Measuring phase delays as large as 20000 degrees at 1GHz

[cmunikat]

Dear all,

I need an instrument or set-up to accurately measure phase delays as large as 20000 degrees at 1GHz.

It is important:

* to measure at the correct frequency (no indirect frequency measurements)
* accuracy of about +/-1 degree

Thanx

 

[cliffcurry]

Re: measure 20e3 degrees

1 GHz changes 360 degrees in 1 nano-second. You want to measure a time delay of 55.5 nano-seconds with an accuracy of 2.8 pico-seconds. This is probably possible. Is this what you want to do?

Comparing the phase of two signals is usually done by hetrodying them both down to some really low frequency, and then measuring the phase difference between the low frequency signals.

 

[cmunikat]

Re: measure 20e3 degrees

yes, cliffcurry, this is what I want to do. In fact I am talking about 100ppm measurement error. This is my target, however, worst errors can be tolerated.

Have you got more information on such heterodyne system you suggest? Thanks again.

 

[sergio mariotti]

Re: measure 20e3 degrees

There is an appropriate measurement technique. It's based to an instruments that can read accurately 100ppm . That instrument is the counter. The high end frequency meter may by used as counter. Two input connectors are necessary.

Quickly:
1) modulate the signal with a convenient square wave, low freq. signal.

2) feed the counter with both the detected waves (before and after the delay).

The modulating freq. should be choosen low enough to avoid aliasing, but high enough to give sufficient resolution.

I've shown the measurement principle, but practically the scheme is more complicated, sometime coherent conversion and/or PLL are used.
Look at Agilent AN's about frequency meters and related applications.

 

[cmunikat]

Re: measure 20e3 degrees

Sergio,

gracias por la respuesta.

I will look agilent's AN.

Cmunikat

 

[cmunikat]

Re: measure 20e3 degrees

Sergio,

Could you please give more details on @gilent AN? I couldn't find it.

I look forward to your response. Thanks!!!

:wink: