FI57503B - TALSTYRD KOPPLINGSANORDNING - Google Patents

Description

ESFH [B] (11) MONTH ».PUBLICATION ς ο ς n ..

jWA LJ '} UTLÄGGN I NGSSKRIFT 3 * O U ύ C (45) Fct'r.ttl vr ".:;' tty II 03 1 <* · Γ0 ^ τ ^ (51) Kv.ik? /int.ci.3 H 04 M 1/64 ENGLISH —FI N LAN D (21) P * t * nttlh * k * mui - PatMtaiNttknlnf 2690/71 (22) Haktmltpllvl - AmBknlngtdtg 27-09-71 (23) Alkuptlv * - Giltigh «tsd« g 27.09-71 (41) Tullut | ulklMk «l - Blivlt offmtllg 08.07.72

PstMtti. and registrars (44) NihUvIktlpanon j. ullutoun date. -

Patent and registration authorities AraBian utltgd ech utl.akrlftan pubiland 30.04.80 (32) (33) (31) Requested atuolkaut— Begird prlorltat 07 01.71 08.06.71 Federal Republic of Germany-Förbunds-republiken Tyskland (DE) P 2100522.1 Totken (71) Compur-Electronic Gesellschaft mit beschränkter Haftung,

Steinerstrasse 15, 8000 Munchen 70, Federal Republic of Germany-Förbundsrepubliken Tyskland (DE) (72) Ernst Dumler, Munchen, Paul Fahlenberg, Baierbrunn bei Munchen,

Federal Republic of Germany-Förbundsrepubliken Tyskland (DE) (7 ^) Oy Kolster Ab (5 ^ +) Voice-controlled switching device - Talstyrd kopplingsanordning

The invention relates to a speech-controlled switching device for storage devices, in particular telephone call answering devices, which device distinguishes between speech frequencies and certain signal frequencies, e.g. frequencies of charge signals, and is provided with frequency detection means with discriminating and rectifying means.

As is known, there may be difficulties in voice-controlled switching devices, which can be used, for example, in telephone call answering machines, due to the presence of signal frequencies in the speech frequency band in addition to the speech frequencies. Thus, e.g. in telephone answering machines, e.g. signal frequencies can have the same effect as the speech frequency, so that the presence of a busy signal can mask the transmitted information and possibly the entire data allocation capacity becomes occupied by such unusable information.

It is previously known from German Offenlegungsschrift 1,180,709 to connect a signal from a storage device to the input of a single-position multivibrator, followed by a derivative circuit, a rectifier and a second single-position multivibrator. In this element, a voltage proportional to the frequency of the incoming signal is generated. Depending on whether this voltage is above or below a certain threshold, the corresponding switch will be controlled or not. However, despite the high implementation costs of 2 57503, it is not always possible to achieve a satisfactory solution to the problems encountered with such a speech-controlled switching device. This is due, firstly, to the fact that reaching and exceeding the operating threshold at a higher frequency takes place only rather slowly, so that the switching criterion o is not always completely unambiguous. The main disadvantage of this known connection is that it is not possible to suppress the detrimental effects based on the signal frequencies at all if these signal frequencies are located in the central or upper speech frequency range.

According to the invention, which relates to a speech-controlled switching device of the type mentioned at the outset, the difficulties and disadvantages of the known device are avoided so that said frequency detecting means form a discriminator a DC link is connected to the output side, followed by a reference stage having a level threshold which, in the absence of demodulated signal frequencies having a level below the threshold, constitutes an output criterion other than the level of demodulated speech frequencies above the threshold. depending on whether speech or signal frequencies are present, allows the recording device (A) to continue to operate or not. Regardless of whether the signal frequencies are located in the central, upper or lower range of the transmitted speech frequency band, this reference circuit can certainly be used to distinguish between speech frequencies and signal frequencies. Since the signal frequencies, e.g. in connection with the busy signal, operate at a constant frequency, there is no frequency modulation, so there is no output voltage at the discriminator output, or only a relatively small output voltage compared to the speech frequencies, while , which, after demodulation in a discriminator, provides a high output voltage suitable for use as a difference criterion.

According to a preferred embodiment of the invention, the switching is such that the reference stage has two switching stages in alternating and in the inhibit state, which are connected so that the switching device can only be actuated when both switching stages are conducting simultaneously, each switching stage comprising a transistor and the time constants of the transistors have different values, so that only the pulses occurring at very small intervals as a result of the speech frequencies can produce a simultaneous conducting state of both switching stages.

3 57503

Some embodiments of the invention will now be described with reference to the accompanying drawings.

Figures 1 and 2 show two different block circuit diagrams of the total circuit.

Figure 3 shows a circuit diagram of the reference circuit.

Figures 4 and 5 show impulse diagrams of this reference circuit.

The first element of the control circuit according to Fig. 1 is an amplitude limiter 4 »which causes the speech signals S and the reserved signal £ to have the same amplitude. The output of the amplitude limiter 4 has the shape indicated by the symbol SL for the speech signal, while the spare symbols have the shape indicated by the symbol BL. It turns out »that the frequency of the speech signals SL is subject to time-dependent changes» so that it is a kind of frequency modulation. Instead, limited reserved characters are not subject to any time-dependent frequency changes »so they form only a single frequency.

After the amplitude equalizer 4, a discriminator 3 is connected, which converts the frequency-modulated speech signals SL into amplitude modulation, while the reserve signals BL, due to their missing frequency variation, do not cause any output voltage or cause only a very small output voltage. After passing through the rectifier stage and the separating element 6 in the discriminator terminal 3, the speech signals have a shape marked SL 'and are characterized by a large variation in amplitude and relatively large voltage peaks. Instead, the reserve characters have, after the separator 6, either a shape marked BL '(dashed reserve sign) or a shape BL ”(the reserved sign is a continuous sound). With the exception of the initial oscillation events, the signals BL * and BL "have no amplitude modulation, or their amplitude modulation is quite small, so a level threshold must be applied to the reference stage 8 connected after the amplifier 7 so that the level threshold is Short voltage peaks, which may occur e.g. at the beginning of a busy signal, can be prevented from interfering by using a deceleration circuit which does not allow any signal that suffers the operation of the recording device in the event that the voltage threshold of reference 8 is only briefly exceeded.

Depending on whether the suitably adjustable level threshold in reference level 8 is exceeded (speech signal) or undershot (busy signal), the switching device 9 activates the recording device when a speech signal occurs, while the recording device becomes switched off and pre-trained when a busy signal occurs.

The output signal of the limiter 4 becomes, in the region of the discriminator 5 with respect to its frequency-modulated part, converted into a time-dependent variable amplitude function as a function of time by the frequency-dependent resistor 4 57503, the diodes D4 are rectified and fed to a leveling capacitor C. The transverse branch of capacitor C9 has an ohmic resistor RIO. Through the control resistor P4, the signal demodulated in the isolating element 6 enters the switching capacitor C1.

The mode of operation of the circuit according to Figure 1, the function of which is to provide a judging criterion according to the invention, can be explained as follows:

When speech signals enter the device, the time-varying frequency of these signals develops a variable voltage at the terminals of the capacitor C9 and thus at the resistor RIO, which is rectified by the diode D4 and causes the CIO to at via the switching capacitor C1 to the input of the amplifier 7 and the threshold switch 6.

If, on the other hand, separate signal frequencies with a constant frequency occur, e.g. in the form of a reserved character, then a constant voltage is generated at the terminals of the capacitor C9 over time, so that after rectification in the diode 4 a constant voltage also acts at the capacitors CIO. Under the influence of the connected switching capacitor C1l, practically no input voltage is connected to the threshold switch 8, because no AC voltage is present, so this switch 6 does not receive control. In this case, there is no voltage, or there is a voltage that is too low in relation to the operating threshold, so that no voltage is present in the switching device 9. The criterion formed by the missing signal is interpreted as meaning that the switching device then disconnects the recording device, because there is no speech signal but only a busy signal.

When a symmetric phase discriminator is used, the output voltage after demodulation is set to zero in connection with the busy signal when this frequency of the busy signal is switched to a constant suppressed interference frequency in the middle of the discriminator characteristic curve. Furthermore, in many cases it may be expedient to branch, after demodulation and rectification, a second transmission path with an integrating element 10, suitably an RC element, and an amplifier 11 and a relay 12. In this case it is suitable to connect the output side of this second transmission path to a switching device 9 connected after reference stage 8. »And that this switching device can also be controlled by the signals of the second transmission path, regardless of the first transmission path. This provides an even better chance of eliminating interference.

The connection according to Figure 2 shows another embodiment constructed in a similar manner to the former embodiment. This new connection thus needs only a brief explanation.

5 57503

The first element of the circuit according to Fig. 2 is an amplitude limiter 4 «which causes the speech signals S and the truncated busy signal B to have the same amplitude. At the output of the amplitude limiter, the shape of the speech signals is labeled SL and the shape of the busy signal is labeled BL. It turns out that the frequency of the speech signals SL varies with time, so that there is a kind of frequency modulation. The frequency of the reserved signal, on the other hand, does not vary with time, so these signals form a single frequency.

After the amplitude limiter 4, a discriminator 5 »is connected which converts the frequency modulated speech signals SL into amplitude modulation, while the reserve signals BL due to their missing frequency variation do not give any output voltage or give only a relatively small output voltage. After passing through the rectifier stage in the discriminator 5 and the separator 6, the speech signal has a shape marked with the symbol SL * in Fig. 5 and is characterized by a strong variation in amplitude and relatively large voltage peaks. Instead, the reserve characters after the separating member 6 have the shape indicated by the symbol BL * in Fig. 4. With the exception of the voltage peaks at the beginning and end of the signals BL *, these signals have virtually no amplitude modulation or only a relatively small amplitude modulation.

The output signal of the limiter 4 becomes a time-varying amplitude function with respect to its frequency-modulated portion in the region of the discriminator 5 under the influence of a frequency-dependent resistor capacitor C9, and this amplitude function is rectified in a diode D4, after which it is passed to a rectifier capacitor C10. The transverse branch downstream of capacitor C9 has an ohmic resistor RIO. The demodulated signal enters the switching capacitor C1 through the control resistor P4 in the isolating element 6.

According to Fig. 3, the reference circuit Θ has switching stages formed by two transistors T4 and T9, each having different large capacitors C14 / C16 and C12, which together with the base emitter resistor of the corresponding transistor form different large time constants of both switching stages. Diodes D5 and D6 are connected for rectification and voltage doubling. Resistors R18, R19 and transistor T4 determine the discharge time of capacitor C16. A switching device 9 * is connected to the terminals ΚΙ, K2 of the reference circuit 8, which controls the recording device A, e.g. a tape recorder. Before the reference circuit 8, the transistor T9 forming the amplifier 7 is still drawn in Fig. 9.

The circuit according to Figures 2 and 3 works as follows: when speech signals enter the device, a variable voltage develops in the terminals of capacitor C9 and thus in resistor RIO due to the time-varying frequency of n ^ A »\ signals, which diode D4 rectifies and causes capacitor CIO to charge rapidly in succession and discharge. Depending on the sensitivity set by the control resistor P4, a correspondingly varying part of this voltage becomes the input of the transistor T3 of the amplifier 7 »vast, via the switching capacitor C11.

Instead, when the signal frequencies of the busy signal enter the instrument, a positive pulse is generated at the output of the amplifier transistor T3 at the beginning of the busy signal and a negative pulse at the end of the busy signal * These pulses are caused by the above-mentioned voltage peaks and are about 20 ms long. When the length of the busy signal is 250 ms and the length of the associated pause is likewise 230 ms, the impulse diagram shown in Fig. 4 is obtained. According to this, there are positive pulses every 500 ms and, when transferred in 250 ms, also negative pulses every 500 as at the input of the amplifier 7 », the transistor T3, which pulses, respectively, are fed to the after-switched reference circuit 8.

The positive pulse entering the reference circuit 8 shown in Fig. 3 results in the charging of the capacitor C16, whereby when the switching threshold is reached, the transistor T4 becomes conductive for a time of 50-500 ms. This conductive state of the transistor T4 is shown in broken lines in the diagram of Fig. 4. Thereafter, the next negative pulse instead causes the charge of the capacitor C12 to change, whereby when the switching threshold is reached, the transistor T5 becomes conductive for a time of 10-20 ms (shown by the dotted lines in Fig. 4).

However, the circuit 9 connected to the terminals K1 and K2 of the reference circuit 8 for controlling the recording object A, i.e. for starting, becomes controlled only when both stages T4 and T3 of the reference circuit 8 are simultaneously conductive. This is not the case - as is clear from Fig. 4 - when the signal frequencies of the busy signal occur, because the conductive states of the transistors T4 and T5 occur successively at a time interval from each other.

However, when the speech signals enter the instrument, the positive and negative pulses occur quite rapidly in succession in time, the distance between them being only about 10-20 ms. as a result, even a very short time after the start of the speech frequency, the simultaneous conducting state of both transistors T4 and T5 of the reference circuit 8 is reached (Fig. 5), so that the circuit 9 becomes controlled. The recording device A thus starts up.

It should also be mentioned that the invention is not limited exclusively to the described connection examples of the reference circuit 8, as there are other possibilities to form these switching stages. Thus, the time constants of both switching stages T4, T5 could also be considered equal if the pulse lengths of both stages are sufficiently large.

Claims (3)

7 57503 A voice-controlled switching device for recording devices, in particular telephone answering devices, which device distinguishes between speech frequencies on the one hand and certain signal frequencies on the other hand, e.g. frequencies of charge signals, and is provided with frequency detecting means having discriminating and rectifying means. the detecting means do not form a discriminator (5) which converts the frequency modulation into amplitude modulation and which on its input side is connected to an amplitude limiter (U) having an output voltage equal to speech frequencies and signal frequencies, the output side of the discriminator being connected to a DC separation stage (6) having a level threshold which, in the presence of demodulated signal frequencies having a level below the threshold, constitutes an output criterion other than in the presence of demodulated speech frequencies having a level above the threshold, which reference level controls the switching device (9) such that the switching device allow the storage medium (A) to continue to operate or not. Switching device according to claim 1, characterized in that the discriminator (5) is a first capacitor (C9) in the longitudinal branch connected to the input, followed by an ohmic resistor (R10) in the first transverse branch, a rectifier in said longitudinal branch being connected at the junction of this resistor and the first capacitor (EU), followed by a second capacitor (C10) acting as a smoothing capacitor in the second transverse branch, from which the demodulated signal is taken. Switching device according to claim 1 or 2, characterized in that said reference stage (8) has two switching stages (TU *, T5) which are alternately conductive and in the inhibited state, which are connected so that the switching device (9) can only be actuated when both switching stages conduct simultaneously, each stage comprising a transistor (TU ', T5) and the time constants of these transistors having different values, so that only pulses occurring at very small intervals as a result of speech frequencies can produce a simultaneous conducting state of both switching stages.