JP2001036767A - Intra-building incoming signal frequency converter and intrabuilding catv system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To unify the voltage gain of the whole transmission lines of an intra- building CATV system also before and after the installation of an intra-building incoming signal frequency converter without substituting existing transmission equipment. SOLUTION: The intra-building incoming signal frequency converter 20 for returning an intra-building incoming signal transmitted from a terminal 15 through a transmission line 11 to an incoming signal of frequency allowed to be used for an external bidirectional CATV system is attached to a connection part between the transmission line 11 of the intra-building CATV system and the lead-in wire of the external bidrectional CATV system. The converter 20 is provided with an outgoing signal passing circuit 20a for selecting voltage gain so that the voltage level of an outgoing signal inputted from a terminal T1 matches with that of an intra-building incoming signal inputted from a terminal T2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an external bidirectional CA.
An in-building CAT that draws a drop line from a TV system into a building and connects a terminal terminal in the building to a drop line of an external two-way CATV system via a transmission line in the building.
The present invention relates to a V system and an in-building upstream signal frequency converter that converts an in-building upstream signal transmitted from a terminal terminal side to a frequency that can be transmitted by an external bidirectional CATV system.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3, a drop-in line 5 from an external bidirectional CATV system constituted by a head end 1, a branch amplifier 2, an extension amplifier 3, a tap-off 4, a security device 6, etc. is connected to an apartment house. And the like, and a down signal (specifically, a down signal transmitted from the head end 1) input from the drop line 5 is sent to the building 1.
0 to the terminal terminal 15 via the transmission line 11 inside, and the upstream signal input from the terminal terminal 15
The CATV system in a building which is configured to transmit data to the head end 1 side from the service line 5 is practically used.

[0003] A subscriber of the CATV system connects a personal computer 17 to a terminal 15 in the building 10 via a cable modem 18 and transmits various data (up signals) from the personal computer 17 to the head end 1. By doing so, viewing reservation of a pay program, television shopping, and the like are performed.

The frequency of an upstream signal transmitted from the personal computer 17 via the cable modem 18 is usually about 10 to 50 MHz, and this frequency band is the frequency band of various noises generated in the building 10. Since the signal overlaps with the frequency band, noise flows into the signal on the transmission line 11 of the CATV system in the building, and a correct signal may not be transmitted to the head end 1.

Therefore, in recent years, personal computers 1
7 is temporarily transmitted by the terminal-side frequency converter (so-called up-converter) to a frequency band higher than the frequency band of the noise and to the frequency band of the downlink signal (for example, 70 to 770 MHz), and the frequency is converted to an upstream signal of a high frequency band (for example, 800 MHz band) (hereinafter, referred to as “in-building up signal”) which is transmitted to the service line 5 side. Immediately before outputting an upstream signal from the transmission line 11 to the drop-in line 5, the frequency of the upstream signal in the building is returned to an upstream signal of 10 to 50 MHz by using a upstream signal frequency converter (so-called down converter) in the building. In-building CATV systems that reduce the effects of ingress noise have been considered.

[0006]

However, CATV in the ridge
The transmission line of the system includes a bidirectional amplifier 12, a two-way splitter 1
A large number of transmission devices such as a 3, 4 distributor 14 and the like are provided, and the voltage gain of each transmission device is determined by the terminal terminal 15 and the television receiver 16 therebelow in a state in which the down signal input from the drop line 5 is good. Is set strictly so as to be transmitted to terminal equipment such as the above, if a new in-building upstream signal frequency converter is provided, the voltage gain in the entire transmission line 11 changes, and the downstream signal is in a good condition. And transmission to the terminal terminal 15 is stopped.

[0007] By replacing each transmission device,
It is conceivable to make the voltage gain before the installation of the in-building up-signal frequency converter and the voltage gain after the installation match, but it takes time and money to replace the transmission equipment. Accordingly, the present invention provides a method of installing a voltage gain and an in-building upstream signal frequency conversion device on the entire transmission line of a building CATV system before installing the in-building upstream signal frequency conversion device without replacing any existing transmission equipment. It is intended to match the voltage gain after the above.

[0008]

Means for Solving the Problems and Effects of the Invention In order to achieve such an object, an in-building upstream signal frequency conversion apparatus according to the first invention has the following features.
A drop-in line from an external two-way CATV system is pulled into a building, and a down signal input from the drop-in line is transmitted to a terminal terminal in the building via a transmission line in the building, and An in-building CATV system for transmitting an up signal input from a terminal terminal in a building to the service line, provided between the service line and a transmission line in the building, and connected to the terminal terminal via the transmission line. Transmitted by the terminal-side frequency converter and converted to a higher frequency than can be transmitted by the external bidirectional CATV system in the building, is transmitted by the external bidirectional CATV system. An upstream signal frequency conversion means for converting the frequency to a possible frequency and outputting the converted signal to the service line, and the downstream signal input from the service line via the transmission line at the same frequency. Downstream signal passing means for outputting the signal to the terminal terminal side, and an in-building upstream signal frequency conversion device comprising: a downstream signal amplifying means for amplifying the downstream signal passing through the downstream signal passing means. Features.

According to the in-building upstream signal frequency converter according to the present invention, for example, when a personal computer is connected via a cable modem to the end of the terminal terminal, the upstream signal transmitted from the personal computer is transmitted. Is converted into an in-building upstream signal having a high frequency by the terminal-side frequency conversion device, and transmitted to the upstream signal frequency conversion means via the transmission line. Then, the upstream signal frequency conversion means converts the frequency of the transmitted upstream signal in the building to a frequency that can be transmitted by an external bidirectional CATV system, that is, returns the signal to the original upstream signal. Then, the frequency-converted signal is output to the service line. On the other hand, the downstream signal transmitted from the drop line is transmitted to the terminal terminal (and the television receiver ahead) via the transmission line at the same frequency by the downstream signal passing means. Then, the downstream signal amplifying unit amplifies the downstream signal passing through the downstream signal passing unit. Therefore, if the voltage gain of the downstream signal by the downstream signal amplifying means is appropriately adjusted, even if the voltage gain of each transmission device is newly set on the transmission line of the CATV system in the building where the voltage gain is strictly set, the entire transmission line can be installed. The voltage gain for the downstream signal does not change at all. Therefore, the voltage gain in the entire transmission line of the in-building CATV system before installing the in-building up-signal frequency converter and the voltage after installing the in-building up-signal frequency converting device without replacing any existing transmission equipment. The gain can be made to match, and the downlink signal can be transmitted to the terminal terminal in a favorable state.

Specifically, as described in claim 2, the down signal amplifying means compensates for the insertion loss of the down signal caused by providing the down signal passing means, so that the drop-in line is provided. It is preferable that a downstream signal is output to the terminal terminal side at the same level as the input level of the downstream signal input from the side.

When the in-building upstream signal frequency conversion device according to the present invention is configured as described above, the insertion loss of the downstream signal caused by providing the downstream signal passing means is compensated by the downstream signal amplifying means. The level (input level) of the downstream signal input from the drop-in line matches the level (output level) of the downstream signal output to the terminal terminal side. That is, the downstream signal compensating means is for setting the voltage gain of the downstream signal in the in-building upstream signal frequency converter to substantially zero.

When the in-building upstream signal frequency converter according to the present invention is configured as described above, a new installation is performed on the transmission line of the in-building CATV system in which the voltage gain of each transmission device is strictly set. However, the voltage gain for the downstream signal in the entire transmission line does not change at all. Therefore, the voltage gain in the entire transmission line of the in-building CATV system before installing the in-building up-signal frequency converter and the voltage after installing the in-building up-signal frequency converting device without replacing any existing transmission equipment. The gain can be made to match, and the downlink signal can be transmitted to the terminal terminal in a favorable state.

Alternatively, as described in claim 3, the downstream signal amplifying means compensates for the insertion loss of the downstream signal caused by providing the downstream signal passing means, The terminal terminal may be configured to amplify the signal to a predetermined level or more.

When the in-building upstream signal frequency conversion apparatus according to the present invention is configured as described above, not only the insertion loss of the downstream signal caused by providing the downstream signal passing means is compensated, but also the downstream signal is further reduced. The signal is amplified at a terminal terminal so as to be higher than a predetermined level. Therefore, when the in-building upstream signal frequency conversion device according to the present invention is configured in this manner, it is not necessary to separately install an amplifier on the transmission line of the in-building CATV system. A simplified system can be constructed at low cost.

As for the upstream signal, it is not always necessary to make the voltage gains equal before and after the in-building upstream signal frequency converter is installed. In the ridge upstream signal frequency converter according to the present invention, an upstream signal amplifying means for amplifying the ridge upstream signal before the frequency conversion by the upstream signal frequency conversion means or the upstream signal after the frequency conversion is provided. Is more preferred.

In such a configuration, if the voltage gain of the upstream signal amplifying means is appropriately adjusted in the same manner as the downstream signal amplifying means, the voltage gain of the upstream signal in the entire transmission line can be increased. Since there is no change before and after the signal frequency conversion device is installed, the upstream signal can be output to the service line in a good state.

More specifically, as described in claim 5, the upstream signal amplifying means reduces the insertion loss of the upstream signal and the upstream signal caused by providing the upstream signal frequency converting means. By compensating, it is preferable that an up signal is output to the drop-in line side at the same level as the input level of the in-building up signal input from the terminal terminal side.

In such a configuration, the insertion loss caused by the provision of the upstream signal frequency converting means is compensated by the upstream signal amplifying means. (Input level)
And the level (output level) of the upstream signal output to the drop-in line coincides.

Therefore, when the in-building upstream signal frequency converter according to the present invention is configured as described above, the in-building upstream signal frequency converter is installed with respect to the voltage gain for the upstream signal in the entire transmission line. Since there is no change between before and after the installation, the upstream signal can be output to the drop-in line side in a good state.

Alternatively, as described in claim 6, the upstream signal amplifying means compensates for the insertion loss of the in-building upstream signal and the upstream signal caused by providing the upstream signal passing means. In addition, a configuration may be adopted in which the upstream signal is amplified so as to be higher than a predetermined level in the drop-in line.

When the in-building upstream signal frequency conversion device according to the present invention is configured as described above, not only the insertion loss caused by providing the upstream signal frequency conversion means is compensated, but also the upstream signal is further reduced. The signal is amplified so as to be higher than a predetermined level in the drop-in line. Therefore, when the in-building upstream signal frequency conversion device according to the present invention is configured in this manner, it is not necessary to separately install an amplifier on the transmission line of the in-building CATV system. A simplified system can be constructed at low cost.

Further, in the building CATV system according to the second invention, as described in claim 7, a service line from an external two-way CATV system is drawn into a building.
Via the transmission line in the building, the down signal input from the service line is transmitted to the terminal terminal in the building, and the up signal input from the terminal terminal in the building is transmitted to the service line. An in-building CATV system, wherein the in-building upstream signal frequency converter according to any one of claims 1 to 6 is provided between the service line and the transmission line in the building.

The in-building CATV system according to the present invention comprises:
Since the in-building upstream signal frequency conversion device according to the first invention is provided between the service line and the transmission line in the building,
The effect of the in-building up signal frequency conversion device according to the first invention, that is, the effect of being able to transmit the down signal (and the up signal) in a favorable state is achieved.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. First, the overall configuration of the in-building CATV system of the present embodiment will be described. Figure 1 shows the CAT inside the building
FIG. 2 is a block diagram for explaining the overall configuration of the V system, and FIG. 2 is a block diagram for explaining the configuration of an in-building upstream signal frequency converter.

As shown in FIG. 1, CATV in the ridge of this embodiment
In the system, a drop-in wire 5 branched from a tap-off 4 of an external bidirectional CATV system constituted by a head end 1, a branch amplifier 2, an extension amplifier 3, a tap-off 4, etc. is connected to a building such as an apartment house via a protector 6. The transmission line 11 in the building 10 and the bidirectional amplifier 12, the two-way distributor 13,
The down signal (frequency: 70 to 770 MHz) of the external bidirectional CATV system input from the service line 5 is transmitted to a number of subscriber terminal terminals 15 in the building 10 via the four distributor 14 or the like. At the same time, the up signal (up signal in the building) input from the terminal terminal 15 is transmitted to the service line 5, and the bidirectional amplifier 12, the two-way distributor 1
The voltage gain of the transmission equipment such as the three-to-four distributor 14 is
Strictly set so that the downstream signal input from the terminal is transmitted to the terminal 15 in a good state.

When the downstream signal transmitted via the transmission line 11 is received by the television receiver 16 via the terminal 15, the television receiver 16 demodulates the downstream signal and converts audio and video. Output. Also, the CA in the building of this embodiment
In the TV system, a personal computer 17 is connected to a terminal 15 via a cable modem 18, and various types of data are transmitted from the personal computer 17 to the head end 1 to reserve viewing of pay programs, television shopping, and the like. It is configured so that More specifically, various data generated by the personal computer 17 is transmitted by the cable modem 18 to a frequency band (10 to 50 MHz in this embodiment) that can be transmitted by an external bidirectional CATV system.
And is input to the terminal 15.

However, as described above, 10 to 50 MHz
Since the signal of z is easily affected by various noises generated in the building 10, the terminal-side frequency converter 19 is installed between the terminal 15 and the cable modem 18, and the personal computer 17 transmits the signal from the cable modem. The uplink signal transmitted via the terminal 18 is converted into a terminal-side frequency converter 19
, The signal is converted into an in-building up signal having a frequency band higher than that of the down signal (810 to 850 MHz in this embodiment) and then input to the terminal 15.

In accordance with the terminal-side frequency converter 19, a connection portion between the transmission line 11 of the in-building CATV system and the drop-in line 5 of the external CATV system is transmitted from the terminal 15 via the transmission line 11. An in-building up-signal frequency converter 20 for returning the in-building up-signal transmitted to an up-signal of a frequency usable in an external bidirectional CATV system.
Is installed.

The in-building up signal frequency converter 20 includes a down signal passing circuit 20a and an up signal frequency conversion circuit 20b.
An external system side terminal T1, a subscriber side terminal T2,
Is provided. More specifically, as shown in FIG. 2, the downstream signal passing circuit 20a includes a high-pass filter (hereinafter, referred to as “HPF”) 201 for blocking an upstream signal and a unidirectional amplifier 202.
And a low-pass filter (hereinafter referred to as "L
PF ". And 203).
The upstream signal frequency conversion circuit 20b has an H for blocking the downstream signal.
A PF 204, a mixer 205, an oscillator 206, a band-pass filter (hereinafter referred to as “BPF”) 207,
Unidirectional amplifier 208 and LPF 209 for blocking a downstream signal
And is constituted by.

The passable frequency band of the HPF 201 is 70 MHz or more, the passable frequency band of the LPF 203 is 770 MHz or less, the passable frequency band of the HPF 204 is 810 MHz or more, the oscillation frequency of the oscillator 206 is 800 MHz, and the passable frequency band of the BPF 207 is 1
0 to 50 MHz, the passable frequency band of the LPF 209 is 50 MHz or less.

Further, the unidirectional amplifier 202 includes an HPF 201
And LPF 203 for compensating for the transmission loss (insertion loss) of the downlink signal.
Of the signal (input level) of the down signal input from the external system side terminal T1 and the subscriber terminal T2
Are selected so that the level (output level) of the downstream signal output from the terminal is the same. That is, the voltage gain of the downstream signal between the external system terminal T1 and the subscriber terminal T2 of the in-building upstream signal frequency converter 20 is configured to be substantially zero.

Similarly, the voltage gain of the one-way amplifier 208 depends on the level (input level) of the in-building up signal input from the subscriber side terminal T2 and the level of the up signal output from the external system side terminal T1 (input level). Output level). In other words, the voltage gain of the up signal (in-building up signal) between the subscriber side terminal T2 and the external system side terminal T1 of the in-building up signal frequency converter 20 is substantially zero.

The downstream signal of 70 to 770 MHz input from the external system side terminal T1 is
1, output from the subscriber side terminal T2 via the unidirectional amplifier 202 and the HPF 203. On the other hand, the in-building upstream signal of 810 to 850 MHz input from the subscriber side terminal T2 is input to the mixer 205 via the HPF 204.
The mixer 205 receives the 800M input from the oscillator 206
Frequency conversion of the in-building up signal using the
It returns to the upstream signal of 50 to 50 MHz. The upstream signal is supplied to the BPF 207, the unidirectional amplifier 208, and the LPF 209.
Is output from the external system side terminal T1 via

In this embodiment, the downstream signal passing circuit 20a (HPF 201, unidirectional amplifier 202, LPF 2
03) corresponds to the above-mentioned downstream signal passing means, and includes the upstream signal frequency conversion circuit 20b (HPF 204, mixer 205, oscillator 206, BPF 207, unidirectional amplifier 208, LP
F209) corresponds to the aforementioned upstream signal frequency conversion means,
In particular, the one-way amplifier 202 corresponds to the above-described downstream signal amplifier, and the one-way amplifier 208 corresponds to the above-described upstream signal amplifier.

Next, the effects of the in-building CATV system (in-building up signal frequency converter) of this embodiment will be described. A CATV system in a building in which the voltage gain of the bidirectional amplifier 12 or the like is strictly set to transmit the downstream signal input from the service line 5 to the terminal 15 in a good state,
When a new in-building upstream signal frequency converter 20 is installed,
Due to the passage loss (insertion loss) in the HPF 201 and the LPF 203, the voltage gain in the entire transmission line 11 changes, and the down signal is not transmitted to the terminal 15 in a good state. The inbound signal frequency conversion device 20 includes the HPF 201 and the LP
In consideration of the passing loss (insertion loss) in F203, the level of the downstream signal (input level) when input from the external system terminal T1 and the level of the downstream signal when output from the subscriber terminal T2 (output level) ), The voltage gain of the unidirectional amplifier 202 is selected so that the voltage gain of the transmission equipment is strictly set.
Even if the in-building upstream signal frequency converter 20 is newly installed in the V system, the voltage gain for the downstream signal in the entire transmission line 11 does not change at all. Accordingly, the transmission line 11 of the in-building CATV system before the in-building upstream signal frequency converter 20 is installed without replacing any existing transmission equipment.
Voltage gain in the whole and in-building up signal frequency converter 2
0 can be matched with the voltage gain after installing 0, and the downstream signal can be transmitted to the terminal 15 in a favorable state.

Similarly, the level (input level) of the in-building up signal when input from the subscriber terminal T2 and the level (output level) of the up signal when output from the external system terminal T1 are determined. Are provided so that the voltage gain is selected so that the voltage gain is matched, the voltage gain for the upstream signal does not change at all before and after the installation of the in-building upstream signal frequency converter.

As described above, one embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment at all, and it is needless to say that the present invention may be implemented in various modes. For example, in the embodiment, the downstream signal passing circuit 20a including the HPF 201, the unidirectional amplifier 202, and the LPF 203, the HPF 204, and the mixer 20
5, oscillator 206, BPF 207, unidirectional amplifier 20
8, the upstream signal frequency conversion circuit 20b constituted by the LPF 209 is collectively used as the in-building upstream signal frequency conversion device 20, but it is not always necessary to combine them into one device, and the downstream signal passing circuit 20a and the upstream signal frequency conversion circuit 20b may be configured as a separate component, or each circuit may be further subdivided into HPF 201, unidirectional amplifier 202, L
PF 203, HPF 204, mixer 205, oscillator 20
6, BPF 207, unidirectional amplifier 208, LPF 209
May be configured as one component.

Alternatively, conversely, the downstream signal passing circuit 20
a, a bidirectional amplifier 12 is connected to the upstream signal frequency conversion circuit 20b.
In addition, the in-building upstream signal frequency conversion device 20 may be used. Specifically, the voltage gain of the unidirectional amplifiers 202 and 208 may be set to a value obtained by adding the voltage gain of the bidirectional amplifier 12 to the voltage gain in the present embodiment. In such a configuration, the bidirectional amplifier 12 is removed and the in-building upstream signal frequency converter is installed, and the bidirectional amplifier 12 can be omitted. Is simplified, and a system can be constructed at low cost.

[Brief description of the drawings]

FIG. 1 is a block diagram for explaining the overall configuration of a CATV system in a building according to an embodiment.

FIG. 2 is a block diagram for explaining a configuration of an in-building upstream signal frequency conversion device.

FIG. 3 is a block diagram for explaining the overall configuration of a conventional in-building CATV system.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Head end 2 ... Branch amplifier 3 ... Extension amplifier 4 ... Tap-off 5 ... Drop-in line 6 ... Protector 1
DESCRIPTION OF SYMBOLS 1 ... Transmission line 12 ... Bidirectional amplifier 13 ... 2 distributor 14 ... 4 distributor 15 ... Terminal terminal 16 ... Television receiver 17 ... Personal computer 18 ... Cable modem 19 ... Terminal side frequency converter 20 ...
In-building up signal frequency converter 20a ... down signal passing circuit 20b ... up signal frequency conversion circuit 201,
204 ... HPF (High Pass Filter) 202, 20
8. Unidirectional amplifier 203, 209 LPF (low-pass filter) 205 Mixer 206 Oscillator
207 BPF (Band Pass Filter) T1 External System Terminal T2 Subscriber Terminal

Claims (7)

[Claims] 1. A drop line from an external two-way CATV system is drawn into a building, and a down signal input from the drop line is transmitted to a terminal terminal in the building via a transmission line in the building. In addition, in a building CATV system that transmits an up signal input from a terminal terminal in the building to the service line, the CATV system is provided between the service line and the transmission line in the structure, The external bidirectional CAT is transmitted by the terminal-side frequency converter transmitted from the terminal terminal side.
Up signal frequency conversion means for converting an in-building upstream signal converted to a frequency higher than a frequency that can be transmitted by the V system into a frequency that can be transmitted by the external bidirectional CATV system, and outputting the frequency to the drop-in line side. And a downstream signal passing means for outputting the downstream signal input from the drop-in line to the terminal terminal side via the transmission line at the same frequency, a ridge upstream signal frequency conversion device comprising: An in-building up signal frequency converter, comprising down signal amplifying means for amplifying the down signal passing through the signal passing means. 2. The downstream signal amplifying unit compensates for the insertion loss of the downstream signal caused by providing the downstream signal passing unit, so that the same level as the input level of the downstream signal input from the drop-in line is provided. The in-building up signal frequency converter according to claim 1, wherein the down signal is output to the terminal terminal side. 3. The downlink signal amplifying means, in addition to compensating for the insertion loss of the downlink signal caused by providing the downlink signal passing means, so that the downlink signal has a predetermined level or more at the terminal terminal. The in-building upstream signal frequency converter according to claim 1, wherein the signal is amplified. 4. An upstream signal amplifying means for amplifying an in-building upstream signal before frequency conversion by the upstream signal frequency conversion means or an upstream signal after frequency conversion is provided. 3. The in-building upstream signal frequency converter according to any one of 3. 5. The ridge input from the terminal terminal side by compensating for the insertion loss of the ridge signal in the ridge and the uplink signal caused by providing the uplink signal frequency conversion means. The in-building up signal frequency converter according to claim 4, wherein the up signal is output to the service line side at the same level as the input level of the inbound signal. 6. The upstream signal amplifying means, in addition to compensating for the insertion loss of the upstream signal and the upstream signal caused by the provision of the upstream signal passing means, further includes the upstream signal having a predetermined level in the drop-in line. The in-building upstream signal frequency conversion device according to claim 4, wherein the amplification is performed as described above. 7. A drop-in line from an external two-way CATV system is pulled into a building, and a down signal input from the drop-in line is transmitted to a terminal terminal in the building via a transmission line in the building. And an in-building CATV system for transmitting an up signal input from a terminal terminal in the building to the service line, wherein between the service line and the transmission line in the structure.
7. An in-building CATV system, comprising the in-building upstream signal frequency conversion device according to any one of claims 6 to 6.