What is spectrum actually measuring?

PJS111111 · Post by **PJS111111** » Mon Sep 19, 2005 4:38 am

1. The documentation (ADC-212) is cryptic as far as what piece of data the spectrum performs an FFT on. Can I be sure that if I collect temporal data in a display window that the spectrum is actually calculated from that same data, not some other piece of the data stream? This conclusion seems inconsistent with the fact the you can vary the timebase at will regardless of the spectrum settings.

2. How do I set the vertical scale of the FFT to fixed limits (e.g. from -20 dB to -100 dB) so it doesn't fly around all over when the spectrum changes rapidly?

Paul

Michael · Post by **Michael** » Fri Sep 23, 2005 3:26 pm

Hello,

Thank you for your posts.

Rest assured the data in the spectrum analyser is fed by its own independant data stream from the driver. Each PicoScope window exists independantly of each other.

Simply try opening a two scope windows and setting the time base on one, then select the other and set a different timebase.

You would need to create a custom range to fix to a specified scale.

Best regards,
Michael[/img]