Q:

Handheld oscilloscope for saving waveform in memory

I am looking for an handheld oscilloscope which can save some single frozen waveforms on memory and transfer it later to a computer. The saved waveform should have a lot of points so that I can process it on the computer with FFT for spectrum.
I want it to be a handheld oscilloscope instead of a USB oscilloscope are numerous:
More lightweight, less boot time,...
I wonder why I have found none with this capability, some difficulties with this approach?

A:

Like DKNguyen said in comments, your looking at equipment that is too cheap and/or low end.  
All the big names make one or more handheld scopes.
Almost all of them use 8bit ADCs, and can capture 3K to 30K samples.
The cheapest starts around $250(100Msps/20Mhz) and they skyrocket from there.
On the other hand, the cheapy(less than $100) scopes are most likely using a STM32, PSOC3/5 or some Arduino core that is being pushed to it's limit and just could not do it.   
Not enough RAM, not enough CPU and lack of a storage device are all possible problems at this level.
If a real time display is not needed, maybe a data logger might work?  I've done that in the past when I was doing RFI reports.  The logger grabbed 5 different bands at about 100Msps for up to 2 mins and wrote them to a USB dongle.  Then we would take the dongles back to the lab, and let the PC software do the hard work.  Don't know the cost, and that was the only time I've used something like that.

