• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:

    公开号:NL2010237A
    申请号:NL2010237
    申请日:2013-02-04
    公开日:2013-08-13
    发明作者:Jan Ariesen
    申请人:Technetix Bv；
    IPC主号:
    专利说明:

    Title
    Amplifier, cable television and broadband network comprising at least one suchamplifier.
    Field of the invention
    This invention relates to an amplifier and in particular an amplifierused in a cable television and/or broadband network.
    Background to the invention
    In cable television (CATV) and/or broadband networks, it isimportant to prevent signal reflections as these degrade signals in the network.
    Where powered amplifiers are used in such networks, theimpedance of the amplifier across its input and output is set to 75 Ohm to match theimpedance of the remainder of the network and prevent signal reflections.
    If the amplifier stops working due to lack of power, the input andoutput impedance of the amplifier is no longer 75 Ohms and signals sent to theamplifier are reflected, with this reflected energy causing problems in thedownstream and upstream signal bands of the network.
    Summary of the invention
    In accordance with one aspect of the present invention, there isprovided an amplifier comprising an amplifier module, such as provided by anamplifier circuit, amplifier means or amplifier device, in communication with an inputport and an output port and having a power input, wherein the input port and theoutput port are in communication with a switching device or switching meansresponsive to loss of power to connect the input port and the output port to at leastone resistive element, thereby to maintain a constant impedance at the input portand output port. In this way, the impedance of the amplifier is maintained constanteven where there is a loss of power. Whilst the loss of function of the amplifier maybecome apparent when power is interrupted or fails, keeping the impedance constantensures that there is only a localised problem, rather than signal reflections fromimpedance mismatch between the amplifier and an external network, such as a broadband and/or cable television (CATV) network causing problems in the upstreamand downstream signal bands across the network.
    Preferably the switching means, which may be provided by amechanical relay or an electrical switch such as a transistor or diode, is positionedbetween the power input and the ports. Where power is available, the switchingmeans maintains the connection between the input port and the amplifier module andthe connection between the amplifier module and the output port and is operativewhen the power supply stops to break the connection between the ports andamplifier module, connecting the input port and the output port to a resistive elementso as to maintain a constant impedance. When power is restored, the switch willoperate to restore the connection between the input port and amplifier module andthe output port and amplifier module.
    Two switching means may be provided, one between the powerinput and the input port and one between the power input and the output port.Where two switching means are used, preferably they are associated with separateresistive elements, such that the input port will connect to a first resistive elementwhen the first switching means operates in response to loss of power and the outputport will connect to a second resistive element when the second switching means isresponsive to a loss of power.
    Preferably the impedance of the resistive elements is selected to bea value the same as the impedance of the amplifier when powered. By usingseparate resistive elements for the input port and output port, adjustments to theimpedance seen at the respective ports are possible, and for example one mightselect the first resistive element to be a different impedance to the second resistiveelement. However generally the value of each resistive element will be selected tobe 75 Ohms, the common impedance required for a cable television and/orbroadband network.
    In accordance with another aspect of the present invention, there isprovided a cable television and/or broadband network comprising at least oneamplifier as aforesaid. Such an amplifier is of particular advantage for a cable television network as it prevents signal reflections throughout the network should apower failure occur to the amplifier and ensures that the power loss only produces alocalised effect.
    The invention will now be described, by way of example, and withreference to the accompanying drawings in which:
    Figure 1 is a schematic diagram of an amplifier in accordance with the present invention; and
    Figure 2 is a schematic diagram of such an amplifier when a power supply is interrupted.
    Description
    In Figure 1, bidirectional amplifier 10 suitable for use in a broadbandand/or CATV network comprises an amplifier module 12 connected to input port 14and output port 16 by first path 18 and second path 20. Amplifier module 12receives power from power input 22. Amplifier 10 is arranged such that theimpedance across the amplifier from input port 14 to output port 16, i.e. theimpedance in to out, along paths 18 and 20 is set at 75 Ohms so as to match theimpedance of a CATV and/or broadband network in which amplifier 10 is used.
    Switching devices in the form of relays 24, 24’ are associated withpower input 22 and path 18, path 20 respectively. A first switch position of relays 24,24’ completes paths 18 and 20 and a second switch position interrupts paths 18, 20.Resistive elements 26, 26’, typically 75 Ohm resistors, are connected to the secondswitch position of relays 24, 24’.
    As is shown in Figure 1, when power is supplied to input 22, relays24, 24’ are activated and switch to a first switch position which completes paths 18and 20 such that there is a signal communication path directly between input 14through amplifier module 12 to output 16, with amplifier module 12 terminating ports14, 16.
    When the power supply is interrupted, as shown in Figure 2, relays24, 24’ switch to the second switch position so as to connect input port 14 directly to resistor 26 and to connect output port 16 directly to resistor 26’. This ensuresamplifier 10 still presents a 75 Ohm resistance to the external network. As will beappreciated by those skilled in the art, the value of resistors 26, 26’ can be varieddependent on the network within which the amplifier is to be used. If desired, theresistors 26, 26’ can be set to have different values, although generally they are setto have the same value of 75 Ohms.
    Whilst mechanical relays are shown in Figures 1 and 2, as will beappreciated by those skilled in the art, switching can be done by any suitable means,for example electronic switches such as transistors and diodes.
    When such an amplifier is used in a CATV and/or broadbandnetwork, typically within users’ homes directly after the isolator or in-home startingpoint, the amplifier ports are always terminated and the amplifier remains impedancematched to the remainder of the network even when power to the amplifier module12 is interrupted. The amplifier is always terminated to a constant resistance,typically 75 Ohms, with or without power. This ensures that the amplifier does notcause signal reflections on upstream and downstream signal bands of the networkeven when the amplifier is not powered for whatever reason, so avoiding signaldegradation from unpowered amplifiers.
    权利要求:
    Claims (7)
    [1]
    An amplifier comprising an amplifier module in communication with a input port and an output port and with a power input, wherein the input ports are the output port in communication with switching means responsive to loss of education to connect the input port and the output port to at least one resistive element, thus maintaining maintaining a constant impedance at the input port and output port.
    [2]
    The amplifier of claim 1, wherein the switching device is positioned between the power input and the gates.
    [3]
    An amplifier according to claim 1 or claim 2, wherein first and second switching means are provided, the first switching means are positioned between the power input and the input port and the second switching means are provided between the power input and the output port.
    [4]
    An amplifier according to claim 3, wherein each switching means is associated with individual-resistant elements.
    [5]
    5. An amplifier according to any one of the preceding claims, wherein the impedance of each resistive element is the same as the impedance between the input ports and the output port.
    [6]
    Amplifier according to any of the preceding claims, wherein each resistive element has an impedance of 75 ohms.
    [7]
    A cable television and / or broadband network comprising at least one amplifier according to claims 1 to 6.
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    同族专利:
    公开号 | 公开日
    GB2499206A|2013-08-14|
    NL2010237B1|2018-04-26|
    GB201202143D0|2012-03-21|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    JP4136218B2|1999-08-24|2008-08-20|マスプロ電工株式会社|Transmission signal amplifier and bidirectional CATV system|
    US7974586B2|2007-09-14|2011-07-05|Extreme Broadband Engineering, Llc|Constant input port impedance for CATV amplifier with passive modem port|
    US8296818B2|2010-05-13|2012-10-23|Commscope, Inc. Of North Carolina|Distribution and amplification systems that automatically terminate to a matched termination in response to power interruptions and related methods|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    GB201202143|2012-02-08|
    GB1202143.2A|GB2499206A|2012-02-08|2012-02-08|Maintaining cable amplifier impedance during a power failure|
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