GPS Antenna - external connector?

[GregH]

The GPS reception on my PinePhone has been poor (no satellites!), and I'd like to improve it with an external antenna.

Can anyone clarify which u.fl connector is the GNSS antenna (and whether it should be "active")? There seems to be at least three on the mainboard.

I am hoping the coax going to the USB-C board ANT104 could be it, but the schematics "helpfully" inticate only that it's an RF antenna, not which one. Wi-Fi? BT? LTE/CDMA? Or GNSS?

Much appreciated if someone can clarify.

[steffenvongrabau]

I took a look at the schematics and at the mainboard of my PinePhone.

The coax going to the USB-C board is for the main LTE antenna. The GNSS and WiFi antenna is the one located on the top left of the mainboard (Pins top to bottom are GNSS-ANT, GND and WiFi-ANT). I hope this is helpful.

[8bit]

It looks like there are just spring contacts for the antenna in the midframe. https://blog.pineph.one/2021/04/franken-phone.html

[GregH]

I took a look at the schematics and at the mainboard of my PinePhone.

The coax going to the USB-C board is for the main LTE antenna. The GNSS and WiFi antenna is the one located on the top left of the mainboard (Pins top to bottom are GNSS-ANT, GND and WiFi-ANT). I hope this is helpful.

Thanks Steffanvongrabau, much appreciated! Could be handy to link this on the pinephone wiki page.

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It looks like there are just spring contacts for the antenna in the midframe. https://blog.pineph.one/2021/04/franken-phone.html

Fantastic, thanks 8bit!! Love what you're doing with the "franken-phone", a great reference and experiment base.

Good to know the phone uses a passive GNSS antenna. I think I have one around that I can use with the PinePhone.

[8bit]

Works with the flexible GPS antenna. Need to look into maybe a 3D printed case or one of the upcoming keyboard/fingerprint cases.
https://blog.pineph.one/2021/04/flexible...tenna.html

[GregH]

Works with the flexible GPS antenna. Need to look into maybe a 3D printed case or one of the upcoming keyboard/fingerprint cases.
https://blog.pineph.one/2021/04/flexible...tenna.html

Thanks again 8bit, your blog is a wonderful resource! I now also understand that the internal antennas are connected with spring contacts, not u.fl (though there is a coax carrying LTE to the USB-C PCB where those antenna contacts are).

Inspired by your work, I hooked up an external antenna and was impressed with the results. In fact I used an active antenna (fairly high quality Tallysman) since I had one available, which worked nicely - valid lock within a couple of minutes (indoors) where previously it had never even worked out the time (RMC). The built-in antenna really is woeful.

Now to solder on the coax leads as a semi-permanant solution.

[8bit]

I ordered some of these https://www.ebay.com/itm/171873811385 I am going to remove the MHF connector and solder it to the antenna pads. Then I can test other antennas without destroying the U.FL ends. The seller has a bunch of other cable assemblies that might work with your antenna.

Interesting that the active antenna works. I could not find any reference whether it would work or not. I will try out the ones I have when I get the adapter.

[GregH]

Ahh, I just made a terrible error.

I tried to remove the antenna springs in order to solder direct to the PCB. Bad idea!! I've managed to destroy the solder pads, and I can't see any material to solder to now. So I've gone from woeful GPS to absolutely no GPS. :-(

Best to use the spring contacts than to remove them. The MHF u.fl connectors sounds like a good idea.

Any chance the tiny connector near the LTE coax connector is GPS? It's not u.fl but something even smaller. Pity, since I don't have any connectors that small or I'd try it.

[8bit]

Ahh, I just made a terrible error.

I tried to remove the antenna springs in order to solder direct to the PCB. Bad idea!! I've managed to destroy the solder pads, and I can't see any material to solder to now. So I've gone from woeful GPS to absolutely no GPS. :-(

Best to use the spring contacts than to remove them. The MHF u.fl connectors sounds like a good idea.

Any chance the tiny connector near the LTE coax connector is GPS? It's not u.fl but something even smaller. Pity, since I don't have any connectors that small or I'd try it.

Damn, that sucks. I believe the cluster of small pads below the spring connectors is connected to the antenna. On page 15 https://files.pine64.org/doc/PinePhone/P...ematic.pdf search for ANT1501 and you will see the section that leads to the antenna pads. There is a 0ohm resistor connecting pads C1519 and C0201. You can connect to the GNSS feed there.

But that cluster might be for the WiFi, it has a similar setup in the schematics. Need to test if it is connected to the GNSS pad. Will have to do that with a DMM at work tomorrow.

Another possibility, I think both the Braveheart and UBports have the pads around the EG25 module exposed. https://pine64.com/wp-content/uploads/20...46c16e2e66

The link on the wiki for the EG25 module PDF is broken, but it had the pinout for which pad is the GNSS antenna, it has a ground pin right next to it. Originally I was planning to solder to those pads, but the 1.2 PCB does not have the exposed pads.

That connector by the cell connector is some kind of switch. Search for J1500 on page 15 of the schematics.

[GregH]

Thanks, I have the v1.2 PCB so no extra exposed pads. No luck with soldering replacement pads to the PCB either. Sadly the 0R would be too tiny for my soldering skills even if I could locate it. Good idea though.

I'll try to look at it as the GNSS was useless before I stuffed it, and the GNSS is useless afterwards. Hopefully a GPS USB dongle will fulfil my immediate needs.