Monitor/hands-free intercom

• US 6,091,329 A
• Filed: 09/25/1997
• Issued: 07/18/2000
• Est. Priority Date: 11/13/1995
• Status: Expired due to Fees

• Current Assignee: Evenflo Company Incorporated (Goodbaby International Holdings Limited)
• Original Assignee: Evenflo Company Incorporated (Goodbaby International Holdings Limited)
• Inventors: Newman, Perran V. L.
• Primary Examiner(s): Bost, Dwayne D.
• Assistant Examiner(s): Gantt, Alan T.
• Application Number:
  US08/937,482
• Time in Patent Office: 1,027 Days
• Field of Search: 455/88, 455/67.3, 455/134, 455/9, 455/507, 455/517, 455/519, 455/526, 455/521, 340/539, 340/573.1, 340/286.05, 340/286, 379/38.3
• US Class Current: 340/539.15
• CPC Class Codes: G08B 21/0208 Combination with audio or video communication, e.g. combination with "baby phone" function
• CPC Class Codes: G08B 21/0222 Message structure or message content, e.g. message protocol
• CPC Class Codes: H04B 1/40 Circuits

Abstract

A monitor/hands-free intercom system includes a child unit and a parent unit which are each transceivers. The parent unit operates primarily as a receiver, unless and until a talk switch is actuated on the parent unit, enabling the parent unit to transition to a transmitter. The child unit acts primarily as a transmitter unless and until it detects a carrier signal at the appropriate frequency during one of its short sniff periods. If a carrier signal is detected, the child unit extends the sniff period to look for a non-audible hidden tone encoded into the transmission from the parent unit. If the hidden tone is detected, the child unit transitions to a receiver mode and is able to play back the sound waves detected by the parent unit so that the parent can reassure or provide instructions to the child.

Claims

1. A monitor system, comprising:

a first transceiver having a first transducer to detect and convert sound waves in the vicinity thereof to a transmitted RF signal representative thereof and a second transducer with a first portion to detect and convert a received RF signal into an audio signal and a second portion to convert the audio signal to sound waves in the vicinity thereof, the first and second transducers operating one at a time, with the one operating being selectable; and

a second transceiver having a first transducer to detect and convert sound waves in the vicinity thereof to a transmitted RF signal representative thereof, the transmitted RF signal also including a predetermined code inserted therein, and a second transducer to detect and convert a received RF signal into sound waves in the vicinity thereof, the first and second transducers operating one at a time, with the one operating being selectable;

wherein the first transceiver primarily and automatically has the first transducer selected and the second transceiver primarily and automatically has the second transducer selected, to provide communication from the first transceiver to the second transceiver, and wherein the second transceiver can select the first transducer of the second transceiver when actuated by an operator thereof, and further wherein the first transceiver automatically and periodically disables the first transducer of the first transceiver and enables the first portion of the second transducer for a predetermined time duration during each period to analyze whether an RF signal is being received and whether the received RF signal includes the predetermined code and, if the predetermined code is included, maintaining the selection of the second transducer to provide communication from the second transmitter to the first transmitter.

2. A monitor system, comprising:

a first transceiver having a first transducer to detect and convert sound waves in the vicinity thereof to a transmitted RF signal representative thereof and a second transducer with a first portion to detect and convert a received RF signal into an audio signal and a second portion to convert the audio signal to sound waves in the vicinity thereof, the first and second transducers operating one at a time, with the one operating being selectable; and

a second transceiver having a first transducer to detect and convert sound waves in the vicinity thereof to a transmitted RF signal representative thereof, the transmitted RF signal also including a predetermined code inserted therein, and a second transducer to detect and convert a received RF signal into sound waves in the vicinity thereof, the first and second transducers operating one at a time, with the one operating being selectable;

wherein the first transceiver primarily has the first transducer selected and the second transceiver primarily has the second transducer selected, to provide communication from the first transceiver to the second transceiver, and wherein the second transceiver can select the first transducer of the second transceiver when actuated by an operator thereof, and further wherein the first transceiver periodically disables the first transducer of the first transceiver and enables the first portion of the second transducer for a predetermined time duration during each period to analyze whether an RF signal is being received and whether the received RF signal includes the predetermined code and, if the predetermined code is included, maintaining the selection of the second transducer to provide communication from the second transmitter to the first transmitter;

wherein the predetermined code includes a hidden tone.

3. A monitor system as defined in claim 2, wherein the hidden tone is a tone outside of the core range of humanly-perceptible audio frequency.

4. A monitor system as defined in claim 3, wherein the hidden tone is greater than approximately 5 kHz.

5. A monitor system as defined in claim 3, wherein the hidden tone is less than approximately 1 kHz.

6. A monitor system as defined in claim 2, wherein the first transceiver also inserts a hidden tone into its transmissions when the first transducer is selected, and the second transceiver only produces sound waves when the hidden tone is received.

7. A monitor system as defined in claim 6, wherein the hidden tone inserted by the first transceiver is different than the hidden tone inserted by the second transceiver.

8. A monitor as defined in claim 7, wherein the hidden tones are greater than approximately 5 kHz.

10. A monitor system as defined in claim 2, wherein the predetermined time period is approximately 0.6 seconds.

11. A monitor system as defined in claim 2, wherein the predetermined time duration is approximately 6 ms.

12. A monitor system as defined in claim 2, wherein the predetermined time duration includes a first predetermined time duration to determine if an RF signal is being received and a second predetermined time duration which is only entered if an RF signal is being received, the second predetermined time duration existing to determine if the predetermined code is being received.

13. A monitor system as defined in claim 12, wherein the first predetermined time duration is approximately 6 ms.

9. A monitor system, comprising:

a first transceiver having a first transducer to detect and convert sound waves in the vicinity thereof to a transmitted RF signal representative thereof and a second transducer with a first portion to detect and convert a received RF signal into an audio signal and a second portion to convert the audio signal to sound waves in the vicinity thereof, the first and second transducers operating one at a time, with the one operating being selectable; and

a second transceiver having a first transducer to detect and convert sound waves in the vicinity thereof to a transmitted RF signal representative thereof, the transmitted RF signal also including a predetermined code inserted therein, and a second transducer to detect and convert a received RF signal into sound waves in the vicinity thereof, the first and second transducers operating one at a time, with the one operating being selectable;

wherein the first transceiver primarily has the first transducer selected and the second transceiver primarily has the second transducer selected, to provide communication from the first transceiver to the second transceiver, and wherein the second transceiver can select the first transducer of the second transceiver when actuated by an operator thereof, and further wherein the first transceiver periodically disables the first transducer of the first transceiver and enables the first portion of the second transducer for a predetermined time duration during each period to analyze whether an RF signal is being received and whether the received RF signal includes the predetermined code and, if the predetermined code is included, maintaining the selection of the second transducer to provide communication from the second transmitter to the first transmitter;

wherein the first transceiver also inserts a predetermined code into its transmissions when the first transducer is selected, and the second transceiver only produces sound waves when the predetermined code is received;

wherein the first transceiver disables the code momentarily before each periodic selection of the second transducer.

14. A monitor system comprising:

a first transceiver having a first transducer to detect and convert sound waves in the vicinity thereof to a transmitted RF signal representative thereof and a second transducer with a first portion to detect and convert a received RF signal into an audio signal and a second portion to convert the audio signal to sound waves in the vicinity thereof, the first and second transducers operating one at a time, with the one operating being selectable; and

a second transceiver having a first transducer to detect and convert sound waves in the vicinity thereof to a transmitted RF signal representative thereof, the transmitted RF signal also including a predetermined code inserted therein, and a second transducer to detect and convert a received RF signal into sound waves in the vicinity thereof, the first and second transducers operating one at a time, with the one operating being selectable;

wherein the first transceiver primarily has the first transducer selected and the second transceiver primarily has the second transducer selected, to provide communication from the first transceiver to the second transceiver, and wherein the second transceiver can select the first transducer of the second transceiver when actuated by an operator thereof, and further wherein the first transceiver periodically disables the first transducer of the first transceiver and enables the first portion of the second transducer for a predetermined time duration during each period to analyze whether an RF signal is being received and whether the received RF signal includes the predetermined code and, if the predetermined code is included, maintaining the selection of the second transducer to provide communication from the second transmitter to the first transmitter;

wherein the predetermined time duration includes a first predetermined time duration to determine if an RF signal is being received and a second predetermined time duration which is only entered if an RF signal is being received, the second predetermined time duration existing to determine if the predetermined code is being received;

wherein the sum of the first predetermined time duration and the second predetermined time duration is approximately 20 ms.

15. A method of providing an intercom function in a primarily one-way monitor system, the monitor system including a first transceiver which primarily transmits signals representative of detected sound waves for reception and transduction into sound waves by a second transceiver, the intercom function providing the capability for the first transceiver to receive signals representative of sound waves detected and sent by the second transceiver, the method comprising the steps of:

the second transceiver receiving a signal indicating the intent of an operator of the second transceiver to transmit signals representative of sound waves detected by the second transceiver;

the second transceiver transmitting the signals representative of sound waves detected by the second transceiver, and inserting a predetermined code into the transmission; and

the first transceiver automatically and periodically ceasing to transmit for predetermined time durations and analyzing the signal received by the first transceiver to determine if the second transceiver is transmitting, and, if so, analyzing the received signal to determine if the predetermined code is being received, and, if so, leaving the first transceiver in a receive mode wherein the received signal is converted to sound waves by a transducer therein.

16. A monitor system, comprising:

a first transceiver and a second transceiver, each transceiver including;

a transmitter including;

a microphone generating a detected signal;

a microphone preamplifier receptive of the detected signal and generating an amplified detected signal;

a hidden tone generator generating a hidden tone;

a modulator receptive of the amplified detected signal and the hidden tone and supplying a modulated signal;

an oscillator receptive of the modulated signal and supplying an RF signal;

an RF power amplifier receptive of the RF signal and supplying an amplified RF signal;

an antenna receptive of the amplified RF signal and generating transmitted electromagnetic waves and also receptive of received electromagnetic waves and supplying a received RF signal; and

a receiver including;

an impedance matching network receptive of the received RF signal and generating a matched RF signal;

a mixer receptive of the matched RF signal and mixing the matched RF signal with a generated RF signal to produce an IF signal;

a demodulator receptive of the IF signal and supplying a demodulated audio signal;

a hidden tone detection circuit receptive of the demodulated audio signal and detecting the presence of a hidden tone therein;

an audio power amplifier receptive of the demodulated audio signal and supplying an amplified audio signal; and

a speaker receptive of the amplified audio signal and supplying sound waves;

wherein the first transceiver acts primarily as a transmitter and the second transmitter acts primarily as a receiver, the second transceiver also including a switch to convert the second transceiver to a transmitter while actuated, the first transmitter including a sniffing oscillator to periodically convert the first transceiver to a receiver for predetermined time durations to determine if an RF signal is being received and to maintain the first transceiver as a receiver while the hidden tone from the second transceiver is being detected.