Why is frequency limited to 2 MHz in standard mode, when I can set it in sweep mode up to 25 MHz? Is some difference in signals of standard and sweep mode?
Thank You
This is good question - why not. The generator can output very constant signal amplitude up to about 25MHz.
The reason to the 2MHz limit is to keep all the waveforms “good looking”.
On the frequencies above 2MHz the sine is rather good but triangle and square not.
There is no difference between the sweep mode waveform and normal mode waveform.
You may use sweep mode if you like to get (sine) waveforms beyond the 2MHz limit.
The sampling frequency of the digital to analog converter of the PCGU1000 is 50MHz.
The number of samples per one period of the output wave is quite low at 10MHz and above. The signal is still good enough for sweep purposes to measure frequency responses of amplifiers and filters.
I.e. At 25MHz output the waveform is represented by only two samples. Per Nyquist’s theorem if you “assume” the waveform to be sinusoidal of no more than 1/2 the sample frequency then the defined wave can be a usable signal–otherwise things fall apart fast.
From a perspective of making a solidly accurate signal source the PCGU1000’s 2MHz limit is fully justified.
I have been told that an elephant would be quite ill-defined, if such definition were based upon only six observations of restricted scope–imagine trying to define an elephant with only two data points?