DE19525705A1 - Optical wave guide telephone set - has automatic switching within each telephone device between transmission and reception modes depending on received speech signals - Google Patents

Abstract

The telephone set has at least two identical telephone devices at either end of an optical wave guide (5,6). Each device has transmission and reception stages (1,2) which employ a modulator (10) and a demodulator (14). Batteries are used to supply the operating voltage. An automatic switching device (3) within each telephone device responds to speech signals from the telephone device for blocking the reception stage, or to signals received from the optical wave guide for blocking the transmission stage.

Description

The invention relates to a fiber optic telephone set with at least two identical structures, each as Sender and serving as receiver, on both sides to one Fiber optic connectable fiber optic telephone Apparatus, each with a modulator and a demodulator and with integrated and / or connectable batteries for Provision of a required operating voltage.

Such telephone sets are usually used by assembly teams for fiber optic cabling, especially for Use in communication, used to e.g. B. after the Laying a fiber optic cable a first To carry out a functional test and for longer distances further action between the sub-groups on the two To coordinate fiber optic end points. To do this simply at the end of the routed cable Telephone connected and it can then over the Optical fibers can be communicated by means of the telephones. This allows fitters who are interested in different Locations, but located on a common route, Exchange measurement results, discuss errors, measures advise or signal readiness. This allows the Setup and unnecessary ways of maintaining fiber optic networks avoided and the work accelerated enormously.

There is a problem with such fiber optic phones always in the feed of the optical signal in the Optical fiber, since the signal is very precise in the Core of the respective optical fiber, in the order of magnitude  of a few µm, must be threaded. So single mode Optical fibers usually have a core diameter of 9 µm, gradient index optical fibers have one Core diameter in the size of 50 µm. The diode must therefore be positioned very precisely in the socket so that the optical signal emanating from the diode is well threaded. Conversely, the receiving diode must of course also be corresponding be positioned in front of the end of the light guide. It will therefore optical ping-pong diodes are usually used, which can serve as both sender and receiver.

Unfortunately, these ping-pong diodes cannot Send and receive at the same time, but always alternately, either send or receive, d. H. they are not "duplexable". Therefore, conventional fiber optic Provide telephones with a talk button by the operator must be pressed if he uses his phone as a transmitter wants to use. If this key is not pressed, this serves Telephone only as a recipient.

For this reason, so-called "duplex diodes" have been on for a short time the market, which is basically two in one Diode housing arranged diodes, one of which serves as a transmitter and the other as a receiver diode. For Feed into an optical fiber is in the small one A special prism arrangement is also installed in the housing. With this type of diodes, true duplex operation is possible and the constant pressing of a talk button during the Phoning is not necessary. This has in particular the advantage that the phone is in operation without The hands can be used so that the Users have both hands free for their assembly work.

However, a crucial disadvantage of these duplex diodes is the currently very high price, since this is right elaborately manufactured components. In stores so far  offered are fully duplex-capable fiber optic telephones therefore relatively expensive.

It is an object of the invention to provide an optical fiber telephone To create sentence of the type mentioned, which at inexpensive, simple and stable build a freehand Operation of the telephones enabled.

This object is achieved in that the telephones each have an automatic switching device, which depending on the first incoming voice signal of the respective own voice recorder of the telephone or transmitted signal received via the optical fiber other telephone set, in a transmission mode, in which the own transmission part unlocked and the Receiver part is blocked, or in one Receiver operating state in which the receiver part unlocked and the transmitter part is blocked, switches.

In the optical fiber telephone set according to the invention can there is no need for a talk button, d. H. the operator can, just like the fully duplex-capable telephones, the device during operation without using your hands to use. Because in the rarest of cases both users start speaking at the same time, or each other to interrupt the optical waveguide according to the invention Telephone set for the user a fully duplexable Fiber optic phone set almost the same.

Since there are no duplex Diodes are required is a corresponding phone set can be produced much more cost-effectively than a full one duplex-capable telephone set.

The sub-claims contain particularly advantageous Refinements and developments of the invention.

The fiber optic telephone set according to the invention is in following with reference to the attached drawings described an embodiment. They represent:

Fig. 1 is a block diagram of an embodiment of a telephone apparatus of the invention,

Fig. 2 plan view of an upper front panel of an embodiment of the telephone set according to the invention,

Fig. 3 is a perspective view of a telephone set of FIG. 2.

An optical fiber telephone set consists of at least two identical optical fiber telephone sets, each of which serves as a transmitter and a receiver and can be connected to an optical fiber ( 5 , 6 ) on both sides. These each have a modulator ( 10 ) and a demodulator ( 14 ) for modulating or demodulating the speech signal, as well as an integrated accumulator for providing the required operating voltage.

According to the invention, the telephone sets each have an automatic switchover device ( 3 ), which, depending on the first incoming voice signal of the respective own voice recording device ( 4 ) of the telephone set or via the optical waveguide ( 5 , 6 ), transmitted signal of another telephone set either in a transmission operating state in which the own transmitter part ( 1 ) is activated and the receiver part ( 2 ) is blocked, or switches to a receiver operating state in which the receiver part ( 2 ) is activated and the transmitter part ( 1 ) is blocked.

For this purpose, each telephone set has a speech circuit ( 7 ) which, triggered by the speech signals from the respective own voice recording device ( 4 ), generates a switching signal for the switching device ( 3 ).

In the present exemplary embodiment, the speech recording device ( 4 ) is a microphone with a subsequent amplifier stage for the speech signal.

In the receiver section ( 2 ), the telephone sets each have a receiving circuit ( 13 ) which, triggered by a signal received in an optical fiber input ( 20 , 21 ), generates a switching signal for the switching device ( 3 ).

The switching device ( 3 ) can, as in the present exemplary embodiment, be implemented by a flip-flop. This flip-flop has two inputs and two outputs. Depending on the assignment of the signal inputs, either the first output is switched to "High" and the second output is switched to "Low", or vice versa. One of the two outputs switches, such as. B. in Fig. 1, in the "high" state via an AND gate ( 27 ), the transmission line from the modulator to the fiber optic output ( 20 , 21 ) free; the second output is then routed to the receiver part and switches an amplifier circuit ( 23 ) here in the "high" state, so that the demodulated signal from the demodulator ( 14 ) to the speech reproduction element, e.g. B. a headphone ( 12 ), can be forwarded increasingly.

Depending on the assignment of the inputs on the switchover device ( 3 ), either the transmitter part ( 1 ) or the receiver part ( 2 ) is activated via the outputs. The other part is blocked.

The block diagram shown in Fig. 1 shows only a special embodiment of a telephone set according to the invention. Of course, various other circuit variations are also possible here. B. amplifier stages ( 28 , 29 ) sit at any other point, additional switches can be inserted or the signals of the speech circuit ( 7 ) or the receiving circuit ( 13 ) can be used to directly enable the transmitter part or the receiver part and to block only the other part via a slightly changed switching device. Depending on the components selected, the polarity of the switching signals can of course be reversed.

The speech circuit ( 7 ) in the present case essentially consists of a discriminator element ( 9 ) for setting a threshold value for the speech signal, a push button ( 22 ) and a time delay element ( 8 ).

The threshold value can be set by the respective user via a controller ( 9 R), which is located on the outside of the telephone housing. Only when a speech signal from the speech recording device ( 4 ) lies above the set threshold value, a switching signal for the switching device ( 3 ) is generated by the speech circuit ( 7 ). The user can use this threshold to set the sensitivity at which noise volume his device switches to "Send". This can prevent that the telephone set is constantly set to "send" due to unwanted background noise and is therefore not ready to receive.

Via the button ( 22 ) arranged on the speech circuit ( 7 ), regardless of the threshold value set and without speaking into the microphone, a switching signal for the switching device ( 3 ) can be generated and, if necessary, also a signal (ring tone in internal mode, noise in Headphones in external mode - see below -) are triggered on the other telephone set to signal readiness.

The actual core of the speech circuit ( 7 ) is a time delay element ( 8 ). In the exemplary embodiment shown, this is a retriggerable timing element which generates a continuous switching signal from the oscillating voice signal or from the signal (or potential) applied to the input via the push button ( 22 ). The duration of the outgoing signal can be set in the factory such that a switching signal for the switching device ( 3 ) is generated beyond the end of an incoming signal for a defined period of time. This means that shorter pauses in speech do not immediately lead to a switch to another operating state of the telephone set. This time period is preferably between 0.1 and 1.0 sec.

The voice signal goes from the voice recording device ( 4 ) (microphone + amplifier) simultaneously via the modulator ( 10 ) and is modulated there onto a corresponding carrier frequency. From there, the signal continues via a gate ( 27 ) serving as a disconnector and a further amplifier unit ( 28 ) to the optical fiber connection ( 20 , 21 ).

The telephones each have two optical fiber connections ( 20 , 21 ) which serve simultaneously as optical fiber signal input and as optical fiber signal output. These are each provided with a so-called "ping-pong diode" ( 15 , 16 ), which can both send and receive.

One of the connections is designed as a single-mode optical waveguide ( 20 ), the other as a gradient index optical waveguide connection ( 21 ). In front of the connections ( 20 , 21 ) there is a changeover switch ( 17 ) for switching over to the connection ( 20 , 21 ) used in each case. By installing these two different connections with different diodes, it is possible to use the telephone set according to the invention both for the care and relocation of single-mode fibers, in which transmission takes place in a wavelength range of 1300 nm, and for gradient index fibers, which transmit in a wavelength range of 850 nm. The operator only has to insert the fiber connector into the corresponding socket ( 20 a, 21 a) and set the changeover switch ( 17 ) to the appropriate use. The sockets ( 20 a, 21 a) are designed as so-called "ST" sockets with a bayonet lock.

Signals arriving at the "ping-pong diodes" ( 15 , 16 ) are routed via an amplifier unit ( 29 ) to the demodulator ( 14 ) in the receiver part ( 2 ).

In the present exemplary embodiment, the signal sampling frequency of the demodulator ( 14 ) is a multiple of the transmission carrier frequency of the modulator ( 10 ). The demodulator ( 14 ) is equipped with a so-called "phase lock loop" (PLL circuit), ie it is able to search for an incoming carrier frequency within a certain frequency range and then stabilize at the frequency found. With the selected carrier frequency in the transmitter range of approx. 65 kHz and in the reception range of approx. 180 kHz, a range of up to 70 km is possible.

Part of the demodulator ( 14 ) together with a retriggerable timer ( 13 Z) forms the receiving circuit ( 13 ).

When the carrier frequency is correctly applied, a switching signal is generated by the demodulator ( 14 ) and sent to the retriggerable timer ( 13 Z). A corresponding continuous switching signal is generated from the input signal, which is then sent to the switching device ( 3 ). In principle, the retriggerable timer ( 13 Z) can also be dispensed with and the output signal of the demodulator ( 14 ) can be fed directly to the switching device ( 3 ). In this ball, the corresponding part of the demodulator ( 14 ) alone forms the receiving circuit ( 13 ).

For the simple realization of such modulators and Demodulators with PLL circuit offer the use of manufacture TC modules, such as B. the 4046 B (CD 4046 from RCA or 14046 from Motorola). These can because of their low Power consumption also well used in battery devices will.

The signal is then demodulated in the demodulator ( 14 ) and passed to the playback device, in the present case a headphone ( 12 ), via an amplifier unit ( 23 ) which can be controlled by the switching device ( 3 ) and regulated by the operator to adjust the volume.

There is another switch ( 19 ) between the amplifier unit ( 23 ) and the headphones ( 12 ). This switch is designed as a double changeover switch. At the same time, either the signal coming from the amplifier ( 23 ) is routed to the headphones ( 12 ) ("external mode"), or a tone generator ( 11 G) with connected loudspeaker ( 11 ) is switched on via the switching signal coming from the switching device ( 3 ) ("Internal mode"). This "internal" or "call mode" is provided in the event that one of the two fitters has to do something at a fixed location, while the other first has to leave for its place of use at the other end of the optical fiber that can be used. So that the fitter at the fixed location is not forced to constantly wear the headphones of the fiber optic telephone set during the waiting time, he switches his fiber optic telephone set into this mode. Then the output of the switching device ( 3 ) is placed directly on the input of the tone generator ( 11 G). The connection from the amplifier unit ( 23 ) to the headphones ( 12 ) is interrupted, ie it cannot be heard on a connected headphone. If the other employee has now reached his place of use, he can generate a call signal by speaking into the microphone or pressing the call button ( 22 ). This transmission signal then triggers a beep via the receiving circuit ( 13 ) and the switching device ( 3 ) and the tone generator ( 11 G). The waiting fitter learns that the other party is ready to receive.

The telephones are each together with their accumulator in a housing ( 24 ) which has connection sockets ( 20 A, 21 A) for the corresponding optical fiber cables ( 5 , 6 ) and a connection socket ( 25 ) for an accumulator charger. There is also a two-color light-emitting diode ( 18 ) on the housing, which is connected to the outputs of the switching device ( 3 ) and lights up red or green depending on the operating state. There is also a switch ( 17 ) on the housing for switching between the two fiber optic connections ( 20 , 21 ), a switch ( 19 ) between ringing mode and headphone mode, a call button ( 22 ) for triggering a ready call signal, a threshold value - or sensitivity regulator ( 9 R) for setting the speech signal threshold values for the speech circuit ( 7 ) of the transmitting part ( 1 ) and a volume regulator ( 23 ) for regulating the amplifier stage ( 23 ) of the receiving part ( 2 ).

A headphone-microphone unit can be connected via a connection socket ( 12 A).

To save energy, the operating voltage supply line is led through the connection socket ( 12 A) for the headphone-microphone unit and interrupted there. The two open ends of the supply line are then designed as contacts in the connection socket ( 12 A). The corresponding mating contacts of the associated connector of the headphone-microphone unit are interconnected to form a short-circuit connector. The telephones are therefore only in operation when the headphone / microphone unit is plugged in. This has the advantage that, in contrast to the use of an on / off switch, the device cannot be switched on unnoticed during transport and energy is thus used unnecessarily.

On one side of the housing there is a clip ( 26 ) for fastening the housing to the user's belt.

The entire structure is extremely compact. In the present Embodiment, the outer dimensions of the housing are only approx. 100 × 100 × 60 mm.

Of course, alternative protection options are also conceivable, so that, for. B. a hidden and secured on / off switch is attached to the housing. In this case, z. B. the internal / external switch can be dispensed with, or this switch can be connected to the headphone connection such that when the headphones ( 12 ) are plugged in, the connection between the switching device ( 3 ) and the tone generator ( 11 G) is automatically interrupted and the received and demodulated signal is switched to the headphones ( 12 ).

To further save energy and to increase the operating time without a mains connection, the modulator ( 10 ) has a so-called "inhibit" input ( 10 I), which is connected to the corresponding output of the switching device ( 3 ) and via which the modulator ( 10 ) is put out of operation when the transmitter part ( 1 ) is blocked by the gate ( 27 ) anyway. Correspondingly, the demodulator ( 14 ) has an "inhibit" input ( 14 I), which is also connected to an output of the switching device ( 3 ) and via which the demodulator ( 14 ) is deactivated when it is not required can. The modulator ( 10 ) and demodulator ( 14 ) therefore only take up power when they are actually needed.

Due to these energy saving measures, the Telephones according to the invention in battery operation up to 24 Hours with normal use and 8 hours with continuous use be used.

Claims (18)

1. Optical fiber telephone set with at least two identically constructed, each serving as a transmitter and receiver, can be connected on both sides to an optical fiber optical fiber telephone apparatus, each with a modulator ( 10 ) and a demodulator ( 14 ) and with integrated and / or connectable accumulators Provision of a required operating voltage, characterized in that the telephone sets each have an automatic switchover device ( 3 ) which, depending on the first incoming voice signal of the respective own voice recording device ( 4 ) of the telephone set or via the optical fiber ( 5 , 6 ) received signal from another telephone set , in a transmission operating state in which the own transmitter part ( 1 ) is activated and the receiver part ( 2 ) is blocked, or in a receiver operating state in which the receiver part ( 2 ) is activated and the transmitter part ( 1 ) is blocked. 2. Optical fiber telephone set according to claim 1, characterized in that the telephones each have a speech circuit ( 7 ) for generating a switching signal for the switching device ( 3 ) and / or for activating the transmitter part ( 1 ), which by the voice signals each own voice recording device ( 4 ) is controlled. 3. Optical fiber telephone set according to claim 1 or 2, characterized in that the telephones each have a receiving circuit ( 13 ) for generating a switching signal for the switching device ( 3 ) and / or for activating the receiver part ( 2 ), which by at a fiber optic input ( 20 , 21 ) received signal is controlled. 4. fiber optic telephone set according to one of claims 1 to 3, characterized in that in front of the speech signal input of the speech circuit ( 7 ) or in the speech circuit ( 7 ) integrated a discriminator element ( 9 ) is arranged for setting a threshold value, when it is exceeded the switching signal for the switching device ( 3 ) and / or for activating the transmitter part ( 1 ) is generated by the voice signal. 5. fiber optic telephone set according to one of claims 1 to 4, characterized in that the speech circuit ( 7 ) has a time delay element ( 8 ) which, beyond the end of a voice signal coming from the voice recording device ( 4 ), a defined period of time a switching signal generated for the switching device ( 3 ) and / or for the activation of the transmitting part ( 1 ). 6. Optical fiber telephone set according to one of claims 1 to 5, characterized in that the speech circuit ( 7 ) a button ( 22 ) or switch for generating the switching signal for the switching device ( 3 ) and / or for activating the transmitter part ( 1 ) having. 7. fiber optic telephone set according to one or more of the preceding claims, characterized in that the telephones each have at least one indicator light ( 18 ) for displaying the respective operating state. 8. Optical fiber telephone set according to one or more of the preceding claims, characterized in that the telephones each have two optical fiber connections ( 20 , 21 ), each serving as an optical fiber signal input and as an optical fiber signal output Transmit / receive diode (ping-pong diode) ( 15 , 16 ), one connection being designed as a single-mode optical waveguide connection ( 20 ) and the other as a gradient index optical waveguide connection ( 21 ), and that Telephones have a switch for switching between the two connections ( 20 , 21 ). 9. fiber optic telephone set according to one or more of the preceding claims, characterized in that the telephones each have a headphone ( 12 ) and a tone generator ( 11 G) with connected loudspeaker ( 11 ) for generating a ringing tone, and that before Inputs of the tone generator ( 11 G) and the headphones ( 12 ) a double switch ( 19 ) is arranged, with which either a switching signal from the switching device ( 3 ) to the tone generator input (ringer operation) or the received and demodulated signal can be switched to the headphone input (headphone mode). 10. Optical fiber telephone set according to claim 9, characterized in that the two-way switch ( 19 ) is connected to a headphone socket ( 12 a) that when the headphones ( 12 ) are plugged in automatically the connection between the switching device ( 3 ) and the tone generator ( 11 G) interrupted and the received and demodulated signal is switched to the headphones ( 12 ). 11. Optical fiber telephone set according to one or more of the preceding claims, characterized in that the receiving part ( 2 ) has a controllable amplifier stage ( 23 ) for the received signal. 12. Optical fiber telephone set according to one or more of the preceding claims, characterized in that the modulator ( 10 ) has a blockade or enable input ( 10 I) ("inhibit" input), which with the output of the speech circuit ( 7th ) or is connected to an output of the switching device ( 3 ) and via which the modulator ( 10 ) can be deactivated. 13. Optical fiber telephone set according to one or more of the preceding claims, characterized in that the demodulator ( 14 ) has a blockade or enable input ( 14 I) ("inhibit" input), which with the output of the receiving circuit ( 13th ) or is connected to an output of the switching device ( 3 ) and via which the demodulator ( 14 ) can be deactivated. 14. Optical fiber telephone set according to one or more of the preceding claims, characterized in that the signal sampling frequency of the demodulator ( 14 ) is a multiple of the transmission carrier frequencies of the modulator ( 10 ). 15. Optical fiber telephone set according to one or more of the preceding claims, characterized in that the demodulator ( 14 ) has a circuit for searching for a multiple of a possible carrier frequency to be received and for subsequently stabilizing the demodulator ( 14 ) on the frequency found ( Phased lock loop circuit). 16. Optical fiber telephone set according to one or more of the preceding claims, characterized in that the telephones are each integrated together with their accumulator in a housing ( 25 ), which connection sockets ( 20 A, 21 A) for the corresponding optical fiber cables ( 5 , 6 ), a connection socket ( 25 ) for an accumulator charger, a two-color light-emitting diode ( 18 ) for displaying the operating state, a switch ( 17 ) for switching between the two optical fiber connections ( 20 , 21 ), a switch ( 19 ) between ringer operation and headphone operation, a connection socket ( 12 A) for a headphone-microphone unit, a call button ( 22 ), a threshold controller ( 9 R) for setting the speech and signal threshold for the speech circuit ( 7 ) of the transmitter part ( 1 ) and a volume control ( 23 R) for controlling the amplifier stage ( 23 ) of the receiving part ( 2 ). 17. Optical fiber telephone set according to one or more of the preceding claims, characterized in that at least one connection element ( 2 G) for fastening the apparatus to a carrying strap or to a belt is arranged on the housing of the telephone sets. 18. Optical fiber telephone set according to one or more of the preceding claims, characterized in that the operating voltage supply line is guided through the connection socket ( 12 A) for the headphone-microphone unit and is interrupted there and the two open ends of the supply line as contacts in the connection socket ( 12 A), and that the corresponding mating contacts of the associated connector of the headphone-microphone unit are connected to one another to form a short-circuit connector.