COMMUNICATION SYSTEM USING LOW BANDWIDTH WIRES

• US 20140079077A1
• Filed: 11/22/2013
• Published: 03/20/2014
• Est. Priority Date: 10/22/2007
• Status: Active Grant

• Current Assignee: Corning Optical Communications LLC (Corning Incorporated)
• Original Assignee: Corning Mobileaccess Ltd.
• Inventors: Saban, Ofer, Shapira, Isaac, Shapira, Yair Zeev
• Granted Patent: US 9,813,229 B2
• Time in Patent Office: Days
• US Class Current: 370/503
• CPC Class Codes: H04J 1/06 Arrangements for supplying the carrier waves ; Arrangements for supplying synchronisation signals synchronisation in general H03B; frequency multiplication H03B19/00, H03B21/00; mixing H03D7/00, H03D9/00; carrier supply H04L5/10
• CPC Class Codes: H04L 7/0083 taking measures against momentary loss of synchronisation, e.g. inhibiting the synchronisation, using idle words or using redundant clocks
• CPC Class Codes: H04L 7/0331 with a digital phase-locked loop [PLL] processing binary samples, e.g. add/subtract logic for correction of receiver clock H04L7/0337 takes precedence

Abstract

A high frequency signal is down-converted into an intermediate frequency signal, transmitted over a limited bandwidth medium from a master unit to a remote unit and up-converted back into its original high frequency at the remote unit. The up-conversion is aided by reconstruction of a reference signal embedded at the master unit as a carrier for a management signal which is transmitted to the remote unit through the same limited bandwidth medium together with the intermediate frequency signal. The reference signal is reconstructed using a phase locked loop which includes a charge pump and is kept stable during intervals between bits and messages by a charge pump shutter.

Claims

1. A method for reconstruction of a reference signal transmitted in a communications system between a master unit having a master local oscillator and a remote unit having a remote local oscillator, the master and remote units connected by a conductive wires, the reference signal being transmitted over the wires together with a signal which is down-converted from an original high frequency signal to an intermediate frequency signal at the master unit and up-converted back into the original high frequency signal at the remote unit, the method comprising:

at the master unit, embedding the reference signal as a carrier of a management signal using a master modem;

transmitting the management signal with the embedded reference signal over the wires to the remote unit;

at the remote unit, reconstructing the reference signal from the management signal using a phase locked loop (PLL), wherein the PLL comprises a phased detector, a charge pump, a voltage controlled crystal oscillator and a capacitor; and

using the reconstructed reference signal for synchronizing the remote local oscillator with the master local oscillator.

2. The method of claim 1, wherein the management signal comprises a management data bit stream and wherein the step of reconstructing the reference signal from the management signal further comprises using a charge pump shutter coupled to the PLL and synchronized with the management data bit stream to keep the reconstructed reference signal stable.

3. The method of claim 2, wherein using a charge pump shutter coupled to the PLL and synchronized with the management data bit stream to keep the reconstructed reference signal stable comprises using the charge pump shutter to shut off the charge pump at least during intervals between transmissions of the management signal.

4. The method of claim 1, wherein the reference signal is a discontinuous signal and the PLL is adapted to filter the discontinuous reference signal.

5. The method of claim 4, wherein the charge pump controls a frequency of the voltage controlled crystal oscillator.

6. The method of claim 1, wherein transmitting the management signal from the master unit to the remote unit comprises transmitting from a first duplexer to an input duplexer.

7. The method of claim 6, further comprising separating the transmitted signal by frequency band at the input duplexer.

8. A method for reconstruction of a reference signal transmitted in a communications system between a master unit having a master local oscillator and a remote unit having a remote local oscillator, the master and remote units connected by a conductive wires, the reference signal being transmitted over the wires together with a signal which is down-converted from an original high frequency signal to an intermediate frequency signal at the master unit and up-converted back into the original high frequency signal at the remote unit, the method comprising:

at the master unit, embedding the reference signal as a carrier of a management signal using a master modem;

transmitting the management signal with the embedded reference signal from a first duplexer over the wires to an input duplexer;

separating the transmitted signal from the first duplexer by frequency band at the input duplexer;

at the remote unit, reconstructing the reference signal from the management signal using a phase locked loop (PLL); and

using the reconstructed reference signal for synchronizing the remote local oscillator with the master local oscillator.

9. The method of claim 8, wherein the management signal comprises a management data bit stream and wherein the step of reconstructing the reference signal from the management signal further comprises using a charge pump shutter coupled to the PLL and synchronized with the management data bit stream to keep the reconstructed reference signal stable.

10. A system for reconstructing a reference signal transmitted in a distributed communications over electrically conductive wires between a master unit having a master local oscillator and a remote unit having a remote local oscillator, the system comprising:

a master modem configured to embed the reference signal at the master unit as a carrier of a management signal carrying a management data bit stream and management messages between the master unit and the remote unit;

a first duplexer configured to transfer the management signal to an input duplexer; and

a phase locked loop (PLL) for reconstructing the reference signal at the remote unit, the reconstructed reference signal used to synchronize the master and remote local oscillators.

11. The system of claim 10, wherein the input duplexer is configured to separate the signal from the first duplexer according to frequency band.

12. The system of claim 10, further comprising a charge pump shutter for keeping the reconstructed reference signal stable during intervals between the management data bits and management messages.

13. The system of claim 12, further comprising a control modem at the remote unit coupled to the input duplexer and to the charge pump shutter and configured to demodulate the management signal.

14. The system of claim 12, wherein the charge pump shutter is synchronized with the management data bits.

15. The system of claim 10, wherein the PLL comprises a charge pump, a voltage controlled crystal oscillator and a capacitor configured to reconstruct the reference signal.

16. The system of claim 15, wherein the PLL has a lock time designed to be faster by a factor of at least two than the period of a management data bit.