Datasheet

However, the power of the MDO4000C Series goes well beyond simply

observing the frequency domain as you would on a spectrum analyzer. The

real power is in its ability to correlate events in the frequency domain with

the time domain phenomena that caused them.

When both the spectrum analyzer and any analog or digital channels are

on, the oscilloscope display is split into two views. The upper half of the

display is a traditional oscilloscope view of the Time Domain. The lower half

of the display is a Frequency Domain view of the spectrum analyzer input.

Note that the Frequency Domain view is not simply an FFT of the analog or

digital channels in the instrument, but is the spectrum acquired from the

spectrum analyzer input.

Another key difference is that with traditional oscilloscope FFTs, you can

typically either get the desired view of the FFT display, or the desired view

of your other time domain signals of interest, but never both at the same

time. This is because traditional oscilloscopes only have a single

acquisition system with a single set of user settings such as record length,

sample rate, and time per division that drive all data views. But with the

MDO4000C Series, the spectrum analyzer has its own acquisition system

that is independent, but time correlated, to the analog and digital channel

acquisition systems. This allows each domain to be configured optimally,

providing a complete time correlated system view of all analog, digital, and

RF signals of interest.

The spectrum shown in the Frequency Domain view is taken from the

period of time indicated by the short orange bar in the time domain view -

known as the Spectrum Time. With the MDO4000C Series, Spectrum Time

can be moved through the acquisition to investigate how the RF spectrum

changes over time. And this can be done while the oscilloscope is live and

running or on a stopped acquisition.

The upper half of the MDO4000C Series display shows the Time Domain view of the

analog and digital channels, while the lower half shows the Frequency Domain view of

the spectrum analyzer channel. The orange bar - Spectrum Time - shows the period of

time used to calculate the RF spectrum.

1. Time and Frequency Domain view showing the turn-on of a PLL. Channel 1 (yellow) is

probing a control signal that enables the VCO. Channel 2 (cyan) is probing the VCO tune

voltage. The SPI bus which is programming the PLL with the desired frequency is probed

with three digital channels and automatically decoded. Notice Spectrum Time is placed

after the VCO was enabled and coincident with the command on the SPI bus telling the

PLL the desired frequency of 2.400 GHz. Note that the RF is at 2.5564 GHz when the

circuit turns on.

2. Spectrum Time is moved about 90 μs to the right. At this point, the spectrum shows

that the PLL is in the process of tuning to the correct frequency (2.400 GHz). It has made

it down to 2.4924 GHz.

MDO4000C Series Oscilloscope