Ive done some reading and this is what I found out about noise jamming.

Because noise jamming is range denying, to know how it works we have to know how radars measure range to target. Pulse radars sends energy in small packets many times a second and because of that they get their name. Also there are some terms to simplify things:
PW (Pulse Width - duration of each individual pulse transmitted, measured in microseconds [us]),
PRF (Pulse Repetition Frequency - number of pulses transmitted in a second),
PRI (Pulse Repetition Interval - time from begining of one pulse to the begining of the next one),
Max unambiguous range (Maximum range where a target can be located in a way that reflecting energy from a pulse is received before the next pulse is sent).

Range to target is calculated by measuring the time from transmitting the pulse to receiving reflected energy from the target. After that its easy math to calculate range:

R = (c * t)/2
c - speed of light, t - measured time

Radars maximum unambiguous range is dependent on its PRF, larger PRF results in shorter maximum (unambiguous) range and vice-versa.

Lets suppose we are in command of a pulse radar, we see a target inbound. We are happily transmitting radar energy towards the target on our radars PRF and see him nice and bright on the screen. He then activates his noise jammer. (Lets say his jammer is really simple, transmitting on same frequency as our radar and double our PRF). As our radar transmits a pulse and the pulse reaches the target, targets jammer transmits its own pulse, and just as the reflected+targets pulse reach half way between target and radar target transmits another pulse. So by the time we send the next pulse we have two separate pulses received. Resulting in two targets appearing on the screen. Now target switches its jammer to advanced mode (still simplified) resulting in increasing its PRF many times ourown. This results in our radar registering many targets along the same azimuth and elevation. When the PRF is increased enough to overcome resolution of the radar, all those targets meld into one continuous band of 'targets', making it impossible to track the target in range.

Now I still have a question. I read that radars can simply employ PRF filter thus ignoring most noise jamming. Radar will still process pulses of PRF equal to its own, but that just ads one more target, and if EWR or IADS is present it would practically eliminate the jamming completely. Now, how is it possible to go around that and still noise jam a pulse radar. Is it adding a possibility to change PRF on the fly, and not just set it to a fixed high value? Im sure that could confuse the radar computer.

Also if I got something wrong, please point it out.