Effective ranging signal recovery from coherent IQ receiver

An optical ranging system, comprising:

• a coherent IQ receiver configured to receive a radio frequency (RF)-encoded optical signal encoded with an RF pattern based on a plurality of RF signal components having different frequencies,
• wherein the coherent IQ receiver comprises a coherent IQ demodulator configured to split the RF-encoded optical signal into an in-phase (I) optical signal and a quadrature (Q) optical signal that has, relative to the I optical signal, an optical phase ambiguity that changes over time, and
• wherein the coherent IQ receiver is configured to generate an I electrical signal corresponding to the I optical signal, and generate a Q electrical signal corresponding to the Q optical signal;
• a first analog-to-digital converter (ADC) configured to convert the I electrical signal into an I digital signal;
• a second ADC configured to convert the Q electrical signal into a Q digital signal;
• and
• a processing circuit configured to square the I digital signal and the Q digital signal to generate a squared first I digital signal and a squared first Q digital signal, respectively, and sum the squared first I digital signal and the squared first Q digital signal to generate a power signal having a plurality of signal peaks,
• wherein the processing circuit is configured to analyze the power signal to determine a first signal phase corresponding to first signal peaks associated with a first target frequency and to determine a second signal phase corresponding to second signal peaks associated with a second target frequency that is different from the first target frequency,
• wherein the processing circuit is configured to determine a first distance value based on a first phase difference between the first signal phase and a reference power signal, and
• wherein the processing circuit is configured to determine a second distance value based on a second phase difference between the second signal phase and the reference power signal.

An optical ranging system, comprising:

• a coherent IQ receiver configured to receive a radio frequency (RF)-encoded optical signal encoded with an RF pattern based on a plurality of RF signal components having different frequencies,
• wherein the coherent IQ receiver comprises a coherent IQ demodulator configured to split the RF-encoded optical signal into an in-phase (I) optical signal and a quadrature (Q) optical signal that has, relative to the I optical signal, an optical phase ambiguity that changes over time, and
• wherein the coherent IQ receiver is configured to generate an I electrical signal corresponding to the I optical signal, and generate a Q electrical signal corresponding to the Q optical signal;
• a first analog-to-digital converter (ADC) configured to convert the I electrical signal into an I digital signal;
• a second ADC configured to convert the Q electrical signal into a Q digital signal;
• and
• a processing circuit configured to apply a first time interpolation to at least one of the I digital signal or the Q digital signal based on at least one first IQ skew correction value to generate a first pair of IQ signals with a first IQ skew corresponding to a first target frequency compensated,
• wherein the processing circuit is configured to apply a second time interpolation to at least one of the I digital signal or the Q digital signal based on at least one second IQ skew correction value to generate a second pair of IQ signals with a second IQ skew corresponding to a second target frequency compensated,
• wherein the processing circuit is configured to square the first pair of IQ signals to generate a squared first I digital signal and a squared first Q digital signal, and sum the squared first I digital signal and the squared first Q digital signal to generate a first power signal having a first plurality of signal peaks,
• wherein the processing circuit is configured to square the second pair of IQ signals to generate a squared second I digital signal and a squared second Q digital signal, and sum the squared second I digital signal and the squared second Q digital signal to generate a second power signal having a second plurality of signal peaks,
• wherein the processing circuit is configured to analyze the first power signal to determine a first signal phase corresponding to first signal peaks associated with the first target frequency,
• wherein the processing circuit is configured to analyze the second power signal to determine a second signal phase corresponding to second signal peaks associated with the second target frequency,
• wherein the processing circuit is configured to determine a first distance value based on a first phase difference between the first signal phase and a reference power signal, and
• wherein the processing circuit is configured to determine a second distance value based on a second phase difference between the second signal phase and the reference power signal.