Thinkpads Forum

I promise this is the last in my triple post ...


Is there a way to find out the Signal to Noise Ratio and dB (signal strength) for my wireless in Access Connections or somewhere?

I am not where I can use WiFi at the moment to verify, but I believe this is what you are looking for. Open Access Connections, on the top menu, choose Configure > Global Settings... > Notification > and check box next to: "Show wireless status icon in task tray". You should see a stair-step type icon on the lower right side of the task bar. I am not sure of the info displayed when you hold the mouse over the icon, but if you double-click on it, all the connection status information is displayed.

I see the Access Connections tray icon with the graphical meter, but it does not show the SNR/dB when I double click access connections, nor when I mouseover it.

Well on mine, Signal Strength and Signal Quality is displayed, but I guess not in the format you are looking for. I have an Intel 2200bg wireless adapter. It is possible if you are not using an Intel wireless adapter, you may see something different.

If you have an Intel wireless adapter, you could try going to Start > All Programs > Intel Network Adapters > Intel(R) PROSet for Wired Connections. Perhaps that will give you better information.

Oh. Oops, I guess I wasn't specific enough. I was looking for numerical values for dB/SNR, and not just a bar meter with a %.

Not your fault. I understood what you were looking for. I just didn't remember exactly what was displayed, and I have no WiFi signal at my present location to test first. Sorry to send you on a wild goose chase.

Okay. Well if you find out, please let me know

Netstumbler shows some sort of values at least..

www.netstumbler.com

I see dBm in Netstumbler and in Cain, but it is not much more illuminating than the Find Networks function in Access Connections.
... JD Hurst

jdhurst wrote:I see dBm in Netstumbler and in Cain, but it is not much more illuminating than the Find Networks function in Access Connections.
... JD Hurst

dBm would be your transmit power, not your RSSI (received Signal Strength).

Your RSSI should be in dB, not dBm (decibels above a milliwatt).

I suspect the values aren't show in the drivers / GUI for any of the WiFi cards because 99.999% of the population wouldn't know what to do with them. And also because the values themselves can be meaningless, unless you know what a good SNR is for WiFi.

Generally the % values in the graphs will show SNR, as opposed to received signal strength, as it's more applicable to data rate (in a region of heavy interference, you can get lots of RSSI, but poor SNR, for example).


Patrick

I am no expert in this - I just read the screen. Looking at Cain right now, it sees three signals: Mine and two others (both unsecured). My signal reads -46 dBm, the other two read -88 and -89. Now if it were measuring transmit power, wouldn't they all be the same?

If I pull up Find Networks in Access Connections, it shows my signal at 100 percent, one of the others at 70 percent and one at 50 percent.

Like I said, I was just observing. ... JD Hurst

Previous posters gave good info. You may want to look into getting NetStumbler, I think this gives you the readings you want.

Netbuster will not work for my T60 WS which uses the Atheros card.

jdhurst wrote:I am no expert in this - I just read the screen. Looking at Cain right now, it sees three signals: Mine and two others (both unsecured). My signal reads -46 dBm, the other two read -88 and -89. Now if it were measuring transmit power, wouldn't they all be the same?

If I pull up Find Networks in Access Connections, it shows my signal at 100 percent, one of the others at 70 percent and one at 50 percent.

Like I said, I was just observing. ... JD Hurst

Typically, RSSI is listed in dB, not dBm, but it's not necessarily inaccurate to list it in dBm (decibels above a milliwatt). It merely applies a reference value to the number (in this case, the milliwatt), as opposed to be dimensionless (such as SNR ratio).

Since the chipsets and power output are fairly standard, then it should be accurate.

How close are you to your AP? An RSSI of -46 dBm is pretty high, though I don't know the upper end of sensitivity for a WiFi chipset...

Also, I'm not sure what the antenna gain is on a laptop; I suspect 0 dBi is common for most laptop implementations.


Patrick

Patrick B wrote:<snip>
Typically, RSSI is listed in dB, not dBm, but it's not necessarily inaccurate to list it in dBm (decibels above a milliwatt). It merely applies a reference value to the number (in this case, the milliwatt), as opposed to be dimensionless (such as SNR ratio).

Since the chipsets and power output are fairly standard, then it should be accurate.

How close are you to your AP? An RSSI of -46 dBm is pretty high, though I don't know the upper end of sensitivity for a WiFi chipset...

Also, I'm not sure what the antenna gain is on a laptop; I suspect 0 dBi is common for most laptop implementations.

Patrick

At the time I wrote my post, I was on the main floor of my house above the rack in the basement that holds the cable modem, wireless router, switch and miscellaneous. So that would make it only about 10 feet away or even less. ... JD Hurst

jdhurst wrote:

Patrick B wrote:<snip>
Typically, RSSI is listed in dB, not dBm, but it's not necessarily inaccurate to list it in dBm (decibels above a milliwatt). It merely applies a reference value to the number (in this case, the milliwatt), as opposed to be dimensionless (such as SNR ratio).

Since the chipsets and power output are fairly standard, then it should be accurate.

How close are you to your AP? An RSSI of -46 dBm is pretty high, though I don't know the upper end of sensitivity for a WiFi chipset...

Also, I'm not sure what the antenna gain is on a laptop; I suspect 0 dBi is common for most laptop implementations.

Patrick

At the time I wrote my post, I was on the main floor of my house above the rack in the basement that holds the cable modem, wireless router, switch and miscellaneous. So that would make it only about 10 feet away or even less. ... JD Hurst

JD,

That's probably fine....generally once an 802.11 chipset gets into receive power in the -40s, you're reaching the maximum of what it can handle. Too much power can result in waveform clipping etc, causing dropped wireless frames, CRC errors etc.

As a point of curiosity, you may want to look at how much signal strength you get in the far reaches of your house (winter here now, so outdoor coverage isn't really pleasant to test....). It may be possible / recommended to even turn down the Tx power on your AP / Router (unless you're offering services to your neighbours, for example).


Patrick