Systems for Sensing Doppler Shifts

A radar system, comprising:

• a transmitter system configured to transmit an outgoing series of radio frequency (RF) pulses toward a target region, the outgoing series of RF pulses having a reference phase modulation;
• and
• a receiver system configured to receive an incoming series of RF pulses that is based on the outgoing series of RF pulses after passing through the target region, the receiver system comprising:
• a vapor cell system comprising a vapor and configured to produce output signals that are based on laser signals and the incoming series of RF pulses interacting with the vapor, the laser signals generated by a laser system;
• and
• a signal processing system configured to receive the output signals and perform operations that comprise:
• generating, based on the output signals, response data that represents a response of the vapor to the laser signals and the incoming series of RF pulses, the response data comprising transient response data that represents one or more transient responses of the vapor to respective phase changes in the incoming series of RF pulses, the respective phase changes based on the reference phase modulation of the outgoing series of RF pulses, and
• determining, based on the transient response data, a Doppler shift in the incoming series of RF pulses, the Doppler shift resulting from the outgoing series of RF pulses interacting with an object in the target region, and
• determining a velocity of the object based on the Doppler shift.