Asymmetric modem communications system and method

Abstract

An asymmetric modem communications system achieves high speed data transfers through a telephone network that includes both digital and analog communications mediums. In general, the system includes means for concurrently communicating first and second signals, respectively, in opposite directions along the connection between the communications devices and means for modulating the first and second signals with different modulation techniques. The communications occur in full duplex manner. In a possible implementation, a digital modem is interfaced to a digital network. The digital network is connected with a coder/decoder (codec). The codec is interfaced with a two-wire analog telephone connection, sometimes referred to as a copper loop. The telephone connection is interfaced with an analog modem. Both the digital and analog modems have a transmitter and a receiver. The digital modem has a transmitter that pulse modulates digital data in the sense that it generates and transmits pulse levels and a receiver that receives and demodulates signals in accordance with the standard V.34 communications protocol (employs quadrature amplitude modulation/demodulation). The analog modem has a transmitter that transmits and modulates signals in accordance with the V.34 communications protocol and a receiver that demodulates the pulse levels into digital data. With the foregoing configuration, asymmetric data communications are realized. Specifically, the analog modem communicates to the digital modem using the V.34 communications protocol at a data rate of between 33,600 b/s and 2400 b/s, inclusive, while the digital modem communicates to the analog modem at a data rate of between 64,000 b/s and 2400 b/s, inclusive.

Wherefore, the following is claimed:  
     
         1 . A system for bidirectionally communicating information between communications devices along a connection, comprising: 
 means for concurrently communicating first and second signals, respectively, in opposite directions along said connection between said communications devices; and    means for modulating said first and second signals with different modulation techniques.    
     
     
         2 . The system of  claim 1 , wherein said first signal is modulated via quadrature amplitude modulation and said second signal is modulated via pulse level modulation.  
     
     
         3 . The system of  claim 1 , wherein said concurrent is communication is asymmetric in that said first and second signals transfer data at different rates.  
     
     
         4 . The system of  claim 1 , wherein said connection includes a two wire telephone connection in series with a digital connection.  
     
     
         5 . The system of  claim 1 , further comprising: 
 a first transmitter at a first site capable of modulating said first signal using a first modulation technique and capable of transmitting said first signal from said first site to a second device along said connection;    a first receiver at said second site capable of receiving said first signal from said connection and capable of demodulating said first signal using said first modulation technique;    a second transmitter at said second site capable of modulating said second signal using a second modulation technique and capable of transmitting said second signal from said second site to said first site along said connection; and    a second receiver at said first site capable of receiving said second signal from said connection and capable of demodulating said second signal using said second modulation technique.    
     
     
         6 . The system of  claim 5 , further comprising: 
 one communications device having said first transmitter and said second receiver;    another communications device having said second transmitter and said first receiver;    a mu-law codec disposed between said one communications device and said connection; and    a digital connection interconnecting said mu-law codec and said another communications device.    
     
     
         7 . A transceiver for communicating information along a connection, comprising: 
 a transmitter capable of modulating a transmit signal using a first modulation technique and capable of transmitting said transmit signal to said connection;    a receiver capable of receiving a receive signal from said connection and capable of demodulating said receive signal using a second modulation technique that is different than said first modulation technique; and    wherein said transmit and receive signals are communicated in full duplex.    
     
     
         8 . The system of  claim 7 , wherein said first modulation technique is quadrature amplitude modulation and wherein said second modulation technique is pulse level modulation.  
     
     
         9 . The system of  claim 7 , wherein said first and second signals have different data rates.  
     
     
         10 . The system of  claim 7 , wherein said connection is a two wire analog telephone connection and said transceiver is an analog modem.  
     
     
         11 . The system of  claim 7 , wherein said connection is a digital connection and said transceiver is a digital modem.  
     
     
         12 . The system of  claim 7 , wherein said connection is an analog connection and said transceiver is an analog modem.  
     
     
         13 . A method for bidirectionally communicating information between first and second communications devices along a connection, comprising the steps of: 
 concurrently communicating first and second signals in opposite directions along said connection between said first and second communications devices; and    modulating said first and second signals with different modulation techniques.    
     
     
         14 . The method of  claim 13 , further comprising the steps of modulating said first signal with quadrature amplitude modulation and modulating said second signal with pulse level modulation.  
     
     
         15 . The method of  claim 13 , further comprising the step of communicating said first and second signals with asymmetric data rates.  
     
     
         16 . The method of  claim 13 , further comprising the step of communicating said first and second signals along both an analog connection and a digital connection.  
     
     
         17 . A method for communicating information along a connection, comprising the steps of: 
 transmitting a transmit signal to and receiving a receive signal from said connection in full duplex at a communications device;    modulating said transmit signal with a first modulation technique at said communications device; and    demodulating said receive signal with a second modulation technique that is different than said first modulation technique at said communications device.    
     
     
         18 . The method of  claim 17 , further comprising the steps of modulating said first signal with quadrature amplitude modulation and modulating said second signal with pulse level modulation.  
     
     
         19 . The method of  claim 17 , further comprising the steps of transmitting said transmit signal to and receiving said receive signal from an analog connection.  
     
     
         20 . The method of  claim 17 , further comprising the steps of transmitting said transmit signal to and receiving said receive signal from a digital connection.  
     
     
         21 . The method of  claim 17 , further comprising the step of modulating said first and second signals to have different data rates.  
     
     
         22 . The method of  claim 17 , further comprising the step of performing said steps in a modem.