Wave transmission lines and networks – Coupling networks – Frequency domain filters utilizing only lumped parameters
Reexamination Certificate
2002-01-15
2002-11-05
Lee, Benny T. (Department: 2817)
Wave transmission lines and networks
Coupling networks
Frequency domain filters utilizing only lumped parameters
C333S185000, C439S620040
Reexamination Certificate
active
06476688
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to filters for the cable television industry.
DESCRIPTION OF THE RELATED ART
Filters and traps are well known in the cable television (CATV) industry. For example, an electrical filter for CATV use is described in U.S. Pat. Nos. 4,901,043 and 5,278,525 by the present inventor, which are expressly incorporated by reference herein.
Filters or traps are often used to limit access to specific channels to customers who have subscribed to those channels. The filters may block out frequencies corresponding to channels for which the customer has not paid. Alternatively, if the premium channels have a scrambling frequency imposed on them, the filters may block out the scrambling signals, only for the customers who have subscribed to the services.
It is common to use a plurality of filters in series. Filters having different pass bands may be combined to admit/restrict a combination of frequencies. Alternatively, more than one filter having the same pass band may be used to provide increased attenuation outside of the pass band. The multiplicity of filters for a given customer are typically placed inside a housing, which may be mounted outside of the customer's house on a pole or above ground. As the number of channels increases, it is desirable to decrease the size of the filters, so that more filters can be stored inside the housing without increasing the size of the housing.
At the same time, the requirements for integrity and ease of fabrication of the filter package have not been reduced. Therefore, an improved filter is desired.
SUMMARY OF THE INVENTION
The present invention is a filter assembly, comprising a printed circuit board having a filtering circuit and a ground plane thereon. A body receives the printed circuit board. The body is shaped so as to provide a first cable connector at an end thereof. The ground plane of the printed circuit board is connected to an inner wall of the body by solder. A nut fits on an end of the body opposite the cable connector of the body. The nut provides a second cable connector at an end thereof opposite the first cable connector. The nut is connected to the body by solder along a periphery of the nut to form a water tight seal.
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Duane Morris LLP
John Mezzalingua Assoc. Inc.
Jones Stephen E.
Koffs Steven E.
Lee Benny T.
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