The Wiki is doing my nut 
I know what you mean. It can take a lot of filtering to get to the information you want. Unfortunately that is the problem with something like that which acts as a discussion board, ideas forum and information source all in one place. Hopefully this forum will overcom that by seperating those areas out (by different posts or topics)
Anyway, I don't quite understand your first question. What is it you need help with - the initial setting up of the sensor and knock frequencies? Sod it, here is my view on doing the whole lot.
Ok, well first, choose a decent knock sensor. The modern generation of Bosch or Denso sensors are good. Try and choose one with a flying lead as these pick up less electrical noise than the ones that have no lead attached.
Next find somewhere to mount it, preferably on the cool side of the block away from exhaust manifolds, near the top of the block, and for a single sensor in between cyls 2 and 3. Of course the chances of there actually being a mounting boss of the right size in that location is slim, so you may just have to go with whatever you can find. Generally the head will pick up more noise from the valvetrain etc, but it is possible to mount it there. Wherever you choose to mount it, make sure you fit it according to the manufacturers spec, particularly regarding bolt torque, as this affects the detection ability.
With the sensor fitted you next need to set up the detection side of VEMS by determining the correct detection frequency. Personally I don't subscribe to the 'hit the block wih a spannner' method, but Rob tells me he has had some success with this, so you will need to make up your own mind. The chart that was posted on the wiki gives you a good starting point for the frequencies you should expect from your engine depending on the bore size.
To be able to measure the frequency you need something that can band pass filter and then perform an FFT analysis on the signal coming from the knock sensor. The knock sensor should only be used in the 5kHz to 20kHz range normally, and there will be several frequencies generated in this range. The trick is to choose one that gives the best correllation to knock and a good signal to noise ratio under all conditions. Note that signal and noise increase substantially with engine speed, so accurate knock detection (i.e. detection without mis-detection of events that are not knock) at the redline becomes increasingly difficult.
In my opinion, to generate knock, you need to run the engine and make it knock in the region where knock will actually occur in normal service. Whilst you can force the engine to knock by advancing past MBT, this is not what you will do in reality (you shouldn't have mapped the ignition more advanced than MBT), so the true signal will be masked. I suggest running the engine at low speed (1500rpm) and WOT, and advancing the ignition to BLD (approximately 1 ping per second).
This is where your 'det cans' come in. They will allow you to correllate real knock that you can detect with your very sophisticated filtering and pattern recognition system (your brain) with the signals you measure from the sensor. From there, take similar measurements at 1000 rpm steps to as high a speed as you dare to run with DET. The way I see it, if i'm going to rely on a knock system at a given point, then I should have tested it there first to convince myself it will work. If you want your knock system to bail you out at 7000rpm, then you need to go there and measure the sensor signal to see if its possible or not. Its not nice, and it may seem risky, but in the long run its much less risky than relying on an unproven system to save your engine.
At each condition knocking, you will also need to take a noise log, typically at BLD-3 (or whatever retard gives you no pings) With all that data collected, tabulate the knock frequencies detected at each speed. You should be able to chose a couple of clear knock frequency bands at least. Then do a signal to noise calculation of the peak signal voltages of the knock and noise data having been filtered to your selected detection frequency ranges. This will allow you to make the best choice of detection frequency for all conditions.
Once you have selected your detection frequency, you can plumb it back into the ECU and validate it by looking for detection of knock events vs your det cans. You'll have to get Rob to explain how the window length and integrator bits work 'cos I'm not clear on that myself yet. However, once you are happy you can rely on the detection (or you have defined the speed range where you can and can't rely on it) you can start to calibrate the actions - the retard step, advance step and delay to achieve the level of control you require.
And I think thats about it really.......
