[SI-LIST] Re: Q on TDR coupon measurements
- From: "Lee Ritchey" <leeritchey@xxxxxxxxxxxxx>
- To: "Charles Grasso" <Charles.Grasso@xxxxxxxxxxxx>, si-list@xxxxxxxxxxxxx
- Date: Wed, 22 Mar 2006 11:07:29 -0800
This is one of the techniques used to measure impedance. The Polar tool
averages the impedance over the length of the test trace. The problem with
this method is that it includes the DC resistance of the trace in the
answer. That's not what you want. You want the impedance from the L & C
only. The best way to get this is to measure impedance right after the TDR
waveform has settled after the transition from the test cable to the trace.
That way, your answer is not skewed by the DC component of the copper.
> [Original Message]
> From: Grasso, Charles <Charles.Grasso@xxxxxxxxxxxx>
> To: <si-list@xxxxxxxxxxxxx>
> Date: 3/22/2006 10:00:50 AM
> Subject: [SI-LIST] Q on TDR coupon measurements
>
> Hi all,
>
>
> In researching the "state-of-the-art" for TDR measurement I ran across
> an interesting measurement that I would welcome comments on from the
> group.
>
> After the coupon has been probed, the impedance is only measured over a
> small portion (<25%) of the resultant waveform and then using
> an "average mean* technique for reporting the impedance values.
>
>
>
> In the opinion of the group - is this a valid technique? What are the
> reasons for only using a small portion of the waveform ? Does anyone
> know what an *average mean* value is??
>
>
>
> Thanks in advance!!
>
> Best Regards
> Charles Grasso
> Senior Compliance Engineer
> Echostar Communications Corp.
> Tel: 303-706-5467
> Fax: 303-799-6222
> Cell: 303-204-2974
> Pager/Short Message: 3032042974@xxxxxxxx
> Email: charles.grasso@xxxxxxxxxxxx;
> Email Alternate: chasgrasso@xxxxxxxx
>
>
>
>
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