Method and apparatus for transmitting coded audio signals through a transmission channel with limited bandwidth
First Claim
1. An portable audio transmission system comprising:
- a coder for coding an input audio signal into a digital signal at a transmission speed including 28.8 kbit/s to be transmitted through a traditional analog copper telephone line generally supporting a digital signal transmission rate of at least 28.8 kbit/s; and
a decoder for decoding the digital signal that is received from a telephone network to provide an output audio signal with a, frequency range of greater than 4 kilohertz.
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Accused Products
Abstract
A digital audio transmitter system capable of transmitting high quality, wideband speech over a transmission channel with a limited bandwidth such as a traditional telephone line. The digital audio transmitter system includes a coder for coding an input audio signal to a digital signal having a transmission rate that does not exceed the maximum allowable transmission rate for traditional telephone lines and a decoder for decoding the digital signal to provide an output audio signal with an audio bandwidth of wideband speech. A coder and a decoder may be provided in a single device to allow two-way communication between multiple devices.
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Citations
35 Claims
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1. An portable audio transmission system comprising:
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a coder for coding an input audio signal into a digital signal at a transmission speed including 28.8 kbit/s to be transmitted through a traditional analog copper telephone line generally supporting a digital signal transmission rate of at least 28.8 kbit/s; and
a decoder for decoding the digital signal that is received from a telephone network to provide an output audio signal with a, frequency range of greater than 4 kilohertz.
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2. A portable CODEC for transmitting high quality audio signals over a standard telephone line having a limited bandwidth and maximum transmission rate, said portable CODEC comprising:
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a single portable housing;
a memory within the housing and storing a lossy audio compression routine;
an encoder within the housing and including a program to convert an audio input signal to a digital input signal at a sampling rate and encode said digital input signal based on said lossy compression routine stored in memory to produce an encoded digital signal having a compression ratio with respect to said audio input signal;
an analog modem within the housing and establishing a connection with, and a transmission rate for, a standard telephone line of a telephone network, said modem converting said encoded digital signal to an encoded analog output signal and outputting said encoded analog output signal at said transmission rate established by said analog modem along the standard telephone line through the telephone network; and
a processor within the housing and enabling said analog modem to output said encoded analog output signal at a transmission rate that does not exceed a predetermined transmission rate of the standard telephone line, said standard telephone line generally supporting a transmission rate of at least 28.8 kbit/s. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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17. A portable CODEC according 1 wherein said analog modem receives a single incoming encoded analog signal from said standard telephone line on said telephone network, said modem converting said single incoming encoded analog signal to a incoming encoded digital signal.
Specification