Object locator system employing variable frequency code tone generators

DETAILED DESCRIPTION In accordance with the present invention, the vehicle capacity of a vehicle locator system is increased by employing a plural interval coding sequence and by arranging each coding tone oscillator to generate more than one tone.
In this manner any oscillator can provide different tones during different intervals in the sequence, thereby minimizing the number of oscillators required to provide the various tone combinations.
The repetition rate of the pulse modulated transmitted tones is synchronized to the vehicle odometer to assure that a complete coding sequence is transmitted while the vehicle is within the receiving range of a sensor station.
In order to permit vehicle location in regions encompassing more than one local telephone office, long distance telephone lines and automatic dial up connections are employed.
To maximize efficient utilization of telephone lines, a party line system is employed wherein the locator system shares telephone lines with other telephone system users.
Other features are disclosed, such as: the use of radio links between sensor stations and a central office (in place of telephone lines); delayed from one or more vehicle emitters which are proximate the same sensor station to avoid garbling of two or more simultaneously received codes; and adaptation of the system for use in predestrian (rather than vehicle) location.