摘要:
An audio processing system (100) for use in a teleconferencing system (10) utilizes complementary comb filters (42, 52, 220, 320) in combination with an echo suppressor (210, 310) and/or a frequency scaler (60, 120) to substantially improve acoustic stability margin and reduce far-end talker echo.
摘要:
An audio processing system for use in teleconferencing systems having high and low transmission delays. The audio processing system utilizes complementary comb filters in combination with auxiliary echo suppressors, a frequency scaler, expander/gates and automatic level controlling devices to substantially improve acoustic stability margin and reduce far-end talker echo.
摘要:
A teleconferencing system (100, 100') provides a wide aspect ratio view at each site utilizing a single NTSC camera (250, 350) and projector (260,360). At the transmitting end of a teleconference, a transformation element (280, 380, 510, 610) maps a wide aspect ratio field of view into the field of view of an NTSC camera. The transformation is reversed at the receiving end of the teleconferencing system.
摘要:
A teleconferencing system 100 is disclosed having a video camera for generating a video signal representative of a video image of a first station B. A microphone array 150, 160 is also provided in the first station for receiving a sound from one or more fixed non-overlapping volume zones 151, 152, 153, 154, 155, 156, 157, 158, 159, into which the first station is divided. The microphone array is also provided for generating a monochannel audio signal 170 representative of the received sound and a direction signal indicating, based on the sound received from each zone, from which of the volume zones the sound originated. The teleconferencing system also includes a display device 120A at a second station A for displaying a video image of the first station. A loudspeaker control device 140 is also provided at the second station for selecting a virtual location 121 on the displayed video image depending on the direction signal, and for generating stereo sound from the monochannel audio signal which stereo sound emanates from the virtual location on the displayed video image.
摘要:
A method and apparatus for reducing the bit error probability of data transmitted over a Rayleigh fading channel are disclosed.A relatively high bit rate serial stream of data is divided into N parallel relatively low bit rate streams of data. A controlled amount of intersymbol interference is introduced in the parallel streams. The N parallel streams are then transmitted simultaneously over the Rayleigh fading channel. Each bit in the N parallel stream of data has a duration longer than the duration of the typical Rayleigh fade. Thus there is a reduced probability that a Rayleigh fade will cause a bit error.