CN2309019Y

CN2309019Y - Television signal amplifier

Info

Publication number: CN2309019Y
Application number: CN 96224903
Authority: CN
Inventors: 李国良
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-11-08
Filing date: 1996-11-08
Publication date: 1999-02-24
Anticipated expiration: 2006-11-08

Abstract

The utility model relates to a television signal amplifier, comprising an input level regulating circuit, an equalizing circuit, an amplifying circuit, an output monitoring circuit and a power circuit. The utility model is provided with an output level slope regulating circuit connected in series between a television signal amplifying circuit and the output monitoring circuit. The circuit can separate and regulate and synthesize television signals without selecting an equalizing slice used for lowering the signal level of the lower end in an input level of the television signal amplifying circuit so as to ensure that the level between any one channel of a system output interface is not greater than the index of 10 dB. Thus, the utility model improves the carrier to noise ratio of the low channel and ensures consistency of the carrier to noise ratio of each channel. Meanwhile, the utility model solves the conflict of the carrier to noise ratio and the level difference not greater than 10 dB of any one channel.

Description

TV signal amplifiers

The utility model belongs to a kind of subscriber's amplifier (or claiming distribution amplifier) in the cable TV transmission network network.

The subscriber's amplifier that is used for CATV Project at present, be divided into several types such as integrated circuit, thick film circuit and discrete component assembling substantially, function according to the amplifier built-up circuit, flow process by TV signal, its circuit structure block diagram is adjusted circuit 1, equalizing circuit 2 by incoming level basically all as shown in Figure 1, amplifying circuit 3, several sections such as output, observation circuit 4 are formed.The subscriber's amplifier of this structure, be used in short-range distribution network, every technical indicator can meet the demands basically, when being used in the distribution network of long distance, in order to satisfy the ministry standard that level difference between arbitrary channel is not more than 10dB, compromise commonly used in current engineering is to select suitable balanced inserted sheet for use, make the low-side signal level ratio high-side signal of input subscriber's amplifier low, then the output level of amplifier is that low side is than high-end low tilting, the System Outlet level at the first family of result is that low side is lower than high-end, the family then is that low side is than high-side signal level height endways, level difference is not more than 10dB between arbitrary channel though can satisfy like this, requirement: but forced down the low channel level in amplifier input terminal, then therefore the carrier-to-noise ratio of low channel just reduces than high channel, and the contradiction of these two technical indicators of level difference just is difficult to coordinate between carrier-to-noise ratio and arbitrary channel.

The purpose of this utility model is to provide a kind of and is applicable in the long range transmission networks, can guarantee that arbitrary channel level difference is not more than 10dB, does not reduce the TV signal amplifiers of any channel carrier-to-noise ratio simultaneously again.

For achieving the above object, the utility model is to be connected in series an output level slew rate adjustment circuit between TV signal amplifying circuit and output, observation circuit, this circuit is a characteristic of utilizing inductor, capacitor, composition series connection accent shakes or forms antiresonant circuit, select for use SJ-B to make adjustable no part, TV signal can be separated into low-frequency range, Mid Frequency and high band, its function is the collection frequency division, and---adjusting (or part is straight-through by slope)---is mixed into the synthetic circuit of one.

Because the effect of output level slew rate adjustment circuit, need not select balanced sheet to force down low-side signal level in the TV signal amplifying circuit incoming level, just can guarantee that level difference is not more than the carrier-to-noise ratio that 10dB has so just improved low channel between arbitrary channel, guarantee the consistency of each channel carrier-to-noise ratio.

The utility model will be further described below in conjunction with the drawings and specific embodiments.

Fig. 1 is not improved subscriber's amplifier block diagram at present;

Fig. 2 is the utility model block diagram;

Fig. 3 is the distribution network schematic diagram;

Fig. 4 is the utility model circuit theory diagrams;

Fig. 5, Fig. 6, Fig. 7 are three kinds of dissimilar circuit theory diagrams of the utility model output level slew rate adjustment circuit.

Embodiment 1 as shown in Figure 4, empty frame 6 middle parts are divided into the output level slew rate adjustment circuit, the output of TV signal amplifying circuit connects inductance L 1, capacitor C 1 ground connection is leaded up in L1 output, one the tunnel is connected in series capacitor C 2, resistance R 1, inductance L 2 and capacitor C 3 successively, also have one the tunnel to export with capacitor C 3 with capacitor C 5 back through inductance L 4 and to be connected, ground connection after inductance L 5, capacitor C 6 are connected in series again, the output of L5 connects output monitoring circuit.Two inputs of S-JB adjuster are connected in parallel on resistance R 1, capacitor C 2 two ends, connect parallel circuits that inductance L 3, capacitor C 4 form ground connection again after the centre tap of its earth terminal and inductance L 2 is connected together.The operation principle of level slew rate adjustment circuit is: L1 and C1 form coupling and promote circuit, can certain the component frequency level in the high band be promoted, L4 and C5 form the high frequency band signal passage, its Insertion Loss is that the rising with frequency reduces, C2, R1, L2, C3 forms the Mid Frequency signalling channel, its Insertion Loss also is that the rising with frequency reduces, SJ-B, L3, the right half part C3 of C4 and L2 forms the adjustable channels of low-band signal, regulate SJ-B and can change throughput, be actually low-band signal is carried out the part decay, because the network that L3 and C4 form is serially connected in the earth terminal of SJ-B, so be that rising with frequency reduces to the pad value of low-band signal.L5 and C6 form coupling and promote circuit, promote the level of certain component frequency in the high band.Utilize the characteristic of three paths of high, normal, basic frequency range to compensate mutually, the numerical value of each components and parts of choose reasonable, because the mass action of circuit, make the linear slope of amplitude-frequency characteristic of output level slope circuit output level, be that the low side level can arbitrarily be adjusted on demand, and the output level amplitude raise and the linear gradient formula of increase output gradually with frequency.The carrier-to-noise ratio that in long range transmission networks, just can satisfy the arbitrary channel level difference of custom system mouth to be not more than the ministry standard of 10dB like this and can not reduce each channel of System Outlet.

Embodiment 2 output level slew rate adjustment circuits are Fig. 5, when Fig. 6, circuit shown in Figure 7, also can finish embodiment 1 described function.

Embodiment 3 is in the cottage area in cities and towns or the residential area in rural area, supposing has 10 family residents in 100 meters, if build the 550MHZ cable television system, then the one-way transmission length of dividing network is exactly 100 meters, the distribution network schematic diagram as shown in Figure 3, provide the television program receiving signal with five two splitters to 10 families, two splitters calculate by average 0.8dB the Insertion Loss difference of high low-side signal level, and then the Insertion Loss difference of five splitters is exactly 4dB.When the installation of this user area and subscriber's amplifier ground at a distance of 30 meters, when connecting with the SYKV75-9 cable, then the sending allowance difference of high and low end signal is 2.04dB, i.e. (9.2dB-2.4dB) * 0.3=2.04dB, other has two the top of a wall splitters or distributor Insertion Loss difference meter 1.6dB, and the above-mentioned sending allowance difference aggregate-value of family System Outlet endways is 7.6+4+2.04+1.6=15.24dB.If adopt existing not improved subscriber's amplifier, when output level is pressed the flat type debugging, then can be than the high 15.24dB of high channel at the low channel level value of last family System Outlet, surpassed the ministry standard that level difference between arbitrary channel is not more than 10dB, this obviously is not all right.Compromise commonly used in current engineering is to select suitable balanced inserted sheet for use, make the low 6dB of low-side signal level ratio high-side signal of input subscriber's amplifier, then the output level of amplifier is the tilting of low side than high-end low 6dB, the result is that the System Outlet level at first family is that low side is than high-end low 6dB, the family then is that low side is than the high 9.24dB of high-side signal level endways, make the carrier-to-noise ratio of low channel just therefore reduce 6dB like this, the contradiction that can not meet the demands simultaneously of these two technical indicators of level difference between carrier-to-noise ratio and arbitrary channel occurred than high channel.When adopting the subscriber's amplifier of band output level slope conditioned circuit shown in Figure 4, just can overcome this contradiction.

Claims

1. TV signal amplifiers, comprise incoming level adjustment circuit, equalizing circuit, amplifying circuit, output observation circuit and power circuit, it is characterized in that: in amplifying circuit and output, serial connection one output level slew rate adjustment circuit between the observation circuit, this circuit is to utilize inductor, the characteristic of capacitor, form series resonance or form antiresonant circuit, select the SJ-B adjustable element for use, TV signal can be separated into low-frequency range, Mid Frequency and high band, specifically consisting of of this circuit: the output of TV signal amplifying circuit connects inductance (L1), (L1) electric capacity (C1) ground connection is leaded up in output, one the tunnel is connected in series electric capacity (C2) successively, resistance (R1), inductance (L2) and electric capacity (C3), also have one the tunnel behind inductance (L4) and electric capacity (C5), to export and be connected with electric capacity (C3), again through inductance (L5), electric capacity (C6) serial connection back ground connection, (L5) output connects output monitoring circuit, two inputs of S-JB adjuster are connected in parallel on resistance (R1), electric capacity (C2) two ends connect inductance (L3) after the centre tap of its earth terminal and inductance (L2) is connected together, the parallel circuits that electric capacity (C4) is formed is ground connection again; (L1) and (C1) form coupling and promote circuit, (L4) and (C5) form the high frequency band signal passage, (C2), (R1), (L2), (C3) form the Mid Frequency signalling channel, (SJ-B), (L3), (C4) and right half part (L2) (C3) are formed the adjustable channels of low-band signal, by (L3) and the network of (C4) forming be serially connected in the earth terminal of SJ-B, (L5) and (C6) form coupling and promote circuit.