Weak WIFI reception
 

First time poster, long time lurker.

Just managed to bag myself a replacement for my busted N900.

Powered it up, re-set everything to defaults and started using with WIFI only.

For the first few hours everything was fine but after maybe 8 hours, the phone stopped picking up WIFI signals. At first I thought I was out of range but then I noticed that previous hotspots I connected to stopped working also. Once I got home, I discovered that WIFI still works on the phone, but I have to be very close (about 3 meters away) from the router for it to work.

I already tried re-flashing multiple times, as well as replacing the entire back assembly which houses the antennas and what looks like some sort of transmission coils.

One thing I did do the day before although I'm not sure if it's related, is dropping a Softbank (Japanese) SIM card into the phone to see if it would work, which it did. I thought maybe the SIM card overwrote some settings which caused very weak reception, but the time between the SIM card going in and the weak WIFI was about 8 hours.

If this phone has weak WIFI, it's potentially useless for anything, so if anyone has any suggestions, I would greatly appreciate it.

Thanks!

Re: Weak WIFI reception
 

You can pick up the signal, so the electronics are working, but something is weakening the signal. Loose contact between the board and the antenna? Dirt or moisture on the PCB? I would try opening it up, cleaning it (which may be a good idea anyway, a second-hand device is bound to be full of fluff and dust) and perhaps spring up the antenna contacts. With no guarantee of success.

Re: Weak WIFI reception
 

I like the optimism of the last bit. :)

I'll give that one a shot. I guess I didn't really clean it all that well the first time around. Cheers.

Re: Weak WIFI reception
 

You can configure wifi power management in connection settings.

It is on auto by default, try to set it at 100mw manually and see what happens (low power mode is 10mw only)

EDIT: You can find the setting under:

phone settings/internet connections/connections/*connection name*/edit/next/next/next/advanced/other/WLAN transmission power

If it is already at 100, you can try to change to 10, then save, exit and reopen to modify back to 100. It is sometime usefull to do this. Don't ask why ;)

Re: Weak WIFI reception
 

I'm now at a loss. Cleaned it out but the same problem persists. Also the power output is set to maximum globally through iwconfig, with power management off.

Anyone have any other suggestions? Would really appreciate it.

Also tried two other antennas so that's not the issue. Contact are nice and clean, as is the PCB.

Re: Weak WIFI reception
 

The point with the contact springs was to bend (I used the word 'spring'; sory if that confused you, English is not my first language) them up a bit to achieve a better contact with the antenna. Carefully, lest they rip off from the PCB. I am only speaking from experience: I had a similar lack of sensitivity problem while I was swapping a housing and was temporarily with no antenna.

If you've tried that then I am equally at a loss, sorry.

Re: Weak WIFI reception
 

Have you tried to set the power management on and the transmit power down and see if you can get the reception even worse and see if the settings have any effect on the reception. If this does not affect the performance in any way, could it be possible that the power management off and 100mW settings are actually not in effect and the WLAN defaults to the worse settings somehow. I have no idea how, but just thinking that you could check that your settings are getting through.

Re: Weak WIFI reception
 

Thanks for the advice so far. Greatly appreciated.

No worries pichlo. English is not my first language either, and your explanation was not confusing at all. :) I did try to bend the pins up a bit more but to no avail. May try that again though as I might not have bent the damn things up enough.

I also tried lowering the transmit power values bit by bit through iwconfig, until I had them all the way down to 1dBm, which did not make a lick of difference unfortunately. Was using the "iwconfig wlan0 txpower xx" command, while connected to the AP. Will try again though at home.

On a side note, is it possible that the WLAN chip itself might have been slightly damaged for whatever reason, resulting in a power drain of some sort? Maybe even a short circuit somewhere along the antenna lines?

I also noticed that when I was connected, even with the signal strength at maximum (for when I am standing next to the AP), the noise margin iwconfig reports is at -113. Is that normal?

Thanks heaps for the help so far. I'll persist!

Re: Weak WIFI reception
 

From upstairs about six meters from cheap buffalo router running dd-wrt. Weak reception normally through walls and floor:
Near the router good reception distance one meter:

N900 touching the router:

Re: Weak WIFI reception
 

I got similar results as Kossuth except I'd gone even lower down:
How did you manage to get -113 dBm noise? I envy you.

Re: Weak WIFI reception
 

I'll post some stats later on....

Re: Weak WIFI reception
 

Okay. Stats be thus:

1) Touching the Access Point:
2) 1 meter away from the AP
3) About 3 meters directly above the AP on the second floor of the house. NOTE: The floors in a Japanese house are paper-thin, so there wasn't really any obstruction to speak of:
How bizarre, how bizarre....

Re: Weak WIFI reception
 

My router is in the garage and I got 39/100 in the room just above it, perhaps 2 metres from the router (the floor void thickness plus my height). By the sound of it, the English houses are built to the Japanese model (or at least mine is :)), with paper-thin floors. Curiously, moving about 2 m to the left increased the signal to 46/100, moving even a bit more away to 68/100. Must be something to do with the directional properties of the router's antenna: better sideways than up and down.

Back to the topic, your numbers confirm what we already know: either your router's signal level has dropped or your phone's receiver has reduced sensitivity for some reason. Having tested with other WiFi hotspots, as mentioned in the first post, rules out the former.

You've mentioned having replaced the housing. Can you confirm that the replacement has indeed good working antennas? My experience with similarly reduced sensitivity comes exactly from my replacing the housing exercise. This picture clearly shows what the antennas should and should not look like (note the golden pads):

http://talk.maemo.org/attachment.php...9&d=1385258851

Re: Weak WIFI reception
 

Thanks for the response.

The antenna does indeed have gold pads. Attached is an image of one of them.

The pads are all in roughly the same shape.

EDIT:
Quick question. What the hell are those two silver square(ish) things on the left and right of the inside of the back cover? They look some sort of transmitter coils. Both have two pins on them.

Re: Weak WIFI reception
 

You mean like in this picture? (Please ignore the arrows, they belong to a different topic where the picture comes from)...

http://talk.maemo.org/attachment.php...0&d=1385258897

Those are the speakers.

Your antenna looks OK. Sorry, I am out of ideas :(

Re: Weak WIFI reception
 

Ah of course! Thanks for clearing that up.

Thanks for you effort by the way.

I'll keep trying to fix this. I'm also thinking it may be some sort of grounding issue inside the phone so I'll do some tests later this week and hopefully I can solve this.

Cheers!

Re: Weak WIFI reception
 

That's pretty normal - regular omni-directional monopole (aka stick) antennas have, in fact, radiation pattern simillar to doughtnut mixed with disc:
http://www.antenna-theory.com/antenn...edMonopole.jpg

...wchich results in worst signal directly above or under antenna. In your example, you were standing in the "blue" depression, shown in picture. (z-axis is your antenna - that is, signal is worst where antenna tip points).

Of course, alligning antenna stick horizontaly instead of verticaly, would result in better reception at higher (and lower) floors, but worse to the sides (but only to the two sides - the one that antenna is pointing at, and the opposite one).

/Estel

Re: Weak WIFI reception
 

Ok, I think maybe I know what is wrong now but if that is indeed the case, I have no idea how to fix it.

I have a bad feeling that it is indeed a grounding issue on the mainboard somewhere. I have been noticing that each time I hold the N900, I seem to get a very slight tingle through my fingertips (and it ain't from the excitement of finally having anN900 again :) )

The second my hands move, it stops. I understand that there's a slight electrical charge moving through the screen but the keyboard?

Maybe that's what's causing the weakness in the wifi? A kind of signal bleed maybe?

Correct me if I'm wrong, which I probably am.

Re: Weak WIFI reception
 

Sounds strange and I can't say that you dont feel it, but you only have 3,7V voltage on your phone, and I suspect that it is hardly enough to push any current trough dry skin. On the other hand sensitivity to electricity varies a lot form person to person.

You can test it yourself, by shorting the the contacts of removed battery with your finger. I just tested with 12V car battery and wet fingers and couldn't feel anything. You dont have any other potential in your phone as it is not connected to any outside antenna or powersupply.

Basically I have always thought that grounding issues cause static and signal errors when you connect two appliances that are in different potential and that causes the current to flow from higher potential to the lower potentia for example from a ungrounded television to grounded DVR or vice-versa.

If you want to research this grounding issue more, you should check the current that your phone is using, with the bq27200.sh script and see if there is actually a current draining from the battery. I'm not sure where in the circuitry the ampere meter is located in N900, but I think it should capture most of the current that leaves the battery.

Re: Weak WIFI reception
 

Hey Kossuth,

Thanks for the info. I'll give this a go in the next day or so.

Much appreciated! :)

Re: Weak WIFI reception
 

@Estel,
I know, I was a member of a radio club in my early teens :) And I had a year of electromagnetic field theory at the Uni. But I did not want to over-complicate it with technical details. Moreover, although the router's antenna looks like a simple stick dipole, I don't know what's inside. Maybe some coil or something to change the directional properties, who knows?

@Kossuth,
Ineffective grounding may well cause issues in the RF area. RF is a sensitive beast, grounding is about more than just currents between two points. The higher up you go in frequency the more complex the issue becomes, which is why not every Jim and Mary can design high frequency RF circuits.

On the tingling issue and safe voltages, the most powerful transmitter in the phone is GSM with a peak power output of 2W. I do not know the GSM antenna's impedance, but I don't think that 50Ω would be too far-fetched. Hugely simplified, V = √(P*R), meaning the GSM trasmitter pumps at least √(2*50) = 10V to the antenna at peak power. (For WiFi the figure is much lower, only about 2.2V.)

There is no electric contact from inside the phone to the surface that one could touch, so any sensation must be either induced or mechanical vibrations confused for electric current. I have not noticed any tingling so I cannot tell.

@bosss7,
If you suspect grounding issues then you can try to bend the ground plane springs up to make a better contact with the PCB. You can see four of them clearly in my last picture, plus one highlighted with the blue arrow which is the FM transmitter antenna contact. However if grounding were the problem then I would expect all RF to suffer: WiFi, BT, GPS and GSM.

Re: Weak WIFI reception
 

@pichlo,
You are absolutely right that the grounding is very important in the RF-domain and even tiny variations in the impedance caused by for example oxidation in contact can dramatically reduce the performance of the circuitry. My EE degree is from heavier electricity (<1000V) so when I have to deal with faulty grounding it is always potentially deadly, so I tend to see the grounding stuff from that point of view and was sceptical about the fact there could be high enough voltage for average user to feel. On the other hand, the frame around the screen is metal and nice oval shape, so theoretically you could induce some current to it, and if there would be crack in it, there could be some voltage over the opening, maybe only millivolts though. There are ofcource other parts that could suffer from millivolt level noise that could alter their performance.


@bosss7,
I'm with pichlo on the matter that the most likely cause for your problem and also the easiest to repair, would be the contacts between the board and the antenna, so make sure you check them for good contact and they are clean. Altough this has been mentioned to you more than once, so I feel we start to sound like a broken record ;-)