EP2621014A1 - Système et procédé pour réduire les interférences dans des systèmes de réception de signaux de télévision - Google Patents

Système et procédé pour réduire les interférences dans des systèmes de réception de signaux de télévision Download PDF

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Publication number
EP2621014A1
EP2621014A1 EP12382021.9A EP12382021A EP2621014A1 EP 2621014 A1 EP2621014 A1 EP 2621014A1 EP 12382021 A EP12382021 A EP 12382021A EP 2621014 A1 EP2621014 A1 EP 2621014A1
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EP
European Patent Office
Prior art keywords
antenna
signals
fixing
rod
television
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP12382021.9A
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German (de)
English (en)
Inventor
Mª Belen Barroso Benito
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Angel Iglesias SA
Original Assignee
Angel Iglesias SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Angel Iglesias SA filed Critical Angel Iglesias SA
Priority to EP12382021.9A priority Critical patent/EP2621014A1/fr
Publication of EP2621014A1 publication Critical patent/EP2621014A1/fr
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q19/00—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic
    • H01Q19/28—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using a secondary device in the form of two or more substantially straight conductive elements
    • H01Q19/30—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using a secondary device in the form of two or more substantially straight conductive elements the primary active element being centre-fed and substantially straight, e.g. Yagi antenna
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/12—Supports; Mounting means
    • H01Q1/125—Means for positioning

Definitions

  • the present invention has its field of application in reducing interferences in signals received by antenna systems and more specifically, in reducing interferences in antenna systems which receive television signals.
  • the compression systems of the current digital television systems allow transmitting several normal digital television channels (usually up to six according to the coding and modulation techniques used) of acceptable quality in the radio-frequency space previously used by a single analogue channel.
  • a comparison of the spectrum (14) taken up by the previous analogue systems with respect to the current digital systems is depicted therein.
  • New coding, compression and modulation techniques for digital terrestrial television broadcasting have indirectly contributed to the process of creating this so called digital dividend.
  • ITU-R BT.798 Recommendation stipulates "that digital terrestrial television broadcasting should fit in the channels (6, 7 and 8 MHz) intended for analogue television emission in the very high frequency and ultrahigh frequency wave bands”. That Recommendation, which prohibits the bandwidth used for digital programmes to be larger than the bandwidth of the analogue channels, has paved the way for the development of advanced digital compression techniques.
  • the amount (quantity) of released spectrum with the change from analogue to digital transmission mainly depends on national particularities such as geography and topography of the country, degree of penetration of digital transmission services, needs for regional or minority television services, and use of the spectrum in the neighboring countries. This amount also depends on digital television technology adopted for replacing the analogue services. Therefore, the size of the digital dividend changes from one region to another and from one country to another. Although the specific location of the digital dividend also varies from one country (or region) to another, since it depends on the assigned frequencies of each country/region, it is usually placed between 200 MHz and 1 GHz. This released band (dividend) is placed in the range between 790 and 862 MHz, particularly in Europe.
  • LTE Long Term Evolution
  • WiMAX WiMAX
  • frequency channels for example television channels
  • television channels which are not assigned and are free in each geographical area.
  • These free channels can be used for other services, especially inside (not in the borders of) the assigned geographical areas, where they would not interfere with the adjacent geographical areas.
  • These free channels are called "white spaces", which can be used by other services (usually advanced mobile telephony services such as LTE, mobile internet).
  • These white spaces tend to be used in a dynamic manner such that when a user is in a specific geographical area, he/she consults the white spaces (unassigned channels) of that area in a database and uses them for the mentioned services.
  • these white spaces are channels within the frequency range of the television channels but which are free and unassigned in a specific geographical area. These white spaces by definition will therefore be close to the television channels which are indeed assigned and are not free.
  • FIG 2 a profile view (2a) and a frontal view (2b) of an antenna system which is used for television signal reception mainly in the UHF band (in the example of the figure, a Yagi type antenna), arranged in a position making it having a vertical polarization (i.e., having maximum sensitivity to signals with vertical polarization, such as that depicted in Figure 6a ).
  • a vertical polarization i.e., having maximum sensitivity to signals with vertical polarization, such as that depicted in Figure 6a
  • the position of the antenna is shown on the left and, the corresponding position of the dipole on the right (25), in both cases with respect to the ground plane (26).
  • FIG 3 a profile view (3a) and frontal view (3b) of an antenna system which is used for television signal reception mainly in the UHF band (in the example of the drawing, a Yagi type antenna), arranged in a position making it having a horizontal polarization (i.e., having maximum sensitivity to signals with horizontal polarization such as that depicted in Figure 6b ).
  • the position of the antenna is shown on the left and the position of the corresponding dipole on the right (35), in both cases with respect to the ground plane (36).
  • the present invention proposes an antenna system (e.g., TV signal reception) solving the problems of the existing systems in a simple manner. Particularly in the cases explained above (digital dividend, white spaces) where the unwanted communications signals are so close to the television channels that filtering is not a viable solution (due to the lack of effectiveness and/or economic reasons). This occurs for example, in the case of wanting to receive a TV channel 60 (782 to 790 MHz) and there is a telephony emission in the band of 791 to 796 MHz.
  • TV signal reception e.g., TV signal reception
  • the present invention describes an antenna system for optimal television signals reception consisting of a television signal receiving directional antenna comprising at least one dipole, said directional antenna being pointed in a specific direction, called antenna pointing axis, which will be the direction in which the antenna has maximum sensitivity to the received signals and a fixing system which allows fixing the antenna to a mast, said fixing system comprising a first fixing element fixed to the mast, said antenna system being characterized in that said fixing system further comprises:
  • the antenna pointing axis (also called antenna axis) is perpendicular to the mast.
  • the desired rotation position in which the rotating element is blocked with the blocking device is that in which the received power of the television signal is maximum or that rotation position in which the received power of interfering signals is minimum or a compromise between these criteria.
  • the antenna is a directional antenna with planar polarization, for example Yagi type and the signals received are digital television signals, for example in the UHF frequency band, particularly in the frequency range between 470 MHz and 821 MHz and more particularly in the frequency range between 470 MHz and 790 MHz.
  • the antenna comprises at least one longitudinal rod, the dipole being mounted on said at least one rod, at least one reflective element and at least one directing element, and where said at least one rod together with the at least one directing element determine the antenna pointing axis, said at least one rod being able to be a central rod in the direction of the antenna pointing axis.
  • the blocking device is a screw which prevents the rotation of the rotating element when tightened and the rotating element can be a first longitudinal rod in a direction coinciding with the antenna pointing axis, which can rotate about said axis;
  • the first fixing element can include a second longitudinal rod without the possibility of rotating, said second longitudinal rod being a prolongation of the first longitudinal rod and attached to said first rod, and where the first and second rod have hollow sections in which there is included a round section, fixed to the second rod and free in the first rod, allowing the rotation of the first rod about the second rod.
  • the present invention describes a method for reducing interference in television signals which uses an antenna system such as that of any of the embodiments described above in the first aspect, said method comprises the following steps:
  • the rotation position in which the received power of the television signal is maximum is selected in step c) or in an alternative embodiment, the rotation position in which the received power of the interfering signals is minimum is selected in step c) (a compromise between both positions, if they do not coincide, is also possible), the interfering signals in question being for example, LTE communications signals although interfering signals of any other type is possible.
  • FIG 4 shows an example of television reception antenna system according to one embodiment of the present invention.
  • Said antenna would prevent the problems (co-channel interference, noise, saturation of amplifiers) which are produced in television signal reception, particularly in the cases where the telephony signals are very close to the television channels (the aforementioned digital dividend and white space scenarios) by allowing a very significant reduction of the ratio between the telephony signal received by the antenna and TV signal (greater than 15 dB in most cases).
  • the antenna would be a digital television signal receiver antenna for receiving digital television signals (although they could also be analogue) in the frequency range of the UHF band, in the entire band or in sections of the band and more specifically in the frequency range comprised between 470 and 821 MHz.
  • the UHF digital television signal reception antenna is a flat polarization antenna, and particularly a Yagi type antenna (as the ones shown in Figures 2 and 3 ).
  • Antennas of this type use to be made up of a main active element, in most cases a dipole (20, 30, 40), followed at a certain distance at one side by a reflector formed by an association of conducting rods (21, 31, 41) (forming reflective grids 22, 32, 42 in many cases) and on the other side of the dipole (the side opposite to the reflector), a number of directing elements (23, 33, 43).
  • All these components are mounted on a rod or rods (24, 34, 44) determining, according to their position, an axis which will be the direction in which the antenna has maximum sensitivity to the received signals (i.e., those signals whose direction of propagation coincides with said direction will be received with maximum sensitivity).
  • This will be the axis of the main antenna lobe or in other words, the direction in which the antenna points (therefore, it can also be called antenna axis or antenna pointing axis).
  • said axis must ideally be aligned with the trajectory of the radio-frequency signals to be received (the direction of signal reception trajectories being the one going from the directing elements towards the reflector passing through the dipole).
  • this alignment of the axis with said trajectory (of the wanted radio-frequency signals) is not performed in an exact manner (i.e., the axis deviates a little from this "ideal" alignment) because, due to an interference source, the "ideal" alignment leads to a substantial increase in the received interference.
  • the plane formed by the antenna axis together with the dipole axis determine the plane of polarization (or simply called the polarization) of the antenna, i.e., the plane of propagation (or polarization) of the signal for which the antenna has maximum sensitivity.
  • the signal captured by the antenna will be maximum for those signals whose polarization (plane of propagation) coincides with that of the antenna and minimum for those signals whose plane of polarization is orthogonal to the plane of polarization of the antenna.
  • LTE new generation telephony signals
  • the antenna fixing systems currently used for DTT television signal reception are usually provided with anchoring or fixing systems for anchoring or fixing to the mast, which only allow pointing in any of the two plane of propagations of the TV signal (horizontal or vertical) but not in others. Neither does it allow a specific adjustment within the chosen plane. In other words, it only has 2 positions (vertical Figures 2a, 2b or horizontal Figures 3a, 3b ) and neither an adjustment in each plane nor positioning in intermediate planes is allowed.
  • TV antennas pointed in the horizontal or vertical plane
  • receive most of the telephony signals whose plane of propagation is inclined at +/-45° with respect to the horizontal or vertical plane.
  • the inclination is not exactly 45° so the interference will be even greater in one of the reception planes.
  • the basis of the proposed solution is making use of the difference in polarization (plane of propagation) and of the behaviour of the TV antennas to cross polarization, for which they usually have a rejection of around 20 dB to orthogonal polarizations.
  • a TV reception antenna will thus receive a specific signal from the TV channels and also a telephony signal.
  • changing the polarization of the TV reception antenna is achieved in one embodiment of the present invention, such that it forms 90° with the polarization plane of the telephony antenna thus rejecting a telephony signal of around 20 dB since it has a polarization orthogonal to the reception plane.
  • the current reception antennas only allow a horizontal or vertical positioning so it is not possible for them to point in a manner in which they form 90° with the emission plane of the telephony antenna.
  • the inclination of the reception plane of the unwanted signals does not always have to be exactly 45° but the exact inclination depends on the particular scenario in which the reception occurs (so other deviations with respect to this inclination or other different inclinations are frequent).
  • the present invention responds to this need of continuously adjusting the angle of rotation in the plane of polarization, allowing the antenna to rotate about its axis and position it at any angle in order to find the optimum unwanted signal rejection position (normally 90° with respect to the plane of propagation of the unwanted signal).
  • the rotating element may be connected in solidarity with the antenna (binded or rigidly connected to the antenna).
  • the connection between the antenna and the rotating element may be any connection which makes that the rotation of said rotating element causes the continuous rotation of the antenna about its pointing axis.
  • the antenna Since the antenna is fixed to the mast, a continuous and precise adjustment of the plane of polarization can be made by rotating the antenna about its axis and once the adjustment is achieved (e.g. the plane of polarization is such that the television signal reception is optimum), it is blocked by means of a fixing or blocking system (for example a screw 54) which allows blocking the rotation of the antenna axis (and therefore of its plane of polarization) in any desired rotation position, for assuring the blocking of the adjustment made. With this blocking system, the antenna can be blocked in any desired rotation position.
  • a fixing or blocking system for example a screw 54
  • This part of antenna will be longitudinal and coinciding with or parallel to the antenna axis (as can be seen in Figure 4 ).
  • the plane of polarization of the antenna changes gradually as the antenna rotates about its main axis. Then when the antenna reception is to be adjusted, the antenna is rotated about its axis (by rotating the rotating element) and fixed in the position in which the interfering signal rejection is maximum (plane of polarization of the antenna orthogonal to that of the telephony signals) or the TV signal reception is optimum (usually both positions coincide, i.e., where the TV signal reception is optimum is because the interfering signal rejection is maximum). Other adjustment criteria are also possible. Although it can be performed in several ways, to that end it is convenient to have a measurement equipment which indicates the levels of the signals (power level) captured by the antenna and is able to search for the suitable inclination position of the antenna in polarization. At the point in which said measurements indicate that the power of the interfering signals is minimum and/or the received power of the television signal is maximum, the antenna is fixed blocking it in said rotation position.
  • the adjustment position will be close to 90° with respect to the plane of propagation of the downlink of the telephony signal to be rejected (e.g. LTE), a situation in which the power of said signal will be minimum.
  • LTE the plane of propagation of the downlink of the telephony signal to be rejected
  • the system will preferably search for the rejection of the LTE channel whose frequencies are comprised between 791 and 796 MHz (first antenna) and consequently there will also be a rejection of the LTE channels which are transmitted by the same antenna as the latter (the third and the fifth).
  • the adjustment can be made manually by a technician when the antenna is installed and every time a check to improve signal reception is carried out.
  • the adjustment can be made automatically, providing the system with a motor.
  • This motor can be controlled locally or remotely.
  • the measurements and the adjustment can also be made remotely, which will allow a more frequent adjustment (even continuous) since going to the antenna location to perform the adjustment is not required. Therefore, the antenna can be rotated about its axis such that the TV signal reception is optimum every time it is desired.
  • This system also enables a quick and easy change between the polarizations used in TV, valid in the situations where rejecting the LTE is not necessary, but adapting easily and quickly to the situation of the polarization of the TV signal in a specific location is desired.
  • the polarization of the TV signal is not exactly horizontal or vertical and therefore, the reception of said signals is not optimum with the current antennas.
  • the plane of polarization of the antenna can be changed until it coincides with the exact polarization of the TV signal.
  • filters for rejecting other signals particularly those emitted by the other LTE antenna of different polarization can be added.
  • the LTE channels emitted by the antenna with orthogonal polarization (not rejected with the present invention, since they have a different polarization) must be rejected with the aid of filters.
  • the filters do not have to be so discriminating, because the rejected signal it is already more than at least 5 MHz away from the desired signal.
  • the main interfering signal LTE telephony signal in frequencies close to those of television
  • these filters would not need to be so discriminating, therefore they would be much more cost effective and affordable to make.
  • TV signal reception is optimized with this adjustment of the plane of polarization of the television reception antennas, even in situations where the interfering signals (telephony signals or signals of other type) are in frequencies very close to those of the television channels.
  • this invention is certainly not only applicable to Yagi type antennas but to antennas of any other type, particularly television signal receiving directional flat polarization antennas.
  • antenna includes both the electromagnetic part (i.e., the active, directing elements, reflective elements and in general any electromagnetic element which allows radio-frequency signal reception) and the mechanical part which allows fixing the antenna (to a mast).
  • electromagnetic part i.e., the active, directing elements, reflective elements and in general any electromagnetic element which allows radio-frequency signal reception
  • mechanical part which allows fixing the antenna (to a mast).

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EP12382021.9A 2012-01-24 2012-01-24 Système et procédé pour réduire les interférences dans des systèmes de réception de signaux de télévision Withdrawn EP2621014A1 (fr)

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EP12382021.9A EP2621014A1 (fr) 2012-01-24 2012-01-24 Système et procédé pour réduire les interférences dans des systèmes de réception de signaux de télévision

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EP12382021.9A EP2621014A1 (fr) 2012-01-24 2012-01-24 Système et procédé pour réduire les interférences dans des systèmes de réception de signaux de télévision

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2020254886A1 (fr) * 2019-06-21 2020-12-24 Bick Anthony Aaron Antenne à grille

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070229379A1 (en) * 2006-03-31 2007-10-04 Eckwielen Bradley L Digital UHF/VHF antenna
JP2009225024A (ja) * 2008-03-14 2009-10-01 Nec Tokin Corp アンテナ支持台
WO2011018969A1 (fr) * 2009-08-11 2011-02-17 マスプロ電工株式会社 Antenne et procédé de fabrication d'antenne
EP2346115A2 (fr) * 2010-01-15 2011-07-20 Televés, S.A. Antenne

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070229379A1 (en) * 2006-03-31 2007-10-04 Eckwielen Bradley L Digital UHF/VHF antenna
JP2009225024A (ja) * 2008-03-14 2009-10-01 Nec Tokin Corp アンテナ支持台
WO2011018969A1 (fr) * 2009-08-11 2011-02-17 マスプロ電工株式会社 Antenne et procédé de fabrication d'antenne
EP2346115A2 (fr) * 2010-01-15 2011-07-20 Televés, S.A. Antenne

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2020254886A1 (fr) * 2019-06-21 2020-12-24 Bick Anthony Aaron Antenne à grille

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