JPS63263985A - Signal transmitting method between center and terminal in tv community receiving system - Google Patents

Abstract

PURPOSE:To wholly receive a fall signal from a center 1 by the same terminal device even when the number of terminals comes to be large by providing respective distributing line frequency-converters and individually frequency- converting in a signal transmitting method between a center and a terminal in a television community receiving system. CONSTITUTION:From a center 1 of a television community receiving system, fall signals F1-F4, whose frequencies are different, are transmitted to distributing lines 2a-2d which are larger than 2 lines. The respective fall signals F1-F4 are individually frequency-converted by frequency-converters 3a-3d, which are provided in the respective distributing lines 2a-2d, and all converted to a fall signal F5 having the same frequency and the fall signal F5 is transmitted to respective terminals. From the respective terminals, a rise signal R5 having the same frequency is transmitted, the rise signal R5 is individually converted to rise signals R1-R4, which have different frequencies, by the frequency- converters 3a-3d which are provided in the respective distributing lines 2a-2d and the rise signals R1-R4 are transmitted to the center 1.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a signal transmission method between a center of a common television viewing system (CATV system) and many terminals. It is used when transmitting data between

(Prior art) When transmitting data between the terminal status monitor and the center in a television shared listening system, conventionally each terminal is addressed, and an address signal (calling signal) is transmitted from the center to the called terminal to call the terminal. Data was being transmitted between the called terminal and the center.

In this case, if the address is 8 bits at the center, for example, the number of addresses is only 256.

For this reason, for example, if the number of terminals a in Fig. 3 is more than that, even if the terminals are called with a paging signal of one frequency (for example, Fl), only a maximum of 256 terminals can be called, and all terminals can be called. cannot be called.

In such cases, conventionally, multiple call signals with different frequencies (for example, Fl, F2, F3, F4) are used as shown in Figure 3.
is transmitted from the center, calls the terminal connected to distribution line A with the calling signal Fl, calls the terminal connected to distribution line B with the calling signal F2, and so on. They were calling with different calling signals of different frequencies.

(Problems with conventional technology) Conventional data transmission methods have the following problems.

(1) As the frequency of the paging signal increases, the receiving frequency of the terminal must be matched to the frequency of the paging signal, so terminals with different reception frequencies must be prepared for the frequency of the paging signal, and There will be more types.

(2) As the number of types of terminals increases, the cost of the terminals increases.

(Object of the Invention) An object of the present invention is to enable data transmission using one type of terminal even if the number of terminals increases.

(Means for Solving the Problems) As shown in FIG. 1, the data transmission method of the television communal listening system of the present invention is such that the data transmission method is as shown in FIG. signal F1
~F4, and transmits the downlink signals F1 to F4, respectively, to the frequency converters 3a provided in the respective distribution lines 2a to 2d.
~3d, the frequencies are individually converted into downlink signals F5 of the same frequency, and the downlink signals F5 are transmitted to each terminal, and each terminal transmits an uplink signal R5 of the same frequency,
The upstream signal R5 is individually converted into upstream signals R1 to R4 of different frequencies by frequency converters 3a to 3d provided in each distribution line 2a to 2d, and the upstream signals R1 to R4 are individually converted into upstream signals R1 to R4 of different frequencies.
is transmitted to center 1.

(Function) FIG. 1 is a schematic explanatory diagram of the signal transmission method of the present invention, and FIG. 2 is an internal explanatory diagram of the frequency converters 3a to 3d in FIG. 1.

In Fig. 1, when the downlink signals F1 to F4 with different frequencies are transmitted from the center 1, the downlink signals F1 to F4 are
Only a portion of the signal is extracted by bandpass filters 4 (FIG. 2) in frequency converters 3a to 3d, which are provided in distribution lines 2a to 2d, respectively. By the way, the bandpass filter 4 in the frequency converter 3a in FIG.
The band pass filter 4 in the frequency converter @3c receives the F3 downstream signal, and the band pass filter 4 in the frequency converter 3d receives the F4 downstream signal.

The respective downlink signals F1 to F4 extracted by the bandpass filters 4 of the respective frequency converters 3a to 3d are converted into the downlink signals F5 of the same frequency by the converters 5 (FIG. 2) in the respective frequency converters 3a to 3d. The downlink signal F5 is transmitted to each terminal and received by the data transmission terminal (eg, modem) of each terminal.

In addition, since it is necessary to send not only data but also TV signals to each terminal, each frequency converter 3a to 3
As shown in Fig. 2, a pass line 6 is provided in the center d to transmit downlink signals (TV signals and F1 to F4) transmitted from the center 1.
) is transmitted as it is to the terminal through the pass line 6, and the TV signal contained therein is received by the terminal's television receiver.

In addition, the data transmission terminal of each terminal uses frequency conversion @3a~
Since only the downlink signal F5 frequency-converted by 3D can be received, other downlink signals F1 to F4 and TV signals are not received by the data transmission terminal.

Next, all the terminals connected to the distribution lines 2a to 2d are configured to be able to send upstream signals R5 of the same frequency toward the center 1. Upstream signals R5 sent from each terminal are converted into upstream signals R1 to R4 of different frequencies in converters 7 (Fig. 2) in frequency converters 3a to 3d connected to distribution lines 2a to 2d. Sent to Center 1. This allows the center 1 to determine from which distribution line the received uplink signal has been transmitted.

(Example) FIGS. 1 and 2 are explanatory diagrams of a system that implements the present invention.

In FIG. 1, 1 is a center head end, 10 is a distributor, 2a to 2d are distribution lines, and 3a to 3d are frequency converters.

The frequency converters 3a to 3d shown in FIG. 1 have a configuration as shown in FIG. 2. In FIG. 2, 4 is a band pass filter, 5 is a downstream signal converter, 7 is an upper Lily signal converter, 6 is a pass line, 8a and 8b are bypass filters, and 9a and 9b are low pass filters.

(Effect of the invention) The signal transmission method of the present invention has the following effects.

(1) Even if the number of terminals increases, all downlink signals from the center 1 can be received by the same terminal, reducing the cost of the terminals.

(2) Since there is only one type of terminal, maintenance of the terminal,
Easier to manage.

(3) Even if the number of terminals increases, the system between the center 1 and the terminals is simple, so implementation is easy and costs are reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram of the signal transmission method of the present invention, FIG. 2 is an internal explanatory diagram of the frequency converter in FIG. 1, and FIG. 3 is an explanatory diagram of the conventional signal transmission method. 2d is a distribution line 3a to 3d is a frequency converter Fl-R4 is a downstream signal R5 is a frequency converted downstream signal R5 is an upstream signal R1 to R4 is a frequency converted upstream signal 1 and 2;

Claims (1)

[Claims] Downlink signals F1 to F4 with different frequencies are transmitted from the center 1 of the television common listening system to two or more distribution lines 2a to 2d, and each of these downlink signals F1 to F4 is transmitted at a frequency provided to each distribution line 2a to 2d. Frequency conversion is performed individually by converters 3a to 3d to generate downlink signals F5 that all have the same frequency.
The downstream signal F5 is transmitted to each terminal, and each terminal transmits an upstream signal R5 of the same frequency, and the upstream signal R5 is transmitted to frequency converters 3a to 3d provided in each distribution line 2a to 2d. The upstream signal R has a different frequency depending on the
1 to R4, and transmits the upstream signals R1 to R4 to a center 1 in a television shared viewing system.