DE2051683C3 - Passive amplitude limiter - Google Patents

Description

In Fig. 3, the output level P _{A is} plotted as a function of the input level P _E at approximately 1 kHz for a nominal level P _n.

F i g. 4 shows the emitted noise voltage U _a at the relative level - 2Np with a 25 Hz ringing voltage _{U R} on a two-wire line. The transistor limiter according to the invention initially shows a falling noise voltage U% above the limitation insert. The rise in the noise voltage U _a with a higher ringing voltage U _{R is} due to the fact that the upstream fork transmitter is already heavily overdriven at this voltage. In connection with the high-pass effect of the fork, this results in more and more zero crossings within a 25 Hz period, and the limiter accordingly emits more and more needle pulses per unit of time.

For this purpose 2 sheets of drawings

Claims (2)

1 2 two transistors of the same type are provided, the claims of which are: base-emitter paths connected anti-parallel at the input of a four-pole attenuation known per se 1. Passive amplitude limiter with two are and their collectors at the output of the damping-like transistors, dadurchgekenn- 5 fungivierpols each with the Langsghed of the damping that the base-emitter lines are connected to the four pole, at the input of which the input (El, E2) is one per se known damping base of the respective transistor is connected
fungsvierpols (D) are connected in antiparallel and advantageous is the use of the erfindungsgedaß the KoHektoren at the output (A1, A2) of the moderate amplitude limiter in outgoing four-attenuation four-pole (D) each with the longitudinal io wire lines in the low-frequency and service line element of the four-pole attenuation (D) ) are connected, end circuits of telephone systems, in particular whose input (£ 1, E2) the base of the respective carrier frequency, radio relay or pulse code transistor (Dl, D2) is connected to modulation multiplex systems. 2. Amplitude limiter according to claim 1, it is advantageous that in the known end, characterized by its use in disconnected 15 usually already an attenuator for existing four-wire lines in low-frequency level adjustment between two-wire and four-wire and Djenstleitungs-endcircuits from remote - line is provided, which can be included in the speech transmission systems according to the invention, in particular, the amplitude limiter,
gerfrequency. Directional radio or pulse code modules with the amplitude limiter according to the invention multiplex systems. 20 you get a circuit that is connected to the input of the Attenuation quadrupole acts like a diode limiter, but also during control of the base-emitter paths of the transistors of the output passage of the attenuator through the KoHectors 15 is attenuated. That means the output voltage becomes smaller as soon as the input voltage decreases The invention relates to a passive amplitude base-emitter threshold which transistors exceeds, limiter with two similar transistors. With very high sinusoidal input voltages In low-frequency or service line end switches, the output voltage only consists of very Telephone transmission systems are generally half-wave in 30 narrow pulses at the beginning and end of each sine in the outgoing four-wire line. Amplitude limiter is provided, which is based on an exemplary embodiment, the Two-wire line resulting voltage peaks, as the invention explained in more detail below. Call tension and crackling, to the permissible maxi- The F i g. 1 shows a passive according to the invention limit malvalues. This creates a downstream amplitude limiter with a quadrupole D attenuation tetes multiplex system, such as carrier frequency, rectilinear and two transistors 71 and 72. The inputs of the Radio or pulse code modulation system, before switching over are with El and E2, the outputs with A 1 burdens protected. The previously designated for this purpose and A 2 . Applied diode limiter or limiter amplifier The amplitude limiter according to the invention has the disadvantage that the output amplitude of 40 at the input El, E2 through the base-emitter paths at the beginning of the limitation use increases with increasing one of the two transistors 71 and 72 like a diode output voltage by several dB. The limiter, in which, however, in addition at every half-half, the limit insert must be far below the wave that the base-emitter threshold voltage of the control limit of the subsequent four-wire line exceeds. Transistors 71 and 72 are output. Another disadvantage lies in this that the output 45 of the attenuation quadrupole D is short-circuited. Dagangsspannung of the limiter is the more a by results at the output of Al, A 2 is a chip-square-wave voltage approaches, the larger the input voltage U _A extending over the time /, as shown in F i g. 2 voltage is. If one carries this tension over one is shown. Filters, for example a low-pass filter, then result in In FIG. 2 shows the curve α the limited prospect because of the delay time distortions at the filter output voltage U _A when the input EMF can only be output voltage peaks that are considerably above the limit input level c, c ' , limiter output voltage. At higher input voltages, such as at 25 Hz, this also applies to the one from the magazine "The Rufspannungen, the short circuit at the output Post Office Electrical Engineers'Journal", Vol. <S2, A1, A2 , so that one, as Part. 4, January 1970, pp. 213 to 217, known Be 55 curve b shows, at each zero crossing only limiters, in which the base-emitter paths of two receives a positive or negative pulse, the opposite of transistors in series switched so narrower, the greater the input voltage are arranged between the two-wire line, is. This means that the output amplitude U _A rend the interconnected KoHectors, on the one hand, no longer on per se from the limitation onwards and the interconnected bases, on the other hand, each increase to 60 and the output power is with increasing one supply voltage. The input voltage requirement drops significantly,
additional supply voltages means a Die F i g. Figures 3 and 4 show another disadvantage. Measurement results obtained comparison between the object of the invention is to specify a solution which avoids these disadvantages for an amplitude mode of action of a known diode limiter and the transistor limiter according to the invention. The diode limiter is shown in dashed lines and the limiter according to the invention is assigned a solid curve in a passive amplitude transistor limiter in that the limiter is assigned.