SE437318B - CLUTCH DEVICE FOR A REMOTE COMMUNICATION SYSTEM - Google Patents

Description

BNSDOCID; 7812929-3 2 achieved that the loudspeaker is disconnected during the speech pauses, The sounds thus do not become audible. During the speech, on the other hand, 10 15 '20 30 35 the voice as well as the disturbances are audible, however the amplitude of the amplitudes is significantly less than the amplitude of the speech frequency.

Preferably, a filter is inserted before the speaker, which separates' the pilot signal from the speech frequency signals.A The invention is explained in more detail below with reference to the appended drawing, which shows a coupling device according to the invention.

Fig. 1a schematically shows a transmitter; Fig. 1b schematically shows a receiver; Fig. 2 illustrates the superposition of speech frequencies and interference without utilizing the present invention; and Fig. 3 shows a corresponding oscillogram using present invention.

The transmitter according to Fig. 1a consists of a microphone 1 and an amplifier. kare 2. the transmission distance then branches off, whereby a wire goes directly to a transmitter 5, while a second line contains a diode 3 and an oscillator 4, which generates a pilot frequency. The rectified speech frequencies are controlled oscillator 4 in such a way that the pilot frequency is generated only then speech frequencies occur. The transmitter 5 consists of a high frequency transmitters of a suitable type, in which they are picked up by the microphone 1 the speech frequencies and the pilot frequency generated by the oscillator 4 then superimposed with a high frequency radiated from an antenna 6.

The receiver according to Fig. 1b receives this high frequency via a antenna 9. A suitably designed receiver 10 emits them from the high frequency demodulated the frequencies via a filter 11 to. a transmission distance. This is divided into two branches, which each contains an amplifier 12 resp. 13 and a diode 14 resp. 15. Via the amplifier 13 and the diode 15 a current is influenced. iii / o and DDR cli fi lamïf BNSUOCID: 10 15 25 30 35 '7812929-3 3 switch 17 in such a way of the carrier frequency that it is only when the carrier frequency signal is applied. This corresponds to the in and known device, which disconnects a speaker for the time being there is no carrier frequency. Those of the amplifier 12 the amplified frequencies are applied via the diode 14 to a receiver 16, which is tuned to the pilot frequency. This pilot frequency affects via a diode 18 a switch 19, which thus only is closed when the pilot frequency signal is applied. At closed current switch 19 reaches the speech frequencies, including the pilot frequency, one filter 20, which filters out the pilot frequency, so that only speech- held occurs the speech frequency reaches the speaker 22 via the amplifier 21. I the breaks, during which the pilot frequency also disappears, switch 19 open, so no disturbing noise closed. in the speaker 22 although the switch 17 is still As shown in Fig. 2, appearing at the known speaker devices in addition to the speech frequencies 25 different interference frequencies 24, which can be heard in the loudspeaker in particular during the speech pauses 26 such as rustling and crackling sounds.

In Fig. 3 it is illustrated that by disconnecting the speaker by means of the switch 19 the interference frequencies in the speech are eliminated. pauses 27, and the interference signals thus appear only together with the speech frequencies 25 at a sufficient interference distance from the latter.

The different relays resp. the current emitters can consist of electrical magnetic relays, although preferably of electronic relays, or by an equivalent electronic coupling device.

The invention is not only applicable when the speech is transmitted by means of high frequency energy through the air, as shown in the embodiment, but can also be used when the transmitter and receiver are connected with each other by means of wires, for example telephone wires, i what disturbances may occur, e.g. from power lines, or in particular via a pipe network.

As a pilot frequency, for example, a frequency of 5000 Hz is suitable.

The filter 20 is really only required, if the pilot frequency is in the audible frequency range. /, »~ '

Claims (2)

BNSDOCID: 7812929-3 _t 4 P5? 'EFILLRILY 1. Coupling annexednxnq for a remote communication system with a transmitter unit (fig. 1a) and a receiver unit (fig. Lb). a carrier frequency signal to be transmitted is superimposed on a carrier frequency signal and a low-frequency pilot signal which triggers a switching process in the receiver unit, and in which high-frequency disturbances can occur in the transmission distance, which can be recognized by the transmitter unit (fig. la) contains an oscillator (4) generating the pilot signal, which is switched on by the speech frequency signals to be transmitted, and that the receiver unit (Fig. 1b) has a receiver (16) tuned to the pilot signal and a switch (19) controlled therefrom, which switches on a speaker (22) as long as the pilot signal is received by the receiver (16). 2. The switching device according to claim 1, characterized in that a filter (20) is inserted in front of the loudspeaker (22), which separates the pilot signal from the speech frequency signals.