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Old 01-01-2012, 03:11 PM   #1
sqn
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Question External anntenna to bcm4312 802.11b/g


Hi all, and happy new year.

I own a Dell Inspiron 1721. It's equipped with broadcom BCM4312 802.11b/g LP-PHY (rev 01), as the lspci command shows me.

The problem is that I am quite far from the AP and my signal is bouncing around and even though I'm just 5m in straight line from the AP I have:
Link Quality 1/5
Signal Level -81dBm
Noise Level -90 dBm
signal to noise ratio +7 dB
This I got from wavemon.

Now I've googled and I found no ways to boost the signal from Linux, so I try turning to hardware hacks, so I am wondering if my card supports an external antenna. I don't have an outside connector, but I can unplug it's antenna and plug a bigger external one.

Thanks in advanced.
 
Old 01-01-2012, 03:50 PM   #2
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A better idea would be to buy a real wifi card (preferably N) that already has a connector. It's a lot safer than trying to hack anything. I've found broadcom wifi to be absolutely worthless. Even when they are working the signal is all over the place. I recommend realtek or atheros.
 
Old 01-01-2012, 07:05 PM   #3
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Move it right next to the router and see what it reports before you get too far along.

Those numbers seem very low.
 
Old 01-02-2012, 05:03 AM   #4
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if I go closer the signal gets better, but as I share the flat it's not always convenient to stay in the same room with the AP. As I watched wavemon i noticed that sometime the quality goes up to 2 or 3, so I'm guessing the walls are generating a lot of noise and the signal is weak. I'll start searching for an atheros adapter to change it with.

Thanks for the answers
 
Old 01-02-2012, 07:07 AM   #5
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I would advise against fiddling with external aerials, as they are chosen after many calculations, with specific wavelengths, etc. If you do go that road, make sure it's powered down or you can blow things.

The solution is to move your AP.
 
Old 01-02-2012, 07:52 AM   #6
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Hi,
Quote:
Originally Posted by sqn View Post
if I go closer the signal gets better, but as I share the flat it's not always convenient to stay in the same room with the AP. As I watched wavemon i noticed that sometime the quality goes up to 2 or 3, so I'm guessing the walls are generating a lot of noise and the signal is weak. I'll start searching for an atheros adapter to change it with.

Thanks for the answers
First, the antenna is matched to the device. If you do not get the proper antenna for your device then you will do more harm than good.

Depending on the types of wall construction; plaster utilizes wire mess that can attenuate or concrete with mesh/reinforcement then you can have block which can be heilige concrete block that has clay with metallic properties that cause shielding.

I use multiple wireless routers throughout my home to insure that access is available. 5000 sq ft to cover, and I do not want any complaints from the family. I am in the country and desire to work outside with access on the patio. So things are placed to help provide access. I don't worry about war drivers, my lane is far enough from the county rd plus two sides are wooded with the other sides are farm ground.

I suggest adding a wireless router and purchase a 'Good' wifi card.
 
Old 01-02-2012, 09:38 AM   #7
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I would blame the wifi card much more than the router. At a hotel I was recently, I could get wifi from across the street. I have a wireless-N realtek card + 1 watt wifi antenna (it is massive, but it's awesome).
 
Old 01-02-2012, 10:30 AM   #8
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Hi,

Depends on the Wireless AP/Router. Consumer grade do not have the range nor quality as a Commercial/Professional Grade unit. Even the antenna systems are better and do support remote setups.

Last edited by onebuck; 01-02-2012 at 02:54 PM. Reason: typo
 
Old 01-02-2012, 10:30 AM   #9
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Exactly what kind on numbers do you get when next to the router? That would help.

Could be any number of other signals that are affecting this.

Might get good enough results by moving the route and it's antennas around some.
 
Old 01-02-2012, 12:03 PM   #10
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I'm coming round to the idea that your building is totally hostile to wifi or your card is knackered. I have a broadcom 4312 here near the front window. I ran 'iwlist wlan0 scan |less' and checked. I got 10 networks, and that's only because the rest of them are not switched on atm. I'm in number 8, beside the router, and get 68/70 and -42dbm. Number 24 is showing as 31/70 and -79dbm - that's 8 doors up the road on my side!
The conclusions are obvious.
 
Old 01-26-2012, 08:04 AM   #11
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thanks for all the answers
how I've solved this
Talked with my flat mates, and moved the router in a different phone plug (it's ADSL). some of them had also low signal, so we moved it closer to us. Now the signal is not excellent, but is more or less fair. Now surfing and connecting to it is ok. Could be better, but unfortunately the house is really not proper for the wifi signal.

I am thinking to buy a USB wifi adaptor and hack some can antena or such just to experiment a little bit, maybe I'll get a better signal

Thanks again
 
Old 01-27-2012, 09:59 AM   #12
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Quote:
Originally Posted by sqn View Post
thanks for all the answers
how I've solved this
You can mark it solved, then.

Quote:
Originally Posted by sqn View Post
I am thinking to buy a USB wifi adaptor and hack some can antena or such just to experiment a little bit, maybe I'll get a better signal

Thanks again
On the antenna - don't hack it. If you're lucky, you'll only make the signal worse. People have the illusion that a longer areial gives a better signal. The optimum length is 1/4 lamda (wavelength), where wavelength = 3 x10e8 / frequency. Voltage and current are different at different points on the aerial; and as you are handling sine waves, the square root of -1 comes in when you analyse it.
 
Old 01-27-2012, 02:29 PM   #13
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I was thinking to follow one of the tutorials listed here: http://www.usbwifi.orconhosting.net.nz/
Thanks again for all the replies
 
  


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