JPH0114746B2 - - Google Patents

Description

[Detailed description of the invention]

In this invention, each antenna was received by a separate antenna.
A television reception system that transmits a UHF band broadcast signal and a VHF band broadcast signal to an output terminal for television broadcast reception through a single transmission line.
By converting the signal frequency to that of the UHF band and transmitting it through the transmission line, the signal can be transmitted with less loss, and by returning the signal frequency to the original UHF band frequency near the output terminal, television reception is possible. This relates to a television reception system that allows the receiver to receive images in the same way as regular UHF broadcasts. The purpose of this is to be able to obtain a good screen image by eliminating adjacent channel beats even if both of the above signals are sent at frequencies in the VHF band; It is an object of the present invention to provide a television reception system that can reduce the cost even when the frequency is returned to the UHF band. The drawings showing the embodiments of the present application will be described below. In FIG. 1, reference numeral 1 denotes an antenna for receiving broadcast signals in the VHF band, which is capable of receiving low band television broadcast signals from channels 1 to 3 and high band television broadcast signals from channels 4 to 12. Reference numeral 2 denotes an amplifier, which is used to amplify the signal received by the antenna 1 when the level of the signal is low. 3 is an antenna for receiving broadcast signals in the UHF band, channel 13
A device that can receive television broadcast signals in the UHF band on channel 62 is used. 4
is a first frequency converter, which converts the frequency of the broadcast signal received by the antenna 8 into a mid-band channel in the VHF band. 5 is a mixer, 6 is a transmission line, for example a coaxial cable is used, and 7 is a pilot signal generator, for example, a stable oscillation circuit such as a crystal oscillation circuit is used. Also, the frequency is selected to be 73MHz, 246MHz or 148MHz. 8 is a brancher used to superimpose the pilot signal from the pilot signal generator 7 onto the transmission line 6, and is generally used by connecting its input end 8a, output end 8b, and branch end 8c as shown in the figure. . Incidentally, this superposition of the pilot signal may be performed using a resistor 8' as shown in FIG. Reference numeral 9 designates a frequency conversion signal generator, which uses a stable oscillation circuit similar to the pilot signal generator described above. Further, the frequency is selected to a value as described below. Furthermore, this signal generator 9
As in the case of the pilot signal generator described above, the signal is sent to the transmission line 6 using a brancher 8''. An amplifier is shown. In this line amplifier 10, 11 is an input terminal, 12 is an output terminal, and 13 is a branch output terminal. 14 is an AGC amplifier,
A well-known or well-known circuit configuration capable of AGC amplifying signals in the VHF band (90 to 222 MHz) is used. Reference numeral 15 denotes a second frequency converter, which converts the mid-band frequency signal sent via the transmission line 6 to the original UHF band frequency signal. The frequency converter 15 also uses the signal sent from the frequency conversion signal generator 9 as a frequency conversion signal (generally called a local oscillation signal). 16 indicates a well-known distribution circuit. Next 17
indicates a television receiver connected to the branch output terminal 13. Incidentally, this television receiver 17 is generally installed at each subscriber's home in a communal reception facility. In the above configuration, the VHF band broadcast signal received by the antenna 1 is amplified by the amplifier 2. On the other hand, the UHF band broadcast signal received by the antenna 3 is converted to a mid-band frequency by the first frequency converter 4. These signals are sent to a transmission line 6 via a mixer 5. On the other hand, the pilot signal generated by the pilot signal generator 7 and the frequency conversion signal generated by the frequency conversion signal generator 9 are also transmitted along the transmission line 6 together with the broadcast signal. Next, the four types of signals sent through the transmission line 6 are input to the line amplifier 10 from its input terminal 11. These input signals are AGC-amplified by the AGC amplifier 14 based on the level of the pilot signal, and are outputted from the output terminal 12 to the subsequent stage, and a portion thereof reaches the distribution circuit 16. On the other hand, the mid-band frequency signal input to the input terminal 11 is converted back to the original UHF band frequency signal by the frequency converter 15, and the signal reaches the distribution circuit 16. The signals that have entered these distribution circuits 16 are distributed by this distribution circuit 16 and sent from a plurality of branch output terminals 13 to a television receiver 17.
Output to. Next, the frequency of the frequency conversion signal generated by the frequency conversion signal generator 9 will be explained. The frequency of this signal is the difference between the frequency of the UHF band broadcasting signal input to the frequency converter 4 and the mid-band frequency output from the frequency converter 4 after converting the frequency of that signal, as an integer. The divided value is used. Furthermore, the value used is a frequency that can be amplified by the AGC amplifier circuit 14 (generally 90 to 222 MHz) and that does not interfere with the VHF band television signal and the pilot signal. In this example, the frequencies shown in Table 1 below are selected.

[Table] That is, to explain example 1 in Table 1, the channel number of the input broadcast signal in the UHF band is 13 (the frequency is 470 to 476M).
Hz), and the channel number of the converted output signal in the mid-band is G (frequency is 144 to 150MHz).
In this case, subtract 144MHz from 470MHz and get 326MHz as the difference. Next, divide this 326MHz by an arbitrary integer such as 2 to obtain 163MHz.
This 163MHz can be amplified by AGC amplifier 14
Since it is a frequency in the VHF band and does not interfere with television signals and pilot signals, this 163MHz can be used as a frequency conversion signal. On the other hand, in the second frequency converter 15, frequency conversion is performed as follows. For example, referring to Example 1 above, the frequency converter 15 first doubles the 163 MHz frequency conversion signal to obtain 326 MHz. Next, by using this 326MHz as a signal for frequency conversion, the G channel broadcast signal in the mid-band can be converted back to the original 13MHz in the UHF band.
channel (its frequency is 470-476MHz). As the frequency conversion signal, in addition to the 163 MHz in Example 1, values such as those shown in Examples 2 to 8 or other various values can be used. Next, a description will be given of FIG. 2, which shows the circuit configuration of the line amplifier 10 in more detailed block form. first
The AGC amplifier 14 is composed of well-known or well-known blocks, and 21 is a front-stage amplifier section;
22 is a variable attenuator, 23 is a post-stage amplification section, and 24 is a pilot signal extraction section, which is constructed using a bandpass filter that allows only the pilot signal to pass through. 25 is a high frequency amplification section, 26 is a detection circuit, and 27 is a DC amplification section, each of which can control the amount of attenuation of the variable attenuator 22 in accordance with the output thereof. Next, in the frequency converter 15, 28 is a band pass filter, which has a pass band that allows only mid-band frequency signals to pass through. 29 is a high frequency amplification section, and 30 is a band pass filter, which is similar to the filter 28 described above. 31 is a mixing section, 32 is a high frequency amplification circuit, and 33 is a frequency conversion signal selection section, which is configured using a bandpass filter so as to be able to extract the frequency conversion signal. 34
is a multiplier circuit, which uses a circuit that multiplies the frequency conversion signal as described above. 35 indicates an amplifier circuit. Reference numeral 36 denotes a television signal distribution circuit which distributes the signal input to the input terminal 11 into two. Also, 37 is a mixed circuit,
The output signal from the AGC amplifier 14 and frequency converter 15 is mixed and sent to a distribution circuit 16. 38 and 39 are power supply separation filters,
The transmission line is superimposed on the above TV signal so that only the AC power sent can be extracted.
It is constructed with a low pass filter. 40
indicates the power supply circuit. With the above configuration, the signal input to the input terminal 11 is divided into two by the distribution circuit 36, one of which is amplified by the AGC amplifier 14. On the other hand, the other one is input to the frequency converter 15. In this frequency converter 15, a broadcast signal of a mid-band frequency passes through a bandpass filter 28, an amplifying section 29, and a bandpass filter 30, and reaches a mixing section 31. On the other hand, the frequency conversion signal extracted by the frequency conversion signal selection section 33 is multiplied by a multiplier circuit 34, and further multiplied by an amplifier circuit 35.
The signal is amplified and reaches the mixing section 31. Mixing section 31
In this case, a mid-band frequency signal is frequency-converted by a frequency-converting signal from the amplifier circuit 35 in a well-known manner. The converted signal is outputted from the terminal 13 via the amplifier circuit 32, the mixing circuit 37, and the distribution circuit 16. Next, FIG. 3 is a graph showing a trial calculation of the relationship between the number of line amplifiers 10 used in the above system and the costs required for the frequency conversion signal generator 9 and the second frequency converter 15. As is clear from this graph, in the above receiving system, the more line amplifiers 10 are used, the more the line amplifiers 10 are used, the more , the entire system can be constructed at low cost. Next, FIG. 4 shows a different embodiment of the present application, in which a divider 41 is provided on the output side of the AGC amplifier 14e, and one of the divided outputs is inputted to the frequency conversion signal selection section 33e. be. In addition, in the circuit shown in FIG. 3, the branch output terminal 13e
Only one is used. It should be noted that the same reference numerals as those in the previous figure are appended with an alphanumeric letter "e" for parts that are functionally the same or equivalent to those in the previous figure, and redundant explanations are omitted.
(Also, in the following figures and subsequent figures, the same idea is applied sequentially to the alphabet f and g, and redundant explanations will be omitted.) Next, Fig. 5 shows a further different embodiment of the present application. This shows a circuit in which all signals to the frequency converter 15f are obtained from the distributor 41f. Also, in the circuit shown in Fig. 4,
Since the level of the signal obtained from the distributor 41f is relatively high, the amplifier section 29 as in the previous embodiment is not used. Further, two branch output terminals 13f are used as shown in the figure. Therefore, the distributor 16
A two-distribution type f is also used. Next, FIG. 6 shows a different embodiment of the first frequency converter, and an example in which the first converter also utilizes the frequency conversion signal from the frequency conversion signal generator. This shows that. In FIG. 6, 45 is an input terminal, which is a terminal to which a signal from a UHF antenna is input. 46
is a high frequency amplifier that can amplify broadcast signals in the UHF band. 47 is a mixer, and 48 is a high frequency amplifier, which is capable of amplifying VHF mid-band frequency signals. 49 is a band elimination filter, which is a filter designed to block only the frequency of the frequency conversion signal. Reference numeral 50 indicates an output terminal, which is a terminal connected to the mixer 5. Reference numeral 51 denotes a band pass filter, which uses a filter that allows only the frequency conversion signal to pass. Reference numeral 52 denotes a multiplier circuit, which has the same multiplier as the multiplier circuit 34 described above. 53 is a power supply separation filter, 54 is a power supply circuit, and each amplifier 4
6, 48 or a multiplier circuit 52, etc., are operated. With such a configuration, when a signal from the frequency conversion signal generator enters the output terminal 50, the frequency conversion signal is passed through the bandpass filter 5.
1, and is further multiplied by a multiplier circuit 52 and sent to a mixer 47. On the other hand, the UHF band broadcast signal input to the input terminal 45 is transmitted to the high frequency amplifier 4.
The signal is then amplified in the mixer 47, based on the signal from the multiplier circuit 52, and converted into a signal with a mid-band frequency. This signal is amplified by an amplifier circuit 48, passed through a band-elimination filter 49, and then sent out from an output terminal 50. As described above, in the present invention, a UHF band broadcast signal and a VHF band broadcast signal are transmitted through a single transmission line 6, and a plurality of line amplifiers cascaded on the transmission line 6 are used. 10, 10, and even if the UHF band broadcast signal is transmitted with less loss by converting its frequency to the VHF band frequency, the above UHF band broadcast signal is the frequency
Since it is designed to convert to a mid-band frequency in the VHF band for transmission, it has the advantage that broadcast signals in both bands can be transmitted without worrying about adjacent channel beats. This means that when receiving UHF or VHF band broadcasts by receiving signals from the branch output terminals 13 of each line amplifier 10 to the television receiver, it is possible to receive either broadcast with high quality. Demonstrates the effect that can be received on the screen. Moreover, as described above, a plurality of line amplifiers 10 are connected to the transmission line 6, and each line amplifier 10 transmits the UHF band broadcast signal sent at the above-mentioned mid-band frequency to a normal television receiver. For each, the second
Even if the frequency converter 15 is used to return the signal to the original frequency of the UHF band, in the present invention, the signal from the frequency conversion signal generator 9 connected to the input side of the transmission line 6 is Since the signal is supplied to each frequency converter 15 of each line amplifier 10, even if there are a large number of frequency converters, one frequency conversion signal generator 9 is sufficient for the entire system. This means that since good frequency stability of the signal returned to the UHF band is required, the generator of the above signal must have high frequency accuracy and is very expensive. , As mentioned above, since one unit is sufficient, the price of the entire system can be reduced as shown in FIG. 3. Furthermore, the frequency output by the frequency conversion signal generator 9 in the present invention is
A frequency within a band that can be amplified by 4,
Moreover, it is different from the above-mentioned VHF band broadcast signal and the above-mentioned pilot signal, and moreover, the value used is the difference value between the above-mentioned mid-band frequency and the above-mentioned UHF band broadcast signal frequency divided by an integer,
What frequency value is the frequency of the UHF broadcast signal received by the second antenna 3 (for example, the signal shown in Table 1, and the specified pilot signal "148MHz" must be used) It has the advantage of being able to exhibit the above-mentioned effects even when the signal has a frequency that cannot be used. This means that a wider variety of frequencies can be used than when the pilot signal is used as a frequency conversion signal.
There is a versatility advantage that allows the above effects to be exploited for signals in the UHF band. Furthermore, as described above, frequency conversion signals are successively supplied from the input side of the transmission line 6 to each of the frequency converters 15 in the plurality of amplifiers 10 arranged in series on the transmission line 6. In other words, even if the above-mentioned signal is sent to the frequency converter 15 in the line amplifier 10 on the downstream side via a long transmission line 6 or another line amplifier 10 interposed in the middle, each In the line amplifier 10, an AGC amplifier 14 which is designed to perform AGC amplification based on a pilot signal is used as an amplifier for amplifying a signal that has entered its input terminal and sending it out from its output terminal. Since the conversion signal has a frequency that can be amplified by this amplifier 14, the AGC amplifiers 14, 14...14
are a VHF signal and a mid-band signal, respectively.
It is possible to appropriately amplify each of the four types of signals, the pilot signal and the frequency conversion signal, and is economical, as the AGC amplifier can be an ordinary product that meets normal NHK standards. Moreover, the above-mentioned signal can be supplied at a stable level to the frequency converter 15 of the latter-stage amplifier 10, and the frequency conversion operation can be performed satisfactorily. As a result, among the plurality of line amplifiers, the line amplifier 1 on the subsequent stage side
A stable signal in the UHF band can be outputted from the output terminal 13 of 0, which has the effect of providing a good screen to a television receiver connected to the terminal 13. To reiterate the above points, the present invention provides a method for converting the frequency of a frequency conversion signal into a frequency within a band that can be amplified by an AGC amplifier, and
It is different from both the VHF band broadcast signal and the above pilot signal, and moreover, the difference value between the above mid-band frequency and the above UHF band broadcast signal frequency is 2
The biggest advantage is that it is set to a value divided by the above integer. This makes it possible for the first antenna to receive
VHF band broadcast signals, signals obtained by converting the UHF band broadcast signals received by the second antenna to mid-band frequencies in the VHF band, and VHF band signals such as pilot signals are transmitted through multiple channels connected in cascade in multiple stages. with the line amplifier 10 of
Not only does it have the feature of being able to send the above UHF band broadcasting signal at an appropriate level to the subsequent stages one after another while being amplified by AGC, but in order to transmit the above UHF band broadcasting signal with less loss, it is possible to convert the signal to a mid-band frequency and send it to a large number of stations. Each original UHF in line amplifier
When returning to a band signal, the frequency conversion signal of the above frequency sent out from the single frequency conversion signal generator 9 can be AGC-amplified by the line amplifiers 10 at various locations, and the frequency conversion signal can be kept at an appropriate level and fluctuated. In addition, when the mid-band frequency signal is returned to the original UHF band signal at each line amplifier 10, the original UHF band signal is transmitted sequentially to the line amplifiers 10 at various locations. (All UHF bands from channel 13 to channel 62) No matter which channel the signal is from, the frequency conversion signal sent at the appropriate level as described above is multiplied by the same number as the divisor above. By using this, it is possible to return to the original UHF band channel itself, and users of the broadcast signal can easily use it (for example, by simply tuning to the channel number shown in the program section of a newspaper). effective.

[Brief explanation of drawings]

The drawings show an embodiment of the present application, and FIG. 1 is a system diagram of a television receiving system, the first two diagrams are diagrams showing different examples of pilot signal superimposition methods, and FIG. 2 is a block diagram of a line amplifier. Figure 3 is a graph showing the relationship between the number of line amplifiers used and the price, Figures 4 and 5 are block diagrams showing different embodiments of the line amplifier, and Figure 6 is a graph showing different embodiments of the first frequency converter. FIG. 2 is a block diagram showing an example. 1, 3... Antenna, 4... First frequency converter, 7... Pilot signal generator, 9... Frequency conversion signal generator, 6... Transmission line, 10... Line amplifier, 14... AGC amplifier, 15...second frequency converter, 13...branch output terminal.

Claims (1)

[Claims] 1. A first antenna for receiving broadcast signals in the VHF band, a second antenna for receiving broadcast signals in the UHF band, and connecting to the second antenna, and transmitting the frequency of the received broadcast signal in the UHF band to VHF. a first frequency converter configured to convert to a mid-band frequency in the band;
a transmission line connected to the antenna and the frequency converter, a pilot signal generator for transmitting a pilot signal connected to the input side of the transmission line, and a connection point of the pilot signal generator to the transmission line. In a television receiving system comprising a plurality of line amplifiers arranged in cascade on the latter stage, the input side of the transmission line is configured to send a frequency conversion signal to the plurality of line amplifiers via the transmission line. Connect the frequency conversion signal generator set to
On the other hand, the line amplifier has an input terminal and an output terminal connected to the transmission line, a branch output terminal that sends out a signal to a television receiver, and an input terminal and an output terminal that are interposed between the input terminal and the output terminal. an AGC amplifier and a second frequency converter connected to the input terminal, and an output end of the AGC amplifier and an output end of the second frequency converter are both connected to the branch output terminal; Furthermore, the AGC amplifier receives the signal from the first antenna.
It is configured to AGC amplify three types of signals: a VHF band broadcast signal, a mid-band frequency signal sent from the first frequency converter, and the pilot signal, based on the pilot signal. The frequency output from the frequency conversion signal generator is within the band that can be amplified by the AGC amplifier, and is different from the broadcast signal in the VHF band and the pilot signal, and is in the mid-band. Frequency and above
A value obtained by dividing the difference value between the frequency of the UHF band broadcast signal and the frequency by an integer of 2 or more is used, and the second frequency converter converts the signal sent from the frequency conversion signal generator into the above frequency converter. A multiplier circuit that multiplies the frequency by the same number as the divisor, and a signal of the mid-band frequency sent from the first frequency converter is multiplied by the multiplier circuit to reproduce the original UHF signal.
What is claimed is: 1. A television receiving system comprising: a mixing section configured to convert the signal into a band signal and output the converted signal to the branch output terminal.