JPH04207685A - Catv subscriber system transmission method - Google Patents

Abstract

PURPOSE:To interconnect an off-premise equipment with all subscriber equipment by one transmission line by allocating an outgoing signal and an incoming signal to each subscriber equipment through frequency multiplex. CONSTITUTION:The above system consists of an off-premise equipment 10 selecting a signal of a channel among signals 1 of all channels in response to a reception request of a channel as an incoming signal from each of subscriber equipment 30-1 to 30-n and sending the selected signal to each of the subscriber equipment 30-1 to 30-n as an outgoing signal and plural subscriber equipment connected to the off-premise equipment 10 by a bus type transmission line 20. Then a difference frequency band is allocated to each of the subscriber equipment 30-1 to 30-n as an incoming signal and an outgoing signal. Through the configuration above, the incoming signal being a reception request from each of the subscriber equipment 30-1 to 30-n to the off-premise equipment 10 and an outgoing signal being an information signal from the off-premise equipment 10 each of the subscriber equipments 30-1 to 30-n are frequency-multiplexed. Thus, the off-premise equipment is interconnected with all the subscriber equipment by one transmission line.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a subscriber system transmission method for LcATV, and particularly relates to frequency multiplexing transmission.

BACKGROUND ART Conventional subscriber transmission systems for CATV include systems that use off-premises equipment (for example, as shown in the block diagram of Figure 4).
- It is a device that realizes the function of a receiving converter used in CATV for boat fishing outdoors, and it is a device that selects the signal of the channel that has been requested to be received and transmits only the signal of that channel indoors. It has been adopted as an effective means to prevent eavesdropping. There are two types of off-premise equipment: one that handles one subscriber, and one off-premise equipment that handles multiple subscribers.The subject of the present invention is the latter off-premise equipment. In the figure, ① is an all-channel signal 40 in which all the signals sent from the CATV center station are multiplexed.
, off-premise devices 60-1 to 60-N are N subscriber devices (N is an integer) connected to the off-premise device 40, and 50-1 to 50-N are the subscriber devices from the off-premise device 40 to the subscriber device 60. -1 to 60-N - 55-1 to 55-N are the subscriber devices 60-1 to 6
This is an upstream signal for requesting channel reception from 0-N to the off-premise device 40.

FIG. 5 is a block diagram of the off-premises device 40 shown to explain the functions of the off-premises device 40 in more detail. In FIG. 5, 11 is a demodulation unit that demultiplexes all channel signals 1 and demodulates them into signals of each channel, and the output signal formats are baseband, AM, FM,
PCM etc. can be considered. 12 selects signals of N channels from the output of the demodulation section 11, allowing overlap, and output selection sections 41-1 to 41N output the selected signals (downlink signals 50-1 to 5O-) to each subscriber device. If the output signal form of the selection unit 12 differs from the signal form receivable by the subscriber devices 60-1 to 60-N, it also performs signal conversion. 42-1 to 42-
N is the number of receptions for receiving the upstream signals 55-1 to 55-N. 16 is the number of signals received from the subscriber devices 60-1 to 60-N by the signals from the receiving units 42-1 to 42-N. In the conventional CATV subscriber system transmission method configured as described above (for example, the subscriber device When 60-1 wants to receive a signal on a certain channel, it sends an uplink signal 55-1 for the reception request to the off-premise device 40. The information is transmitted to the control unit 16, and the control unit 16 controls the selection unit 12 based on the information.When the selection unit 12 receives the signal from the control unit 16, the selection unit 12 selects among the demodulated signals of all channels. Selects the signal of the channel that the subscriber device 60-1 requests to receive from the selected channels and outputs it to the transmitter 41-1.The transmitter 41-1 i
& The subscriber device 6 receives the signal of the channel that the subscriber device 60-1 requests to receive as the downlink signal 50-1.
0-1 The operation explained in the case of the subscriber device 60-1 (exactly the same in the case of other subscriber devices) Problems to be Solved by the Invention In the case of a configuration like this, in order to connect the off-premise device 40 and each subscriber device 60-1 to 69-N, a total of 2N transmission lines (two independent transmission lines each) are required.
A real transmission line is required, and off-premise equipment 40
The present invention has been developed in view of this problem, and has the problem that N transmitting units 41-1 to 41-N are required and the configuration thereof is complicated. The object of the present invention is to provide a CATV subscriber system transmission method that can allocate uplink signals by frequency multiplexing and connect off-premise equipment and all subscriber equipment with a single transmission path.

Means for Solving the Problems The present invention has the following features: In response to a request to receive a channel as an uplink signal from each subscriber device, the signals of those channels are selected from among the signals of all the channels, and the signals of those channels are sent to the respective subscriber devices. It consists of an off-premises device that transmits signals, and a plurality of subscriber devices connected to the off-premises device through a single bus-type transmission line, and each subscriber device uses a different frequency band for upstream and downstream signals. The present invention is also applicable to a CATV subscriber-based transmission method characterized by assigning an uplink signal, which is a reception request from each subscriber device to an off-premises device, and an upstream signal that is a reception request from each subscriber device to each subscriber device. By frequency multiplexing downlink signals, which are information signals, it is possible to connect the off-premise device and all the subscriber devices through one transmission path.

Embodiment FIG. 1 is a block diagram showing a configuration for realizing a CATV subscriber system transmission method in an embodiment of the present invention. In FIG. 1, l represents all signals sent from the CATV center station. The off-premise equipment 20 transmits all channel signals 10 multiplexed with i 30-1 to 30-N.
are N subscriber devices connected to the off-premise device 10.

FIG. 2 is a block diagram of the off-premise device 10 shown to explain the functions of the off-premise device 10 in more detail. In FIG. 2, 11 is a demodulation unit that demultiplexes all channel signals 1 and demodulates them into signals of each channel, and the output signal form is based on AM, FM.
, PCM, etc. The system 12 selects signals of N channels from the output of the demodulation section 11, allowing overlap, and the output selection sections 13-1 to 13-N select signals to be transmitted to each subscriber device. This is a modulation unit that modulates the received signals for frequency multiplexing, and if the output signal form of the selection unit 12 is different from the signal form that can be received by the subscriber devices 60-1 to 60-N, it also converts the signal. conduct. 14 is the modulation section 13-1
A multiplexer 15 frequency-multiplexes the outputs of 13-N and outputs the frequency-multiplexed signals to the transmission path 20. A multiplexer 15 receives uplink signals from the subscriber devices 30-1 to 30-N. A receiver 16 receives signals from the receiver 15. This is a control unit that controls the connection relationship of the selection unit 12 so that signals of channels requested by each subscriber unit can be transmitted to the subscriber units 30-1 to 30-N.

FIG. 3 shows the frequency spectrum of the signal on the transmission line 20.
Frequencies for downlink signals (from off-premise equipment to subscriber equipment) assigned to 30-N, respectively, f11 to fa
x is a frequency for uplink signals (from the subscriber device to the off-premise device) assigned to each of the subscriber devices 30-1 to 30-N. The condition is that these signals are frequency multiplexed, and it does not depend on how the signals of each frequency are modulated.
3-1 to 13-N output signals modulated in their respective assigned frequency bands. On the other hand, each subscriber device 30-1 to 30 to N transmits and receives only signals in the frequency band assigned to itself.As for uplink signals, the occupation time is short, and it is not necessarily necessary to assign a fixed frequency; The operation of this embodiment, which is configured in a multi-channel access system that dynamically allocates frequencies, will be described below.For example, when subscriber equipment 30-1 receives a signal on a certain channel, The uplink signal for the reception request is sent to the off-premise device 10 via the transmission line 20f using the assigned frequency fat. Section 15 receives the upstream signal from the subscriber device 30-1 as a signal of frequency fit, transmits the information to the control section 16, and the control section 16 controls the selection section 12 based on it. When the selection unit 12 receives the signal from the control unit 16, it selects the signal of the channel that the subscriber device 30-1 requests to receive from among the demodulated signals of all channels, and modulates the signal of the channel that the subscriber device 30-1 requests to receive.Modulation unit 13-1 Output to. The modulator 13-1iL modulates the signal of the channel that the subscriber device 30-1 requests to receive using the frequency f1 assigned to the subscriber device 30-1. The output of the modulator 13-1 is frequency-multiplexed with the outputs of the other modulators 13-2 to 13-N in a multiplexer, transmitted to the transmission path 20 as a downlink signal, and received by the subscriber device 30-1. In this way, the subscriber device 30-1 can select a channel and receive a desired signal.

Although the operation was explained for the case of subscriber device 30-1, it is exactly the same for the other subscriber devices.

If the signal corresponding to the upstream signal can be multiplexed as part of the downstream signal, full-duplex transmission similar to telephone transmission is also possible.

As described in detail about the invention (2), according to the present invention, an off-premises device and all subscriber devices connected thereto can be connected through a single transmission path, and the overall length of the transmission path can be shortened. Only one transmitter is required on the equipment side (℃) Also, since bidirectional signals are frequency multiplexed, it is easy to add subscriber equipment as long as there is enough frequency band, and it is easy to connect to the transmission line. There are no restrictions on the position where the image is modulated.
With AM, commercially available receivers can be used as is, and the practical effects are significant.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing a configuration for realizing the entire CA:rV subscriber line transmission method according to one embodiment of the present invention. Figure 2 is a block diagram of an off-premises device according to the embodiment. Figure 3 is the frequency spectrum of a signal on a transmission path. Figure 4 shows conventional CATV
Block diagram showing the configuration for realizing the subscriber-based transmission method
FIG. 5 is a block diagram of a conventional off-premise device. 1... All channel signals 10... Off-blemish device 11... Demodulation dish 12... Selection section 13-
1~13-N...Modulation starvation 14...Multiple sum 15.
...Receiving section 16...Control a20...Transmission line 3
0-1 to 30-N...Subscriber device 40...Off-miss device 50-1 to 50-N...Down signal 55
~1~55-N...Uplink signal q, 60-1~60-
N...Subscriber equipment 41-1 to 41-N...Transmission i 42-1 to 42-N...Name of receiving department agent Patent attorney Akira Kokaji and two others Figure 1 JU- 1,

Claims (1)

[Claims] The signals of all the channels are received from the center station, and in response to the channel reception request as an uplink signal from each subscriber's premises transmitting/receiving device (hereinafter referred to as subscriber device), the above-mentioned signals are selected from among the signals of all the channels. A CAT consisting of an off-premises device that selects a signal of a channel requested for reception and transmits it to each subscriber device, and a plurality of subscriber devices connected to the off-premises device through a single bus-type transmission line.
In the V subscriber system, different frequency bands for downlink signals are fixedly assigned to all of the connected subscriber devices, and the off-premise device transmits the signal of the selected channel using each frequency band. , to the subscriber device that has issued the reception request, transmits it as a downlink signal to the transmission path by frequency multiplexing, and on the other hand, each of the subscriber devices receives the signal in the allocated frequency band, thereby transmitting the reception request. Each subscriber device receives the channel signal from the off-premises device via the transmission path, using an uplink signal frequency band that is fixed or assigned as needed. A CATV subscriber system transmission method, characterized in that a request signal is transmitted, and the off-premise device receives a channel reception request signal by receiving signals in all frequency bands for uplink signals.