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TDS Measurements
PostPosted: Tue Jan 12, 2016 7:33 pm Reply with quote
M.Ermilio
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Joined: 11 Jan 2016
Posts: 4
Location: Chester, PA




Setup the TDS module on my measurement system. We're switching from TEF20 to EASRA for this measurement setup. So far the measurements are FAR more consistent with the TDS module. But I do not understand how to process the data. The cabinet is a 8in coax that has a lower operating range of 100hz.

Question 1: Why does the magnitude climb up like that in the low frequencies? It's accurate down to 400hz then it swings up in dB. The sweep should be accurate down to 131hz for this measurement.


Question 2: Why is DUT distance linked to sweep time?

Question 3: Why does the Time in the TDS post processing window not match the measured time in the impulse response?


Question 4: How do I apply the TDS post processing and make it stick so that you can view multiple post processed magnitudes at once? Or how can I make it a pre-sweep processing step so every sweep has that performed such as for measuring polar data?

Thank you.
Michael Ermilio
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PostPosted: Wed Jan 13, 2016 1:15 pm Reply with quote
Waldemar
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Joined: 05 Dec 2005
Posts: 105




Hi Michael,

1. I cannot answer this question. Did you try to do TDS processing with different (higher) Bandwidth?
2. The distance is a function of the bandwidth and the sweep rate. The sweep rate is calculated from the frequency range and the sweep time.
3. The (bandwidth) time is bandwidth / sweep rate.
4. Unfortunately this is not possible. You have to process every curve separately.

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SDA, Waldemar Richert
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PostPosted: Wed Jan 13, 2016 3:16 pm Reply with quote
M.Ermilio
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Joined: 11 Jan 2016
Posts: 4
Location: Chester, PA




1) Yes, No change is observed. However after two days of measurements that looked like the image above, EASRA crashed. After rebooting and starting another measurement with the same settings the rise in LF is now gone (after processing). Bug?


2+3) Okay, disappointing that it's a MUCH longer sweep rate than the TEF20 system. A full polar is going to take a whole week to measure with such long sweep times. Why does a 43.7 second recording time only sweep for 21.7 seconds?

4) Then this module and EASRA for this test system does not meet our needs. Performing an entire polar measurement and having to go back in and manually apply processing to 15,000+ measurements is less than ideal. This is such a a shame because we're so heavily invested in the GLL data system and still do not have a solution for collecting that data for our large systems. Yes an anechoic chamber would solve this problem, but presenting a million dollar solution isn't feasible.

Thank you for your time.

~Mike Ermilio
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PostPosted: Wed Jan 13, 2016 6:33 pm Reply with quote
Charlie
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Joined: 28 Apr 2005
Posts: 51
Location: Charlotte, NC USA




Hi Mike,
It seems you want to use EASERA in an laboratory environment for loudspeaker measurements. I'd be delighted to talk to you about that and how to best set things up. I'll call you shortly. If for some reason we do not make contact today (Wednesday) please send an email to support@afmg.eu. I'll pick that up and hopefully be able to help out.

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Charlie Hughes
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TDS Measurements
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