low frequency or random pulse amplification

[panfilero]

Hello,

I have a question about where do frequencies end and pulses start?

I'm trying to make an impact detection circuit, I have some sensors on a mat, and when something strikes the mat I get a small voltage (like 100mV).... so I'd like to amplify this 100mV to something around 1V....

I've been reading up online on how to do this, and the app notes and other sources I've found say that it's important to take the frequency of my system into account and make sure my amp can handle that frequency range...

I don't know what the frequency of my system could be... if I get one impact a minute... is that even a frequency? or just detecting a pulse... do I even need to worry about the frequency range if I'm just detecting random events? maybe I start seeing 1 impact per second... now I'm at 1Hz.... does this require a special kind of op-amp?

Does a single voltage spike have a frequency associated with it that I need to take into consideration when creating my amplifier?

as you can see I'm pretty confused about this low frequency/impulse stuff.... any help is greatly appreciated,
thanks!

 

[MikeMl]

Even if it is a pulse, you need to consider the rise and fall times of the leading and trailing edge, respectively. Frequently, such a signal is capacitively-coupled, which means that the amplifier does not have gain to DC. To enhance the pulse in the presence of noise, frequently, the high frequencies are rolled off, too.

 

[crutschow]

The highest frequency associated with a pulse is approximately 0.35 divided by the pulse rise-time where the rise-time is measured from the 10% to the 90% point of the rise (or fall). Thus if your system has a frequency response higher than this calculated value, it will pass the pulse rise and fall.

The width of the pulse determines the required low frequency response. For 10% droop of a flat top pulse, the low frequency response must be no higher than 1/(2*Pi*0.1t) where t is the time of the flat top part of the pulse.