SU105390A1 - Device for dividing high-frequency communication channels - Google Patents

Description

A device is proposed for dividing the tonal frequency spectrum of a high frequency telephone channel, allowing two telephone conversations to be transmitted simultaneously on this channel.

A known device of this kind is used for a wide bandwidth high frequency channels, and effectively transmitting a width of at least 320 UHz to the width of the 15th-1th band. However, this known device is not used for dividing channels with a smaller bandwidth, since a reduction in the channel bandwidth leads to a sharp decrease in the quality of speech transmitted in an additional narrowband channel.

The distinctive features of the proposed device is that in order to obtain the possibility of deleping the most common high-frequency telephone communication channels with a minimum bandwidth of 2,300 Hz, there are provided

1) transmission on both narrow-band channels of the optimal bands of conversational frequencies 410-1650 Hz, ensured, their best intelligibility of speech transmitted in

narrowband channel width 1250 Hz;

2) the use of corrective, amplifiers with deep feedback and variable frequency gain characteristics, allows us to expand the effectively transmitted frequency bands of the high-frequency channel;

3) a change in the non-frequency frequencies of high-frequency equipment by an average of ± 200 Hz.

In order to improve the quality of telephone transmission over narrowband channels, the proposed device uses a device for expanding the range of conversational frequencies received over narrowband channels and correction circuits, allowing us to establish optimal frequency characteristics of residual attenuation in narrowband telephone paths, in accordance with the sensitivity characteristics of telephone sets. .

As a result, the proposed device allows the use of a minimum frequency band of a high-frequency communication channel 2300 Hz wide, formed by equipment with individual headers of frequencies, their frequencies, for

No. 105390

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it is necessary to change the carrier frequencies of the transmitter and receiver of the HW equipment by 200 Hz upwards - when transmitting the lower sideband, or downwards - when transmitting the upper sideband.

At the receiving station of the high-frequency channel (Fig. 1), the currents of both conversations are fed to the input of a KUpr correction amplifier. After the receive correction amplifier, the talk currents of the channels a and b are divided by the receive filters LK-1.7. The talk currents of the channel and after the throttle separating filter D, 7 are fed through the VU leveling extension cable to the input of the low-frequency amplifier Unch. The Unch ,, amplifier is designed to add transmission levels and to equalize the frequency response of an orthotelephonic amplifier for the microphone system.

The diagram and frequency characteristics of the Unch amplifier, as well as the average characteristic (R cp ortho-phone amplification of the microphone-telephone system are shown in Figures 4 and 5. Parallel to the input and output of the Unch amplifier, a high-frequency telephone transmission path is connected, consisting of two amplifiers Unch., and Unchd, frequency converters of the frequency converter and bandwidth of the PF-1,8-2,5 trigger filter.

The restoration path serves to artificially form the high frequency components of the telephone transmission over the frequency components received in the narrowband channel. The talk currents amplified in an Unch amplifier are fed to a frequency converter assembled according to a balanced modulator circuit on DGTs-8 crystalline semiconductor elements, in which a positive bias voltage from the DC source is applied through the midpoints of the transformers. The frequency converter circuit is shown in FIG. 6. At the output of the frequency converter

odd harmonic and combination components of conversational currents are formed. Using the PF-1.8-2.5 bandpass filter, the high-frequency components of the converted telephone transmission are allocated from the frequency converter output, occupying a frequency band of approximately 1800 to 2500 7 c. The circuit and frequency characteristic of attenuation of the PF-1.8-2.5 bandpass filter is shown in FIG. 7. Amplifier Unch. raises the level of these high-frequency components to the extent necessary to improve speech intelligibility and naturalness.

From the output of the amplifier, the amplified high-frequency components, together with the spoken currents received via the narrow-band channel, are fed through a differential system, touch-tone devices and a transit extender to a long-distance switch.

The frequency characteristics of the main and additional narrow channels are presented in FIG. eight.

The receiving part of the path of the additional channel is similar to that considered and differs from it only by the presence of the demodulator Dem and the low pass filter and ..., 1.7, which are used to convert the inverse frequency band into the original range of conversational currents.

Subject invention

1. A device for dividing high-frequency communication channels using a 5ph apparatus for expanding the range of conversational frequencies, characterized in that, in order to enable dividing the most common high-frequency telephone communication channels having a frequency range of 300 -: - 2700 Hz, and increasing the efficiency of use frequency bands of the HF channel, corrective amplifiers with deep feedback and variable frequency response amplification are applied.

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