Transmit/receive switch for 10BASE-T home network

• US 6,393,050 B1
• Filed: 10/30/1998
• Issued: 05/21/2002
• Est. Priority Date: 10/30/1998
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Compaq Computer Corporation (HP Inc.)
• Inventors: Liu, Ce Richard
• Primary Examiner(s): Ghayour, Mohammad H.
• Application Number:
  US09/183,145
• Time in Patent Office: 1,299 Days
• Field of Search: 375/219, 375/220, 375/222, 379/171, 379/172, 379/173, 370/445, 370/447, 370/282, 370/293, 370/296
• US Class Current: 375/219
• CPC Class Codes: H04L 5/16 Half-duplex systems; Simplex/duplex switching; Transmission of break signals non-automatically inverting the direction of transmission

Abstract

An apparatus and method is disclosed for providing 10BASE-T Ethernet compatible data communications between multiple network elements, such as computers, computer peripherals, computerized appliances, and the like, over a two wire residential phone line. Each network element may include a 10BASE-T compatible network interface card (NIC) for interfacing between the network element and the residential phone line through the device of the present invention. A transmit/receive switch, set to a default receive position, is coupled between the two wire residential phone line and a NIC, each NIC having a transmit and receive wire pair. The NIC senses receive energy originating from the residential phone lines. When receive energy is no longer sensed at the NIC, a transmit signal may be generated by the NIC, placed on the transmit wire pair. A carrier sensor having a control logic unit changes the transmit/receive switch to transmit position when the transmit signal is detected, coupling transmit data through the switch to the residential phone line. The carrier sensor/control logic unit returns the transmit/receive switch to the receive position to resume carrier sensing in accord with CSMA/CD protocol specifications on the two wire medium.

Claims

1. A device for providing data communications over a two-wire medium between at least two units, each unit having a network controller for transmitting and receiving data, the network controller including a transmit wire pair and a receive wire pair, the device comprising:

a carrier detector for detecting signal energy on the receive wire pair and further for inhibiting the network controller from transmitting data responsive to the detection of signal energy; and

a transmit/receive switch coupled to the carrier detector, the transmit wire pair, the receive wire pair, and the two wire medium, the transmit/receive switch for selectively coupling the transmit wire pair and the receive wire pair to the two-wire medium.

2. The device as recited in claim 1, wherein the transmit/receive switch further includes a transmit position and a receive position, the transmit position forming a connection between the transmit wire pair and the two-wire medium for carrying a transmit signal, the receive position forming a connection between the receive wire pair and the two-wire medium for carrying a receive signal, and wherein the transmit/receive switch is normally positioned in the receive position.

3. The device as recited in claim 2, wherein the carrier detector further includes a control logic unit.

4. The device as recited in claim 3, wherein the control logic unit is configured to generate a signal for changing the position of the transmit/receive switch from the receive position to the transmit position, and wherein the generation of the signal is responsive to the control unit detecting energy on the transmit wire pair.

5. The device as recited in claim 1, wherein the two wire medium is a residential phone line.

6. The device as recited in claim 2, wherein the transmit signal is phase modulated and wherein the receive signal is phase modulated.

7. A method for providing 10 Base-T Ethernet compatible data communications over a two-wire medium between at least two units, each unit having a network controller for transmitting and receiving data, the network controller including a transmit wire pair and a receive wire pair, the method comprising the steps of:

detecting signal energy on the receive wire pair; and

selectively coupling the transmit wire pair and the receive wire pair to the two-wire medium so as to inhibit the network controller from transmitting data while signal energy is detected on the receive wire pair.

8. The method as recited in claim 7, wherein the step of selectively coupling further includes:

switching between a transmit position and a receive position of a switch, the transmit position connecting the transmit wire pair and the two-wire medium for carrying a transmit signal therebetween, the receive position connecting between the receive wire pair and the two-wire medium for carrying a receive signal therebetween; and

positioning the switch such that the switch default position is in the receive position.

9. The method as recited in claim 8, wherein the step of selectively coupling further includes:

generating a signal for changing the position of the switch from the receive position to the transmit position responsive to detecting energy on the transmit wire pair.

10. An interface device for coupling a two-wire phone line to a network card having a transmit wire pair and a separate receive wire pair, the device comprising:

a switch coupled to the two-wire phone line, wherein the switch is configured to couple a transmit signal to the two-wire phone line only when a transmit mode signal is asserted, and is configured to couple the two-wire phone line to a receive amplifier only when the transmit mode signal is de-asserted; and

a carrier detector coupled to the receive amplifier to detect receive signal energy, coupled to the transmit wire pair of the network card to detect transmit signal energy, wherein the carrier detector asserts the transmit mode signal to the switch only when the detected receive signal energy indicates no receive signal is present and the detected transmit signal energy indicates a transmit signal is present.

11. The device of claim 10, further comprising:

a demodulator coupled to the receive amplifier and configured to convert a receive signal to a stream of baseband receive data; and

an encoder coupled to the demodulator to receive the stream of baseband receive data and configured to convert the baseband receive data into an encoded receive signal that is provided to the network card on the receive wire pair.

12. The device of claim 11, further comprising:

a decoder coupled to the transmit wire pair to receive an encoded transmit signal, and configured to convert the encoded transmit signal into a stream of baseband transmit data; and

a modulator coupled to the decoder to receive the stream of baseband transmit data and configured to convert the stream of baseband transmit data into a transmit signal that is provided to the switch.

13. The device of claim 12, wherein the encoded transmit and encoded receive signals are 10Base-T Ethernet compatible signals.

14. The device of claim 12, wherein the transmit and receive signals are differential phase shift keying signals modulated on a carrier frequency of about 30 MHz.