Narrowband tia and signaling for optical distance measurement systems

Abstract

An optical distance measurement system includes a transmission circuit and a receive circuit. The transmission circuit is configured to generate narrowband intensity modulated light transmission signals over a first band of frequencies and direct the narrowband light transmission signal toward a target object. The receive circuit is configured to receive reflected light off the target object, convert the reflected light into a current signal proportional to the intensity of the reflected light, filter frequencies outside a second band of frequencies from the current signal to create a filtered current signal, and convert the filtered current signal into a voltage signal. The second band of frequencies corresponds with the first band of frequencies.

What is claimed is: 
     
         1 . An optical distance measurement system, comprising:
 a transmission circuit configured to generate narrowband light transmission signals over a first band of frequencies and direct the narrowband light transmission signals toward a target object; and   a receive circuit configured to:
 receive light and convert the light into a current signal proportional to an intensity of the light; 
 filter frequencies outside a second band of frequencies from the current signal to create a filtered current signal, the second band of frequencies corresponding with the first band of frequencies; and 
 convert the filtered current signal into a voltage signal. 
   
     
     
         2 . The optical distance measurement system of  claim 1 , wherein the transmission circuit includes:
 a modulation signal generator configured to generate modulated narrowband carrier signals in the first band of frequencies; and   a transmission driver coupled to a light-emitting circuit, the transmission driver optimized for narrowband modulation of current.   
     
     
         3 . The optical distance measurement system of  claim 2 , wherein the modulated narrowband carrier signals are single tone signals. 
     
     
         4 . The optical distance measurement system of  claim 2 , wherein the modulated narrowband carrier signals are single tone signals with phase modulation. 
     
     
         5 . The optical distance measurement system of  claim 2 , wherein the modulated narrowband carrier signals are single tone signals with amplitude modulation. 
     
     
         6 . The optical distance measurement system of  claim 2 , wherein the modulated narrowband carrier signals are multiple tone signals with fixed frequencies. 
     
     
         7 . The optical distance measurement system of  claim 2 , wherein the modulated narrowband carrier signals are signals with frequency modulation over a narrowband frequency range. 
     
     
         8 . The optical distance measurement system of  claim 2 , wherein the modulated narrowband carrier signals are signals with pulse position modulation over a narrow frequency range. 
     
     
         9 . The optical distance measurement system of  claim 2 , wherein the receive circuit is further configured to determine a distance from the optical distance measurement system to the target object based on an estimated phase shift between the modulated narrowband carrier signals and the voltage signal. 
     
     
         10 . The optical distance measurement system of  claim 1 , wherein the receive circuit is further configured to determine a distance from the optical distance measurement system to the target object based on a direct time of flight of the narrowband light transmission signals. 
     
     
         11 . The optical distance measurement system of  claim 1 , wherein the received light is light reflected off the target object. 
     
     
         12 . The optical distance measurement system of  claim 2 , wherein the light-emitting circuit is a laser diode circuit. 
     
     
         13 . The optical distance measurement system of  claim 1 , wherein the receive circuit includes a tuning network. 
     
     
         14 . The optical distance measurement system of  claim 13 , wherein the tuning network is configured to tune the receive circuit to a resonant frequency of the light transmission signals. 
     
     
         15 . The optical distance measurement system of  claim 13 , wherein the tuning network includes a bandpass filter.