WO2003041412A1

WO2003041412A1 - Repeating system for satellite broadcasting

Info

Publication number: WO2003041412A1
Application number: PCT/KR2001/002104
Authority: WO
Inventors: In Yong Jang
Original assignee: Korea Digital Satellite Broadcasting Co., Ltd.
Priority date: 2001-10-18
Filing date: 2001-12-05
Publication date: 2003-05-15
Also published as: KR100431930B1; KR20030033094A

Abstract

The present invention relates to a satellite receiving and repeating system, a repeater and a receiver which are suitable the system, more specifically, to the satellite receiving and repeating system which receives first type polarized downlink satellite signals from a satellite, comprising repeaters for receiving and amplifying the first type polarized signals, converting the first type polarized signals into the second type polarized signals, and transmitting the second type polarized signals to each predetermined areas, and subscriber's receivers located in the predetermined areas, for receiving the second type polarized signals, converting them into the mid-frequency signals and outputting the mid-frequency signals as electronic signals.

Description

REPEATING SYSTEM FOR SATELLITE BROADCASTING

TECHNICAL FIELD

The present invention relates to satellite reception, and more particularly, to a satellite reception repeating system for transmitting a satellite signal received from a satellite to a plurality of subscribers in a particular area via repeaters without transmitting the satellite signal directly from the satellite to subscribers.

BACKGROUND OF THE INVENTION In a conventional satellite reception system, each receiver is provided with a reflector for directly receiving a satellite signal from a satellite. FIG. 1 is a schematic view of the conventional satellite reception system. As shown in FIG. 1, an uplink signal U transmitted from a satellite transmission station 10 via a satellite transmission antenna is converted to a downlink signal D in a satellite 20 and then transferred to subscribers via satellite reception antennas 30 and 40, set- top boxes (STBs) 32 and TVs 34.

The above satellite reception system, however, has the following problems. First, the download signal D cannot reach a satellite reception antenna 40 due to a tall building 50 in a dense apartment area or a building area. These areas in which the downlink signal D is not received are called satellite shadow areas. As houses get clustered and buildings are taller, the shadow areas become wider, thereby impeding normal satellite reception.

Second, each subscriber must install a satellite antenna equipped with a separate reflector to receive a weak signal from a satellite because (s)he receives the satellite signal directly from the satellite in the conventional satellite reception system. The satellite antenna is difficult to install because of the reflector occupying a large area, spoils the scenic beauty, and increases the price of receivers.

In apartments, subscribers can receive satellite signals using an SMATV system with a common satellite reception equipment. This system additionally requires devices such as cables, headends H/E, distributors, etc. because the system distributes a signal to each subscriber receiver from the common satellite reception equipment by cables. The devices and cables are difficult to install and cost a lot.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide a satellite reception repeating system which operates wirelessly and prevents generation of satellite reception shadow areas, a satellite reception repeater for receiving a downlink signal from a satellite and transferring the downlink signal to a plurality of subscribers in a predetermined area, and a satellite signal subscriber receiver having a small reception antenna.

According to the features of the present invention, in a repeating system for satellite reception that receives a downlink satellite signal with a frequency of a first polarization group from a satellite, a plurality of repeaters are positioned to cover their assigned areas. Each repeater receives the signal with a frequency of a first polarization group, converts the received signal to a signal with a frequency of a second polarization group, amplifies the converted signal, and outputs the amplified signal to an assigned area. A plurality of subscriber receivers are provided in the assigned areas, for receiving the signal with the frequency of the second polarization group, converting the received signal to an IF signal, and outputting the IF signal as an electrical signal.

A repeater according to the present invention includes a reflector for converting the phase of a downlink satellite signal with a frequency of the first polarization group by 180°; a reception feedhorn for collecting electronic waves with the phase-converted frequency of the first polarization group and converting the collected electronic waves to an electrical signal; a low noise amplifier for amplifying the electrical signal while reducing the noise of the electrical signal; a waveguide for converting the electrical signal received from the low noise amplifier to electronic waves; and an output feedhorn for converting the electronic waves received from the waveguide to a signal with the frequency of the second polarization group.

A subscriber receiver according to the present invention includes a planar antenna for receiving a satellite broadcast signal with a frequency of a second polarization group and converting the received satellite broadcast signal to an electrical signal; and an IF converter for converting the signal with the frequency of the second polarization group received from the planar antenna to an IF signal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating a conventional satellite reception system;

FIG. 2 is a schematic view illustrating a repeating system for satellite reception according to an embodiment of the present invention;

FIG. 3 is a circuit diagram of a repeater in the repeating system for satellite reception according to the embodiment of the present invention; FIG. 4 is a circuit diagram of a subscriber receiver in the repeating system for satellite reception according to the embodiment of the present invention;

FIG. 5 is a sectional view of a reception feedhorn and a low .noise amplifier in the repeater shown in FIG. 3;

FIG. 6 is a sectional view of a transmission feedhorn in the repeater shown in FIG. 3;

FIG. 7 is a perspective view illustrating an example of polarization transformation in the reception feedhorn shown in FIG. 5 and the transmission feedhorn shown in FIG. 6; and

FIG. 8 is a sectional view of a reception unit in the subscriber receiver shown in FIG. 4.

<Description of Reference Numerals of Important Components in the Drawings> 200: repeater 400: subscriber receiver 510: reception frequency collector 520, 640: dielectric 530, 630: waveguide 550: low noise amplifier 540, 620, 820: probe 560: power supply connector

570, 610: SiVlA connector 650: output feedhorn 810: reception antenna 830: IF converter 840: connector

An embodiment of the present invention will be described in detail referring to FIGs. 2 to 8.

DETAILED DESCRILTION OF THE PREFERRED EMBODIMENTS

FIG. 2 schematically illustrates a repeating system for satellite reception according to an embodiment of the present invention. The repeating system for satellite reception includes a repeater 200 and a subscriber receiver 400. The repeater 200 is installed in a position suitable for good reception of a downlink signal from a satellite 110, for example, on the roof of a building B20. An antenna of the subscriber receiver 400 is installed in a position suitable for reception of a signal from an output antenna of the repeater 200. As shown in FIG. 2, the single repeater 200 on the roof of the building B20 can cover all subscribers in a building B10 opposite to the building B20. Even a subscriber on a lower floor of the building B10, which is likely to be a shadow area due to the neighboring building in a typical satellite reception system, can receive a satellite signal through the satellite reception repeating system according to the present invention. Moreover, since the subscriber receiver 400 receives a signal amplified by the repeater 200, it need not have a bulky reflector for receiving weak signals from the satellite. FIG. 3 is a circuit diagram of the repeater in the satellite reception repeating system according to the embodiment of the present invention. The repeater includes a reception antenna 210, a low noise amplifier 220, a coaxial cable 230, a linear amplifier 240, and an output antenna 250. The reception antenna 210 has a feedhorn for collecting satellite signals and the output antenna 250, a feedhorn for transmitting satellite signals.

In accordance with the embodiment of the present invention, the repeater can find out a reception frequency FI and a transmission frequency F2 each ranging from 11.7 up to 12.75GHz. Left-hand circular polarization (LHCP) for broadcasting and horizontal polarization (H-POL) for communications can be applied to a signal with the reception frequency FI and right-hand circular polarization (RHCP) for broadcasting and communications, to a signal with the transmission frequency F2.

A reflector at the front of the feedhorn reflects the LHCP signal with the reception frequency FI . Since the phase of the reflected reception frequency signal is converted by 180°, the LHCP is changed to the RHCP and an H-POL signal is collected in the feedhorn of the reception antenna 210 without polarization transformation.

The low noise amplifier 220 amplifies the signal with the reception frequency FI collected in the reception antenna 210 by, for example, +60dB. The amplified signal with the reception frequency FI is transmitted to the linear amplifier 240 via the coaxial cable 230. The coaxial cable 230 is used to transfer a satellite signal to the output antenna 250 and usually experiences a loss of-lOdB for a short distance. The linear amplifier 240 transmits the signal with the reception frequency

FI as a signal with the transmission frequency F2 via the feedhorn of the output antenna 250. Here, the linear amplifier 240 amplifies the signal with the reception frequency FI by +0dB.

FIG. 4 is a circuit diagram of the subscriber receiver in the repeating system for satellite reception according to the embodiment of the present invention. The subscriber receiver 400 is comprised of a subscriber reception antenna 410, a low noise amplifier 420, a mixer 430, an IF amplifier 440, and an IF cable 450. The thus-constituted subscriber receiver 400 is connected to an STB 460 and a TV 800. The subscriber reception antenna 410 receives the RHCP signal with the transmission frequency F2 from the repeater 200. The received signal with the transmission frequency F2 is amplified in the low noise amplifier 420 and inputted in the mixer 430. For example, the signal with the transmission frequency F2 is amplified by about +30dB in the low noise amplifier 420 and experiences an attenuation of about -5dB in the mixer 430.

The IF amplifier 440 amplifies an IF signal received from the mixer 430 and transmits it to the STB 460 via the coaxial cable 450. The STB 460 outputs a subscriber-selected IF channel signal to the TV 800.

FIG. 5 illustrates the structure of the reception feedhorn and the low noise amplifier in the repeater shown in FIG. 3. The reception feedhorn and the low noise amplifier include a reception frequency collector 510, a dielectric 520, a waveguide 530, a probe 540, a low noise amplifier 550, a power supply connector

560, and an SMA connector 570.

The reception frequency collector 510 collects signals with the reception frequency FI from the reflector. The collected signals with the reception frequency FI are subject to filtering in the dielectric 520.

The waveguide 530 guides the filtered signal with the reception frequency FI in the KU band to the probe 540 and the probe 540 converts the filtered signal to an electrical signal. The low noise amplifier 550 removes noise from the electrical signal, amplifying the electrical signal. The dielectric 520 is plate- shaped and fixedly inserted in a diagonal direction in compliance with the phase of an RHCP signal. A DC voltage of about +15 volts is applied to the low noise amplifier 550 via a power supply connector 560.

FIG. 6 illustrates the structure of the transmission feedhorn in the repeater shown in FIG. 3. The transmission feedhorn is comprised of an SMA connector 610, a probe 620, a waveguide 630, a dielectric 640, and an output feedhorn 650.

The SMA connector 610 is an input port for receiving the electrical signal amplified by the low noise amplifier. The input electrical signal is converted to electronic waves by the probe 620 and the waveguide 630. The dielectric 640 converts the electronic waves received from the waveguide 630 to an RHCP signal. Therefore, the dielectric 640 is installed in a diagonal direction in a waveguide of the output feedhorn 650 to convert the electronic waves to the RHCP signal. That is, one of two orthogonal linear polarization components is affected and thus the RHCP is generated in the. dielectric 640. The output feedhorn 650 outputs the RHCP signal to the subscriber.

FIG. 7 illustrates an example of polarization transformation in the reception feedhorn shown in FIG. 5 and the transmission feedhorn shown in FIG. 6.

The feedhorn shown in FIG. 7 can be used commonly as a reception feedhorn and a transmission feedhorn. Especially, the feedhorn is adaptively applied to any polarization by control of the combination angle of a waveguide according to the present invention.

Referring to FIG. 7, the feedhorn is applicable to RHCP by inserting a first pin 740a into a first hole 730a and a second pin 740b into a second hole 730b. Also, the feedhorn is applicable to LHCP by inserting the first pin 740a into a fourth hole 73 Od and the second pin 740b into the first hole 730a.

FIG. 8 illustrates the structure of a reception unit of the subscriber receiver shown in FIG. 4. The reception unit includes a reception antenna 810, a probe

820, an IF converter 830, and a connector 840. The reception antenna 810 is a planar antenna capable of receiving an

RHCP signal. A signal with a frequency ranging from 11.7 to 12.75GHz from the RHCP signal is transmitted to the IF converter 830 via the probe 820. Then, the IF converter 830 converts the input signal to an IF signal ranging from

950MHz to 2.15GHz, for example. The IF signal is transmitted as an electrical signal to an STB via the connector 840. INDUSTRIAL APPLICABILITY

In accordance with the present invention, the repeating system for satellite reception enables reception of a satellite signal through repeaters even in a shadow area where satellite reception is impossible in a conventional satellite reception system, and each subscriber receiver in the repeating system receives a signal amplified by a repeater, which obviates the need of a reflector. Therefore, a satellite reception area is maximized and the installation cost and area of the subscriber receiver are reduced.

Claims

WHAT IS CLAIMED IS:

1. A repeating system for satellite reception that receives a downlink satellite signal with a frequency of a first polarization group from a satellite, comprising: a plurality of repeaters, each repeater being positioned to cover an assigned area, for receiving the signal with the frequency of the first polarization group, converting the received signal to a signal with a frequency of a second polarization group, amplifying the converted signal, and outputting the amplified signal to the assigned area; and a plurality of subscriber receivers in the assigned areas, for receiving the signal with the frequency of the second polarization group, converting the received signal to an IF signal, and outputting the IF signal as an electrical signal.

2. The repeating system of claim 1, wherein each repeater comprises: a reflector for converting the phase of the signal with the frequency of the first polarization group by 180°; a reception feedhorn for collecting electronic waves with the phase- converted frequency of the first polarization group and converting the collected electronic waves to an electrical signal; a low noise amplifier for amplifying the electrical signal while reducing the noise of the electrical signal; a waveguide for converting the electrical signal received from the low noise amplifier to electronic waves; and an output feedhorn for converting the electronic waves received from the waveguide to the signal with the frequency of the second polarization group, and outputting the converted signal.

3. The repeating system of claim 2, wherein the repeater has a plurality of waveguides and output feedhorns.

4. The repeating system of claim 1, wherein each subscriber receiver further includes a reception unit for receiving the signal with the frequency of the second polarization group, converting the received signal to an IF signal, and outputting the IF signal as an electrical signal.

5. The repeating system of any of claims 1 to 4, wherein each of the first and second polarization groups are selected from the group consisting of circular polarization, linear polarization and a combination thereof.

6. The repeating system of claim 5, wherein the first polarization group includes a combination of circular polarization and linear polarization; and the second polarization group includes one of circular polarization and linear polarization.

7. The repeating system of claim 5, wherein the first polarization group includes left-hand circular polarization (LHCP) and linear polarization; and the second polarization group includes right-hand circular polarization (RHCP).

8. A repeater comprising: a reflector for converting the phase of a downlink satellite signal with a frequency of the first polarization group by 180°; a reception feedhorn for collecting electronic waves with the phase- converted frequency of the first polarization group and converting the collected electronic waves to an electrical signal; a low noise amplifier for amplifying the electrical signal while reducing the noise of the electrical signal; a waveguide for converting the electrical signal received from the low noise amplifier to electronic waves; and an output feedhorn for converting the electronic waves received from the waveguide to the signal with frequency of the second polarization group and outputting the converted signal.

9. The repeater of claim 8, wherein the repeater comprises a plurality of waveguides and output feedhorns.

10. The repeater of claim 8 or 9, wherein each of the first and second polarization groups are selected from the group consisting of circular polarization, linear polarization, and a combination thereof.

11. The repeater of claim 10, wherein the first polarization group includes a combination of circular polarization and linear polarization; and the second polarization group includes one of circular polarization and linear polarization.

12. The repeater of claim 11, wherein the first polarization group includes LHCP and linear polarization; and the second polarization group includes RHCP.

13. A subscriber receiver comprising: a planar antenna for receiving a satellite broadcast signal with a frequency of a second polarization group and converting the received satellite broadcast signal to an electrical signal; and an intermediate frequency (IF) converter for converting the signal with the frequency of the second polarization group received from the planar antenna to an

IF signal.

14. The subscriber receiver of claim 13, wherein the second polarization group are selected from the group consisting of circular polarization, linear polarization, and a combination thereof.

15. The subscriber receiver of claim 14, wherein the second polarization group includes RHCP.