Adjust signal to account for increase in gain

I have 2 signals recorded at 2 different locations along a beam. I excite one end of the beam, and measure the signals at 2 different points.

Within the system I have pre-amp and post-amp gain on both sensors. However, the 2 sensors have different levels of fixed gain - i.e. if sensor 2 does not hear the impulse then I turn up the gain at sensor 2 using the pre- or post-amplifier (sometimes both). Therefore, I have 2 sensors with 2 different levels of gains.

I want to compare the 2 sensors, e.g. measure amplitude change along the beam by comparing the 2 signals. Due to the difference in gain, sometimes sensor 2 has a high amplitude than sensor 1. Therefor calculating difference in gain is not possible.

Is there any way of 'reducing' sensor 2 so that is has the same gain as sensor 1? So I can compare like for like.

I am doing the processing in MATLAB.

• well, the gain might be different, but you know that gain. So, it'd be a simple manner of dividing each signal's values by the gains of the respective amplifiers to get a normalized signal. I must admit I'm not quite sure where the problem arises? Mar 25 '20 at 13:18
• Thanks. It is that simple? Mar 25 '20 at 13:58
• e.g., the pre-amp gain on one sensor is zero, but the pre-amp gain on the second sensor is 10. We just divide everything at sensor 2 by 10? Mar 25 '20 at 13:59
• Yes I agree with Marcus, if the gains you set are known you can easily remove them. Just be careful about the units. When you say pre-amp gain on second sensor is 0, I guess it must be 0dB (which translates to unity gain). OR you could add a diagram about these different stages to get a better answer. Mar 25 '20 at 14:56