Nokia N97 GPS Antenna Hack or modification. -- CONTAINS LARGE PICS - no 56k

[Slug69]

I was really happy the N97 had GPS and it worked really well.

After visiting www.symbian-freak.com I saw an interesting modification to make the GPS lock onto satellites a lot faster and also be more accurate. (Instead of 60m accuracy it is more like 15m after the mod.)

Thanks to Bruno Macek and Teo for posting on the Symbian Freak website at this link: http://www.symbian-freak.com/tunning...tenna_hack.htm

I did it as well and I am posting here my steps taken as Bruno's video and diagram were good but his English typing maybe not so good.

If you are not confident doing this mod and voiding your warranty, the stock GPS is adequate to find out where your rough whereabouts are so it's up to you how accurate you want to get. It took me two weeks to get the courage to do this as the phone is only about a month old now. (No problems either.)

First thing you do is get some: Acetone or thinners you are comfortable with. Acetone is a very dangerous substance and will ruin any plastic it touches so keep it well away from the phone.

Then some very thin copper wire. I suggest you get several fine thicknesses (see pics on Symbian website and mine below). I got mine from the guts of a defunct CRT monitor. (There are heaps of copper wire transformers etc in those things - don't chuck yours out until you get the copper out.)

Pliers, a hobby knife, some cotton buds, and possibly a rule.



Take the back cover off the back of the phone and locate the GPS antenna which is embedded in a black plastic tape like material immediately above the camera lens housing. It curves around to the side of the housing.



Cut some wire about 16 to 17cm long.


When you cut the wire you should try and get a nice little crimp like this. It will help you later.



You may need to cut the tape up against the lens housing to free it. Don't go past the lens housing dimensions, there is no need and if you did, you may sever the antenna. (Not good)



After cutting a slit along the top of the housing, start to peel back the antenna.





My pictures will look different to when you do yours as I decided to do this tutorial after I had done the mod. So when you peel back the antenna for the first time it won't look like this. It will be quite dark and you will see the top of the antenna loop underneath the adhesive and also a plastic protective film.



Get some acetone or thinners and pour a teaspoon of it into a ceramic or steel container; using the very tip of the cotton bud dip it into the Acetone and then start applying it to the top of the antenna loop only. Not the whole length of the antenna tape!

Again these pics already show the exposed copper, doing this step for the first time will look different.



Then use the hobby knife to gently scrape back the softened plastic film if your acetone hasn't already done so. I needed to be quite patient and scrape for about 5 to ten minutes before exposing the copper antenna underneath (Be careful with the acetone you will not need more than two dips of the cotton bud tip.)





The antenna tape and the copper antenna itself are quite robust so I got quite confident when I first exposed the copper to keep going a bit to make more of an opening.

Now the fiddly bit. Get your wire and position it so your nicely crimped end makes contact with it to give you a representation in your mind how it works and how it needs to end up.





And this is how it should end up. Put the cover back on carefully, there is plenty of room for the wire.







It works fantastic with an outdoors average of 15m to 20m and no dropouts in my shielded windscreen car either. Yes, I imagine your warranty would be voided. Thanks again to the original posting by Bruno Macek and Teo at the Symbian-Freak website. When doing this mod you should also view their youtube video on the tutorial and the results. It makes a hell of a difference.

[josh81]

I get ~10 meters accuracy outside with my 5800, with no modification.
Can the N97 really be so much different? The two phones are so similar, i would think they would have the same GPS ability.

Also, you just leave the copper lenght sitting on the battery, right under the battery cover?

Can't you wrap it up around the top of the inside of the phone, like above and beside the camera module?

[Slug69]

Originally Posted by josh81

I get ~10 meters accuracy outside with my 5800, with no modification.
Can the N97 really be so much different? The two phones are so similar, i would think they would have the same GPS ability.

Also, you just leave the copper lenght sitting on the battery, right under the battery cover?

Can't you wrap it up around the top of the inside of the phone, like above and beside the camera module?

Yes, the N97 accuracy isn't as good. If you watch the Youtube embed on the Symbian-freak website it shows the accuracy and mine was worse because of the location of my house.

As for wrapping the wire around; you can but my wire is quite thick and it would apply too much tension to where it is connected so it just floats free behind the battery cover. I am trying to source some adhesive to secure the tape better.

[isaaus]

I have seen quite a lot of these mods done around regional parts of INDIA where network coverage isn`t upto scratch. I didn`t beleived they work.

Usually they use very fine copper wire, apparently its meant to be used for repairing tracks on mobile phones. Should check out some websites who supply mobile phone repair parts.

[CDman]

great macro shots.
I have blocked access to the internet altogether.
And now I can't get any GPS working at all. I know that in my old N95 I could use the navigation fine. Even though I never had the internet setup up.

Maybe my GPS is faulty

[bsbozzy]

Originally Posted by CDman

great macro shots.
I have blocked access to the internet altogether.
And now I can't get any GPS working at all. I know that in my old N95 I could use the navigation fine. Even though I never had the internet setup up.

Maybe my GPS is faulty

You do realise that GPS and the Internet are not accessed by the same means? Your internet would maybe use GPRS not GPS...

[MagyaR]

Originally Posted by bsbozzy

You do realise that GPS and the Internet are not accessed by the same means? Your internet would maybe use GPRS not GPS...

probably means GPS-A.

[Slug69]

Thanks for the comment about the macro shots. A lotta work went into getting them lit properly -wireless off camera flash etc. still a bit underexposed but oh well.

The mod works well but I think the jury is still out if it's worth it or not. You would really have to be using it (GPS) a lot to justify the risk/hassle.

Google maps works really quickly in conjunction with GPS-A. The OVI Maps works pretty good without the GPS-A . I haven't tried the latest version of OVI Maps so I will have a look at that later.

I have been on OCAU for a long time and this is my first tutorial. I have a better appreciation for people who do this sort of thing.

[Noah]

This looks great but has anyone tested the effects it will have on

GSM/UMTS signal
WLan signal
Bluetooth Signal
Battery life..

not to mention testing the radiation output of the phone after this mod? if the wire gets in the way of the GSM radio, it might boost the transmit power, lowering battery life..

I've got an N97 too, and I'd be tempted to try this mod down the track.. if someone who knows about RF could determine it won't interfere with these other points..

[LINUX]

Originally Posted by Noah

not to mention testing the radiation output of the phone after this mod? if the wire gets in the way of the GSM radio, it might boost the transmit power, lowering battery life..

I've got an N97 too, and I'd be tempted to try this mod down the track.. if someone who knows about RF could determine it won't interfere with these other points..

A phone is a very non-ideal environment for any antenna. All phone antennas have hideous efficiency and SWR whether they be GSM, GPS, WiFi etc.

Anyway, the addition of the wire above will likely improve GPS reception as the stock antenna is the wrong length. The ideal length in a vacuum is 1/4 the wavelength, google for dipole design for more info. Look up the Wikipedia article on GPS to get the frequencies it uses.

To address your concerns:

Battery life should be insignificantly different. The transmit power put out by the final transmitter stage is not effected by the antenna. Any energy not transmitted as radiation either heats up the antenna, transmission line or the final output stage transistors.

The only thing which will change is the AGC (automatic gain control) amplifier on the GPS module will operate with slightly less gain due to increased antenna signal. This will drop power consumption in the microwatt scale.

Everything else should be unaffected. This piece of wire is introducing insignificant non-idealism compared to either phone design (ie: the antennas not being perfect tuned dipoles operating in a vacuum) or the fact that your conducting flesh is in close proximity.

But that's all in theory. Antenna design is serious Black Magic at times as the mathematics required to model electromagnetic interaction in real environments is far too complex. So, wait for people to give experimental results before making a conclusion from the above theory.

[leebaldock]

The close up pics are fantastic. Won't be doing this but enjoyed the thread. Thanks!

[|AgB|deano]

Basically what you are doing is increasing the surface area of the antenna.

You would get even better reception using a much thinner wire, cutting out a piece of tape about the size of your battery and creating a loop then putting another layer of tape on the top (to hold it in place and make removing it to change battery or sim easy) and resting it between the battery and the cover. it would especially help if you soldered the wire into place, not just prayed for a good connection lol.

Like this;


Click to view full size!

Nice mod though

[Slug69]

Originally Posted by |AgB|deano

Basically what you are doing is increasing the surface area of the antenna.

You would get even better reception using a much thinner wire, cutting out a piece of tape about the size of your battery and creating a loop then putting another layer of tape on the top (to hold it in place and make removing it to change battery or sim easy) and resting it between the battery and the cover. it would especially help if you soldered the wire into place, not just prayed for a good connection lol.

Like this;

pix

Nice mod though

Oh man, I am going to have to try this now. Thanks.

[davidtanhk]

Yes, I have done that. I do not know how to attach the photo here.

The result: improvement in the strength of GPS signals and higher accuracy.

Instead of an ugly exposed wire, I looped a 8cm ultra thin insulated copper wire on a double-sided tape, and then pasted it on the area below the original antenna location (wire between the plastic and double-sided tape). Then I pull back the connecting tip of the wire and pasted in onto the top of the double-sided tape, before putting the original antenna tape back into position. The end result is a concealed extended antenna.

With this, I can get a GPS fix within 1 to 5 seconds, tested under cloudy sky and raining days.

[Noah]

Originally Posted by davidtanhk

Yes, I have done that. I do not know how to attach the photo here.

The result: improvement in the strength of GPS signals and higher accuracy.

Instead of an ugly exposed wire, I looped a 8cm ultra thin insulated copper wire on a double-sided tape, and then pasted it on the area below the original antenna location (wire between the plastic and double-sided tape). Then I pull back the connecting tip of the wire and pasted in onto the top of the double-sided tape, before putting the original antenna tape back into position. The end result is a concealed extended antenna.

With this, I can get a GPS fix within 1 to 5 seconds, tested under cloudy sky and raining days.

Pics would be great, you can upload them here with your forum account:
http://www.overclockers.com.au/pix/

Would be great if we could compare all these results with a stock N97, maybe through walking a course and tracking it with sports tracker, then comparing. (with gps filtering set to off).

I went for a bike ride the other day, rode for 3 hrs 15, and the bike computer said I did 56.46km, while the stock N97 GPS said 56.45km... so pretty close.