Hi,
I'm new to DSP and also don't speak english that good, so please forgive me if my questions somehow sound dumb
At the output of a receiver, I have a 25KHz rectangular signal which is AM-modulated with a 125kHz sine. The modulated signal only has two amplitudes, 0 and 1 (see attached picture from a simulation I made - 010010). Though there are also some intermodulation products of (unwanted) higher frequencies (MHz) at the receiver output.
Now I want to demodulate this signal as I somehow want to convert the 25kHz rectangular signal into a digital signal (1 0 0 0 1 1 0...or whatever). To get rid of the higher frequencies I need a lowpass filter. Also, I want to do several other things with it (e.g. measurement of signal level).
My system would look like this:
| Receiver | - - -> | Amplifier | - - -> | Analog/Digital-Converter fs= ca.500kHz | - - -> | DSP |
I'd like to use the DSP most importantly for
- lowpass filtering (getting rid of all frequencies > 25kHz)
- measurement of signal level
A few questions about that, would be great if someone would be able to answer:
1. Do I need another (analog) lowpass filter before the ADC (sample theorem)?
2. What could be used as an ADC - would a simple Schmitt-Trigger do the job (I just need 1 bit as there are only two amplitudes)?
3. Do you think DSP is the best way to do this at all...are there alternatives maybe?
Thanks in advance for your answers!