Frequency agile transponder

• US 6,433,905 B1
• Filed: 05/18/1999
• Issued: 08/13/2002
• Est. Priority Date: 09/29/1997
• Status: Expired due to Term

• Current Assignee: Alpha Technologies Services, Inc. (EnerSys)
• Original Assignee: Tollgrade Communications Incorporated (Enghouse Systems Limited)
• Inventors: Gibala, Jeffrey A., Price, James N.
• Primary Examiner(s): NEGASH, KINFE MICHAEL
• Application Number:
  US09/308,356
• Time in Patent Office: 1,183 Days
• Field of Search: 359/110, 359/115, 359/125, 359/152, 359/145-146, 359/174, 725/129, 455/73
• US Class Current: 398/139
• CPC Class Codes: H04B 10/272 Star-type networks or tree-type networks

Abstract

One or more pieces of equipment of a hybrid fiber-coaxial (HFC) network has a frequency agile transponder connected thereto. Each frequency agile transponder includes a transmitter (T) and a receiver (R) which are connectable to a coaxial line of the HFC network. Bidirectional communications can occur between a controller and each frequency agile transponder via the HFC network. The frequency agile transponder has analog inputs/outputs connectable to test points of the one or more pieces of equipment of the HFC network. The frequency agile transponder can test the test points and supply to the controller the results of the test. The transmit and receive center frequencies of the transmitter and receiver of the frequency agile transponder can be selectively and remotely adjusted by the controller to avoid signals at carrier frequencies utilized to transmit program material, data signals and/or telephony signals.

Claims

1. A frequency agile (F/A) transponder connectable to at least one test point of equipment of a hybrid fiber-coaxial (HFC) network, the F/A transponder comprising:

a receiver configured to be connected to a first cable of an HFC network, to receive from the first cable signals around a receive center frequency and to obtain from the received signals receive data;

a controller connected to receive the receive data from the receiver, with the controller configured to detect an electrical condition at the at least one test point, to compare the detected electrical condition to a predetermined electrical condition and to produce transmit data as a function of the comparison; and

a transmitter connected to receive from the controller the transmit data, with the transmitter configured to produce from the transmit data signals around a transmit center frequency and to supply the signals around the transmit center frequency to one of the first cable and a second cable of the HFC network, wherein;

the receive center frequency and the transmit center frequency are different frequencies; and

in response to a frequency change command signal received by the receiver on the first cable at the receive center frequency, at least one of (i) the receiver changes to receive signals at another receive center frequency and (ii) the transmitter changes to transmit signals at another transmit center frequency.

2. The F/A transponder as set forth in claim 1, wherein:

the transmit data includes first transmit data and second transmit data;

as a function of the comparison, the controller produces comparison digital data having at least one binary bit;

the controller converts each bit of comparison digital data having a binary value of 0 into the first transmit data and converts each bit of comparison digital data having a binary value of 1 into the second transmit data; and

the transmitter converts each first transmit data into a first frequency and converts each second transmit data into a second frequency, with the first frequency one of greater than and less than the transmit center frequency and with the second frequency the other of greater than and less than the transmit center frequency.

3. The F/A transponder as set forth in claim 1, wherein the receiver includes:

at least one band-pass filter configured to be connected to the first cable, to be tuned via the controller to receive the signals at the receive center frequency, and to band-pass filter the received signals;

at least one adjustable oscillator which produces oscillator signals;

a tuner connected to the at least one adjustable oscillator and the at least one band-pass filter, with the tuner configured to adjust the frequency of the oscillator signals of the at least one adjustable oscillator to a mixing frequency, to receive from the at least one band-pass filter the band-pass filtered signals, and to heterodyne the band-pass filtered signals and the oscillator signals at the mixing frequency to produce IF signals; and

a demodulator connected to receive from the tuner the IF signals, with the demodulator configured to demodulate from the IF signal the receive data and to provide the receive data to the controller.

4. The F/A transponder as set forth in claim 1, wherein the transmitter includes:

a direct digital synthesizer (DDS) connected to receive from the controller the transmit data, with the DDS configured to convert the transmit data into the signals around the transmit center frequency; and

a low-pass filter connected to receive from the DDS the signals around the transmit center frequency, with the low-pass filter configured to low-pass filter the signals around the transmit center frequency and to provide the low-pass filtered signals around the transmit center frequency to the one of the first cable and the second cable.

5. The F/A transponder as set forth in claim 4, wherein the transmitter further includes an enable circuit connected between the controller and the DDS, with the enable circuit configured to one of enable and disable the DDS in response to receiving a control signal from the controller.

6. The F/A transponder as set forth in claim 4, wherein:

in response to the comparison, the controller produces comparison digital data;

the transmitter further includes a programmable gate array (PGA) connected between the controller and the DDS;

the PGA is connected to receive from the controller the comparison digital data; and

the PGA is configured to convert the comparison digital data into the transmit data.

7. The F/A transponder as set forth in claim 1, further including:

an analog multiplexer connected between an analog input of the controller and the at least one test point, with the analog multiplexer configured to connect the at least one test point to the analog input of the controller; and

an attenuator connected between the analog multiplexer and the analog input of the controller, with the attenuator configured to attenuate an electrical condition at the at least one test point.

8. The F/A transponder as set forth in claim 1, wherein the controller has an analog input connected to detect an electrical condition at the at least one test point.

9. A hybrid fiber-coaxial (HFC) network for communicating data between a fiber optic head end and a subscriber, the HFC network comprising:

a fiber optic network;

a conductive cable;

a fiber optic node connected between the fiber optic network and the conductive cable, with the fiber optic node configured to receive via the fiber optic network optical signals, to convert the received optical signals into signals around a receive center frequency, to supply to the conductive cable the signals around the receive center frequency, to receive from the conductive cable signals around a transmit center frequency and to convert the received signals around the transmit center frequency into optical signals that are supplied to the fiber optic network;

a power supply configured to supply electric power to the fiber optic node; and

a frequency agile (F/A) transponder connected to the conductive cable and a test point in one of the fiber optic node and the power supply, with the F/A transponder configured to detect an electrical condition at the test point, to receive from the conductive cable the signals around the receive center frequency, and to supply to the conductive cable the signals around the transmit center frequency, wherein;

in response to receiving via the conductive cable a frequency change command signal at the receive center frequency, the F/A transponder adapts itself to at least one of (i) receive signals around another receive center frequency and (ii) to supply signals around another transmit center frequency.

10. The HFC network as set forth in claim 9, wherein the F/A transponder includes:

a receiver configured to be connected to the conductive cable, to receive from the conductive cable the signals around the receive center frequency, and to obtain from the signals around the receive center frequency receive data;

a controller connected to receive from the receiver the receive data, with the controller configured to detect the electrical condition at the test point and to produce as a function of the detected electrical condition transmit data; and

a transmitter connected to receive from the controller the transmit data, with the transmitter configured to produce from the transmit data the signals around the transmit center frequency and to supply to the conductive cable the signals around the transmit center frequency.

11. The HFC network as set forth in claim 10, wherein the receiver includes:

a band-pass filter connected to the controller, with the band-pass filter configured to be connected to the conductive cable, to be tuned via the controller to receive the signals around the receive center frequency and to band-pass filter the received signals around the receive center frequency;

an oscillator configured to be adjusted via the controller to a mixing frequency and to supply oscillator signals at the mixing frequency;

a tuner connected to the band-pass filter and the oscillator, with the tuner configured to receive from the band-pass filter the band-pass filtered signals around the receive center frequency, to receive from the oscillator the oscillator signals at the mixing frequency and to heterodyne the band-pass filtered signals around the receive center frequency and the oscillator signals at the mixing frequency to produce IF signals; and

a demodulator connected to receive the IF signals from the tuner, with the demodulator configured to obtain from the IF signals the receive data and to supply the receive data to the controller.

12. The F/A transponder as set forth in claim 10, wherein the transmitter includes:

a direct digital synthesizer (DDS) connected to receive from the controller the transmit data, with the DDS configured to convert the transmit data into the signals around the transmit center frequency; and

a low-pass filter connected to receive from the DDS the signals around the transmit center frequency, with the low-pass filter configured to low-pass filter the signals around the transmit center frequency and to supply the filtered signals around the transmit center frequency to the conductive cable.

13. The F/A transponder as set forth in claim 12, wherein:

in response to the detected electrical condition, the controller produces comparison digital data;

the transmitter further includes a programmable gate array (PGA) connected between the controller and the DDS;

the PGA is connected to receive from the controller the comparison digital data; and

the PGA is configured to convert the comparison digital data into the transmit data.

14. The HFC network as set forth in claim 9, further including:

a fiber optic head end connectable to an end of the fiber optic network opposite the fiber optic node, with the fiber optic head end configured to convert optical signals into electrical signals, and vice versa; and

a subscriber connectable to an end of the conductive cable opposite the fiber optic node.

15. The HFC network as set forth in claim 14, further including a line amplifier connected to the conductive cable between the fiber optic node and the subscriber.

16. A method of communicating over a conductive cable of a hybrid fiber-coaxial (HFC) network, the method comprising the steps of:

(a) receiving on the conductive cable a frequency change command signal modulated around a first receive center frequency; and

in response to receiving the frequency change command signal, at least one of;

(b) (i) terminating detecting on the conductive cable signals modulated around the first receive center frequency; and

(ii) detecting on the conductive cable signals modulated around a second receive center frequency; and

(c) (i) terminating transmitting on the conductive cable signals modulated around a first transmit center frequency; and

(ii) transmitting on the conductive cable signals modulated around a second transmit center frequency.

17. The method as set forth in claim 16, further including the steps of:

detecting on the conductive cable signals modulated around the first receive center frequency; and

transmitting on the conductive cable signals modulated around the first transmit center frequency.

18. The method as set forth in claim 16, further including the steps of:

converting first optical signals into the signals modulated around the first receive center frequency; and

converting signals modulated around the first transmit center frequency into second optical signals.

19. The method as set forth in claim 16, further including the steps of:

converting program material into first optical signals;

converting the first optical signals into signals modulated around a third receive center frequency; and

transmitting on the conductive cable the signals modulated around the third receive center frequency.

20. The method as set forth in claim 19, further including the steps of:

converting at least one of voice signals and data signals into signals modulated around a third transmit center frequency;

supplying to the conductive cable the signals modulated around the third transmit center frequency; and

detecting on the conductive cable the signals modulated around the third transmit center frequency.