SU44587A1 - Method of multiple radiotelephony - Google Patents

Description

In the proposed method of multiple radiotelephony at several modulating frequencies, using a small extension device, you can turn any radiotelephone transmitter into a two- or three-fold transmitter, i.e., a transmitter serving simultaneously two or three communication lines, which are completely self-contained conversations.

In FIG. 1 shows a circuit diagram in which the proposed method is implemented for the case of double telephony; FIG. 2 and 3, respectively, schemes for receiving the first and second calls; FIG. 4- corresponding frequency spectrum diagrams.

The principle of the proposed method is that with the help of a modulator scheme it is necessary for. The talk frequency band from 150 to 3000 Hz is converted to a higher frequency band, approximately from 6150 to 9000 Hz. Thus obtained e. ds, corresponding to the specified band of sound frequencies, is supplied in series with e. d. from another microphone to the transmitter modulator stage.

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The spectrum of frequencies received by such a transmitter is shown in FIG. 4, where / is the carrier frequency, the A-side bands corresponding to normal conversation and the B-side bands corresponding to the converted audio frequencies of the second conversation. A receiver designed to receive the first conversation (L band) is a normal receiver, equipped in its low-frequency part with a filter that does not pass frequencies above 3000 Hz.

A receiver designed to receive a second conversation of the B band should be broadband, ensuring reception of the entire 18000 Hz band in this example (other options will be indicated below). In its low-frequency part, the receiver is supplied with a filter that transmits sound frequencies from BOOO to 9000 Hz and a modulator device to reverse these frequencies into the natural conversational band (it is even easier to receive a second conversation with a narrowband receiver, which perceives only one of the sidebands With the help of the local oscillator, you can restore the filtered carrier frequency in such a way that you can immediately get a natural conversation on the receiver's phone ( t tune the local oscillator when receiving the upper band B at the frequency / X 3000, where / is the carrier frequency of the transmitter).

On fi1. 1 schematically shows a transmitter adapted for two-way radiotelephony. Here G is the master oscillator, MU powerful amplifier, also modulated cascade, MI first microphone, M second microphone, P converter (according to the balanced modulator circuit), which turns the sound frequencies in the range from 6000 to 9000 Hz (conversion, as will be described below, it is rational to conduct together with the inversion, i.e., converting the low sound frequencies of the spoken range to the higher frequencies of the new range and vice versa), the H-local oscillator of the audio frequency, which is used to convert frequencies, the F-band filter, Frequencies in affairs from 6000 to 9000 Hz.

FIG. 2 shows a receiver diagram for receiving a first call. The only characteristic feature of the receiver is the high frequency filter Φ, which absorbs all frequencies above 3000 Hz and thus excludes interference with the second conversation.

FIG. 3 schematically shows a device for receiving a second conversation. Reception is carried out using a narrowband receiver tuned to the extreme side frequency (for example, the upper one). The local oscillator GET is used to restore the carrier frequency, and the frequency of this local oscillator is chosen such that in the telephone T of the receiver, undistorted conversational frequencies are directly obtained. In the example described, since the frequencies in band B (Fig. 4) are inverse, the local oscillator frequency should be taken above the upper frequency of the spectrum.

The approximate position of the local heterodyne frequency is shown by the dotted straight / 1 in FIG. 4. Here, the difference between the frequency of band A and the carrier frequency / should be equal to the difference between the local heterodyne frequency / and the higher frequency of band B. Filter F is designed to reduce interference with the first conversation.

The advantage of the proposed method of multiple radiotelephony is the possibility of its use on most existing radio telephone transmitters with minimal changes in the low-frequency part of the transmitter.

The subject matter of the invention.

Claims (2)

1. Method of multiple radiotelephony at several modulating frequencies. Wherein, one or several converted conversational bands from the second and following microphones are supplied to the modulator cascade of the transmitter in series with the audio frequency voltage from the first microphone, so that these bands do not overlap, and the first conversation a receiver tuned to the frequency band corresponding to this conversation, and the reception of the second and subsequent conversations is performed using narrowband receivers tuned to one corresponding sideband; the reverse conversion of these frequencies to conversational ones is carried out by restoring the desired carrier frequency at the receiving point. 2. A variation of the method according to claim 1, characterized in that the reception of the second and subsequent conversations is carried out using broadband receivers equipped with filters for selecting the desired band and converters for reversely reversing the received frequencies into the conversational band. - / v,: ji ", Ar I FIG.