I know there are a lot of posts similar to this one but some differences make it worth posting it.
I’m working on a project where I have a 5MHz AC signal with the largest amplitude of +-50V. It’s an ultrasonic signal where the transmitted signal has higher amplitude than the received. I want to sample both the transmitted and the received signals so that I can later calculate the distance between them. The DSP I'm using for this is TMS320F28335 from texas instruments, which only takes in 0-3.3V.
At first I thought a simple resistor divider would do the work but I encountered some problems, almost as those described in “How to Convert 0 to 10V analog signal to 0 to 2.5V for ADC input?”. However, the answers described there show how a signal can be linearly converted to a smaller voltage range. But since I’m not interested in the height of the transmitted signal (only interested in where it is relative the received signal) I want to clip parts of it and at the same time reduce the amplitude of the received signal. I want the received signal to have a good SNR as possible given the 3.3V limitation. Any ideas of methods I can use? I’m also wondering what the DSP will do with all the negative values I have?