Bicycle Mechanics - please explain about wireless cadence

I'm in the market for a new cyclocomputer with cadence. My understanding is that wireless cadence is calculated rather than measured. Is this true? If it is, can someone suggest a wireless computer that has wired cadence?

There is the Flightdeck computer from Shimano with "virtual" cadence -- it uses fairly straight forward math to calculate RPM based on gear inches (you must pre-program your chainring and cassette cog info into the computer) and the bike's speed.

Wireless cadence is new (Vetta & some others have it) and it's the same as wireless speed/distance, i.e., they've developed a wireless transmitter to pass the signal from your crank pick-up to your computer vs using a signal wire.
http://www.velogear.com/vetwircadupk.html Wireless cadence is measured.

Wireless computers with cadence -- SigmaSports BC1400 is a good one but every manufacture offers at least one model with the cadence option. Establish your budget, check the various models and go with the one that fits your needs/preference.

I like virtual over wireless as you don't have to snap anything else on the bike. Wireless sounds like a step in the right directions though.

I've had a computer with wireless (actual) cadence on my road bike for a couple of months, and so far it has worked well. Which is good because I can never hide the wires of 'wired' computers to my satisfaction. Always a big blob of electrical tape somwhere...

Slightly O/T: here's something that's worked well for me re: cadence magnets- I use a small, disk-shaped magnet that fits the end of my left pedal axel (where the allen wrench-slotted end of it comes through the back of the crank). That alleviates the need to tape/elastic band/zip tie the typically bulky cadence magnets that come with a computer. If you do this, you need to get a strong magnet--I use a samarium cobalt magnet (www.scientificsonline.com) which sticks like h*ll and hasn't demagnetized or fallen off. Works great on a roadbike--don't know how well it would work on a moutain bike. A lot more bumps and trail hazards...