Shielding integrity testing for cable drop

• US 9,091,712 B2
• Filed: 10/27/2011
• Issued: 07/28/2015
• Est. Priority Date: 10/27/2011
• Status: Expired due to Fees

• Current Assignee: ComSonics, Inc.
• Original Assignee: ComSonics, Inc.
• Inventors: Zimmerman, Dennis A., Early, Joseph R., Comeau, Marc-Yvon
• Primary Examiner(s): Lau, Tung S
• Assistant Examiner(s): Sun, Xiuquin
• Application Number:
  US13/282,849
• Publication Number:
  US 20130110466A1
• Time in Patent Office: 1,370 Days
• Field of Search: 702/76, 702/189, 455/456, 342/459
• US Class Current: 1/1
• CPC Class Codes: G01R 29/0835 Testing shielding, e.g. for efficiency
• CPC Class Codes: H04B 17/102 Power radiated at antenna
• CPC Class Codes: H04B 17/27 for locating or positioning the transmitter
• CPC Class Codes: H04B 17/318 Received signal strength

Abstract

Signal ingress at an installations site forming a part of a broadband communication system is quantitatively evaluated for resistance to signal ingress using a computed ambient broadcast signal level based on a known location and effective radiated power of one or more transmitters. Anomalies due to signal path obstruction and/or multi-path reception are compensated by performing computations for a plurality of broadcast transmitters located in different directions from the installation site.

Claims

1. A testing instrument for quantitatively determining a measurement of shielding integrity against signal ingress in a subscriber installation of a broadband communication system, said testing instrument comprising

a tunable signal detector that can be tuned to a frequency of an over-the-air broadcast signal and measure signal power at said frequency of said over-the-air broadcast signal appearing in said subscriber installation,

a global positioning system receiver, and

a data processor that is programmed to provide a computation of a signal power level of said over-the-air broadcast signal at a location of said testing instrument determined by said global positioning system based on a location of a transmitter of known effective radiated power of said over-the-air broadcast signal for comparison with said signal power at said frequency of said over-the-air broadcast signal appearing in said subscriber installation as measured by said tunable signal detector as a said measurement of said shielding integrity of said subscriber installation against said signal ingress.

2. The testing instrument as recited in claim 1, wherein said tunable signal detector comprises a spectrum analyzer.

3. The testing instrument as recited in claim 1, wherein said tunable signal detector comprises a signal strength meter.

4. The testing instrument as recited in claim 1, wherein said data processor controls tuning of said tunable signal detector.

5. The testing instrument as recited in claim 4, wherein said tunable signal detector is tuned to a sequence of broadcast signal frequencies, each of said broadcast signal frequencies being separated from another broadcast signal frequency by a frequency interval.

6. The testing instrument as recited in claim 5, wherein said broadcast signal frequencies are FM band broadcast frequencies.

7. The testing instrument as recited in claim 1, wherein said tunable signal detector is tuned to a sequence of broadcast signal frequencies, each of said broadcast signal frequencies being separated from another broadcast signal frequency by a frequency interval.

8. The testing instrument as recited in claim 7, wherein said broadcast signal frequencies are FM band broadcast frequencies.

9. The testing instrument as recited in claim 1, further including

wherein said GPS receiver determines said location of said testing instrument.

10. A testing instrument as recited in claim 1, wherein said data processor provides sorting of signals detected by said tunable signal detector based on signal strength received from an installation site of a broadband communication system.

11. The testing instrument as recited in claim 1, wherein said data processor computes said signal power level at said frequency of said over-the-air broadcast signal at said location of said testing instrument from said location of said transmitter and said known effective radiated power.

12. The testing instrument as recited in claim 1,

wherein said data processor is programmed to include compensation for signal path obstruction and multi-path effects on said over-the air broadcast signal.

13. A method of making a measurement of resistance to signal ingress in an installation site of a broadband communication system, said method including steps of

detecting and measuring a received signal level of a signal in said installation site having a frequency which corresponds to a broadcast signal frequency while said installation site is disconnected from said broadband communication system,

determining a distance of said installation site from a broadcast transmitter of known effective radiated power at said broadcast signal frequency,

computing an over-the-air signal level at said broadcast signal frequency based on a distance from a broadcast transmitter of known effective radiated power and said broadcast frequency, and

comparing signal levels determined in said detecting and computing steps to determine a said measurement of resistance to signal ingress in said installation site of said broadband communication system.

14. The method as recited in claim 13, wherein said broadcast signal frequency is an FM broadcast signal frequency.

15. The method as recited in claim 13, including the further step of

storing locations and effective radiated power of a plurality of radio frequency transmitters in a testing instrument capable of performing said detecting step.

16. The method as recited in claim 13, including a further step of matching a plurality of signals detected in said detecting step with frequencies of transmitters local to said installation site.

17. The method as recited in claim 16, including the further step of

sorting signals detected in said detecting step by received signal strength.

18. The method as recited in claim 17, wherein an over-the-air signal strength is computed for a maximum of two transmitters in each quadrant around said installation site.

19. The method as recited in claim 13, including the further step of

determining a location of said installation site using a GPS receiver.

20. The method as recited in claim 13, wherein said computing step is further based on said known effective radiated power of said transmitter.

21. The method as recited in claim 13, wherein said computing step includes compensation for signal path obstruction and multi-path effects on said over-the air broadcast signal.