Thanks for your answers!
There are certainly a few important points, but I don't really see THE compelling reason why I absolutely need a new scope after one or two years.
It's probably more about quality aspects than hard limits on features.
I guess it depends on how often you use it and what you use it for.
Just like you would choose a different car for shopping once a week, than if you were driving a cab every day.
Perhaps many people don't realize that even the cheapest scopes these days have many of the features you mentioned:
trigger types
DSO2000 has: Edge,Pulse,Video,Slope,Overtime,Window,Pattern,Interval,Delay,UART,LIN,CAN,SPI,IIC
decoding
DSO2000 has: RS232/UART、I2C、SPI、CAN、LIN. "Hello world" in the attached image.
math functions
DSO2000 has: +, -, x, /, FFT. FFT Demo in the attached image.
- if you are trying to measure signal parameters, you can always measure them just by looking at the waveform and counting graticule lines (as we did in the CRO days) but better scopes do a nice job of doing all that for you -- and there is variation in how well they do it.
DSO2000 has Automatic Measurements: PkPk, Frequency, Average, Max, Min, Period, Vtop, Vmid, Vbase, Vamp, RMS, R-Overshoot, Period, Rms, F-Preshoot, PeriodRms, PeriodAvg, RiseTime, FallTime, + Width, - Width, + Duty, - Duty, FRR, FFF, F-Overshoot, R-preshoot, BWidth, FRF, FFR, LRR, LRF, LFR and LFF
remote control lets your automate some measurements.
DSO2000 has SCPI. I made a
bode plot script with it.
I think that even a cheap(-est) scope will keep you busy for a while.
But don't get me wrong, the DSO2000 really is a cheap device and it is a bit rough at many points.
I wouldn't want to
work with it every day, but it does have a lot to offer for beginners.