5 ms·
Do they actually sample the baseband digitally? I would expect that they are looking at the return as an amplitude modulated and phase-shifted signal at the ca
by spott 10y ago
Do they actually sample the baseband digitally?
I would expect that they are looking at the return as an amplitude modulated and phase-shifted signal at the carrier frequency. They remove the carrier frequency and then look at the (much slower) modulation frequency.
I'm not sure what you gain from looking directly at the carrier frequency...
- temac 10y agoYou don't necessarily need the baseband (I'm not even sure if you ever need it) & depending on the mode you can tune the amount of bandwidth needed.
- sharpneli 10y agoThe relative bandwidth in ultasound is immense conpared to radar etc where a relatively narrow bandwidth is used. As an example one of our probes in university days was something like from 5 to 30MHz. Doesn't save much if we would mix it down that 5. Instead of 60MHz ADC we would need 50MHz. Not worth it.