i have problem that arduino due can not read 125khz analoge signal. I am used matlab simulink block (analog in) but no readings. please if any one can help
Yes it can read a signal that fast. But it depends on your hardware and code. Non of which you have posted. Please read the how to use this forum post before posting again.
If you want useful information about the 125KHz waveform, you will need to digitize at a much higher rate.
Several years ago, the PlainADC library was created by Didier Longueville for use with the 328 chip. It would work up to about 130KHz. That library is no longer being distributed. He now has the PlainDSP package but at a slightly lower speed. Perhaps someone has done the same thing for the Due and achieved a higher speed. A lengthy search might find something.