JPH0224426B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field to which the invention pertains) The present invention relates to a multi-point to point connection system that performs bridge connections between n+1 multi-point points.

(Prior Art) FIG. 1 shows a bridge configuration using a conventional multipoint-to-point connection system.

Generally, the bridge 1 adds analog signals for all lines from point (1) to point (n+1) and sends them to an adder circuit.
and from the added analog signal (i) {(i)=
(1), (2),..., (n+1)} points are subtracted by the subtraction circuit 3, and the subtracted analog signal is
The signal is sent to point (i), and this is used as the reception signal to point (i). {For example, JP-A-52-25508 (JP-A-57-
29896) "Digital Conference Telephone Device"} FIG. 2 is an explanatory diagram of a communication method between multiple points when using a bridge, and shows the case where the telephone 4 is regarded as a terminal for transmitting and receiving.

In this connection method, one bridge 1 is connected to (n+1) multi-point telephones 4 which are converted from 2-wire to 4-wire in a hybrid circuit 5.

Figure 3 is an explanatory diagram of the communication method when the idea in Figure 2 is extended to remote locations, with one Bridge 1 installed in Tokyo, Kobe (1), Osaka (2), Tokyo (3), etc. (z
-1), in the system connecting telephones 4 in Sendai (n) and Sapporo (n+1), the line between Tokyo and Osaka and the line between Tokyo and Kobe, and the line between Tokyo and Sendai and the line between Tokyo and Sapporo. This has the disadvantage of being inferior in terms of line efficiency and economy, since the lines overlap each other. Furthermore, since a single bridge can accommodate a large number of lines, it is necessary for the bridge to have the maximum number of lines to accommodate. However, for a connection system that requires only a small-scale line, redundant bridge ports are not used, so the cost of the bridge increases, making it uneconomical.

(Object of the Invention) In order to solve these drawbacks, the present invention provides a multi-point to point connection system in which a plurality of bridges each consisting of an addition circuit and a subtraction circuit are provided, and each bridge is connected by a single line. The drawings will be described in detail below.

(Structure and operation of the invention) FIG. 4 shows the structure of an embodiment of the invention, in which two bridges 1 are connected, one of which is B ₁ and the other is B ₂ , and the bridge B ₁ has a transmission/reception 3 Line (#1
～#3), Bridge B ₂ has 3 sending/receiving lines (#6～
#8) are connected to each other, and lines #4 and #5 are connected between bridges _B1 and _B2 .

B ₁ and B ₂ of each bridge 1 have adder circuits 2, respectively, and the analog signal inputs from lines #1 to #3 are a, b, and c, and the analog signal inputs from lines #6 to #8 are f. , g, h, bridge 1
The analog signal input connected to is _once a+b+c+d (however, d=
f + g + h) added analog signal is
Adder circuit 2 of B ₂ calculates e+f+g+h (where e=a
+b+c) added analog signal is obtained.

Therefore, the received signal on line #1 is obtained by subtracting the transmitted signal on line #1 from the added analog signal by the subtraction circuit 3, resulting in b+c+d. Similarly, the received signals of lines #2 to #8 are a+c+d, a+b+d, and a, respectively.
+b+c, f+g+h, e+g+h, e+f+
h, e+f+g.

By the way, since bridges _B1 and _B2 are connected by lines #4 and #5, it is clear from FIG. 4 that e=a+b+c and d=f+g+h. Therefore, the received signal on line #1 is b+c+d=
b+c+f+g+h, and the sum of all analog signals in the connection system other than the transmission signal of line #1 is obtained.

The same applies to lines #2, #3, #6, #7, and #8.

In this way, by connecting a large number of bridges using a single line, it becomes possible to connect arbitrarily between multiple points using a large number of bridges.

Figure 5 shows an example in which multiple points are vertically connected by multiple bridges, and there are k bridges 1, and each bridge B ₁ to _{B k} is connected to P ₁ , P ₂ . . . P _k lines. An example is a case of vertical connection.

In this case, it is necessary to prepare bridge ports for _k 〓 ⁱ⁼¹ P _i +k-1 lines.

Next, a case in which this concept is applied to a telephone network will be described below.

Generally, telephone networks have 2 subscriber lines and 4 toll lines.
It forms a line. Therefore, echoes occur in the two-wire/four-wire conversion circuit, ie, the hybrid circuit 5, due to line mismatch. Since this echo signal is re-added to the adding circuit 2 of the bridge 1, there is a high possibility that a sounding state will occur.

FIG. 6 shows an embodiment of a line connection in which an echo canceller 6 is inserted to prevent this noise.

Echo cancellers are already well known and are currently in widespread use, so we will not discuss their configuration here, but see, for example, ``Applications of Digital Signal Processing'' published by the Institute of Electronics and Communication Engineers.
It is explained in detail on pages 216-221.

The echo canceller 6 is for canceling the echo signal added by the bridge 1, and is also used for a connection system consisting of a microphone and a speaker for a dedicated line with 4 subscriber lines. It is clear that the echo canceller 6 is necessary because the signal generated from the speaker passes through the microphone and becomes audible at the bridge.

In this case, for the line connecting the bridges, if the echo canceller 6' shown by the dotted line can be set to a disabled state, there is no need to connect it as a dedicated port line between the bridges. Instead, it is possible to utilize this port as a port for a general telephone 4.

Furthermore, since the output of the adder circuit 2 is the sum of analog signals from each point, when transmitting the added signal to the receiving line, the average power will be higher than the general telephone level, so the input signal of the receiving line will be overloaded. It is necessary to devise ways to avoid loading.

FIG. 7 shows an example of a concrete functional configuration of the bridge 1 in which an overload prevention circuit 7 is inserted to prevent the input signal of the receiving line from being overloaded.

Although an AGC type overload prevention circuit 7 is shown here, it is not limited to this, and it goes without saying that a known compressor or limiter may be used.

(Effects) As explained above, the present invention installs bridges for each group of remote points by connecting the bridges with one line using an arbitrary port, and connects the bridges with one line. The usage efficiency of the lines between bridges is increased, and it is more economical than a line configuration using one bridge.

There is no need to prepare ports for accommodating all points in one bridge, and the required number of ports can be arbitrarily configured, so the cost of the bridge is reduced.

By disabling the echo canceller, the bridge port becomes a dedicated line between bridges, and by enabling the echo canceller, it is also possible to connect to a telephone, so it is versatile.

It has the following advantages.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a bridge configuration using a conventional multipoint connection method, Fig. 2 is an explanatory diagram of a multipoint communication method when using a bridge, and Fig. 3 is a diagram showing a bridge configuration using a conventional multipoint connection method.
An explanatory diagram of a communication method when the idea in the figure is extended to remote points, FIG. 4 is a diagram showing the configuration of an embodiment of the present invention, and FIG. 5 is a diagram of an embodiment in which multiple points are continuously connected by multiple bridges. FIG. 6 shows an example of a line connection in which an echo canceller is inserted to prevent noise, and FIG. 7 shows an example of the bridge configuration in which an overload prevention circuit is inserted. 1...Bridge, 2...Addition circuit, 3...Subtraction circuit, 4...Telephone, 5...Hybrid circuit,
6...Echo canceller, 7...Overload prevention circuit.

Claims (1)

[Claims] 1. An n+1 point where an analog signal generated from a first point is received at n multipoints, and a synthesized analog signal from the n multipoints is received at the first point. In the connection method between multiple (k) units (2
≦k≦n), each bridge has 1
The adder circuit has two adder circuits and a plurality of subtracter circuits, all analog signal inputs are added by the adder circuit, the output of the adder circuit is input to each of the subtracter circuits, and each of the subtracter circuits is connected to the adder circuit. subtracting the corresponding analog signal input from the output of the circuit;
In addition, to the plurality of bridges, the line at the n+1 point is connected to the line Pi (i=1, 2,
...k) is separated and accommodated so that n+1= _k 〓 ⁱ⁼¹ Pi,
The multiple point-to-point connection system is characterized in that each of the bridges is sequentially connected by one line, and a line at one or more points and an inter-bridge connection line can be accommodated in any line port of each of the bridges. 2. An echo canceller is provided for each connection between a bridge and one or more points accommodated in the bridge, and the echo canceller is disabled or not used for the connection between the bridges. A multipoint-to-point connection system according to claim 1. 3. Claim 1 or 2, characterized in that an overload prevention circuit is provided between the bridge and the receiving line at each point accommodated in the bridge.
Multipoint-to-point connection method described in section.