Wifi issues anyone?

[Linux-SWAT]

That's a great finding.


I'm glad to have meticulously covered the good part only during the rebirth.

 

[Loonie]

Okay, grabbed a few minutes after I got home to do some testing of my own. Exophase, you're right about needing to dismantle stuff to get the lid off. Luckily, as mono said, you only have to get the lid open enough to get at that PCB, which isn't difficult. So, what did I find?


Here is the Pandora as it was. As you can see, the tape covers a notable portion of the WiFi antenna board. There is a signal strength of approx. -58dBm when connected to the router in the neighboring cupboard. Reading was taken before disassembly.

I couldn't verify that the foil was short-circuiting the points on the PCB, but I was able to get conduction on the adhesive side of the Al tape. Moving the tape to just the conductive exposed area of board and reattaching to the LCD produced a signal level of -45 dBm in the reassembled Pandora. A not inconsiderable gain in... er, gain.

I'd tempt fate by saying the connection is more robust than it was. I find it hasn't produced significant changes in download speed, it still drops from around 500kB/s to around 90kB/s after sucking down a good few megs of data. It does seem to recover in quieter periods, and there is certainly no connection drop. The gain difference is even better downstairs further from the router. Whatever the case, there is clearly a substantial improvement in signal reception and quality.


As I said earlier, I could not find a suitable measuring point to determine if the tape was actually causing a short-circuit without more stripping down than I had time for, but what I think might have been happening is that the foil is covering up a considerable section of the PCB track that forms the actual WiFi antenna, reducing the amount of radio that can actually reach the antenna, especially since the tape is grounded. The antenna's being screened, basically.


I'll do some more testing over time, but so far, it's showing promise, and is worth looking into.


Kudos to you, mono, for your findings, and to you _wb_ for what's turning into a handy little diagnostic tool.

 

[Askarus]

Do you know that you smashed your warranty .


Great to know that.


I'll have some close look at it when repairing Pandoras.


I'd like to check mine, too but it's a mess to do it without smashing my 4 shoulder buttons.

well, I opend it up and everything is working gread now. (so far)


It seems as if a piece of aluminium-Tape covered some leads on the antennamodule next to the screen.

That's interesting, did you check how dBm was affected after gluing antenna to LCD? I always found that LCD part strange (LCD is full of noisy signals), MWeston said it's some wireless magic but I don't have any idea why it has to be done.

If you want to I can test if it affects anything.


I'll build one unit without lid-back and then I can move the antenna as I wish.


I can also test then if the lenght of the silver tape affects anything.


Mono and Loonie, if you want to, you could also do this tests.


Thanks for the info.

 

[skeezix]

The bottom is not hard to get apart and not too risky (cept the power-slider, I find that little bit pretty fragile, and that little tiny switch nub that it hangs on can break pretty easily!), so I prefer to minimize .. can you pry open the lcd-lid at the front, enough to get the wifi pcb out,w ithout detachign the bottom or otherwise disassembling anything? or msut you take apart the bottom, or the hinge?


(I _hate_ taking the hinge apart; didnt' kill one yet, but those suckers are _tight_ and winding the lcd ruibbon through creeps me out; had to do it twice already for bad lcd cables


jeff

 

[mono]

you pretty much need to dismantle everything, unfortunately.

I opend the right side of the top just wide enought so I could get out the small PCB.

 

[Loonie]

The bottom is not hard to get apart and not too risky (cept the power-slider, I find that little bit pretty fragile, and that little tiny switch nub that it hangs on can break pretty easily!), so I prefer to minimize .. can you pry open the lcd-lid at the front, enough to get the wifi pcb out,w ithout detachign the bottom or otherwise disassembling anything? or msut you take apart the bottom, or the hinge?


(I _hate_ taking the hinge apart; didnt' kill one yet, but those suckers are _tight_ and winding the lcd ruibbon through creeps me out; had to do it twice already for bad lcd cables


jeff

Yes, you can open the lid enough to get at that PCB, no dismantling needed.

I'll build one unit without lid-back and then I can move the antenna as I wish.


I can also test then if the lenght of the silver tape affects anything.

I'm not sure the length of the tape is going to have much effect, as the antenna is the zig-zaggy track on the PCB, not the foil. I found no noticeable difference running the module with the tape in situ or removed completely. All that should be needed is for that foil to not cover the antenna or make contact with any of the exposed points of the board (other than the big exposed area to which it is supposed to be joined, of course).


I do hope I'm not talking bollocks here. Hopefully MWeston can correct me if I am.

 

[skeezix]

What about removing the tape entitrely? ie: The benefit of the tape is it..


1) compliance to FCC (ie: I may not care


2) preventing wifi issues by interference by lcd, cpu, etc, or


3) preventing interference on other components (lcd) by wifi?


4) all of the above


it its (1), just toss the tape, who cares, but I rather suspect its (2) and (3) both .. so you should have some tape.


jeff

 

[Loonie]

I don't think the having of tape is an issue, it's just that the tape is in some cases covering something it shouldn't.

 

[_wb_]

I somehow always assumed the wifi antenna was taped to the LCD so that it essentially uses the backplate of the LCD as a huge antenna. If that's not the reason, then why not just put the antenna in the lower part of the Pandora, so it doesn't need to go through the trouble of traversing the hinge.

 

[skeezix]

Trying to keep the antenna away from the cpu while device is in use (open?)


In effect the _Display_ does effect wifi quality .. if you black the display, sometimes that helps; I forget now if thats the LCD or the display controller causing it .. I think its more the controller than the LCD panel, but I forget; my memory is unreliable with the sleep dep of the last year for me


Should try to just put the wifi in the base and see what happens, lol


jeff

 

[Loonie]

I somehow always assumed the wifi antenna was taped to the LCD so that it essentially uses the backplate of the LCD as a huge antenna. If that's not the reason, then why not just put the antenna in the lower part of the Pandora, so it doesn't need to go through the trouble of traversing the hinge.

A slab of metal doesn't actually make that good an antenna. An antenna needs to be a certain length in order to prove effective with the desired wavelength of radio on which it is to operate. Generally they are placed in a similar position in laptops as well, to get them away from all the noisy RFI shit. Having it in a perpendicular orientation probably helps reception as well.


Additionally with Pandora, since your hands are wrapped around the base, that would likely impede reception even more.

 

[sswam]

Ed calls it the brutal and hard part...

For future Pandoras, we should make it easy to open the case (without breaking anything).

I'd tempt fate by saying the connection is more robust than it was.

Hard to believe you get 500kB/s download rate at any point on the internal wifi.


My wifi is unreliable for ssh, it gets stuck and unresponsive, also downloads get slower and slower.


From what I can see, it's repeatedly doing "power save" -> "drop packets" -> "slow down the data rate" ...


There's a software fix for this. I put it in a script called "qos" for "quality of service", and run it when the wifi is up.



sudo iwconfig wlan0 power off rate 54M

This turns power management OFF, and sets the data rate to a fixed 54M rather than auto.


For me, this command makes my wifi "good enough". It's easier than opening the case, voiding my warranty, and likely breaking the Pandora!


Please let me know if it works for you. If it does help, we could add this command as an option in SuperZaxxon.


Unfortunately, /etc/network/if-up.d does not work for Pandora wifi. Maybe I'll hack this into my /usr/pandora/scripts/op_wifi.sh.

 

[skeezix]

Can stick that in a startup script, too.


Its par for the course really


ssh gets 'stuck' like any other TCP application .. lost packets, retransmission hell, etc; I can get 600K/s on many of my units, but the ones with funky wifi will start dropping and tank after a bit .. 'stuck'. My oldest unit works a treat ever since notaz fixed drivers years ago, but new unit, unworkable; I'm going to bust her open soon (was sort of hoping to have one pandora that I didn't break open for some reason.. alas, not to be


jeff

 

[skeezix]

I think its safe to say .. [iMPROVED]


okay, this is not too hard to get at; a little force applied against the inside right edge of the lcd case and you can get that right-side tab out pretty easily; a little pressure similarly on top edge right side inside, to get that rightmost tab out on the top lip, and then the middle one pops out easy.


I used a tiny little rubber coated screwdriver to pry off the little pcb (its taped down of course, being the problem , which came off pretty easy; pretty fiddly in that small space unless you disassemble the unit, but I have no time for that today.


Experiment now.. run without any tape at all, with the little antenna pcb hanging out the side! .. runs like crap (but this unit has been terirbad at wifi anyway, so no different.)


Putting the tap on just the top edge of the little pcb (theres a little line there, just put the tape on that as a guide), and I'm getting about 40K/s - 325K/s, so far holding up; this sucker tends to 300K/s for about 20s and then dies, drops connection, etc.. so if this single long download holds up, then its an improvement, but only a sampling of one


I'll try a few more big downloads and edit this post in a minute..


first download: average of 217K/s on a 120MB file (a fair number of stalls and drops to 50K/s, but it did pop up to 350K/s a few times .. not that I was staring at it the whole time.). Writing to /tmp


second: about 90K/s .. still no dropped connection, which is a huge improvement


third: (still connected!) - the pandora firmware from www.openpandora, to SD .. 85K/s.


So nothing blazingly fast really, but for this unit, a huge improvement.. in that it at least _works_; my other unit can keep up 300-600K/s though, but its at deaths door


jeff

 

[skeezix]

This is working great.. thanks for the tip mate


jeff

 

[Loonie]

Actually, that system info tool has a graph of data transfer speed on the network screen, so you can start a big download and check that graph for speed variations. I wonder if the WiFi antenna could be further improved? This could turn into a hardware hack project...

 

[Askarus]

OK, my Giga Pandora had also Silvertape over two wholes.


After removing them I now can watch Youtube Videos in real time (no cashing needed).


My maximum download speed was 489 KB/s and about 300KB/s is stable now.


I can"t tell you whether it's an improvement or not as my Internet was crap as I removed the tape. I thoughed this was the problem but the repeater was bad.


Only thing I can tell is that I could never watch Youtube in realtime before.

 

[steveway]

OK, my Giga Pandora had also Silvertape over two wholes.


After removing them I now can watch Youtube Videos in real time (no cashing needed).


My maximum download speed was 489 KB/s and about 300KB/s is stable now.


I can"t tell you whether it's an improvement or not as my Internet was crap as I removed the tape. I thoughed this was the problem but the repeater was bad.


Only thing I can tell is that I could never watch Youtube in realtime before.

I should ask ED to fix that too when I send my unit in for the broken nub. Sounds awesome.

 

[EvilDragon]

Already told GC to take care of that in the future, shouldn't affect too many current units though.


I've tested 30 recently and only a single one had that issue.

 

[Askarus]

Take a look at this.


Wifi is great now.


http://boards.openpandora.org/index.php?/topic/10519-picture-of-the-day-pandora-high-speed/