Security listening system

• US 4,527,015 A
• Filed: 12/05/1983
• Issued: 07/02/1985
• Est. Priority Date: 12/05/1983
• Status: Expired due to Fees

• Current Assignee: Colin T. Chambers, James V. Rhodes
• Original Assignee: Colin T. Chambers, James V. Rhodes
• Inventors: Rhodes, James V., Chambers, Colin T.
• Primary Examiner(s): Rubinson, Gene Z.
• Assistant Examiner(s): Dwyer, James L.
• Application Number:
  US06/558,316
• Time in Patent Office: 575 Days
• Field of Search: 179/2 A, 179/5 P, 179/5 R, 179/84 R, 179/84 C
• US Class Current: 379/102.01
• CPC Class Codes: H04M 11/00 Telephonic communication systems specially adapted for combination with other electrical systems

Abstract

A security listening system activated by and transmitting over telephone lines to allow listening for sounds at a remote location over a standard telephone line using a standard telephone instrument at the calling end. The system is connected at the remote site to be monitored across the telephone standard tip/ring pair either in parallel with the standard telephone instrument or in lieu thereof. The system is powered by D.C. voltage obtained by rectifying the telephone voltage or, optionally, by a battery. The unit monitors ring sequences on the telephone line and after a pre-established number, activates the balance of the device. If thereafter during a fixed time duration a pre-established tone signal of minimum duration or longer is applied to the line, the system connects a microphone and amplifier across the telephone line to allow the listener on the other end to hear what is happening in the surrounding area. If the tone is not applied to the line before the timed duration expires, the device deactivates. The need for a tone to connect the microphone is optional.

Claims

1. A security listening system activated by and transmitting over telephone lines, comprising:

connecting means for electrically connecting to the telephone line;

first sensing means operably connected to said connecting means for sensing ring signals on the telephone line;

timer means operably connected to said first sensing means for providing a controlled time period after said sensing means senses a pre-established number of rings in a ring sequence;

second sensing means operably connected to said timer means and said connecting means for sensing the presence on the telephone line of a pre-established tone during said controlled time;

a microphone for detecting sound;

an amplifier operably connected to said microphone for producing sound detected by said microphone amplified at an output thereof;

switch means operably connected to said connecting means, said second sensing means, and said output of said amplifier for connecting said output of said amplifier to the telephone line when said pre-established tone is sensed during the duration of said controlled time period; and

restart means operably connected to said second sensing means, said switch means, and said timer means for restarting said timer upon the receipt of subsequent ones of said pre-established tone when said amplifier is connected to the telephone line whereby said controlled time period can be extended.

2. The security listening system, as claimed in claim 1, and comprising:

rectifier means having a power input connected to said connecting means and a D.C. output connected to the remaining ones of said enumerated means for providing D.C. power to said latter named means for operation derived from the power source on the telephone line.

3. A security listening system activated by and transmitting over telephone lines, comprising:

connecting means for electrically connecting to the telephone line;

counting means operably connected to said connecting means for outputting a signal when a ring sequence on the telephone line reaches a pre-established number of rings;

timer means operably connected to receive said signal from said counting means for establishing a time delay period following receipt of said signal;

frequency responsive sensor means operably connected to said connecting means for detecting the presence on the telephone line of a control signal of a pre-established frequency for a pre-established minimum duration;

switch means having an output operably connected to said connecting means and an input, and being further connected to said timer means and said sensor means for connecting said input to said output when said sensor means detects said control signal during said time delay period;

a microphone for detecting sound;

a sound amplifier having an input operably connected to said microphone and an output producing an amplified electrical signal operably connected to said input of said switch means; and

restart means operably connected to said frequency responsive sensor means and said timer means for resetting said timer means upon receipt of subsequent ones of said control signal when said switch means has said input connected to said output whereby said time delay period can be extended.

4. A security listening system activated by and transmitting over telephone lines, comprising:

sensing means operably connected to said telephone lines for sensing ring signals on said telephone lines;

counter means operably connected to said sensing means for outputting a signal after a predetermined number of ring signals;

timer means operably connected to said counter means for disconnecting said telephone lines in the absence of a tone signal after a given time from said predetermined number of ring signals;

second sensing means operably connected to said counter means for sensing the presence of a tone signal after said predetermined number of ring signals and for then outputting said signals;

microphone means for detecting sound;

switch means operably connected to said telephone lines, said counter means, and said microphone means for connecting said microphone means to said telephone lines upon receipt of said tone signal after said predetermined number of ring signals is sensed; and

restart means operably connected to said second sensing means, said switch means, and said timer means for restarting said timer means on receipt of a subsequent tone signal.