JP3191133U - Broadcast signal filter device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a filter device for rejecting reception of a specific satellite broadcasting channel. A circuit is provided in which a plurality of LC parallel circuits are connected in series to a signal line connecting an input terminal and an output terminal, and a plurality of LC series circuits are connected in parallel between the signal line and the ground line. Attenuate the signal of the center frequency of the satellite broadcasting channel that you want to make it impossible to receive by 20 dB or more, attenuate the signal of the entire frequency band of the satellite broadcasting channel that you want to make it impossible to receive by 15 dB or more, and all of the channels that you want to receive. The inductance value and capacitor capacity of each LC circuit are set so as to have a frequency characteristic that reduces the signal attenuation in the frequency band to 15 dB or less. [Selection diagram] Fig. 2

Description

  The present invention relates to a filter attached to a satellite broadcast receiving antenna.

  A filter that is attached to an antenna and removes a signal having a frequency in a specific band is widely used mainly for the purpose of preventing signal interference from a plurality of radio towers. However, the present invention can receive a broadcast from a specific broadcasting station. The present invention relates to a filter intended to be intentionally rejected.

  If the law stipulates that a broadcasting station must be equipped with equipment that can receive broadcasts and that must be contracted with that broadcasting station, the radio waves from that broadcasting station should only be filtered so that they cannot be received. Therefore, the obligation to make a contract with the broadcasting station will not legally occur. In satellite broadcasting, there is a high-frequency notch filter that achieves this purpose.

  Patent Document 1 (Japanese Patent Laid-Open No. 2007-267344) discloses a polarized band-stop filter that can attenuate a signal of a desired channel without problem without excessively attenuating an adjacent channel signal at a high frequency.

JP 2007-267344 A

  In the example of the above-mentioned patent document, although the performance as a notch filter for greatly attenuating a specific frequency is high, there is a problem that the price is expensive.

  The present invention makes it possible to realize the purpose of making it impossible to receive a broadcast from a specific broadcasting station of satellite broadcasting at a low cost.

  The filter device of the present invention is a filter device for attenuating a signal of a specific frequency of satellite broadcasting, and has a property of attenuating the center frequency of a channel for which image reception is impossible by 20 dB or more and a channel for which image reception is impossible. It has the property of attenuating the entire frequency band by 15 dB or more and the property of attenuating all the frequency bands of all the channels to be received to 15 dB or less.

  Since the present invention does not require steep falling and rising with a filter in a high frequency region, the object of making it impossible to receive broadcasts from a specific broadcasting station can be achieved at low cost.

It is a figure which shows the frequency characteristic of the conventional notch filter. It is a figure which shows the frequency characteristic of the filter of this invention. It is a figure which shows the example of a circuit which implement | achieves the frequency characteristic of the filter of this invention. It is a figure showing a 1st embodiment of the present invention. It is a figure which shows 2nd Embodiment of this invention.

  FIG. 1 is an example of frequency characteristics of a conventional notch filter. The filter of FIG. 1 has a frequency characteristic for the purpose of refusing BS-15 channel broadcasting. On the other hand, an example of the frequency characteristic of the filter of the present invention is shown in FIG. The filter of FIG. 2 has a frequency characteristic that enables reception of BS-15 channel or lower broadcasts and BS-19 channel or higher broadcasts while rejecting BS-15 channel reception. The signal of 1318Mz which is the center frequency of BS-15 channel is attenuated by 20 dB or more, and all the signals of 1304.50Mz and 1331.50 MHz which are frequency bands of BS-15 channel are attenuated by 15 dB or more, and the frequency band of BS-13 channel is reduced. Attenuation of the signal of 1293.14 MHz or less, which is the upper limit, and attenuation of a signal of 1381.22 MHz or more, which is the lower limit of the frequency band of the BS-19 channel, are suppressed to 15 dB or less. An example of a circuit that realizes the frequency characteristics of FIG. 2 is shown in FIG. With the circuit of FIG. 3, the frequency characteristics shown in FIG. 2 can be realized at low cost. As a result, the object of making it impossible to receive only the desired channel is achieved at low cost.

  FIG. 4 shows a first embodiment of the present invention. As shown in FIG. 4, the filter circuit of the present invention is sealed, and BNC type terminals that can be connected to a coaxial cable are attached to both ends thereof. As a result, this filter can be connected to a relay point of the coaxial cable connecting the antenna and the television, and a state in which only a desired channel cannot be received can be created.

  FIG. 5 shows a second embodiment of the present invention. As shown in FIG. 5, by integrating the filter circuit of the present invention with a satellite dish receiving parabolic antenna, it is possible to create a state in which a desired channel cannot be received unless the antenna is replaced.

  If the law stipulates that a broadcasting station must be equipped with equipment that can receive broadcasts from a certain broadcasting station, it is obliged to make a contract with that broadcasting station using the filter of the present invention. No longer occurs legally, and the situation where the user has to pay the reception fee even when the user does not actually watch is eliminated. Therefore, the filter of the present invention can be used as a component of antenna equipment for a person who does not want to pay a reception fee for a channel that is not viewed.

1 Filter body 2 BNC jack 3 BNC plug 4 Parabolic antenna 5 Filtered antenna circuit

The filter device of the present invention is a filter device for attenuating a signal of a specific frequency of satellite broadcasting, and has a property of attenuating the center frequency of a channel for which image reception is impossible by 20 dB or more and a channel for which image reception is impossible. A plurality of parallel LC resonance circuits are arranged in series so as to have a frequency characteristic including a property of attenuating all frequency bands by 15 dB or more and a property of attenuating all frequency bands of all channels to be received to 15 dB or less. A plurality of resonance circuits are arranged in parallel.

In the filter device of the present invention , a plurality of LC parallel circuits are connected in series to a signal line connecting an input terminal and an output terminal, and a plurality of LC series circuits are connected in parallel between the signal line and the ground line. comprising a circuit, a signal having a center frequency of the channel of the satellite to be impossible receiver attenuates or 20 dB, the entire frequency band of the signal of the satellite channels to be impossible receiver attenuates or 15 dB, all to be receiving The inductance values and the capacitor capacities of the LC circuits are set so as to have a frequency characteristic in which the attenuation of signals in all frequency bands of these channels is 15 dB or less .

Claims (2)

A filter device for attenuating a signal at a specific frequency of satellite broadcasting, which attenuates the center frequency of a channel for which reception is impossible by 20 dB or more, and attenuates the entire frequency band of a channel for which reception is impossible by 15 dB or more. And a property of reducing attenuation of all frequency bands of all channels to be received to 15 dB or less. The filter device according to claim 1, wherein the filter device is attached so as to be integrated with a broadcast receiving antenna.