Communications: radio wave antennas – Antennas – Switching between antennas and lines
Reexamination Certificate
1999-01-07
2001-04-03
Ho, Tan (Department: 2821)
Communications: radio wave antennas
Antennas
Switching between antennas and lines
C343S840000, C455S277100
Reexamination Certificate
active
06211844
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to satellite mini-dish multi-switches. More specifically, the invention is related to a Dual Low Noise Block and antenna multi-switch with a DC path for the terrestrial antenna port.
BACKGROUND OF THE INVENTION
Satellite mini-dish multi-switches have been available since the introduction of Dual Low Noise Block (LNB) mini-dish systems. An LNB receives a 10 GHz signal from an orbiting satellite and converts that signal down to 950-1450 MHz for reception by the mini-dish receiver. A dual LNB mini-dish system allows consumers with several receivers to receive multiple satellite signals in their home. The primary function of the multi-switch is to allow a dual LNB digital satellite mini-dish system's signal to be distributed to multiple mini-dish receivers, typically four or eight.
There are many multi-switches in the marketplace today. There are multi-switches with inputs for the A and B-side of a dual LNB system with four or eight outputs. There are multi-switches that also incorporate an outdoor VHF/UHF terrestrial antenna input for distribution to the same four or eight outputs. Amplified multi-switches, like the subject of the present invention, amplify the satellite signals and are necessary to compensate for splitter loses.
The basic function of a multi-switch is as follows. The multi-switch has an A input side rated at 13V/14V DC and a B input side rated at 17V/18V DC. Every time that a channel is changed, the satellite receiver sends either 13 or 17 volts up the coaxial cable to the multi-switch. The multi-switch detects which voltage is sent by means of a sensor and selects the appropriate LNB. The LNB routes the appropriate signal to the designated receiver. A multi-switch with antenna input will also combine the lower 50-800 MHz terrestrial antenna signals with the satellite signal for use with a single coaxial cable. It is then separated at the receiver by the use of a satellite diplexer.
All current satellite multi-switches allow DC voltage to travel up to the A and B inputs for power. However, DC voltage is not supplied to the terrestrial antenna port and hence the outdoor antenna. The main reason for this is that it is not desirable for voltage to reach a passive antenna. Voltage going to a passive antenna would distort the image. For this reason, there has never been a DC path mechanism in place for the terrestrial antenna port of a multi-switch.
There are negative aspects of not having a DC path mechanism to the terrestrial antenna port. Amplified outdoor antennas require the use of a power injector to supply DC voltage through the coaxial cable to the amplifier circuit, which is located in the antenna housing. As shown in
FIG. 1
, a consumer using an amplified outdoor antenna
118
, requiring voltage for proper operation, and a conventional multi-switch
110
, would need to place a power injector
120
between the antenna and the multi-switch. This would necessitate placing the power injector either outside or in an attic, since most cable junctions are located at those locations. These are not the most convenient or safest locations for electrically powered components.
Accordingly, there is a substantial interest in the industry for a Dual LNB multi-switch with a terrestrial antenna port that would allow a consumer to inject DC voltage from the power injector to the amplified antenna, while preventing this DC voltage from reaching a passive antenna.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a dual LNB/antenna multi-switch capable of delivering DC voltage to an amplified terrestrial outdoor antenna, requiring such voltage for its proper functioning.
It is another object of the present invention to provide a system utilizing a dual LNB/antenna multi-switch, where a power injector, necessary for injecting voltage into an amplified antenna, can be conveniently and safely placed indoors.
It is a further object of the present invention to provide a dual LNB/antenna multi-switch with a DC path to the terrestrial antenna port which can be safely used with a passive (non-amplified) antenna without distortion of a transmitted image.
Other objects, advantages and features of this invention will become more apparent hereinafter.
The solution that is subject of the present invention is a terrestrial DC path multi-switch. The new multi-switch will allow DC voltage provided by a satellite receiver to travel through the terrestrial antenna input without causing interference/distortion or lowering the signal strength of the satellite and terrestrial antenna pictures. By including an external DC block adapter with the invention, the multi-switch can be used with both amplified and non-amplified antennas. When using a non-amplified antenna, the external DC block adapter blocks the DC path in the antenna port eliminating any voltage from reaching the passive antenna. When using an amplified antenna, the power is provided by the satellite receiver.
REFERENCES:
patent: 5774194 (1998-06-01), Armbruster
patent: 6038594 (2000-03-01), Puente et al.
Davi Leonard A.
Gilbert Harvey
Ho Tan
Levisohn, Lerner, Berger & Langsam
Recoton Corporation
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