Phase Information (help)

[Russ_NY]

I must be a bit thick headed, because I can't seem to get the phase relationships to make sense to me. I understand that different targets cause a different phase response in the detected signal. I also understand that Ground Effects cause a shift in the normal phase response of those targets. I have read quite a few of the information sources for detector design and tried to make sense of them, but am still having problems understanding just what is going on in the circuitry, especially those detectors that seem to have discrimination functions that have ground balace functioning at the same time. I think I understand that the ground balance channel somehow shifts the detection window created by the discrimination circuitry. I think this is what is supposed to be happening in the Bandito. It seems to me that the discrimination channel would have a variable pulse width as well as a variable delay so that the detection window could be adjusted to allow a variable range of the detected signal to be gated. I would really appreciate an explanation of just what is happening in the different modes of operation. Especially of the Bandito in particular. Any help would be greatly appreciated.
Thanks
Russ_NY

[Goodrat]

Re: Phase Information (help)

The engineers here can give a more detailed explaination, but maybe a technicians view may help.
Notice the uper two gates (analog switches) on the Bandido. The upper disc channel is pulsed by the disc setting which is the xmit reference but delayed by the disc control. The next gate down is the ground channel. Thet gate is pulsed by the xmit reference but delayed by the ground balance control.
The signal out of these gates are highest when the input is high and the control is high. Efectively the outputs represent a value reference to the delay controled by the disc and GB controls. This is changed to a varying DC and filtered in such a way to acount for noise and sweep speed.
Finally these signals are AND'ed together so that you only get a signal when the ground AND a target are present.
This is the way I sort it out at least.

[Russ_NY]

Re: Phase Information (help)

Thanks Goodrat,, Makes sense what you are saying. The big issue I am still having is that a while back you posted scope pictures showing the min/mid/and max ranges of both the Disc pulse and the Ground pulse as they relate to the transmitted waveform. You also posted a block diagram of the Bandito which listed ranges of phase shift for the Disc and Ground channels. I can't see how they are the same thing as far as phase shift. I don't think it's just me being thick headed. I would really appreciate you or anyone else who wants to jump in helping me get on the right track with this.
Thanks again
HH

Russ_NY

[Goodrat]

Re: Phase Information (help)

Is it the values of the shift that are confusing? Or the general theory. Because if it is the numbers, don't take it too literal.

[Russ_NY]

Re: Phase Information (help)

Goodrat,
Sorry for the delay in responding to your question. Honestly at this point I am not sure what I understand or not. Having been a Tech myself for over 30 years I don't usually find myself stumped by too many things. For me personally it is important to have a complete understanding of the numbers. I have been reading and attempting to decipher many of the patent documents on this site in order to get a better understanding of what some of the fundamental truths are as they relate to Target / Ground phase relationships. I think at this point I am going to do some experiments to clarify for myself several points. For me, the building of a functional detector is secondary to my gaining a firm understanding of the concepts, though they are certainly related.
Thanks again for all the help you have given me, and I look forward to perhaps discussing the outcome of my experiments.
HH

Russ_NY