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Switchable coupling apparatus for television receiver only installation
| Details |
Inventors: Singer, Samuel;
Assignee:
Primary Examiner: LaRoche; Eugene R.
Assistant Examiner: Lee; Benny
Attorney, Agent or Firm: Rogers, Bereskin & Parr
A non-radiating broadband microwave coupling device has a housing with first and second signal inputs and outputs, which are connected by respective first and second conductive connection line portions. A third output, also within the housing, is connected to these connection line portions by first and second semiconductor switches, which preferably are connected to parallel coupling line portions to provide inductive coupling. The semiconductor switches are selectively operable to close or switch the respective connection line through to the third output and open the other switch so that there is no significant power transfer to the third output. The connection line portions and the semiconductor switches are shielded within the housing. A corresponding terminator device has a termination resistor, which provides a ground connection for the coupling line portion not connected through to the output. A multiple outlet switch device provides a plurality of output with semiconductor switches controlling the connections to the inputs. One or more of the coupling devices can be combined with the terminator device. |
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DETAILED DESCRIPTION The present invention can be employed in a multiple television receiver only system comprising: a Low Noise amplifier; a block down converter for converting a received signal band down to a band at an intermediate frequency; and coupling means, which can be connected to a plurality of receiver units.
Preferably, the block down converter output has a frequency in the range 950-1450 megahertz, as this frequency band has been selected as the Direct Broadcasting System conversion frequency.
Consequently it makes both the multiple television receiver only and the Direct Broadcasting System compatible, with minor changes.
It should ensure that this frequency band will remain free of interference in the foreseeable future.
The selection of this frequency range has other advantages.
Selection of a band at a lower frequency could enable low cost UHF TV tuners to be used as front ends of the receiver units.
However, the performance of such tuners is quite low.
Further, due to the saturation of the UHF band, such a system is prone to interference.
It is anticipated that interference problems will become more severe as the consequence of the projected growth of cellular radio and mobile communication services, using this frequency band.
Satellite TV transmissions are polarized, in order to get the requisite number of channels into the band that is used.
Thus, each transmitted signal is polarized into so-called horizontal and vertical signals i.
e.
first and second signals which are orthogonal to one another, which need to be separated.
In a simple form of the present invention, as described in greater detail below, a polarizer can be provided at the horn, to select the horizontal or vertical signal, which is then amplified by the low noise amplifier.
However, for more sophisticated systems, it is preferred to use a dual, polarized feed.
The respective horizontal and vertical feeds are then amplified in separate Low Noise amplifiers.
The amplified signals are then converted down in separate block down converters
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