JPS5974744A - Privacy communication system - Google Patents

Abstract

PURPOSE:To realize a privacy call between remote subscribers and at the same time to ensure a free switching between a normal call and a privacy call, by deciding the intervention of a privacy telephone device with a switching signal. CONSTITUTION:The digital privacy telephone devices 6 and 6' are connected to each other with 4 wires for a call between remote subscribers, i.e., telephones 1-1 and 1-2. An exchange 5' detects a call between remote subscribers with a dial number and transmits a switching signal to a switching signal detection/ switch driving circuit 9 of devices 6 and 6' to change switches S21 and S22 to the sides of dotted lines. Through this switching, the privacy signal scrambled by a privacy device 11' is descrambled to be converted into a digital signal. This digital signal is turned into an analog signal through an MODEM13 and sent to the privacy device of the remote side to be supplied to carrier end offices 4-2 and 4-4 by scrambling. In such a way, the deterioration can be prevented for the sound quality of the privacy call between telephones 1-1 and 1-2. At the same time, free switching is ensured between a normal call and a privacy call.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention comprises a first modem, a concealment device, and a voice analysis/synthesis device on the side of a plurality of remote subscribers and on the side of an exchange via a carrier circuit. It is a communication system that has a central subscriber that is directly connected to the exchange by a subscriber line, and that allows for confidential calls between distant subscribers, and allows callers to freely make plain calls. This invention relates to a secret communication system that allows switching between communication and secret communication.

(b) Background of the technology What is a digital privacy device? When transmitting voice, a voice analysis and synthesis device analyzes and encodes the voice signal into a digital signal. A security device performs p-scrambling, and a modem converts the voice signal into a digital signal. When receiving a voice signal that has been converted and transmitted and concealed, first the modem converts it into a digital signal, the concealment device performs digital scrambling, and the voice analysis and synthesis device synthesizes the signal to form the original voice signal. This will convert it to . In addition, as mentioned above, the voice signal is concealed, the concealment is canceled, and the voice analysis and synthesis device performs p-synthesis to obtain the original voice signal. Because it is a synthesized sound, the call quality is poorer than that of a regular telephone, so the above-mentioned procedure is repeated again. If a voice signal is converted into a voice signal by a voice analysis/synthesizer after being concealed and then decondensed, it becomes difficult to grasp the content of the conversation, as the quality of the conversation becomes increasingly poor.

Therefore, in the two-link connection described above, with an exchange installed in between, calls between remote subscribers cannot be made as is, and the remote subscribers and the exchange are connected by zero or more carrier lines. In this case, the contents of the secrecy rules are changed for each transport line to prevent deciphering of the secrecy contents. This is because the exchange and the central subscriber are located at a fixed location, which is easy to manage, and there is no risk of information leakage.

In the figure, 1-1 to 1-3 are the filling machines, 2.2' and 3.3/ are the digital secret communication devices, and 2.3 is the telephone side, the p-vibrid circuit 14, the speech analysis and synthesis device 10. secret'), 2'%
3' is the first modem 12 and the secret device 1 on the carrier end station side.
1. Speech analysis and synthesis device 10. The vibrid circuit 14 is configured in this order. 4-1 to 4-4 are carrier terminal stations, 5 is an exchange 10 is a speech analysis and synthesis device, 11 is a concealment device, 12 is an l-th modem, and 14 is a hybrid circuit. For convenience of explanation, each subscriber in each location will be represented by one telephone.

In the system shown in FIG. 1, it is assumed that information is leaked through the carrier line, so digital privacy devices are provided on both sides of the carrier line. In addition, since the content of the confidentiality agreement is different between the digital privacy device 2.2' between the telephone 1-1 and the exchange 5 and the digital privacy device 3.3' between the telephone 1-2 and the exchange 5, information may be leaked. The original voice signal at the entrance of the exchange 5, which is controlled so that it is not
-3, there is no need to have digital privacy devices corresponding to the telephones 1-1 and 1-2 of distant subscribers passing through each carrier line. Also, when a telephone call is to be made between the remote subscriber's telephone 1-1 or 1-2 and the central subscriber's telephone 1-3, the digital privacy device 2.2' is connected after the line is connected to the exchange 5.
Or they are making secret calls via 3.3'. However, this system has the disadvantage that it is difficult to make a confidential call even if a connection can be established between the telephones 1-1 and 1-2 of the Fi store subscribers because the quality of the calls deteriorates as described above. In addition, in order to prevent information leakage from the carrier line section, when the line is connected, the voice of the other party can be confirmed in 1,000 calls, and only the necessary contents of the secret call are kept secret to shorten the time for concealment. In particular, it is desired to prevent leakage of information, but in the system shown in Stripe 1, a digital secret communication device 2.2'% L 3' is a voice analysis synthesis device, a concealment device,
Since it is composed of multiple modems, it has the disadvantage that it cannot meet the above requirements.

(d) Purpose of the Invention The purpose of the present invention is to eliminate the above-mentioned drawbacks, and to provide a secure communication system that enables confidential communication even between distant subscribers via a carrier line, and allows callers to freely switch between 1,000 calls and a secret call. The purpose is to provide a method.

(e) Structure of the Invention In order to achieve the above object, the present invention provides a digital type system comprising a first modem, a concealment device, and a voice analysis/synthesis device on the side of a plurality of remote subscribers and the exchange side via a carrier line. In a communication system having a central subscriber that has a security device and is connected directly to the exchange by a subscriber line, when a call is made, the switching signal from the caller is passed through or passed through the digital security device. In addition, when making calls between distant subscribers, a digital privacy device on the side of the exchange can be used in case the exchange has a two-wire connection. It is characterized in that the configuration is switched to a 4J1 modem, a hidden device, and a digital signal burst transmission device, and in the case of a 4-wire connection, it is switched to a first modem, a hidden device, and a second modem configuration. (f) Embodiments of the invention Examples of the invention will be described below with reference to the drawings.

FIG. 2 is a block diagram of a communication system according to an embodiment of the present invention, in which an exchange performs #A4M connection for calls between distant parties.

Figure 3 shows the digital secret communication devices fli2# and 3 in Figure 2.
FIG. 4 is a block diagram of the circuit of FIG. 2 of the embodiment of the present invention, in which the exchange 11A5' of FIG. .6' is a block diagram of the circuit.

Components in the figure that have the same functions as those in Figure 41 are indicated by the same symbols.

2'', 3#, 6.6' are digital secret communication devices, 5' is an exchange 7.8 is a switching reversal signal detection and switch drive circuit, 9 is a switching signal detection and switch drive circuit, 801 r
SON + Sll r sst is a changeover switch between a plain communication line and a secret communication line, S□, S3. is a changeover switch for a secret communication line between remote subscribers and the central subscriber and a secret communication line between distant subscribers, lO' is a voice analysis and synthesis device, 11' is a concealment device, and 12' is a first modem. ,
Speech analysis and synthesis device fjtlO1 concealment device 11. 1st
It is the same as the modem 10 of . 13 indicates a second modem.

The digital privacy device of the telephone set shown in Fig. 3 is of the ZfIM type in the hybrid circuit 14, but the carrier end office side has 4 sets, and the carrier end office side and exchange side in Fig. 4 have a ZfIM type. It is a 4-wire system. Also, in the digital type secret device shown in FIG. 3, the switch S is normally used. ll5 (1! is connected to the actual edge side, this switch So+ *, So
The switching back of w is controlled by the switching back signal detection and switch drive circuit 7 of n++. In addition, in the digital secret device shown in FIG. 4, the switch S11゜SuRr
Sur St* is connected to the actual edge side, and switching back of switch SIIISIm is controlled by switching back signal detection and switch drive circuit 8, and switches S1
, 2 is controlled by switching signal detection and switch rotation w69.

First, the communication between the remote subscriber and the central subscriber 1' and JI will be explained by taking as an example the communication between the remote subscriber 1' and the central subscriber 1.1-3.

'Kame8i! The connection between I-1 and 1-3 is carried out in the usual manner, and is connected by a 2-wire system inside the exchange 5' of FIG. This allows mutual subscribers to confirm the other party's identity through a plain call. Switching to the secret communication line is performed by transmitting a predetermined dial signal from the telephone set 1-1 or 1-3, detecting the switch-back signal of the digital form secret communication line 2, and detecting the switch drive N line 7 (No. 3) and the digital private communication device 6 switching back 1 [number detection and switch drive N path 8 (4th line detects the switching number 1g and switches the switch LOI+5O2r SII+ SI2 to the dot side to open the secret communication line. Next, when switching back the secret communication line to the plain communication line, if a specific dial signal is sent in advance at the 1-1 or 1-3, the detection and switch drive circuit will be switched back. 8 detects the switchback signal and switches SI2 to the actual side to make the same line.Voice analysis in Figure 3 and Figure 4 when it becomes a secret call line as described above. Synthesizer 10
゜10'Secret device 1i', 11'First modem 12.1
The motion f'll: of 2' is the same as previously explained.

2* In the case of communication between distant subscribers, see 'a' in Figure 2.
8i 愼1-1, 1-2 O= is' -c Ha
q −a” le.

This one I! 1. The filling is carried out in the usual manner using a digital secret filling device: 6. 6' is connected in 4 matches.

Also, based on the dialed number, the exchange 5' detects that the call is between distant subscribers, and transmits the switching signal to the digital secret device 6. , 6' is transmitted to the switching signal detection and switch driving circuit 1Rr9 shown in FIG. 4, and the switch So +S2! Switch to the dotted line side. With this switching, the digital secret communication device 6. , 6' in the secret device 11' of FIG.
l 1. The signal that is scrambled and made confidential by the voice from 1-2 is de-scrambled and converted into a digital signal. The modem 13 sends it as an analog signal to the other party's digital secure device (6 or 6/ in FIG. 2), where it is scrambled by the secure device 11' of the digital secure device 6, 6' and sent to the first digital secure device (6 or 6/ in FIG. 2). The modem 12' converts it into an analog signal and sends it to the carrier terminal station 4.
-2 or 4-4. By doing so, when a secret call is made between the telephones l-1 and 1-2, deterioration of voice quality is prevented and the secret call is made possible.

Of course, at first it is a flat line as explained earlier, so if you want to confirm the other party and make it a secret call, send a predetermined specific dial signal to the telephone 1 as explained earlier.
If sent from -1 or 1-2, the digital form @2
If you want to switch to a secret communication line and a father-child communication line by detecting the switch-back signal of ``, 3'', 6.6'' and controlling the switch driving circuits 7'' and 8, you can send a specific dial signal to the telephone in advance. 1-1 or 1-2, the switching back signal is detected and the switch drive circuits 7 and 8 are controlled, resulting in a normal call. Not only can you make a call, but you can also freely switch between private and confidential calls.

Next, a case will be explained in which the exchange establishes a two-wire connection when communicating between distant subscribers.

FIG. 5 shows another embodiment of the present invention, in which the exchange 5' of FIG. 2 makes a two-wire connection when communicating between distant subscribers, and the digital privacy device 6, 6' circuit of FIG. 2 is used. It is a block diagram.

Items with the same functions as No. 41 in the figure are indicated by the same symbols.

15.17 connects the 4-wire system to 2 because the exchange makes a 2-wire connection.
The difference between Fig. 5 and Fig. 4, which shows a bibrid circuit and 16Fi digital signal burst transmission equipment for a wire system, is that in this case, calls between distant subscribers are also carried out using two wires at the exchange 5/ in Fig. 2. Since the exchange side of the digital confidential communication device 6゜6' shown in Fig. 2 needs to be a two-wire system because of the type connection, a bibrid circuit is installed on the line for plain communication and the exchange side of the speech analysis and synthesis device 10'. 15. At the point where 17 was inserted and the point where the digital signal burst transmission device i16 was added to the second modem 13 in Fig. The side connected to the other secret device 11' is a four-wire type. In operation, the transmission speed is increased and the digital signal is alternately transmitted to the opposing digital signal burst transmission device at a period of several milliseconds so as not to give a strange feeling to the voice communication. Therefore, when a call is made between distant subscribers, the exchange @5' in FIG. is switched to the dotted line side, and the digital signal burst transmission device 16 is inserted between the secret device 11 and the switch.Even if the 2ν" set is connected, it will be connected to the switch in the same way as the second modem in Fig. 4. In other words, the voice analysis and synthesis device allows signals to be exchanged between distant subscribers as digital signals without converting them to the original voice, which prevents deterioration of voice quality and enables secret calls between distant subscribers. The exchange 5' in Figure 2 performs a 211111 type connection between remote subscribers and the central subscriber, so that this operation and calls between distant subscribers are initially conducted as plain calls, and that plain calls and confidential calls are free. The switching can be performed in the same manner as described above using FIG. 4.

(g) Effects of the Invention As can be explained in more detail, according to the present invention, when the line is connected, it is possible to freely switch between a father-son call and a secret call, reducing the time required for secret calls and calls. This has the effect that it is possible to prevent the leakage of information about progress, and also to enable confidential communication between distant callers via the carrier line.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional communication system, FIG. 2 is a block diagram of a 4R system according to an embodiment of the present invention, and FIG. 3 is a digital private communication device 2'' of FIG. FIG. 2 is a block diagram of the circuit of the digital secure telephone system [6, 6'] in the case where the switching system according to the embodiment of the present invention connects telephone calls between telephone subscribers using the PM2 wire system. 3 is a block diagram of the circuit of the digital secret device 6, 6' of FIG. 2; FIG. In the figure, 1-1 to 1-3 are telephones, and 2.2? 3.3'. 2”, 3”, 6.6! ta digital form secret book &, 4-
1 to 4-4 are carrier terminal stations, 5, 5/ are switchboards, 7 and 8 are switching/return signal detection and switch drive circuits, 9 is a switching signal detection and switch drive circuit, and 10.10' is a speech analysis/synthesis device. , 11. ll' is a secret device, 12.12' is the lth modem, 13Fi second modem, 14, 15° 17 is a hybrid circuit, 16 is a digital signal burst transmission device, set # Son r So + Sst z S
H#S□ indicates a switch〇

Claims (1)

[Claims] Each of a plurality of remote subscribers and the exchange through a carrier line has a digital security device consisting of a first modem, a security device, and a voice analysis/synthesis device, and the exchange has a direct subscriber line. In a communication system having central subscribers connected to each other, in the case of a call, it is possible to switch whether or not to pass the digital confidential communication device by sending a switching signal from the caller. When a call is made between distant subscribers, the digital privacy device on the exchange side is switched to a configuration of a first modem, a security device, and a digital signal burst transmission device when the exchange has a two-wire connection; A secret communication system characterized in that, in the case of a four-wire connection, the configuration is switched to a first modem, a secret device, and a second modem.