DE1804267C2 - Voice-protected, frequency-selective signal receiver for telecommunication systems, especially telephone systems - Google Patents

Description

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In Fcmmclde, in particular telephony systems, when a useful signal from d _Cl , _{Ab occurs} , criteria are often transmitted in the form of signals in at least three consecutive NuII-Sprachfrcnzbcreich. This includes going through the respective received character, for example tone-frequency calling, dialing and control formed krileries, compares them with one another and gives way to them. If these characters are transmitted to the character receiver as a characteristic without the accompanying characters 5, this blocking of the character output is evaluated, during the entire transmission time to the line, the transfer is switched on and, in addition to real characters, there is also an indication that a real one Characters are only exposed to the signal frequency tone frequency which can be caused by noise voltage, a gene simulated by speech and noises from the further transmission path and, in addition to the signal frequency, other frequency components from the tone frequency spectrum can result from the transmission path of the received character. Such does not hold up to the transmitted and that with a single frequency signal the half-character belonging frequencies can also contain character period duration of positive and negative half-wave,! The criteria formed by the subsequent zero crossings that cause them triggered sound devices must match. However, they are next to the can. . In order to avoid such errors in the character transmission, as is normally the case with simulated characters in transmission, so-called voice protection circuits are known, so these criteria can no longer be covered. In principle, these work in such a way that ao agree. The occurrence of this state is when the received character is first broken down by filters into a criterion for the suppression of a signal transmission, useful component and an interference component. This or the blocking of the evaluation device is evaluated, the two components are rectified separately. the significant advantage that no statement with a defined response threshold is supplied to an evaluation circuit as the generation of the speech protection criterion. Is it included as to whether the signal frequency in the band interference component is so large that the difference between the useful center or the band limits lies. This means, and interference components below the response threshold that the speech protection factor lies within the total, the evaluation of such a signal, the useful signal channel width is kept constant, is blocked. The difference between the useful level and 30 can be. In all known methods, it is low in the middle of the band causing the blocking of the signaling, and very high at the band limits; the level is also referred to as the speech protection factor. A link between the voice protection factor and band width is not given in the inventive character working slso with a check of the foreign signal frequency components, since the frequency components foreign to the signal at the 35 frequency components upstream of the receiver are not checked by filter circuits . If the signal is undisturbed, the. As a result, the bandwidth is independent of the absolute bandwidth of a signal channel through the speech protection factor and, if it is changed, the frequency range can be determined in which the voltage can no longer be influenced, thus avoiding the disadvantages described above for the useful component, the value of the response threshold. Since on exceeds. However, this means that there is no interference evaluation between the control circuits, the link between the speech protection factor and the bandwidth, the filter coils can be selected to be small and simple. Even a small interfering component can be built up. It is also possible to use it to narrow the bandwidth. Useful signals, which in their ingeniously provided test circuit are at a frequency position at the channel limits, cannot be voice-protected receivers, which are then no longer evaluated when accompanied, so that a character method is used to suppress speech. Retrofitting an increase in the protected receiver in a speech protection factor results in a narrowing of the bandwidth of the band transmission method without accompanying characters. In the same way run low bar is. Cumbersome setting work, as was the case with the interfering components for an evaluation delay on known speech protection circuits, requires real signals. 50 Hch, voice protection circuits are no longer necessary for the receiver in the character acquaintance according to the invention.

according to the disadvantage that with an increase in the speech protection possible with the test circuit

Language protection factor; » a narrowing of the bandwidth or the control of the evaluation device is shown in

takes place because the speech protection factor and bandwidth are simple in a further embodiment of the invention

are directly linked to each other. 55 carried out in such a way that the character output in an

The object of the invention consists in such a known manner only after a

To avoid disadvantages and to do this, a frequency protection time is effective. The expiration of the protection period

to create a selective character receiver in which the

Setting of the speech protection factor independent of the circuit interrupted and takes place after the connection

the bandwidth can be made. 60 the blocking criterion disappear again. This is

For a voice-protected frequency-selective ensures that for the duration of the blocking criterion

Character receiver for telecommunication, in particular or until the protection time has expired

Telephone systems with one at its entrance - no output of the pending stönings-afflicted

seen limiter circuit, via which the received signal can take place.

Character of a filter and useful signal detector circuit 65 According to a further embodiment of the invention

the criteria to be compared in the

The invention solves this problem by creating test circuits

that a test circuit is provided for speech protection from the intervals of the zero crossings from voltages

which are used to form the difference- separation of his two " ."", ..

,""'will. The result is the difference between the lock UB and BA ™ & * g ^^ z ^. so there is a single-frequency sign without djbe, mn «n JÜ ^ g ^ SÄebt. so

SAB a special embodiment 5 the separation of these two ^. ^^^ Srden

· Testing of the test circuit / for the formation of the band-stop filters BJ and ^BA · »^^ _{and L} ß to-

^d - ^Cr ndcr / u comparative criteria one of each of a B ^^ Ä ginning into a

2, "terschaltung derived Rcchteck panniing-out, the respective ™ ^ P ^ _u ^s T _e ^fc _umfo rmt

^Be f _t LrfSSuct? de »each received character square wave voltage ^k ^ fX ^ fSe KanalfiUer-

^m jührt s "it is possible from this square io This rectangular voltage reach ^ _1UE

fed, »ι b polarity d» arrangements F / l and FB, which nici u b

^{$ pre} fm "ißiiE in such a way that the test circuit at Ab-> ₅ upper channel group Λ and, n the un

^2W ·. "Nf de T s vcrhähnässes this pulse sequence group B ewei te a jign ^ etekwr on, un _g

SS ft £ Sperrsigna, for the character output ^ SS ^^^^ OD ^ O

the invention spracngc:> utiui <.i.wi «.." ..

for a two group code. ° _{on the} character receiver geiangcu _fc u ^^.

In Fig. 1 three voltage curves VE, UB, the third input of the OR gate GG is shown in FIG. 1 and VP over time. The voltage UE is a possible blocking device which is supplied to a character receiver input on a criterion to be described. However, since this does not exempt the interference-free character required for the voltage of a single-frequency next-required interference-free character. At the input limiter of the sensor, a square wave voltage UB can then be triggered with the triggering caused by this real character catcher. are shown. Since the voltage UE has a sinusoidal shape, which is the criterion for the start of a protection time, these square-wave pulses and the negative ones that are generated with the timing circuit ZS are. After the protection time has elapsed, the status »0« appears for the same length of time. If this pulse train in accordance with the output of said timing circuit and causes according to the invention in a test circuit to be Tactile negation in negator N 3 an opening that relationship checked, it is no deviation from 40 two output gate AGl to AG 8, which at its value 1: 1 determined and the Avsgangsspannung uP respectively supplies second control input of one of the test circuit Nutzder no blocking criterion for signal outputs to Al / 14 or AS to AS of character output. are controlled. The signal feedback to the AND

In Fig. 2, an input signal voltage VE is shown gate GS causes that after the expiry of the protection time, which contains a signal frequency and an interference frequency 45, a real character regardless of the following. Both voltage gradients are shown with dashed lines. Disturbances for the character output are maintained. The drawn out cumulative curve represents is.

the actual voltage curve at the receiver - in the following it will be the one in the event of a fault

input that deviates from the pure sinusoidal shape of one of the received characters due to additional signal-frequency characters. The additional generation of an emerging voltage VB at the limited to so foreign tone frequencies consists accordingly of the blocking criterion described for the character output. Square pulses of different lengths. At the time of the detection of a useful signal the duty cycle is checked in the test circuit provided in accordance with the test circuit provided for this purpose in the receiving part ZE , the already described active deviation from the value ί : 1 occurs in each case with a blocking pulse for switching the control output SP. At the same time, the characters are output, as can be seen from the voltage, the connection of the test circuits PA and PS run VP . Also via the OR gate G3

In F ί g. 3 is tUs principle picture of one from which the hand of FIG. Manner described 2 by receiving part ZE, the Zeichenprüfteil ZP and a simulated mark an inhibiting signal for the character output part ZA existing V / ählktan- 60 character output in one or both test circuits signal receiver for telephone installations shown, PA and PB generated so passes this via the for is designed as a two-group code. In the OR gate Gi to the AND gate G 5. This case involves a 2 · 1-out-of-4 code before and during the expiry of the protection time. First of all, the signal state "1" is to be received for this receiver at its other control, the receipt of an interference-free character and will be received when a lock message occurs. signals open. Appears through the OR gate G 6, the character received is first fed to a äsr at the input timing circuit ZS the state "1", input amplifier V, after which it causes the resetting of the timer circuit ZS

WU 7 OJL I / A. I ■

or their start prevented. After the disappearance of the blocking signal, the protection time can start again, if this is the case with a pending one Character the status »0« at the input of the line switching is produced.

Claims (6)

Patent claims: l.Sprachgeschützterfrequenzselekitver ^ ichenempfänger for telecommunication, in particular telecommunication systems using a limiter circuit provided at its input, via which the received characters are fed to a filter and useful signal detector circuit for controlling a character checking device, characterized in that a checking circuit (PA, PB ) is provided which, when a useful signal occurs, compares criteria formed from the intervals of at least three consecutive zero crossings of the respective received character and μ evaluates their mutual difference as a blocking criterion for blocking the character output (ZA). 2. Zeichttiempfänger according to claim 1, characterized characterized that the character output in a manner known per se only after the Expiry of a protection time becomes effective, which when a blocking criterion occurs in the test circuit (PA, PB) is interrupted and takes place again after the blocking criterion disappears. · 3. Character receiver according to claim 1 or 2, characterized in that the criteria to be compared with one another are formed in the test circuit (PA, PB) .
" 4. character receiver according to claim 3, characterized in that the test circuit. (PA, PB) to form the criteria to be compared with one another, a square-wave voltage (UB) derived from the limiter circuit (LA, LB) and having the frequency of the respective received character is supplied. 5. character receiver according to claim 4, characterized in that the test circuit (PA, PB) from the square wave voltage (VB) evaluates the 'half-waves of one polarity of the respective received character pulses and the half-waves of the other polarity corresponding pauses. 6. Character receiver according to one of the preceding claims, characterized in that the test circuit (PA, PB) in the event of a deviation in the duty cycle caused by the square-wave voltage. (UB ) generated pulse sequence with a value of 1: 1, a blocking signal (UP) for the character output (ZA) is generated. 1 sheet of drawings