JPS63127631A - Baseband/broadband coexistence method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a system for transmitting information between devices using a transmission line, for example, using a coaxial cable to transmit information such as images, audio, etc. in addition to normal computer data. This invention relates to a baseband/broadband coexistence system suitable for transmitting information to data terminals, workstations, monitors, etc.

[Conventional technology]

Conventionally, either a baseband method or a broadband method has been used as a method for using network transmission paths. By the way, the characteristics of the broadband system are as follows.
With frequency division, it is possible to have multiple, independent logical channels.

In "A Broadband Network System and its Applications (IEEJ Study Group IP-83-3)" by Akio Sabado et al.

It is noted that the above characteristics can be used to accommodate a baseband network as one channel of a broadband network. However, this was just one channel of the broadband network to accommodate the baseband network, and all transmission paths were broadband analog signals. That is, the baseband digital signal is modulated into an analog signal.

[Problem that the invention seeks to solve]

The conventional system described above requires a high-frequency modem to modulate and demodulate the baseband signal into a broadband signal, which complicates the device and may not be compatible with existing baseband systems. That is, although the above-mentioned conventional technology accommodates the baseband method by taking advantage of the characteristics of the broadband method, no consideration is given to allowing the baseband method and the broadband method to coexist in a true sense.

Information devices connected to the network include those that handle digital signals, such as computers, and monitors.

There are devices such as telephones that handle analog signals, and the above-mentioned conventional technology has a problem in that the same transmission path cannot be used unless these conversions are performed.

An object of the present invention is to provide a baseband/broadband coexistence method that solves the above-mentioned problems in the conventional technology, allows a baseband method and a broadband method to coexist on a single transmission path, and enables effective use of the transmission path. It's about doing. The baseband/broadband coexistence method referred to here means that the baseband method uses a digital signal as is, and the broadband method uses a transmission path with an analog signal.

[Means for solving problems]

The above object of the present invention is to provide an information device that handles various types of information;
In the information network system, the information device is connected to the transmission path through filtering means that cuts a high frequency spectrum of a baseband signal on the transmission path. This is achieved by a baseband/broadband coexistence method characterized in that the frequency band passing through the filtering means is used for the baseband method, and the frequency band cut by the filtering means is used for the broadband method.

[Effect]

Generally, the baseband method uses the entire frequency band of the cable used for the transmission line,
transmit digital signals. In addition, the broadband method divides the frequency band of the cable and determines the center frequency for transmission.

In the present invention, a filtering means is provided to prevent the frequency spectrum of the baseband signal from expanding in a high frequency band, and the frequency band passing through this filtering means is used as a baseband signal, and the frequency band that is cut by this filtering means is By using frequency bands for broadband, baseband and broadband systems can coexist.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

Figure 2 shows an example of the configuration of a system that handles data communications, video signals, audio, etc., which is an embodiment of the present invention. In Figure 1, 1 indicates a communication line or high-speed 2 is a communication line terminal controller (hereinafter referred to as "rTCE"); 3 is a translator unit (hereinafter referred to as rTUJ) that converts the upstream frequency of a broadband signal into a downstream frequency; , 4 is a transmission path, and 5 is a filtering unit (hereinafter referred to as rFUJ) that cuts frequency components higher than a predetermined frequency. Further, 6 is a data terminal, 7 is a transmission path branching device, 8 is an RF modem (RFM) that modulates and demodulates a computer digital signal into an analog signal, 9 is a workstation that performs data communication using the RF modem, and 10 is a workstation that performs data communication using the RF modem. A monitor TV displays a video signal, and reference numeral 11 indicates a bidirectional amplifier in the transmission path.

Here, the TU3 transmits the original function of broadband signal f (upstream signal to TU3) to f2 (TU3
In addition to the function of converting the FU 5 into a downstream signal (downward signal from
) It also has a power supply function. Further, the FU 5 has a function of cutting direct current in addition to the filtering function, which is the original function. The turnout 7 is
It has the function of cutting only the above-mentioned direct current in the transmission line 4 and transmitting other signals.

FIG. 3 shows a situation in which the spread of the frequency spectrum of the baseband signal is suppressed by the FU5, which is the main point of the present invention.
And, it is a diagram for explaining a situation in which baseband and broadband coexist. In the figure, the solid line 2 represents the frequency spectrum of a conventional coaxial interface (baseband IMbps). As is clear from the figure, the frequency spectrum 12
has expanded to over 100MTh. By making this spread as shown by the broken line 13 using the FU 5, for example, the band up to 10 MHz can be used as a baseband band, and the band above it can be used as a broadband band. The upstream frequency band f1 and the downstream frequency band f2 within the broadband band are set, for example, as shown in FIG.

FIG. 1 is a diagram showing how each device operates because baseband data and broadband data coexist in FIG. 2.

Hereinafter, the operation of the system of this embodiment will be explained based on FIG.

The signal input from the TCE2 to the TU3 is a baseband signal f using the entire frequency band of the cable. The above-mentioned input signal f becomes a baseband signal fo whose high frequency is cut off in the TU 3 and is outputted to the data terminal 6 side. Also, the upstream signal fl input to TTJ3
, the downlink signal f2 is output. In other words, the output from TU3 to transmission line 4 in the downstream direction is fc
, f2. It becomes DC. As mentioned above, the FU 5 has the function of cutting off the broadband band and direct current, so the only signal that is drawn into the data terminal 6 is fc.

Furthermore, the signal output from the data terminal 6 is f6, and when this signal is transferred to the transmission line 4 through the FU5, it becomes f6.
It becomes o. As mentioned above, the branching device 7 is connected to the f
,,f2. Of the DC, only the DC is cut and the signal is transmitted to the RF modem 8. The RF modem 8 demodulates the broadband downlink signal f2 and inputs it to the workstation 9. The output F1 from the workstation 9 is modulated by the RF modem 8 and sent to the transmission line 4.
be carried on.

Due to the above operation, the main line of the transmission line has f in the down direction.
c , f 2 , D C is f,, f in the up direction
The l signal will flow. This provides the effect that the data terminal 6 that communicates using the baseband method and the data terminal 9 that communicates using the broadband method can coexist.

FIG. 4 shows a specific example of the configuration of the FU5,
An example is shown in which the filter is configured with two LPFs (low pass filters), two HPFs (bypass filters), and a choke coil (CH). According to this configuration, the baseband signal from the input is sent to the BRl by the LPF, and the baseband signal from the BR is sent to the output via the LPF, and is combined with the high frequency signal via the HPF and output. Ru. Further, DC passes through a choke coil, and broadband signals (fl, f2) also pass through two HPFs.

The above-mentioned LPF and HPF can be of a normal configuration. - An example is shown in FIG.

In determining the cutoff frequency of the FU 5, it is necessary to fully consider the fact that in order to increase the speed of the baseband signal, a wider band is required. One guideline for the above-mentioned cutoff frequency is about IOM)tz shown in FIG. 3, but the present invention should not be limited to this.

〔Effect of the invention〕

As described above, according to the present invention, in an information network system that includes information devices that handle various types of information and transmission paths for connecting them, the information devices are connected to baseband signals on the transmission path. Connecting to the transmission line via filtering means that cuts high frequencies of the frequency spectrum, the frequency band passing through the filtering means is used for baseband method, and the frequency band cut by the filtering means is used for broadband method. This has the remarkable effect of allowing baseband and broadband systems to coexist in a single transmission path in a true sense, and realizing a basepan 1/broadband coexistence system that makes effective use of the transmission path. It is something to play.

[Brief explanation of the drawing]

Fig. 11 is a diagram showing the operation of each device in a system that is an embodiment of the present invention, Fig. 2 is a diagram showing an example of the configuration of a system that is an embodiment of the present invention, and Fig. 3 is a main point of the present invention. FIGS. 4 and 5 are diagrams illustrating the functions of the FU, and are diagrams showing specific configuration examples of the FU. i: L, , AN, 2: T CE, 3: TH14: Transmission line, 5: FU, 6: Data terminal, 7: Branch, 8: R
F modem, 9: Workstation, 10: Monitor TV
, 11: Bidirectional amplifier. Figure 3

Claims (1)

[Claims] 1. In an information network system having information devices that handle various types of information and transmission paths for connecting them, a filtering means for filtering the information devices by cutting a high frequency spectrum of a baseband signal on the transmission path. is connected to the transmission line via a baseband system, and the frequency band passing through the filtering means is a baseband system;
A baseband/broadband coexistence system characterized in that the frequency band cut by the filtering means is used for a broadband system.