ESM Receiver Simulator

[SeaQueen]

Originally Posted by Dr.Sid

Hey SeaQueen .. since you mind .. you know something more about it ? Some links ? I haven't found any. Also about the importance of this in sonar (& ESM) ?

The distribution statistical distribution of the noise? Well... for one it contributes to your false contact rate, although that's just a part of it. In a LOFAR gram, say, just by random chance, you might see a target that's not there due to the noise in the system. That's why you adjust your integration times. If you use long integration times, the noise averages out more and you can see a signal better with fewer false contacts, but at the expense of not getting information as quickly. At shorter integration times you can't see as far, but you can react more quickly albeit at the expense of more false contacts.

In radar it's less important because the rate of sampling is much higher, so things average out much more quickly, but it does have an effect. Most signal processing is designed around Gaussian noise, though. You can generate pairs of Gaussian distributed random numbers with the Box-Muller method.

http://www.taygeta.com/random/gaussian.html

The noise level is a big driver in sonar particularly, but radar as well. A lot of the physics of radar and sonar are the same. The jargon is just different. The basic ideas in both cases is that the atmosphere and the ocean is a waveguide. They just rephrase the jargon. In radar, for example, they plot the refractive index of the atmosphere versus altitude, while in sonar they plot the speed of sound versus depth. Regardless, it's just the speed the wave propagates at. In the end, it's all just Snell's Law.

It's all good stuff.

[timmyg00]

I have added a Word doc describing the "inner workings" of the program to the CADC Downloads center, along with a separate file containing the source code for the signal generation functions.

TG