Slow wifi on time capsule

I have a time capsule that I have owned for about a year without any issues. Recently we moved to a new house and got a new ISP (RCN), and eversince I have been having issues with the speed of my wifi. For the record, I don't think the issue is with my ISP since I get 25Mbps when I connect my computer directly to the modem through an Ethernet cable. My wifi speed through Time Capsule, however, is usually well below 10Mbps, and at times below 5Mbps. Occasionally the speed picks up to the teens, but more often than not it is quite sluggish.

The Time Capsule is in the same room as my iMac, maybe 6 ft away. I have tried changing channels, completely reset the TC to factory settings, removed older/unused SSIDs from the Airport utility, all to no avail... Since the speed is even slower when I go to a lower floor, I got an Airport Epress to extend the range hoping I'd pick up some speed, but even with the Express it is very slow on the lower floor, at times less than 1Mbps.

I am not really sure what to try next, and would appreciate any suggestions!

This sounds like you have localised environmental issues causing interference. There are a few free apps about to help you ascertain signal to noise ratios and monitor other local networks and which channels that they are on. iStumbler is a decent example of such an app.

There is another thread on here discussing similar issues which may be of help.

http://www.mac-forums.com/forums/in...ing-setup-wireless-my-new-home-4-stories.html

Thanks pendlewitch, I downloaded iStumbler (nice little App!) and it shows that my signal strength is around 58% on the 2.4GHz frequency with the computer only a few feet away from the base station. Noise is around 14%. On the 5.2GHz frequency, signal strength is even worse at 43% with noise at 11%.

Not having a reference point I can't compare these values, but the signal strength seems very low to me. Here are a few questions:

- in a relatively good environment, what should signal and noise levels be?
- do I need to broadcast at both 2.4 andw 5.2GHz? I don't even know if I have any devices that work on 5.2 and whether this has anything to do with my issue
- assuming the above values suggest I have interference in the environment, what are some of the things I can do to address this?

Thanks for the help!

Hi now here you have identified on e of the confusing things about iStumbler. It gives you figures as a percentage of a theoretical maximum.

The actual dBm figures that you need to ascertain the SNR can be found if you use the Inspector and choose the Samples tab.


Here is a snapshot of my 5gHz band and if you use one of the samples for example ; -63dBm Signal and -96dBm Noise and subtract the noise from the signal this would give a result of 36dBm SNR which in wireless LAN terms is a very good signal if you use the resource below from JIm Geier with regards to SNR Cutoff recommendations

> 40dB SNR = Excellent signal (5 bars); always associated; lightening fast.

25dB to 40dB SNR = Very good signal (3 - 4 bars); always associated; very fast.

15dB to 25dB SNR = Low signal (2 bars); always associated; usually fast.

10dB - 15dB SNR = very low signal (1 bar); mostly associated; mostly slow.

5dB to 10dB SNR = no signal; not associated; no go.

With regards to dual band your device should be capable of broadcasting over both frequencies simultaneously and you can choose which one to hook your iMac up to. I chose the 5gHz one for my iMac and let everything else default to the 2.4gHz band and have seen a huge improvement in performance.

There is an excellent article here for you to read with regards to the dual band debate.Ask Ars: are dual-band 802.11n routers worth the extra cost? | Ars Technica

Signal strength is normally affected by building fabric and obstacles, noise is normally a result of interference from other equipment such as microwaves, overhead power lines and
the classic issue of cordless phone base stations transmitting on the same 2.4gHz band as your router.

Just as a guesstimate your SNR's are not likely to be that bad it's more likely that the 2.4gHz band is choking up.

Pendlewitch,

Thanks for the very detailed and thorough explanation! I'll play with the dual band settings and see if it makes a difference. My iMac is older (white casing) so I am not even sure if it will accept 5GHz, but I'll look I to it.