CF-31 GPS / WWAN antenna switch

Whilst installing a fingerprint reader to a CF31 mk4 I noticed that the GPS and WWAN Aux antennas were switched. The WWAN antenna was connected to the Leadtek GPS board and the GPS antenna was connected to the WWAN card Aux. I know the colours of the wires but to be sure I traced the wires back to the actual antennas on the screen lid.

Testing the GPS (indoors) using Panasonic's GPS viewer showed 6 satellites and a GPS fix within about half a second of connecting.

I switched the antennas (antennae?) back to the correct way round and retested. After about a minute of connecting there was only one satellite and no GPS fix. My first thought was that the GPS antenna was faulty so connected another GPS antenna - same result no fix.

Just out of interest, I tried another CF31 mk4 with the antennas connected correctly and was still waiting for a GPS fix after 5 minutes - so I tried connecting the WWAN Aux antenna on that unit to the GPS card and got the same result - immediate GPS fix indoors.

(It doesn't work with the WWAN main antenna BTW. Same result as the GPS antenna - just one satellite picked up and no fix..)

I wonder why the WWAN Aux is so much better at picking up the signal. Surely I can't have three faulty GPS antennas.

Any thoughts guys?

 

Make sure you have the antenna cover on when testing. I believe the antenna is orange on the mk4. If not its yellow.
The bios has docking options for the antennas. Make sure they are set to auto.
The GPS antenna is different then the rest of the antennas. I wonder if the GPS antenna is connected to the wwan on the other side of the board?
Steve

 

Thanks Steve. Do you mean that the GPS antenna only works with the plastic cover on ?

GPS wire is orange. GPS antenna is connected directly to the GPS card.

On second "just out of interest" unit GPS antenna was connected to GPS card. I removed it and connected the WWAN Aux.

 

Try a multimeter to check if orange wire is broken internally.

 

Correct, the GPS will not work with the antenna cover off. I'll upload a picture of the switching bank next time we have one opened up.
Steve

 

Thanks for the info.

Thats interesting - I'm intrigued why a plastic cover over the gps antenna would make it work. Or rather why having no cover would stop it working?


I'm happy with how it all should be connected up - its more an observation that the WWAN aux antenna works at all when connected to the GPS card - and especially better than the GPS antenna.....

 

Not sure I agree with needing the cover.

There is no metal or any ground plane that the gps cover or the cover screws would provide with the factory gps antenna.
Now on the WIFI and WWAN antennas and covers, the cover screws might assist with grounding and as such the ground plane of those antennas.

Since many WWAN modules have built in gps, many of the WWAN antennas are multi frequency and will work quite well for gps. My Q2 and Q1 both use WWAN antennas on the gps. Q1 is a dedicated Reyax gps and Q2 uses the gps on the WWAN card. NO cell service on either unit.

I can't recall if I tried a CF 31 gps without the cover. I would be surprised if I had not.

 

Give it a try, no cover.
Cold hard facts

 

When I first read this information it seemed unbelievable so I went and bought a CF-31AHAGX2M for experimental purposes.
The CF-31's GPS picked up 7 satellites on Panasonic GPS viewer.
After removing the cover over the antenna, the satellites received dropped to 3, and then varied between 4 and 0.
Upon inspection, that plastic antenna cover has a magnet attached to the front of it (for indicating a closed lid ?).
That magnet must be the secret reason for the magic antenna cover.

steve.steve does not make up funny stories.

EDIT:
After sitting for a short while with the antenna cover off, the CF-31 GPS once again picked a good 6 satellites. Nothing gained - Nothing lost.

 

The plastic cover has something to do with the way the radio waves are shaped. I had a radio engineer explain it to me. This is the reason the CF-19 units have different 3 different types of antenna covers. I personally put a solid 15 minutes into the testing of the GPS cover on the CF-31.

 

Definitely not.

Nope. These covers are just spacers.

 

Just spacers??

 

Just spacers! )

 

Spacers for what though? Everything is shaped the same behind the different covers. I can post pictures if you need to see

 

I don't need, thanks
It's a known fact spacers are installed on WWAN models to meet FCC requirements.

 

The spacers are to keep a distance between your hand and the source of RF transmissions..
The earlier CF-19 antenna cover(s) is a good example of showing those with WWAN and those without.
Tinfoil hats are worn for a reason.

 

Not that it matters, because until I see it with my own CF 31 with factory dedicated GPS and antenna, I won't believe a plastic cover has anything to do with radio waves.
A plastic cover can not "shape" a radio wave.
Radio waves are "shaped" by the frequency and modulation. Plastic has nothing to do with that. Plastic is invisible to radio waves.

The WWAN antennas and covers on CF 31 and CF19 are not the same cover as the dedicated GPS antenna cover.

 

10 birds no covers.
Put the covers on and had same 10 birds.
Maybe it is different in other parts of the world.
The odd looking foam thing is holding a Taoglas flexible WIFI antenna. They rock.

 

The screenshot shows your GPS using com port 6.
Is that where the factory GPS is ?

 

Depends on the unit. I have not messed with a CF 31 in quite a while and can not recall for sure.
I don't think com6 was the most common gps port.
I do have ALL the options on this. fingerprint, gps, camera, etc... Those might change the port number and availability.