voltage loss/spikes on a "charger" is probably OK so they won't be built to ensure a solid rail. Also if you really measured 5.25V at the PI PCB that is the upper end of the recommended PI range, the original supplies run at 5.1V.

    The genuine Kiwi has DC filtering components after the socket so are more tolerant at the high end, I've run the Kiwi at voltages at which the PI's are known to fry.

    See how it runs on a genuine supply before doing anything else, perhaps also change the SD card for a new one, from a good brand, known to work well with the PI version (youtube is your friend).

    One last thought, that multi port charger, is it being used for just one device? if there are other devices connected it could be a huge source of switchmode DC noise and other (connected device) RF, some of which could be around GPS frequencies, that could kill the lock while the voltage fluctuation kills the SD card.

    73 Stu

  • jksjks
    edited February 2021

    Thanks for pointing out that Chuck is running RaspPIs (I checked, he has one that is public and no KiwiSDRs).

    So Chuck is no longer with us. He can use the RaspPi forum for his questions.

    cathalferris
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