Hi Guys
I had a lab lesson at uni the other week and it was structured to help us understand data communication.
We were using a sig gen as an input and then a piece of kit designed for education to sample the input, encode it and send it to a reciever which decodes it and reconstructs the signal on the scope again.
However what we found was that modulation appeared when we started to increase the frequency past a certain point.
What i didnt understand was why the modulation appeared. What i understand about modulation there must be two signals mixed together to for a modulated signal, up the frequency spectrum. However we were only using one frequency at the input (from the sig gen) and one internal clock frequency on the piece of kit to sample the input and encode it for transmission(but they were not connected or mixed)
where does the modulation come from?
We were told this is why it is very important to use anti aliasing filters to prevent this but i didnt understand where the modulation came from.
andy
sorry for the long post its going to be a couple of weeks until i can get back to uni to ask my lecturer so i though some of you guys could help me out.
I had a lab lesson at uni the other week and it was structured to help us understand data communication.
We were using a sig gen as an input and then a piece of kit designed for education to sample the input, encode it and send it to a reciever which decodes it and reconstructs the signal on the scope again.
However what we found was that modulation appeared when we started to increase the frequency past a certain point.
What i didnt understand was why the modulation appeared. What i understand about modulation there must be two signals mixed together to for a modulated signal, up the frequency spectrum. However we were only using one frequency at the input (from the sig gen) and one internal clock frequency on the piece of kit to sample the input and encode it for transmission(but they were not connected or mixed)
where does the modulation come from?
We were told this is why it is very important to use anti aliasing filters to prevent this but i didnt understand where the modulation came from.
andy
sorry for the long post its going to be a couple of weeks until i can get back to uni to ask my lecturer so i though some of you guys could help me out.