Echo recognition system
AssigneePolaroid Corporation
InventorJohn M. Reynard
Life of this patent
Estimating the term…
Abstract
An echo-type range finding system is rendered unresponsive to spurious signals and electronic noise, and has its object distance determining accuracy improved by rejecting signals that do not persist for a predetermined period of time.
Claims10
A method of detecting a previously transmitted signal of energy returning from a selected target in the presence of energy signals from the source of other than the target, comprising the steps of:
- continuously sampling said returning target signal for a number of consecutive time intervals that are of very short time duration relative to the total time duration of said target signal;
- establishing that the sampled target signal magnitude increases between consecutive sampling intervals;
- establishing that the rate of increase of target signal magnitude between consecutive sampling intervals is greater than or equal to a predetermined rate of increase;
- and
- establishing that said signal magnitude increase and said rate of signal magnitude increase between consecutive sampling intervals is continuous for at least a predetermined portion of the total time duration of said returning target signal.
In a ranging system having means for transmitting a burst of energy toward a selected target and for then receiving energy so as to detect an echo from said target, the improvement wherein said transmitting and receiving means includes:
- means for providing a sum signal by summing a received signal over a number of consecutive sampling intervals of very short duration relative to the anticipated duration of an echo from a typical target;
- and
- means for identifying an echo as received from said selected target only when said sum signal progressively increases during each consecutive interval over a predetermined time.
A ranging method for detecting an echo from a selected target in the presence of spurious signals, said method comprising the steps of:
- summing the energy of received signals over a number of consecutive sampling intervals of short duration relative to the anticipated duration of an echo from a typical target so as to provide a sum signal;
- and
- establishing that an echo is received from said selected target only when said sum signal increases during each consecutive interval over a predetermined period of time.
Dependencies are inferred from the claim text.