DETECTION APPARATUS

• US 3,742,433 A
• Filed: 06/18/1971
• Issued: 06/26/1973
• Est. Priority Date: 06/23/1970
• Status: Expired due to Term

• Current Assignee: Graeme Leslie James, Leslie Kay
• Original Assignee: Graeme Leslie James, Leslie Kay
• Inventors: Kay, Leslie, James, Graeme Leslie
• Primary Examiner(s): Farley, Richard A.
• Application Number:
  US05/154,476
• Time in Patent Office: 739 Days
• Field of Search: 340/1R,3FM
• US Class Current: 367/96
• CPC Class Codes: G01S 15/06 Systems determining the position data of a target
• CPC Class Codes: G01S 15/34 using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal
• CPC Class Codes: G01S 7/5345 Gain control of receivers for seismic signals G01V1/245
• CPC Class Codes: G09B 21/006 using audible presentation of the information
• CPC Class Codes: Y10S 367/901 Noise or unwanted signal reduction in nonseismic receiving system
• CPC Class Codes: Y10S 367/91 Portable sonar devices

Abstract

An apparatus for detecting and providing positional information as to an object in a field of view primarily for aiding blind persons comprising a frequency swept transmitting transducer and two receiving channels receiving reflected frequency swept incoming signals sampled in the channels respectively by encoders fed with time staggered switching pulses to generate a multiplex signal fed to a single variable gain amplifier, the output of which is decoded in the later portions of the two receiving channels to develop audio signals derived from the incoming signals received by the receiving transducers, the amplifier having a gain control circuit responsive to the output of an ambient noise sensor.

Claims

1. Apparatus for detecting and providing positional information as to an object in a field of view comprising:

a. transmitting means for radiating acoustic wave energy to a field of view at a frequency which is varied cyclically through a range of values, b. receiving means for receiving the wave energy on reflection from an object in the field of view and including a receiving channel containing a modulator means, c. means for generating a local signal of a frequency varying cyclically and in conformity with the frequency variation of the transmitting means, d. means for feeding said local signal to said modulator means to heterodyne with an incoming signal in said receiving channel to produce a beat signal of difference frequency therein whereof the frequency is within the audible range and varies through a range of values as the distance of the object varies from maximum to minimum, e. sound reproducing means connected to said receiving channel for reproducing said beat signal audibly, f. an ambient noise sensing circuit providing a control voltage dependant upon the level of ambient noise, g. gain control means in said receiving channel connected to said sensing circuit and responsive to said control voltage to provide an increase in gain as said ambient noise rises and a decrease in gain as said ambient noise falls.

2. Apparatus according to claim 1 wherein:

a. said receiving means includes two channels each containing a respective modulator means, b. said sound reproducing means comprises respective aural elements for providing audible signals to the left and right-hand ears of the user, c. said receiving means includes an encoding means fed with signal components from said two receiving channels and generating a multiplex signal, d. said receiving means further includes an amplifier presenting a single channel and fed with said multiplex signal, e. said amplifier includes said gain control means, f. said receiving means further includes decoding means connected to said amplifier to receive output therefrom and for separating from said multiplex signal two audio components derived respectively from said signal componenets for feeding to said aural elements respectively.

3. Apparatus according to claim 2 wherein:

a. said encoding means comprises a switching circuit, b. said decoding means comprises a switching circuit, c. said receiving means includes a switching signal generator connected to supply a switching signal to both said encoding means and said decoding means,

4. Apparatus according to claim 3 wherein:

a. said encoding means comprises two switching circuits connected in respective receiving channels, b. said decoding means comprises two switching circuits connected in said receiving channels, c. said switching signal generator comprises a pulse generating means having respective outputs at which are furnished two trains of pulses with the pulses of one train occurring in the time intervals between the pulses of the other train, d. one of said outputs of said pulse generating means being connected to said switching circuits in one channel, e. the other of said outputs of said pulse generating means being connected to said switching circuits in the other channel.