Method and appartus for transmitting coded audio signals through a transmission channel with limited bandwidth

A portable CODEC for transmitting high quality audio signals over a standard telephone line having a limited bandwidth and a maximum transmission rate, said portable CODEC comprising:

• a single portable housing;
• an analog mixer, within the housing, receiving an input audio signal from at least one input line, said audio mixer amplifying and mixing input audio signals to produce a single combined audio input signal;
• memory, within the housing, storing a lossy compression routine and storing at least one set of predefined psycho-acoustic parameter levels for said compression routine;
• an encoder, within the housing, converting said single combined audio input signal to a combined digital input signal at a predefined sampling rate and encoding said combined digital input signal based on said lossy compression routine stored in memory to produce a single encoded digital signal having a predefined compression ratio with respect to said single combined audio input signal;
• an analog modem, with the housing, 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 control processor, within the housing, defines said predefined sampling rate for said encoder based on said transmission rate established by said analog modem to enable said analog modem to output said encoded analog output signal at a transmission rate that does not exceed the maximum transmission rate of the telephone line.