The numbers come from the driver software that come with the wireless device. There's usually a "link status" or "signal quality" page in the preferences for the device. Some cards come with seperate diagnostic and monitoring software. The signal strength percentages are actually derived from the RSSI (receive signal strength indicator) numbers that all wireless cards use, that returns a value from 0-255 for the signal strength. To make it more human readable, the RSSI number is divided by in software 2.55 to yield 0-100% values.
Great, thanks for the info. I have a Mac running OS X but it doesn't seem to have such a reading. I have a builtin wireless that I've been trying to improve signal strength but without a reading it's tough to tell if things got better.
Very possibly. Netstumbler also hasn't been updated for quite a while. However, I find that programs that cease development tend to have permanent bugs or fail with hardware that appeared after the program was released. It's not a universal condition that applies to all software, just a noticeable tendency. I'll give it the benifit of the doubt.
Good point. If it works to expectations, then it should be just fine.
Update rate necessary for doing direction finding. I've only tried MacStumbler on one G3 laptop and found it has the same problem as Netstumbler. For direction finding, one needs an analog indication, and fast response time. No accuracy or history graph is required. Just a big analog meter and a fast response time. Both programs allow one to increase the probe transmission time to improve response time. However, it would be a really bad idea to increase it to perhaps 10 times per second, which would in effect turn MacStumbler into a jammer.
Basically, both programs are suitable for crudely optimizing the aim and position of an antenna. The Noise level display is also handy for aiming the antenna away from sources of interference. However, for direction finding, they're both marginally useful.
As for added features and functions, there are LOTS of other numbers buried in the MAC layer that would be nice to have graphed and displayed. Access points that have SNMP often make these available to users. It would be cool to have a MacStumbler or NetStumbler extract SNMP RF transmission statisitics from the access point (with the appropriate password security), or display the same statistics at the client end extracted from the Airport card. I do this all the time for link quality tests in wireless bridges.
This should give you some idea of what can be extracted:
the data and registers are there. The trick is prying the data loose from the Airport driver.
There was a good little app for OSX in the June issue of MacAddict (#106) called "MacStumbler" that will show all the active wireless connections around you and their signal strengths. It is freeware and on the CD that came with the magazine. It is probably available somewhere on the MacAddict website also. If you cant find it let me know and I can email it to you.
There is also some dashboard apps that will do that same thing for Tiger OSX.
Thanks for the reply, Jeff, I didnt think about all the other information that was available. Nor did I consider the abaility to run on the latest operating systems. That seems to be a Mac OS limitation more so than Microsoft. Even MS XP will run old dos programs but Mac OSX will not run hardly any of the older ( four years?) OS9 software.
Have you seen those little wireless detectors that look like a small key fob? I think they sell for about $29. They have five leds on them to indicate signal strength, seem to update fairly fast, and are somewhat directional. I wonder if you placed it into a small cutout at the bottom of a pringles can it would be more directional and sensitive? (gotta try that)