Although `` Doppler '' has become synonymous with `` velocity measurement '' in medical imaging , in many cases it is not the frequency shift -LRB- Doppler shift -RRB- of the received signal that is measured , but the phase shift -LRB- when the received signal arrives -RRB- .

Another word for `` causer '' is `` sender '' . Another word for `` change in distance '' is `` speed '' .
