System and method for enhanced teleconferencing security

• US 20070263085A1
• Filed: 03/30/2007
• Published: 11/15/2007
• Est. Priority Date: 03/31/2006
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Tandberg Telecom AS (Cisco Systems, Inc.)
• Inventors: Winsvold, Bjorn, Marton, Trygve, Holmbakken, Espen
• Granted Patent: US 8,212,854 B2
• Time in Patent Office: Days
• US Class Current: 348/14.90
• CPC Class Codes: H04N 7/147 Communication arrangements, e.g. identifying the communication as a video-communication, intermediate storage of the signals selecting H04Q
• CPC Class Codes: H04N 7/15 Conference systems

Abstract

A method and system with means for preventing unauthorized monitoring of a local conference room (1) in which a local conferencing system (2) is located comprising generation of a deterministic sound signal (300), and loading the deterministic sound signal on a first loudspeaker (5) connected to, or integrated in the conferencing system (2), detecting the deterministic signal (600) by analyzing a microphone signal picked up by a microphone (4) connected to, or integrated in the conferencing system (2), and transferring the conference system (2) into a security mode (1100), if the deterministic signal is not detected.

Claims

1. A method of preventing unauthorized monitoring of a local conference room (1) in which a local conferencing system (2) is located characterized in

i. generating a deterministic sound signal (300), and loading the deterministic sound signal on a first loudspeaker (5) connected to, or integrated in the conferencing system (2),

ii. detecting the deterministic signal (600) by analyzing a microphone signal picked up by a microphone (4) connected to, or integrated in the conferencing system (2),

iii. transferring the conference system (2) into a security mode (1100), if the deterministic signal is not detected.

2. The method according to claim 1, characterized in that said generated signal (300) is an audio signal, inaudible to the human auditory system.

3. The method according to claim 1 or 2,

characterized in,

ii a increasing the volume level (900) of said deterministic signal and repeating step i and ii if said detection fails (800),

ii b Continuing to step iii if said deterministic signal (300) has not been detected (700) within a predefined period of time or after a volume threshold have been reached (1000).

4. The method according to one of the preceding claims,

characterized in that the step of transferring the conference system (2) into a security mode further includes blocking and/or terminating all calls to and from the conferencing system (2), or blocking and/or terminating audio transmissions.

5. The method according to one of the preceding claims,

characterized in that the step of transferring the conference system (2) into a security mode (1100) further includes loading an alarm signal on a second loudspeaker connected to, or integrated in a codec (10) in the conferencing system (2).

6. The method according to one of the claims 2-5,

characterized in that the deterministic audio signal (300) is generated by

iv. splitting the auditory frequency band from the microphone (4) into several sub bands,

v. determining the conference room'"'"'s (1) masking threshold for each sub band,

vi. choosing the most suitable frequencies for masking said deterministic signal in the background noise of the conference room (1),

vii. converting said suitable frequency bands to a broadband signal, and add said broadband signal to said deterministic sound signal.

7. The method according to one of the preceding claims,

characterized in that the deterministic sound signal is a maximum length sequence (MLS) signal.

8. The method according to one of the preceding claims,

characterized in that the deterministic signal is detected by

viii. convolving the received signal with a time-reversed version of the original emitted signal to obtain a impulse response measurement,

ix. adding every odd measurement to an average of odd measurements, and adding every even measurement to an average of even measurements,

x. correlating the two time averaged impulse responses, weighting the peak parts of the impulse response stronger,

xi. verifying a detection if the output from said correlation exceeds a set threshold value.

9. The method according to one of the claims 1-7, characterized in

viii. dividing the received signal into sub bands,

ix. convolving the received signal with a time-reversed version of the original emitted signal to obtain a impulse response measurement for each sub band containing the emitted signal,

x. measuring the microphone energy in each sub band containing the emitted signal,

xi. adding every odd measurement to an average of odd measurements, and adding every even measurement to an average of even measurements, for each sub band containing the emitted signal, weighting the impulse response measurements with the inverse of the microphone energy, before they are added to the average,

xii. correlating the two time averaged impulse responses for each sub band containing the emitted signal, weighting the peak parts of the impulse response stronger,

xiii. adding the correlation result of all evaluated sub bands, and normalizing with respect to the energy of the impulse responses,

xiv. verifying a detection if said normalized correlation result exceeds a set threshold value.

12. The system according to claim 1 or 11, characterized in that

said signal generator is further configured to increase the volume level of said deterministic signal and reload said deterministic signal on the first loudspeaker (5), if said signal detection device is unable to detect said deterministic signal, and that

said control unit is configured to transfer the video conferencing system (2) into a security mode, if said security signal has not been detected within a predefined period of time or after a volume threshold has been reached.

10. A security system for preventing unauthorized monitoring of a local conference room (1) in which a local conferencing system (2) is located, the conferencing system (2) comprising at least a codec (10) for coding and decoding at least audio information, a microphone (4) and a loudspeaker (5) characterized in that the conferencing system further comprises:

a signal generator configured to generate a deterministic signal, and loading said deterministic signal on the first loudspeaker (5) connected to, or integrated in the conferencing system (2),

a signal detection device configured to detect said deterministic signal by analyzing an audio signal picked up by the microphone (4) connected to, or integrated in the conferencing system (2),

a control unit configured to transferring the conferencing system (2) into a security mode, if said deterministic signal is not detected in said signal detection device.

11. The system according to claim 10, characterized in that said signal generator is further configured to generate an audio signal that is inaudible to the human auditory system.

13. The system according one of the claims 10-12,

characterized in that said security system is configured to block and/or terminate all calls to and from the video conferencing system (2) when the video conference system is transferred into a security mode.

14. The system according to one of the claims 10-13,

characterized in that said control unit is further configured to load an alarm signal on a second loudspeaker connected to, or integrated in the video conferencing system'"'"'s codec (10) when the video conference system (2) is transferred into a security mode.

15. The system according to one of the claims 10-14,

characterized in that said signal generator is further configured to

split the auditory frequency band from the audio capture device (4) into several sub bands,

determine the conference room'"'"'s (1) masking threshold for each sub band,

choose the most suitable frequencies for masking said deterministic signal in the background noise of the conference room (1),

convert said suitable frequency bands to a broadband signal, and add said broadband signal to said deterministic sound signal.

16. The system according to one of the claims 10-15,

characterized in that said deterministic sound signal is a maximum length sequence (MLS) signal.

17. The system according to one of the claims 10-16,

characterized in that the signal detection device is further configured to

convolve the received signal with a time-reversed version of the original emitted signal,

add every odd measurement to an average of odd measurements, and add every even measurement to an average of even measurements,

correlate the two time averaged impulse responses, weighting the peak parts of the impulse response stronger,

verify a detection if the output from said convolution exceeds a set threshold value.

18. The system according to one of the claims 10-16, characterized in that the signal detection device is further configured to

divide the received signal into sub bands,

convolve the received signal with a time-reversed version of the original emitted signal to obtain an impulse response measurement for each sub band containing the emitted signal,

measure the microphone energy in each sub band containing the emitted signal,

add every odd measurement to an average of odd measurements, and add every even measurement to an average of even measurements, for each sub band containing the emitted signal, weighting the impulse response measurements with the inverse of the microphone energy before they are added to the average,

correlate the two time averaged impulse responses for each sub band containing the emitted signal, weighting the peak parts of the impulse response stronger,

add the correlation result of all evaluated sub bands, and normalize with respect to the energy of the impulse responses,

verify a detection if said normalized correlation result exceeds a set threshold value.