Light Detection and Ranging (LIDAR) Sensor System Using Digital Down Conversion

An autonomous vehicle control system comprising:

• one or more processors;
• and
• one or more computer-readable storage mediums storing instructions that are executable by the one or more processors to cause the one or more processors to:
• generate a first waveform and a second waveform respectively having a frequency corresponding to a frequency offset;
• process the first waveform to generate down-converted in-phase (I) data;
• process the second waveform to generate down-converted quadrature (Q) data;
• combine the down-converted I data and the down-converted Q data to produce a complex signal;
• and
• determine, based on the complex signal, a range to an object in an environment of an autonomous vehicle.

An autonomous vehicle comprising:

• at least one of a steering system or a braking system;
• and
• a vehicle controller comprising one or more processors configured to:
• generate, based on a beam generated from a laser source, an optical signal that is frequency-shifted by a frequency offset relative to a local oscillator (LO) signal and that is modulated by an IQ modulation;
• control a transmitter to transmit the optical signal to an environment;
• in response to transmitting the optical signal, receive a returned optical signal that is reflected from an object in the environment;
• generate a first waveform and a second waveform respectively having a frequency corresponding to the frequency offset;
• process the first waveform using a digital signal based on the returned optical signal to generate down-converted in-phase (I) data;
• process the second waveform using a digital signal based on the returned optical signal to generate down-converted quadrature (Q) data;
• combine the down-converted I data and the down-converted Q data to produce a complex signal;
• determine, based on the complex signal, a range to an object in an environment of the autonomous vehicle;
• and
• control the at least one of the steering system or the braking system using the range to the object.