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N9342C: Sample Rate in Zero Span mode

Question asked by cmkessell on Mar 20, 2013
Latest reply on Mar 25, 2013 by sleithem

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We've just acquired a N9342C analyzer (as a replacement for an aging N1996A) partly because of its fast zero span sweep capability - it claims to sweep down to 600ns - which we use to observe fast-changing single-frequency signals.

However, it looks as if the N9342C's sample rate is fixed at 600ns, so as the zero span sweep rate gets faster the horizontal resolution deteriorates. At 10us sweep the display comprises about a dozen horizontal points and when set to 600ns sweep the display comprises just two points joined by a straight line! Even the old cheap-and-cheerful N1996A was better.

Is there any way to increase the sample rate or number of horizontal points?

Edited by: cmkessell on Mar 20, 2013 4:38 AM

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xingsali Mar 21, 2013 12:15 AM

Hello,

As you have observed on the N9342C, when you increase the sweep time, the sample number(and horizontal points) will increase.

The sample number can't be manually adjusted when you confirmed the sweep time.

That's right the sweep time under zero span will down to 600 ns, but the the sample number is the least.

Anyhow, N9342C will have better sweep speed than N9342C.

Can it meet your test requirement?

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cmkessell @ xingsali on Mar 21, 2013 9:57 AM

Hi,

Many thanks for the quick response.

The N9342C is disappointing, and doesn't really meet our requirement. Although the N9342C can theoretically sweep slightly faster than the N1996A (which has a minimum sweep time of 1us), the N1996A is better because even at the fastest sweep it still uses a lot of points to provide good waveform resolution. In contrast once the sweep time of the N9342C approaches this speed the displayed waveform becomes very angular because it comprises just a few points at 600ns intervals joined by straight lines!

Can you suggest any other analyzer models that might provide good performance in zero span mode?

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sleithem

@ cmkessell on Mar 25, 2013 3:40 PM

Hi,

Do you need a handheld analyzer? Or can you use a desktop (non-portable) signal analyzer?

The X-Series analyzers (such as the N9010A EXA) can display down to 1 us with a number of samples that is dependent on the sample rate, as you suggested. In I/Q analyzer mode with 40 MHz of analysis bandwidth option enabled (option B40), it is possible to view 1 us with 51 samples. With the standard bandwidth option B25, you can view 32 samples.
http://www.agilent.com/find/EXA
http://www.agilent.com/find/EXA_specifications

The E440xB ESA series analyzers have two options that cover fast zero span sweeps down to 50 (option AYX) or 25 (option B7D) nsec.
The limitation is once again the sample rate and therefore the number of sweep points. For a 1 us view, the ESA can capture up to 41 sample points.
To compare with your previous analysis, for a 600 ns interval, the ESA can capture up to 25 samples.
http://www.agilent.com/find/ESA - check out the specifications guide, section on sweep time

The ESA is also available as a portable configuration.

If you need very fast sampling rates, you may want to consider a high bandwidth oscilloscope.

Best Regards,
Scott

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3 Replies

xingsali Mar 21, 2013 12:15 AM
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Hello,

As you have observed on the N9342C, when you increase the sweep time, the sample number(and horizontal points) will increase.

The sample number can't be manually adjusted when you confirmed the sweep time.

That's right the sweep time under zero span will down to 600 ns, but the the sample number is the least.

Anyhow, N9342C will have better sweep speed than N9342C.

Can it meet your test requirement?
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- cmkessell @ xingsali on Mar 21, 2013 9:57 AM
  Mark Correct
  Correct Answer
  Hi,
  
  Many thanks for the quick response.
  
  The N9342C is disappointing, and doesn't really meet our requirement. Although the N9342C can theoretically sweep slightly faster than the N1996A (which has a minimum sweep time of 1us), the N1996A is better because even at the fastest sweep it still uses a lot of points to provide good waveform resolution. In contrast once the sweep time of the N9342C approaches this speed the displayed waveform becomes very angular because it comprises just a few points at 600ns intervals joined by straight lines!
  
  Can you suggest any other analyzer models that might provide good performance in zero span mode?
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  - sleithem @ cmkessell on Mar 25, 2013 3:40 PM
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    Hi,
    
    Do you need a handheld analyzer? Or can you use a desktop (non-portable) signal analyzer?
    
    The X-Series analyzers (such as the N9010A EXA) can display down to 1 us with a number of samples that is dependent on the sample rate, as you suggested. In I/Q analyzer mode with 40 MHz of analysis bandwidth option enabled (option B40), it is possible to view 1 us with 51 samples. With the standard bandwidth option B25, you can view 32 samples.
    http://www.agilent.com/find/EXA
    http://www.agilent.com/find/EXA_specifications
    
    The E440xB ESA series analyzers have two options that cover fast zero span sweeps down to 50 (option AYX) or 25 (option B7D) nsec.
    The limitation is once again the sample rate and therefore the number of sweep points. For a 1 us view, the ESA can capture up to 41 sample points.
    To compare with your previous analysis, for a 600 ns interval, the ESA can capture up to 25 samples.
    http://www.agilent.com/find/ESA - check out the specifications guide, section on sweep time
    
    The ESA is also available as a portable configuration.
    
    If you need very fast sampling rates, you may want to consider a high bandwidth oscilloscope.
    
    Best Regards,
    Scott
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N9342C: Sample Rate in Zero Span mode

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