<Antti.Suhonen@elektrobit.com> wrote:
> Hi all,
>
> Anyone know how to calculate delay from freq, real- and imaginary values?
>
The group delay is generally the derivative of the phase response,
so take the real-imag values and convert to polar (mag/angle)
then differentiate the phase response.
NOTE - differentiation amplifes noise so you are best off if
you have lots of precise data (rather than a few so-so points).
Stan
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> Hi all,
>
> Anyone know how to calculate delay from freq, real- and imaginary values?
>
The group delay is generally the derivative of the phase response,
so take the real-imag values and convert to polar (mag/angle)
then differentiate the phase response.
NOTE - differentiation amplifes noise so you are best off if
you have lots of precise data (rather than a few so-so points).
Stan
--------------------------------------------------------------------------
Stan Bischof Agilent Technologies 707-577-3994 stan_bischof@agilent.com
--------------------------------------------------------------------------
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To convert from Re-Im to phase, be sure to use the ATAN2 function (requires 2 inputs) rather than the ATAN function. Or make them into a complex number and take phase(a).
You must also phase unwrap the data, or else you will get errors due to the 180 degree transistion points.
But easiest still (and I would recommend it) is change the data format to delay, and output the formatted data array.
Finally, you must always set smoothing on for the group delay measurements, where the smooting width (in MHz) is your group delay aperture.
Best regards, Joel
-----Original Message-----
From: Stan Bischof (Richard S) [mailto:rsb@soco.agilent.com]
Sent: Wednesday, October 20, 2004 8:17 AM
To: VRF
Cc: vrf@agilent.com
Subject: [vrf] Re: 8753 data formats...
<Antti.Suhonen@elektrobit.com> wrote:
> Hi all,
>
> Anyone know how to calculate delay from freq, real- and imaginary values?
>
The group delay is generally the derivative of the phase response,
so take the real-imag values and convert to polar (mag/angle)
then differentiate the phase response.
NOTE - differentiation amplifes noise so you are best off if
you have lots of precise data (rather than a few so-so points).
Stan
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Stan Bischof Agilent Technologies 707-577-3994 stan_bischof@agilent.com
--------------------------------------------------------------------------
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