Chronic bad connection (sorry for the long detail)

[DaveGoTech]

Hi
I have a friend who called me in desperation. They have a new home (about 3 years old). At that time they also purchased 2 new Dell desktop computers. The first PC is on the second floor and wired directly into a wireless router (g) and a cable modem - no problem. The second PC is located on the first floor on the other side of the house, therefore, wireless was the only sensible option. Since day one, there have been connectivity problems to the internet on this wireless PC. Over the years, they have had several computer companies out who replaced the router and or wireless PCI card in the machine. It worked for a little while, but the problems return. I went over last week and checked things out. I could not get the PC to connect reliably with the router, even when I moved it to a closer location. So I brought it home and set it up on my wirelss connection and could not connect either. So I replaced the PCI card (a no name imported cheapie) with a new Netgear PCI card. After loading and configuring the software, it ran great. I let it run overnight, then brought it back to the owner. It would now connect, but drift in and out of connectivity, rendering it pretty much useless. Today, I returned with my laptop which has a Netgear PCMCIA wireless card. It connect fine at any location in the house. The signal strength is also higher (80-90%) compared to the desktop PC which only has 25-35% strength.
Question 1. I was under the impression that the PC should have a higher signal strength due to the external antenna.
Question 2. Any ideas on what could be causing the desktop PC to receive a weak signal? Noise in the PC? I do notice that the Dell PC has 4 PCI slots, of which all are occupied. It has a video card, modem, sound card and the wireless card. Do certain Dells have a design issue when running wireless cards? It does not look like a software problem with Windows XP or the netgear wireless software. Any other ideas???

 

[G0AOZ]

I'd say the main problem is going to centre around the signal strength which you quoted at 25-35%. For reliable wireless data comms you generally need better than this.

Many of the PCI WiFi cards have the aerial attached directly to the backplate of the card so that it's only an inch or so away from the metal backplane of the PC. Bad design feature! At this sort of distance, the backplane might act as a reflector if the measurement was exactly right, but generally I'd say it absorbs signal, hence you often find a WiFi laptop in the same location shows a better signal.

Usually the aerial can be unscrewed from its backplate connection. See if you can obtain one like this:-

http://www.solwise.co.uk/wireless-indoorantenna-omni-105os.htm

The aerial can then be moved around away from the metalwork of the computer and placed where it will hopefully provide better signal strength.

ROGER - G0AOZ.

 

[DaveGoTech]

Thanks for the suggestion, but I neglected to mention that I did try an external antenna attached to a long cable - it was installed on the 'cheapie imported' card. It made no difference at all. It is almost looking like something in the PC (noise interference) is causing the problem. We discussed buying a new PC, but if this didn't work, all that money would be wasted. I am thinking of purchasing a directional dish antenna or a repeater to gain a stronger signal. If I could increase the signal strength, hopefully it is enough to overcome and mask whatever the problem is. Does anyone have any comments on which of these is more effective, as I have never tried either of these before.

 

[G0AOZ]

Before to spend your dosh on repeaters or dish aerials, you should try to eliminate, or at least identify possible sources of noise if you think that's a problem.

You said, "...I did try an external antenna attached to a long cable.... Just how long was this cable? Anything more than 6ft is going to start negating any gain the external aerial might offer.

You say you've tried a WiFi laptop, and that worked fine, with a good signal registering. That rather tends to rule out the possibility of noise, unless that noise is entirely generated from within the PC.

If you have time to check it out, then maybe set the router to a few different channels, and see if that has any effect on received signal strength in the desktop machine.

The biggest likely source of noise (interference) for WiFi, within the PC is probably the PSU. However, it is worth checking to see that eveything is bolted down properly and all earth wires (where appropriate) are in place.

If all else fails, then maybe it might be quicker to slove this issue by providing the user with Ethernet-over-Power adaptors. I am assuming that the PC in question will already provide an RJ-45 LAN connection.

ROGER - G0AOZ.

 

[DaveGoTech]

Thanks for the suggestions.
The antenna cable was a standard length (about 3 feet) that came with the adapter, so it is OK.
I did try different channels - 1, 6 and 11, all with same results.
What is PSU? Do you mean CPU?
I know the video cards can generate noise and this one is not on the motherboard, its in 1 of the PCI slots, along with a modem, sound card and the wireless card.
I really think it's something inside the Dell computer that causing inteference.
The ethernet over power adapter is a good suggestion, but until I get an answer on my question about the directional antenna, the repeater and now the EOP adapter as to which is the most likely to give the best results, I am in a holding pattern.

 

[G0AOZ]

PSU stands for Power Supply Unit. This is the bit in the computer that converts the mains electrical supply down to the various dc voltage rails needed to run the motherboard and peripherals, e.g. 12v, 5v, 3.3v, etc. They use a technology known as switching mode, which is notorious for producing electrical noise (RF signals), if not properly suppressed. Most modern PSUs don't emit much in the way of electrical noise, and it is fairly rare for the suppression part of the circuit to fail. There are many other components which fail long before the suppression parts give out!

Yes, a directional aerial or a repeater AP (access point) will help to boost signals if placed correctly. However, I still believe that you have a fault somewhere as you said earlier, "I could not get the PC to connect reliably with the router, even when I moved it to a closer location."

It is difficult to say whether or not a directional aerial or a repeater will cure this particular problem, without knowing what happens if you place the offending computer within, say, 6ft direct line of site of the existing router. At that distance it should be working 100 per cent, and show a very high signal strength.

One thought for you... Can you temporarily place the Netgear WiFi card in another computer to test it with either your own setup or the user's router?

ROGER - G0AOZ.

 

[countrypaul]

Another option, if the PC has a normal ethernet port would be to use an Access Point in client mode. This would eliminate the wifi card in the PC completely and might work better than a wireless repeater.

 

[DaveGoTech]

Good idea CountryPaul. Never thought of that one and if there is noise in the PC causing the problem, it should not affect this. Meantime, I ordered a directional dish antenna. I figure even if they end up needing a new PC, they will still need a wireless card, so the money is not wasted. It should arrive today. Then I will go out and see what the results are. I am also going to try Rogers suggestion and look at the PS and also bring a spare desktop box with me and try the wireless care in there. Will report back. This should be interesting...

 

[DaveGoTech]

Got the directional dish antenna yesterday and went over to the site. I spent 4 hours and was not successful in getting the wireless to work reliably. When I connected the antenna, I got a very good signal strength of 80%. I opened the browser and went to a couple of pages when suddenly I lost the connection to the internet. A few minutes later it would return, then go out a short time later. I suspect there is either some interference in the AC power lines or rf interference.

 

[G0AOZ]

Did you try the suggestion of temporarily moving the PC to within 6ft of the router?

Is this just a conventional private family house, or is a business being run there? Lots of separate student lodgings? Or what?

Describe the likely RF path between PC and router. Lots of walls and floors in the way? People moving about backwards and forwards in the path of the signal? Electric cabling, waterpipes, equipment rack in between?

Do you see other neighbourhood WiFi networks on the PC?

Cordless phones in the house?

Does the house/immediate neighbourhood appear electrically noisy? Do you get interference on radio and TV for instance? Any close industrial sites which might cause problems?

ROGER - G0AOZ.

 

[DaveGoTech]

Roger
I have configured about 50 wireless setups in the past and have never experienced problems like this. The site is a new rural residential home. There are no industrial facilities nearby. All utility cables are underground. They have comcast cable internet service. I do see that Comcast apparently had signal quality problems as there is a powered amplifier/filter connected to the cable line. Their TV service seems to work fine. With the standard antenna installed, no other network was discovered, but with the directional antenna, I did see 1 other wireless site, but it was only 20% signal strength. I attempted to connect to it for testing, but it is protected. At times it looks like the wireless router is defective, but since this is the fourth box installed, it is highly unlikely. I swapped connections - reversing the wired connection from 1 pc to the other and also swapping the wireless card. I got the same results. I did bring my personal notebook PC and briefly tested it and it seemed to work fine. This leads me to believe there is either ac power line interference or the 2 Dell PCs (both identical 2.8GHZ models) are somehow introducing harmonics affecting the wireless.

 

[countrypaul]

You indicated that your laptop appears to work fine in the same location. Did you try it from beside the DELL - does it suffer interference in that situation?

Is it possible to try a USB wireless card as this will be outside the box and may not suffer the same problems - it would also be easy to move it a few feet away with a suitable USB cable?

Given that both Dell's suffer the same way and presumably both are setup the same way, there is always a chance this is a software problem. You could try a fresh OS install (on a separate HD) just to be sure.

 

[DaveGoTech]

I spoke with the residents today and reviewed the alternatives. They felt bad that I had spent so much time there and also that the machine was out of service for so long, so they chose the option of purchasing a notebook PC to replace the wireless PC. They do not want a Dell machine as this problem has been present since day one. I will purchase either a Lenovo or HP (not Presario) business notebook for them and report back. I'm certain it will solve the issue, but I hate being defeated by these problems - only happened 1 other time.

 

[G0AOZ]

I share your irritation regarding thus far being defeated by this problem! It certainly points to something within the Dell causing an "incompatibility" issue.

When you had this machine back in your premises, at what sort of distance did you try its wireless connection in relation to your WiFi router? If it was within a couple of feet, the signal might have been so strong as to totally override any interference.

Countrypaul's idea with the USB device would enable the WiFi's radio receiver to be placed physically further away from any internal RFI. And you could always get it further away by using a USB extension cable.

Perhaps you might get the opportunity to run Netstumbler on the new laptop (or your own), and bring it up close to the Dell and see if the trace changes appreciably. Also try it with the Dell case open...

ROGER - G0AOZ.

 

[DaveGoTech]

It's fixed!!!
I went back today with a new computer. It was actually ordered for someone else and previously setup in our shop. If it worked, I was going to leave it there and order another. It didn't work. I have the same problem. It would connect to the router with a strong signal, then a short time later totally disappear. Sometimes it would reconnect and sometimes it wouldn't, but definitely not usable as is.
The first day I was there and experiencing problems, I asked about cordless phones. The resident said there was 1 in use (in the same room). It was a 5.8GHz phone and normally they do not cause interference. I disconnected it anyway and it made no difference.
Today, I asked again about cordless phones and the resident suddenly remembered there was an old one in the basement, but no longer used. I asked to take a look at it. Sure enough, it was a 2.4GHz phone - same frequency as the wifi.
The base station was disconnected from the phone line, but still had power - so did the 3 receivers which were apparently constantly searching for the base station. I removed the batteries from all of these units and the wireless now worked perfectly. Sheeze!
The moral of the story? Make sure you quiz the customer well when inquiring about cordless phones. Just because they are not 'plugged in' does not mean they are not actively transmitting and causing interference.

 

[G0AOZ]

Glad you found the answer! It's good when you can finally nail it...

ROGER - G0AOZ.