CN1045357C

CN1045357C - Method for making frequency changer in cable TV

Info

Publication number: CN1045357C
Application number: CN94111546A
Authority: CN
Inventors: 蒋柏平
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-12-26
Filing date: 1994-12-26
Publication date: 1999-09-29
Anticipated expiration: 2014-12-26
Also published as: CN1127968A

Abstract

The present invention provides a method for making a frequency changer on a cable TV. The present invention is characterized in that input is divided into two paths; one input path is mixed with a local oscillation signal and then is mixed with the other path for being output via the two-band gating of a UV frequency band mixer. The present invention effectively solves the problem that a part of signals of an appended frequency channel in a cable TV can not be directly received by an ordinary TV; that is, a product manufactured with the method is convenient for people to use the ordinary TV to watch programs of an appended frequency channel of the cable TV. The present invention has the advantages of low price and practicality, satisfies the requirement that people use the ordinary TV to receive programs of all frequency channels including programs of the appended frequency channel transmitted by the cable TV.

Description

CATV terminal Signal Processing method and device thereof

What the present invention proposed is a kind of CATV terminal Signal Processing method and device thereof, belongs to the cable TV technical field.

Before cable TV (CATV) was used, transmitting and receiving of TV signal all was that mode according to wireless designs, and corresponding frequency range is divided into VHF and UHF two big classes usually, and the frequency range of VHF frequency range comprises the 1-12 channel at 48.5-223MHz; The frequency range of uhf band comprises the 13-68 channel at 470-956MHz.And therefore the frequency range that the middle frequency range of vacating of VHF and UHF is 223-470MHz does not all have the receiving function of this frequency range (223-470MHz) by the general television set of radiovision acceptance criteria design not in the scope of application of radiovision.Along with the appearance of cable TV (CATV) with popularize, the program that needs to transmit gets more and more, and the cable TV network frequency bandwidth is limited, so also the frequency range of the 223-470MHz that vacates in the middle of VHF and the UHF is used for transmitting TV programme, this frequency range is referred to as to augment frequency range in the cable TV field.This has just produced the contradiction that can't receive the cable TV additional channel by the general television set of wireless standard design, in order to solve this contradiction, a kind of CATV terminal Signal Processing method of prior art: this method as shown in Figure 2, it is that all programs that cable TV transmits are input in the frequency mixer 2, under control signal (being the channel signals that the user will the select) effect of adjustable local oscillation circuit 8, carry out mixing, signal after the mixing is delivered to intermediate frequency amplifier 6 and is amplified, the local oscillation signal of getting its medium-frequency TV signal and 3 generations of local oscillation signal source is in another grade frequency mixer 2 ' middle mixing, again through band pass filter 7 filtering, produce a certain fixed channel signal output that the common TV function receives, watch for this fixed channel of television set.Its product is exactly a cable TV station selector high, the intermediate frequency mode.But the weak point of this method is the multichannel signal receiving function that has not originally had in conjunction with general television set, just television set is used as a display, has wasted the multichannel receiving function that television set has originally had.In this way the CATV station selector of Zhi Zuoing be similar in the television set high frequency and in circuit such as put, complex structure, the cost height, also need join dedicated remote control in addition, this is undoubtedly a kind of waste for the television set that has distant control function, and use also inconvenience, and channel selection will be used dedicated remote control, and the control of the volume of television set, color, brightness and contrast etc. then needs with the former remote controller of television set.

In addition, someone has proposed " a kind of cable TV additional channel converter ", and (patent No. is: 94205093.2), it be with cable TV signal after low pass filter, the high pass filter filtering successively of one tunnel series connection, the cable TV frequency signal of only remaining 40-480MHz, and only will this unique one road signal and the signal of local oscillation circuit deliver to frequency mixer, be up-converted into the UHF wave band high-frequency signal of 470-940MHz.This high-frequency signal is the high-frequency signal below filtering 450MHz behind the one-level high pass filter again, exports then, promptly inputs to the input of television set.But this converter is that whole CATV terminal signal is all upconverted to the UHF wave band together by one the tunnel, without any other along separate routes, does not also have the final combination of signal, does not have hybrid circuit; And in final output signal filtering the high-frequency signal below the 450MHz, so fail to keep the standard channel of the following VHF frequency range of former 223MHz, television set VHF frequency range receiving function can't be used, still do not make full use of the VHF that general television set originally had, the signal receiving function of two frequency ranges of UHF, wasted the limited channel resource of television set.And general television set actual reception highest frequency generally only reaches 868MHz (57 channel), signal at 868-940MHz does not generally receive yet, and the signal that promptly this converter produces can not be for general television set whole receptions in its uhf band (470-860MHz) institute can the scope of actual reception.

The objective of the invention is deficiency at above-mentioned existence, a kind of TV signal receiving function of giving full play to the existing VHF of television set, two standard bands of UHF is proposed, cost is low, easy to use, is convenient to satisfy people comprise all channel program demands that the CATV of the additional channel of U, V-band centre transmits with the general television set reception CATV terminal Signal Processing method and device thereof.

Technical solution of the present invention:

A kind of CATV terminal Signal Processing method, it is characterized in that the CATV terminal signal is divided into two-way with distributor or band pass filter earlier, wherein one the tunnel carries out mixing with frequency more than or equal to the local oscillation signal of 247MHz, make being in the UHF TV band after moving in the additional channel mixing with the frequency signal, then through the uhf band high pass filter of UV frequency range blender select to obtain in the original signal greater than each additional channel signal of 223MHz with the frequency signal, promptly become uhf band television signal greater than 470MHz; It is the original signal of 1-12 channel less than 223MHz that another road is directly selected to obtain through the VHF low pass filter of UV frequency range blender; Signal after above-mentioned two-way is handled mixes output and is the VHF by the distribution of tv channel frequency configuration standard that the invention provides to user's television set, each channel TV signal of two frequency ranges of UHF.

A kind of CATV terminal Signal Processing device, it includes distributor or band pass filter, frequency mixer, local oscillation signal source and UV frequency range blender, it is characterized in that the local oscillation signal source is the oscillating circuit of a frequency of oscillation more than or equal to 247MHz, UV frequency range blender is made up of uhf band high pass filter and VHF band low-pass filter, wherein the uhf band high pass filter is the filter circuit of a frequency band range greater than 470MHz, and the VHF band low-pass filter is the filter circuit of a frequency band range less than 223MHz.The CATV terminal signal links to each other with the input of distributor or band pass filter, and distributor or band pass filter divide two-way output.Wherein one the tunnel links to each other with the signal input part of frequency mixer, and another signal input part of frequency mixer links to each other with the output in local oscillation signal source, and the output of frequency mixer links to each other with the input of the uhf band high pass filter of UV frequency range blender.The input of another road output of distributor or band pass filter and the VHF band low-pass filter of UV frequency range blender links to each other, and the high pass filter of UV frequency range blender and the points of common connection of low pass filter are the signal output part of this device.

Accompanying drawing 1 is the functional-block diagram of the inventive method.

Accompanying drawing 2 is prior art block diagrams.

Accompanying drawing 3 is that the device of realizing the inventive method is implemented illustration.

Among the figure 1 is also band pass filter of distributor, 2,2 ' be frequency mixer, the 3rd, local oscillation signal source, the 4th, UV frequency range blender, the 5th, power supply, the 6th, intermediate frequency amplifier, the 7th, band pass filter, the 8th, adjustable local oscillator.

As Fig. 1, for common frequency bandwidth is the terminal signaling (comprising that 48.5-223MHzVHF frequency range and 223-450MHz augment frequency band signals) of the CATV system of 450MHz, the present invention is divided into two-way with it by distributor or band pass filter 1, wherein one tunnel output with frequency more than or equal to the local oscillation signal source 3 of 247MHz through frequency mixer 2 mixing, make after the additional channel mixing with the frequency Signal Move in the UHF TV band, and then be input to UV frequency range blender 4, through its uhf band high pass filter select to obtain in the original cable TV signal greater than each additional channel signal of 223MHz with the frequency signal, promptly become standard television signal greater than the uhf band of 470MHz.Another road is directly inputted to UV frequency range blender 4, selects to obtain the i.e. standard television signal of the original VHF frequency range below 12 channels less than 223MHz through its VHF band low-pass filter.Signal after above-mentioned two-way is handled is mixed output by UV frequency range blender 4 simultaneously, this output signal is the VHF by the distribution of television frequency configuration standard that the invention provides to user's television set, each channel TV signal of two frequency ranges of UHF, can be convenient to general television set and directly watch.

CATV terminal Signal Processing device according to above-mentioned treatment design, it includes distributor or band pass filter 1, frequency mixer 2, local oscillation signal source 3 and UV frequency range blender 4, be characterized in that local oscillation signal source 3 is the oscillating circuit of a frequency of oscillation more than or equal to 247MHz, UV frequency range blender 4 is made up of uhf band high pass filter and VHF band low-pass filter, wherein the uhf band high pass filter is the filter circuit of a frequency band range greater than 470MHz, and the VHF band low-pass filter is the filter circuit of a frequency band range less than 223MHz.The CATV terminal signal links to each other with the input of distributor or band pass filter 1, the two-way output in 1 fen of distributor or band pass filter.Wherein one the tunnel links to each other with the signal input part of frequency mixer 2, and another signal input part of frequency mixer 2 links to each other with the output in local oscillation signal source 3, and the output of frequency mixer 2 links to each other with the input of the uhf band high pass filter of UV frequency range blender 4.The input of another road output of distributor or band pass filter 1 and the VHF band low-pass filter of UV frequency range blender 4 links to each other, and the high pass filter of UV frequency range blender 4 and the points of common connection of low pass filter are the signal output part of this device.

Further describe as follows below in conjunction with accompanying drawing to the embodiment of apparatus of the present invention:

As shown in Figure 3, among the figure 1 is exactly the distributor among Fig. 1 or the functional module of band pass filter 1, wherein distributor can be two distributors, three distributors or splitter etc., band pass filter can be more than or equal to the 223MHz high pass filter with smaller or equal to the combination of 223MHz low pass filter, perhaps is the combination of 48.5-223MHz band pass filter and 223-450MHz band pass filter.Can also be combination more than or equal to 223MHz high pass filter and 48.5-223MHz band pass filter, or smaller or equal to the combination of 223MHz low pass filter and 223-450MHz band pass filter.The points of common connection of combinations thereof is divided into two-way output as input.What provide among Fig. 3 is one two distributor, and it is made up of transformer 1B1,1B2, electric capacity 1C1 and resistance 1R1.The CATV terminal signal is transformer 1B1 input from two distributors 1, and the two-way output of two distributors 1 is drawn from 1B2 and connect frequency mixer 2 and UV frequency range blender 4 respectively.Frequency mixer 2 can be ring mixer, also can be single tube frequency mixer or balanced mixer.What provide among Fig. 3 is a ring mixer 2, it is by input transformer 3B1 and elementary resistor network 3R2 thereof, 3R4,3R6, output transformer 3B2 and secondary resistance network 3R9 thereof, 3R10,3R11, diode-bridge circuit 3BG1-3BG4 and variable-resistor network 3R1,3R3,3R5,3R7,3W1 form, and it is that the end B of coupling transformer 1B2 links to each other that its signal input part is drawn with an output of two distributors 1 from the elementary resistor network of input transformer 3B1.Its output joins from secondary the drawing with UV frequency range blender 4 of output transformer 3B2, and an end of its adjustable resistance network and the secondary centre tap of input transformer 3B1 are joined, and its other end links to each other with the output in local oscillation signal source 3.Local oscillation signal source 3 can be a Colpitts oscillation circuit, also inductance of three-point oscillating circuit, also crystal oscillating circuit etc.What provide among Fig. 3 is the local oscillation signal source 3 that is made of crystal oscillating circuit.It is by quartz crystal oscillator device 2GF, voltage stabilizing didoe 2BG3, transistor 2BG1 and peripheral resistance 2R1-2R4 thereof, electric capacity 2C1-2C3, the first order coupling amplifying circuit that the elementary 2L1 of coupling transformer constitutes, triode 2BG2 and peripheral resistance 2R5-2R7 thereof, electric capacity 2C4-2C7, the secondary 2L2 of coupling transformer, the second level amplification coupling circuit that the elementary 2L3 of output coupling transformer constitutes, the secondary 2L4 of output coupling transformer, electric capacity 2C11-2C17, the frequency-selective network that inductance 2L6-2L8 constitutes is formed, and its signal output part is drawn the variable-resistor network that is connected to frequency mixer 2 from electric capacity 2C17.UV frequency range blender 4 is electric capacity 4C1 by the VHF band low-pass filter among Fig. 3,4C2, inductance 4L1, T mode filter and uhf band high pass filter that 4L2 constitutes are electric capacity 4C3-4C5, inductance 4L3, the pi type filter that 4L4 constitutes is formed, wherein the input of VHF band low-pass filter links to each other with an output C of two distributors 1, the input of its uhf band high pass filter links to each other with the secondary resistance network of the output transformer 3B2 of ring mixer 2, the output of UV frequency range blender 4 is drawn from the points of common connection of its low pass filter and high pass filter, as signal output part of the present invention.

The operation principle of apparatus of the present invention is as follows, the signal input part that the terminal signaling of cable TV is delivered to two distributors 1 is the elementary 1B1 of transformer, two distributors 1 have been divided into two-way, one road output B from two distributors 1 delivers to ring mixer 2, the frequency multiplication local oscillation signal of the 247MHz that produces with local oscillation signal source 3 carries out mixing, according to ring mixer 2 can with frequency input signal and the addition of local oscillation signal frequency produces and principle frequently, just the output at frequency mixer 2 has moved on to uhf band with augmenting of 223-450MHz on the frequency range, mixed frequency signal after moving on being somebody's turn to do is delivered to the input of the uhf band high pass filter of UV frequency range blender 4, obtain the uhf band standard television signal of 470-697MHz wherein through its selection, be 223-450MHz augment frequency range and frequently on signal after moving.Two distributors 1 directly are added to the VHF band low-pass filter of UV frequency range blender 4 from another road signal of its output C output, by its select the VHF band limits promptly less than the standard television signal of the 1-12 channel of 223MHz.The above-mentioned two paths of signals that the high and low pass filter of UV frequency range blender 4 is chosen mixes simultaneously from its points of common connection output, is apparatus of the present invention and offers the VHF by the distribution of tv channel frequency configuration standard of user's television set, each channel TV signal of two frequency ranges of UHF.Can be convenient to general television set and both watch original VHF frequency range standard television signal, can watch the additional channel program uhf band (this frequency range does not normally take) again in the CATV terminal signal.

Among the embodiment of apparatus of the present invention, two distributors 1 shown in Figure 3 also can be replaced by band pass filter, directly export as the TV signal of choosing the VHF frequency range (smaller or equal to 223MHz) in the CATV terminal signal with the VHF band low-pass filter, choose in the CATV terminal signal the local oscillation signal mixing that frequency band signals is delivered to ring mixer 2 and local oscillation signal source 3 of augmenting with a high pass filter or band pass filter again more than or equal to 223MHz, deliver to the uhf band high pass filter of UV frequency range blender 4 then, select output to get final product by it, at this moment, VHF band low-pass filter in the UV frequency range blender 4 can be saved, and can realize purpose of the present invention equally.

To different CATV system and television receivers, can do to select separately to each signal frequency and circuit devcie etc. with reference to said method.As for increasing certain cost with the broadening of catv network frequency band, and the highest 550MHz that expands to of cable TV signal transmits in accordance with regulations, promptly transmit the cable television program except that augment frequency range at 48.5-223MHzVHF frequency range (1-12 channel), 223-450MHz, also be used for transmitting the CATV system of 10 tunnel TV signal at the 470-550MHz of uhf band (13-22 channel), only need the frequency in local oscillation signal source 3 is heightened, adjust the high pass filter of blender 4 and the frequency parameter of low pass filter simultaneously and get final product.As through above-mentioned processing signals insufficient strength, can suitably amplify, die down as the signal strength signal intensity after the mixing, can amplify with U section amplifier earlier, by amplifier signal is strengthened, again with distributor along separate routes, then this device can be watched wherein different channel simultaneously for two above television sets.

The present invention changes traditional CATV terminal Signal Processing method, when keeping original channel signals, again the additional channel conversion of signals is arrived UHF standard channel, so both guarantee the normal reception of the original channel signals of television set, solved the problem that general television set additional channel signal does not receive again.Product structure of the present invention is simple, and cost is low, need not to join in addition remote controller, and this is particularly suitable for the colour TV with distant control function.The present invention has given full play to the existing VHF of television set, UHF standard channel receiving function, make full use of the limited channel resource of general television set, be convenient to satisfy people receive all channel programs of the CATV transmission that comprises additional channel with general television set demand.

Claims

1. CATV terminal Signal Processing method, it is characterized in that the CATV terminal signal is divided into two-way with distributor or band pass filter earlier, wherein one the tunnel carries out mixing with frequency more than or equal to the local oscillation signal of 247MHz, make being in the UHF TV band after moving in the additional channel mixing with the frequency signal, then through the uhf band high pass filter of UV frequency range blender select to obtain in the original signal greater than each additional channel signal of 223MHz with the frequency signal, promptly become uhf band television signal greater than 470MHz; It is the original signal of 1-12 channel less than 223MHz that another road is directly selected to obtain through the VHF low pass filter of UV frequency range blender; Signal after above-mentioned two-way is handled mixes output and is the VHF by the distribution of tv channel frequency configuration standard that offers user's television set, each channel TV signal of two frequency ranges of UHF.

2. CATV terminal Signal Processing device, it includes distributor or band pass filter, frequency mixer, local oscillation signal source and UV frequency range blender, it is characterized in that the local oscillation signal source is the oscillating circuit of a frequency of oscillation more than or equal to 247MHz, UV frequency range blender is made up of uhf band high pass filter and VHF band low-pass filter, wherein the uhf band high pass filter is the filter circuit of a frequency band range greater than 470MHz, the VHF band low-pass filter is the filter circuit of a frequency band range less than 223MHz, the CATV terminal signal links to each other with the input of distributor or band pass filter, distributor or band pass filter divide two-way output, wherein one the tunnel links to each other with the signal input part of frequency mixer, another signal input part of frequency mixer links to each other with the output in local oscillation signal source, the output of frequency mixer links to each other with the input of the uhf band high pass filter of UV frequency range blender, the input of another road output of distributor or band pass filter and the VHF band low-pass filter of UV frequency range blender links to each other, and the high pass filter of UV frequency range blender and the points of common connection of low pass filter are the signal output part of this device.