EP0028688A1 - Installation pour la transmission de signaux de commande par un canal de parole - Google Patents

Installation pour la transmission de signaux de commande par un canal de parole Download PDF

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Publication number
EP0028688A1
EP0028688A1 EP80105445A EP80105445A EP0028688A1 EP 0028688 A1 EP0028688 A1 EP 0028688A1 EP 80105445 A EP80105445 A EP 80105445A EP 80105445 A EP80105445 A EP 80105445A EP 0028688 A1 EP0028688 A1 EP 0028688A1
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EP
European Patent Office
Prior art keywords
voice
transmission
devices
station
speech
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP80105445A
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German (de)
English (en)
Inventor
Hugo Heller
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
CRYPTO AG
Original Assignee
CRYPTO AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by CRYPTO AG filed Critical CRYPTO AG
Publication of EP0028688A1 publication Critical patent/EP0028688A1/fr
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04K—SECRET COMMUNICATION; JAMMING OF COMMUNICATION
    • H04K1/00—Secret communication

Definitions

  • the invention relates to a system for the transmission of control signals via a voice channel between transmitting / receiving stations, at least one end of the transmission link each having a voice key device that can be influenced by the control signals for encrypting or decrypting voice signals.
  • Telephone networks are used today for all kinds of purposes other than voice transmission, since they exist widely and are available 24 hours a day, but are mostly underused. Data transmission or command transmission by means of audio frequency signals are an example of this "misuse”.
  • control device is generally electrically connected to the telephone line, with a changeover switch - usually operated by hand - permitting "operation of the line with the telephone” or "feeding in a group of identification signals to influence the remote station". It is unimportant what the remote station subsequently does for tasks, for example the line can be switched there on a computer, or it can be done in one uninhabited holiday home the heating can be turned on, etc.
  • End points in the simplest case mere keyboards, are also available for data transmission, which are equipped with an audio frequency signal transmitter and a small loudspeaker.
  • a small loudspeaker is e.g. in GB-PS 1 051 791.
  • the loudspeaker is acoustically coupled to the microphone of the telephone station; in this way an electrically independent signal transmission is possible.
  • shelf-legal problems With direct electrical connection, in addition to purely technical problems for laypersons, shelf-legal problems also arise; because most telephone companies make the electrical connection of third-party devices dependent on various conditions.
  • Encryption devices that are electrically looped into an information line in order to perform a line-bound (ON-Line), direct encryption or decryption of the message transmitted on the line to synchronize at least at the beginning of the transmission.
  • the other relates to key synchronization, which has the purpose of controlling the decryption device at the right moment in such a way that it can subsequently decrypt the information encrypted by the sending station.
  • the actual secret message is preceded by certain pulse groups which are recognized by the receiving station upon arrival and evaluated accordingly.
  • voice encryption devices As a rule, this is the case of "manned" stations on both sides.
  • voice encryption works from person to person.
  • the corresponding switching commands - at least the command "switch to secret mode" - are transmitted orally and carried out by manual manipulations on the devices, such as in DE-PS 1 944 861.
  • the voice key devices are each provided with a signal evaluation device for receiving tone-frequency control signals in the voice frequency range via the voice channel and for influencing the functioning of the voice key devices as a function of the control signal, and at least one with each transmitting / receiving station via their voice recording.
  • Microphone acoustically coupled, electrically separated from the transmission link tone frequency signal generator is provided for the control signal generation in the voice frequency range.
  • the station 3 which wants to communicate with one of the stations 1, 2 or 6 to 8, has in most cases no need for voice encryption if the corresponding telephone network is complex enough or is located in a relatively protected zone, which makes it very unlikely that eavesdropping on reports by any opponents. But is now a connection between the station 2 and a vehicle 10 are created, the risk of A is bhorch Rushkeit much greater; firstly, they work wirelessly, everyone can do without eavesdropping on physical interventions in the network; secondly, the number of allocated frequency channels is generally limited and these are generally known. A systematic listening to these areas leads to success for the opponent.
  • All stations are equipped with key devices 11 ... 17.
  • the advantage is that wired calls can also be protected if necessary, but the disadvantage is the great effort involved. All stations would have to be equipped with key devices working in a duplex process, which in practice requires a high level of technical effort. This is because usually only half-duplex is used for voice encryption, i.e. a message is transmitted in one direction or the other from case to case.
  • the function of the key devices is usually influenced by the microphone intercom button, as is common with mobile radios. When transmitting, the button is pressed and the radio station is switched from "reception" to "transmission”; Any key device is switched from the "decrypt” state to the "encrypt” state.
  • the control can also be language-dependent (VOX control) in that a detector is looped into the microphone circuit, which switches the system to send when a signal arrives and to reception again when the signal fails (delayed - in order to bridge speech breaks).
  • FIG. 3 Another conventional solution according to FIG. 3 is less complex, in that only the mobile stations 10 are equipped with a key device 18 and a stationary radio station 9 with a key device 19.
  • the radio link is basically two-channel, the key devices 18 and 19 can, depending on the application, be equipped as full duplex devices or voice or hand-controlled half duplex devices.
  • the fixed radio station will usually have two antennas, a transmitting antenna and a receiving antenna, which is assigned to a receiver 9a.
  • the only antenna is switched accordingly together with the radio system and the key device.
  • an automatically working multiplex system for antenna coupling is generally used in order to avoid the use of two antennas.
  • the receiver in the vehicle 10 will have problems synchronizing his device 18 correctly when a message arrives.
  • This method fails, however, at the moment when several vehicles 10, 20 according to FIG. 4 are in use, which are connected to various fixed radio stations, and where there is no fixed allocation, in that a vehicle moves automatically by means of each The catchment area of a fixed radio station is "supervised” by it and is “taken over” by the next fixed station when it leaves this zone, within the sphere of influence of which the vehicle has entered.
  • Possibility of influencing by the vehicle station is also necessary, namely when it enters the fixed network by calling.
  • An audio frequency signal evaluator 22 is attached to the fixed radio station 9, to which information from the wire line coming from the control center 4, as well as from the receiver 9a, is fed. To generate this information, stations 1 to 3 and 6 to 8 sound frequency signal generator 23 to 28 electrically switched on. In the (or the) mobile station (s) 10, a device 29 is switched on, which works both as a signal transmitter and as a signal evaluator.
  • the device 23 is actuated accordingly. This sends 4 audio frequency control commands via the line via the control center to the detector 22, which switches the device to secret mode. The signal also reaches the mobile device 29 via the radio link, which influences the key device 18 accordingly.
  • E rfindungsgemäss can be Tonfrequenzsignalgeber 23 to 28 electrically disconnected from the transmission path and made only to the voice recording microphone acoustically coupled to the stations.
  • the signaling devices are designed to be personal. For example, a commander in charge can be equipped with an acoustically connectable signal transmitter and is therefore free to move. Depending on the area of application, he can establish a secure radio connection from each telephone booth with the radio trolley 10.
  • FIG. 6 A possible embodiment of an audio frequency signal transmitter is shown in FIG. 6.
  • a sound frequency signal of frequency fo, for example 3200 Hz, generated in an oscillator 31 of conventional type can be divided by means of divider circuits 32.
  • the four audio frequency signals fo, fo / 2 , fo / 4 and fo / 8 thus available are fed to a multiple switch 33.
  • this switch one of the sound frequencies can be selected as a control signal and via a driver circuit 34 of known type a speaker 35 are supplied. If the loudspeaker 35 is held against the voice recording microphone 36 of one of the stations, the corresponding control signal is transmitted to the control center 4 (FIG. 5) and from there to the audio frequency signal evaluator 22 or to the voice key device 19.
  • the illustrated embodiment of the audio frequency signal transmitter is capable to generate four different control signals, but it is easy to see that this number can be increased by suitable adaptation of the circuit.
  • the multiple switch 33 in FIG. 6 can be replaced by a multiplexing device which is connected to a memory in which the signal sequences are stored.
  • the audio frequency signal transmitters can be set to certain different frequencies in a person-specific manner.
  • the voice key devices 18, 19 can be switched between clear and secret mode and their key settings can be made, e.g. the head of an organization can use keys reserved for him, e.g. a tone frequency is reserved for his personal tone frequency signal transmitter and is blocked for the other signal transmitters. Wherever he or she will be calling from, the person called will have the guarantee that the person they are talking to will be the person they claim to be after switching to secret mode.
  • the audio frequency control signals reach the audio frequency signal evaluator 22 via the telephone network and the control center 4 (cf. FIG. 5), as is shown in FIG. 7, for example.
  • the frequency of the control signal can be determined by means of a commercially available frequency decoder 37, a signal being generated on corresponding output lines A to D when one of the frequencies fo, ..., fo / 8 is present.
  • a line switch 38 which is commercially available, the one input line 39 is connected to one of the output lines 40 depending on the signal frequency determined, that is to say the signal appearing on lines A to D, whereby the voice signals arrive at the corresponding input of the key device 19 which corresponds to a specific mode of operation of the device, for example clear operation or secret mode with a specific key setting.
  • the audio frequency signal transmitter 23 is actuated accordingly. This sends 4 tone frequency control commands via the line via the control center to the tone frequency signal evaluator 22, which switches the voice key device 19 to secret mode. Via the radio link, the signal reaches the mobile device 29, which influences the key device 18 accordingly and is constructed similarly to the signal evaluator 22, and it can additionally be equipped with a built-in audio frequency signal transmitter.
  • the acoustic coupling of the audio frequency signal transmitter to the transmission link has the advantage high flexibility.
  • All telephone stations of the civilian telephone network be equipped with electrically connected control devices, the cost would be very high. If only the stations of the bases, i.e. police barracks, garrison or space squadrons were provided with it, the advantage of the system would be that every wagon can run with every fixed station.
  • An acoustically connectable control signal generator enables a secure connection to be established from any telephone station with minimal effort.
  • the key devices 18, 19 to be influenced have already been looped in a priori in the cable run. So it's just about influencing their function.
  • the control device 22 can therefore be integrated into the key device 19.
  • it is not a question of connecting other devices to the line instead of the telephone set and in the mobile station instead of the radio, which only use the telephone line as a means of transmission, but rather to actively include this connection in a given connection and to influence the functioning of the transmission apparatus.
  • the use of the tone frequency control serves different purposes here than with the usual controls.
  • the arrangement according to the invention makes it possible to secure the sections of the line which are at risk of eavesdropping in a transmission network, while the safe parts of the section are operated in clear mode. This allows full duplex operation to be maintained throughout the network with relatively little effort. Furthermore, this results in a high degree of flexibility in use, since a secure connection can be established from any telephone station in the network.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Selective Calling Equipment (AREA)
  • Transmitters (AREA)
EP80105445A 1979-11-07 1980-09-12 Installation pour la transmission de signaux de commande par un canal de parole Withdrawn EP0028688A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH997679 1979-11-07
CH9976/79 1979-11-07

Publications (1)

Publication Number Publication Date
EP0028688A1 true EP0028688A1 (fr) 1981-05-20

Family

ID=4357749

Family Applications (1)

Application Number Title Priority Date Filing Date
EP80105445A Withdrawn EP0028688A1 (fr) 1979-11-07 1980-09-12 Installation pour la transmission de signaux de commande par un canal de parole

Country Status (7)

Country Link
EP (1) EP0028688A1 (fr)
JP (1) JPS5676646A (fr)
AR (1) AR224912A1 (fr)
BR (1) BR8007222A (fr)
ES (1) ES8200802A1 (fr)
NO (1) NO803344L (fr)
ZA (1) ZA806589B (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0313029A1 (fr) * 1987-10-21 1989-04-26 Siemens Aktiengesellschaft Österreich Dispositif de transmission brouillée de signaux analogiques
EP0313576A1 (fr) * 1986-07-03 1989-05-03 Motorola Inc Systeme et procede de communication interreseau d'interconnexion d'appels telephoniques avec un reseau radiophonique audio-numerique protege.

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS58154961A (ja) * 1982-03-10 1983-09-14 Fujitsu Ltd 秘匿通話方法
JPS5961242A (ja) * 1982-09-30 1984-04-07 Fujitsu Ltd 秘匿通信システム

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1051791A (fr) * 1964-01-09 1900-01-01
US2542183A (en) * 1948-07-10 1951-02-20 Bell Telephone Labor Inc Transmission privacy synchronizing and equalizing system

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2542183A (en) * 1948-07-10 1951-02-20 Bell Telephone Labor Inc Transmission privacy synchronizing and equalizing system
GB1051791A (fr) * 1964-01-09 1900-01-01

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0313576A1 (fr) * 1986-07-03 1989-05-03 Motorola Inc Systeme et procede de communication interreseau d'interconnexion d'appels telephoniques avec un reseau radiophonique audio-numerique protege.
EP0313576A4 (en) * 1986-07-03 1990-09-12 Motorola, Inc. Gateway system and method for interconnecting telephone calls with a digital voice protected radio network
EP0313029A1 (fr) * 1987-10-21 1989-04-26 Siemens Aktiengesellschaft Österreich Dispositif de transmission brouillée de signaux analogiques

Also Published As

Publication number Publication date
BR8007222A (pt) 1981-05-19
ES496115A0 (es) 1981-11-16
NO803344L (no) 1981-05-08
ZA806589B (en) 1981-10-28
AR224912A1 (es) 1982-01-29
ES8200802A1 (es) 1981-11-16
JPS5676646A (en) 1981-06-24

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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Effective date: 19811030

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Effective date: 19830622

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Inventor name: HELLER, HUGO