### Instruction:

Extract the cause and effect entities from the following sentence:
Signal frequency will undergo Doppler-shift when the transmitter and receiver are moving relative to one another

### Assistant:

KEYWORD: when
VARIABLE: Signal frequency
AND: and
CONDITION: will undergo Doppler-shift
CAUSE_1: the transmitter
CAUSE_2: receiver are moving relative to one another
EFFECT_1: Signal frequency will undergo Doppler-shift

