Interference from Wireless Routers or other 2.4GHz devices

Can you encase your contraption in lead or something that would inhibit the interfering signal?

Short of shielding the entire room you can either move your stuff closer together or move it further away from any likely interference source. If there are external antennas involved that's what you want closer together and set up with the same orientation.

WiFi is on the ISM band so it's not interference. Other ISM equipment can use the band just like you can. Connect your equipment via an ethernet cable.

I used to work with VHF/UHF radio transmitters and we had a screened room within the main repair centre to stop the transmitter signal leaking out. The room was covered in fine mesh and the door had a metal seal. You had to be careful when opening and shutting the door, because the shielding was less effective when the door was opened.

Obviously a room that helps prevent signals leaking out also helps prevent signals getting in too.

You might also want to consider if there is something else you are carrying or using that uses 2.4 GHz signals - Garmins ANT+ devices use 2.4 GHz and Bluetooth devices also use 2.4 Ghz.

The other approach is to improve the carrier to interference ratio. If one (or both) end of your system is fixed and does not need to be moved about the room, then using some sort of directional antenna to improve the signal level (and reduce interference) would help.

http://www.google.com/search?q=2.4+ghz+antenna

The thing is that these are wireless for a reason. These are accelerometers which are place on people doing movements and the wires interfere with movement. So they need to be wireless.

I cannot think of anything else in the room that could be interfering, but I guess I can try different parts of the room and also keep cell phones away from them (in case any have a bluetooth antenna turned on).

There is a USB base station antenna which connects to the computer, which transmits to the accelerometer, which has a small antenna on it. It's fine if the transmission doesn't leave the room and truthfully shouldn't matter if other transmissions get blocked coming into the room.

Is there any way I could somehow determine where 2.4GHz signals are coming from? Any type of app or program that I could download to detect signal strength in various areas of the room?

netstumblr will help you locate wifi networks but I don't think it does anything for finding bluetooth, 2.4 ghz cordless phones, or any of the other dozens of things that could be interfering on 2.4

Is there a cell antenna on the roof ? and a base station in the building. The pipe (coax) could be leaking microwave high power at 2.4 or nearby frequencies and overloading. Or is there an old leaky microwave oven around. Manufactured ISM devices are very low powered and shutoff after transmitting periodically to let other stations jump in. Look outside, is there a microwave link pointed at you building ? rare chance. It's expensive to use instruments to find it, the monthly rent on a spectrum analyzer is quite high, and good used ones are expensive (>$10k) on eBay.

Good point about other potential sources of interference, such as a microwave link or other transmitter on a nearby frequency band. However, if he is at a university, then it is possible that some other university department has a spectrum analyser.

Interesting thoughts - I will have to see. Maybe somebody in IT or even the physics department could help with something like this.

It is strange - the signal isn't bad all at once and there seems to be no pattern to when I get interference - it really seems to be completely random when I get the interference.

The equipment I am trying to use has a test mode in the software where it sends pings back between the base station and the unit. The frequency it does this is about 40 times per second. When there is interference that screws up the signal, it gets recorded as a "bad ping." In a different building, I managed to go 100,000 pings with only about 5 bad pings, but in this building, I can expect 100+ bad pings by the time the counter hits 2000. I will have a good steady stream of good pings, then a burst of bad ones, and there really seems to be no pattern of when those bursts happen.