More megahertz does not automatically mean a better oscilloscope for your task. Start with the signal: how fast does it change, how many channels must be viewed together and how long must an event be captured?
Check these seven points
- Signal and rise time: fast edges contain frequencies well above the repetition rate.
- Bandwidth: allow margin for relevant components and the required amplitude accuracy.
- Sample rate: check the rate per active channel, not only the headline maximum.
- Record length: this determines capture duration at the selected sample rate.
- Channels and triggering: consider analogue/digital channels, bus decode and rare events.
- Probes: bandwidth, attenuation, input capacitance and voltage limit belong to the system.
- Safe connection: verify ground reference, common mode, isolation and measurement category.
The probe is part of the measurement. A long ground lead or high input capacitance can visibly change a fast circuit. Check scope, probe, connection method and circuit as one system.
Do not measure mains, floating circuits or high differential voltages with a standard grounded probe. Use an appropriate method and have safety-critical measurements reviewed.
Define signal type, maximum voltage, fastest edge, channel count and capture time. Then view oscilloscopes and oscilloscope probes and compare full specifications.