Solved but puzzled: high cpu usage with IBM 802.11abg card

I have observed an almost identical situation using a USB adaptor with a Prime RT2500 chipset. (PESI WU233g). Oddly, the AP is also a Dlink 604. Unfortunately my location can "see" my AP and the annoying AP which is usually running streaming video most of the time. He also runs a power amplifier (big mouth, small ears) and his system is unaware of any other user. Although we have locked down our transmit speeds to 2 Mbs, the receive side appears to recognise all speeds. This probably is because the receive side is clocked from the incoming received data stream. It would appear as if drivers were written and tested in "clean" single user environments!

Peter

"Pierre" hath wroth:

The Dlink DI-604 is not a wireless router. I think you mean DI-514,

524, 624 or 824.

Lovely. Big mouth and small ears is called an "alligator".

Nope. It's because *ALL* 802.11b management (and flow control) frames are sent at the slowest 1Mbit/sec speed. That's to insure that everyone can hear and decode everyone else regardless of their speed settings.

This has nothing to do with the high CPU usage problem.

The Dlink DSL-G604T is a ADSL Wireless Router/Modem

The USB port to the adaptor is working overtime during this high CPU utilisation period. I should get some more tools in place and investigate further but my time is now being spent building a small doubler from the

23cm gear that will quieten the local small eared alligator. The other licence that Jeff and I have is quite handy! Peter de C21TA et al

The DI-604 is not wireless:

DSL-G604T is not listed on the USA site which I guess means that it's not sold in the USA.

Try running the Windoze Task Manager "Processes" tab. Add to the columns with: View -> Columns and add: i/o reads i/o writes i/o other They should show which program has gone nuts. Also, watch the CPU and memory utilization.

Don't bother. The carrier to interference ratio (jamming margin) on spread sprectrum is about 10dB. See table at:

way are you going to belch enough CW (or FM) to trash his receiver. That's the whole idea behind spread spectrum. It's almost totally immune to CW jamming. The best you can do is overload his receiver (blocking). If you modulate your carrier with PN (pseudo-noise), you might simulate an DSSS signal, which would certainly cause your victim a problem. Now, if you really want power, how about just connecting a coax cable to a microwave oven output coupleing loop, and really cook them?

Anyone else remember that guy who built a 2.4GHz amp from a microwave oven klystron? He had a giant circulator so he could feed in a modulating signal, and the klystron would lock onto it. It wasn't clear from the article if he had yet fired it up, but the power supply was truly scary!

William P.N. Smith hath wroth:

Microwave ovens use a magnetron, not a klystron. I went looking for the article on converting a microwave oven into a transmitter. I couldn't find it. Lots of articles on dangerous experiments (plasma generators, ball lightning, sparks, etc) but nothing on use as a communications device.

Well, let's do a bit of math. Let's pretend his antenna has a VSWR of about 1.5:1 which will reflect about 5% of the power at the antenna. The circulator dummy load has to absorb this reflected power. 800 watts coming from the magnetron yields 40 watts in the dummy load. 40 watts of dissipation will require a rather large dummy load. In addition, the circulator usually burns about 1dB of loss, so it will need to dissipate about 80 watts itself. I could probably build a hybrid ring circulator that would handle that, but not a ferrite circulator. How one would use a circulator to modulate a magnetron is beyond my imagination. However, there are articles on phase locking magentrons for use in a particle accellerator, so I guess it can be done by phase locking it to an 802.11 source.

Let me know if you find the construction article. I do remember seeing (and ignoring) it about a year ago.

[Oops, slept since then, and had kids, and all that.]

This had to be back in my serious ham days (before kids), and since my daughter is 12, it was at least a decade ago, well before everything was on the WWWeb.

I just checked my stash of ham publications, and it's not there. IIRC, it was one of those occasional (maybe quarterly) magazines like ATV Magazine or something.

Again, the article didn't exactly say he had ever fired it up, so reading between the lines seemed to indicate that it was a project in process, so he may not have had all the details worked out. Still, a scary power supply and project in general.

Google Groups gets some hits on "microwave oven transmitter", especially in rec.radio.amateur.homebrew which discuss just this subject.

You provided this link in another forum.

Bob