SU45329A1 - Radio transmission method - Google Patents

Description

The present invention relates to a method for the multiple use of radio receiving devices based on amplitude modulation and frequency shift keying of the carrier frequency of the transmitter.

This method allows simultaneous wiring and telephony, with the power of the telegraph channel corresponding to the power of the tone-modulated telegraph transmitter, and the power of the telephone canal — the usual telephone transmitter with the same nominal lamp power. ; The telephone channel can be used for voice telegraphy OR for one of the multiple systems using a kizkfastomnnuk) ibdul; Ldyu.

Already known methods of multiple use of transmitting and receiving

devices are based either on modulation of the carrier frequency of the telephone transmitter by amplitude of the telegraph manipulation generated by the transmitter

and.

frequencies. / G.

The first method is inevitably associated with a significant reduction in the power of each of the 5 channels compared to the usual single-time transmit. The same method has the same nominal power. The second method in the proposed

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so far, the development allows only telegraphic work practically no more than with two channels.

Meanwhile, combining both methods, it is possible to create a two-fold system that allows the use of one of the channels for telephony, with the power of the telephone and telegraph channels corresponding to the telephone power and the power of the carrier of a tone-modulated transmitter.

In FIG. 1 depicts a schematic diagram of the proposed method of radio transmission; FIG. 2 and 3 - electrical circuits by which the proposed method can be implemented.

The idea of the method is as follows. The frequency spectrum of a telephone transmitter can be shifted within certain limits without violating the reception conditions. Manipuliru in these permissible limits, the frequency of the carrier telegraph work and then its amplitude modulation, you can receive, using the transmitter twice.

Said fig. one.

When the key is pressed, the transmitter emits a carrier frequency and sidebands, shown in the figure by solid lines; when the key is released, the entire frequency spectrum is shifted (dotted lines).

Obviously, in order to avoid telegraphic manipulation of telephone work, the receiver must ensure that the entire frequency spectrum is uniformly transmitted at both key positions.

Consider which limits of carrier frequency manipulation can be allowed. The bandwidth of a modern commercial telephone receiver at an intermediate frequency is in the order of kilo cycles. The frequency range of the telephone transmitter (for commercial telephony) is 5 kilo cycles. One kilo cycle is thus left in stock with the expectation of small spontaneous changes in the frequency of incoming signals and the first local oscillator of the receiver. Moving the frequency spectrum during manipulation reduces this margin and therefore it is desirable to reduce the degree of frequency manipulation if possible.

Another circumstance that requires a reduction in the degree of frequency manipulation is the need to maintain a free region in the part of the emitted spectrum immediately adjacent to the carrier frequency. Separation in the receiver of the frequency of release from the frequency of pressing is possible only under the condition that none of the side frequencies when pressed does not coincide with the carrier frequency of release and vice versa. From FIG. 1 it is clear that in order to fulfill this condition, the frequency change during manipulation must be less than the interval between the carrier and the nearest side frequency. In other words, the degree of frequency change during manipulation should be less than the lowest transmitted sound frequency. In commercial telephony, all frequencies below 400 lane / sec are usually filtered out. It follows that the frequency manipulation should not exceed 250-300 lane / s.

If a telephone channel is used for tone telegraphy, then there is no need to limit frequency manipulation to such narrow limits. It is only necessary to comply with the above conditions: a uniform transmission by the receiver of the entire frequency spectrum and the carrier retaining a free area in the overall spectrum.

The resolution of this task of separating high frequencies, which are different in magnitude of the same order as the inevitable oscillations of the intermediate frequency of the receiver, determines the possibility of practical implementation of the proposed method with shortwave waves.

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When the difference between frequencies of several hundred periods, their separation is possible only in the low-frequency 4actH receiver using low-frequency filters. Hence the need for a secondary heterodyning intermediate frequency. It is impossible to eliminate the intermediate frequency oscillations below known limits. Therefore, naturally, it is suggested that the second local oscillator should follow the changes in the intermediate frequency, thereby maintaining the beat frequency unchanged. In other words, the separation of frequencies in these conditions will be quite possible if we apply the automatic frequency control of the second local oscillator of the receiver, which is quite feasible.

The question of the degree of frequency manipulation is also related to the question of the maximum speed of manipulation. In fact, when dividing frequencies, the bandwidth of low-pass filters is associated in a very definite way with the difference in the frequencies to be divided. IF the maximum manipulation speed is set to 200 words per minute, then the filter should have a band of 80 lane / s. For a complete split of the T1 frequency by two filters with a band of 80 periods-YAG-PrSH, we have to stay at a distance of at least 200 periods (also the possibility of frequency deviations from the original values within 20 periods)., / ,.

This value should be considered as the lower limit for the degree | ChangShu 1Gtg1getT |

Before a change in the completions in the diagrams of the transmitting capacitor, (erb2e must be 6bi-ft of angels, for example, it offers a method, с71ВД5 П5 tanoВТГггГТТ 1 in Krakow

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. It is obvious that the power of the Telephone channel is not limited to the telegraph canals and the maximum depth of the telephone modulation is determined solely by the quality of the modulation device of the transmitter.

The power of the telegraph channel corresponds to the carrier power and is equal to the symmetric 100% modulation of one quarter of the telegraphic power of the 1SWSH 1degreeGy. With grid modulation, it drops four times.

It is appropriate to note the following. When comparing different multiple systems, the mere comparison of the powers falling on the individual channels does not reflect the actual ratios of communication quality. The fact of the matter is not power, but how much in a particular transmission and reception system the final effect of incoming signals exceeds the effect of interference. From this point of view, besides power, a whole number of other factors must be taken into account.

In the described method, the following Moments can be noted, which improve the conditions of admission:

1. The absence of manipulation of the power of the carrier frequency allows the receiver to automatically adjust the receiving power (with a sufficiently small, besides, constant time).

2. The presence of two frequencies of manipulation results after their separation and rectification in a differential switching circuit of the relay. Since both frequencies of the telegraph channel are very different from each other, it can be assumed that the percentage of interference with the spectrum that simultaneously captures areas adjacent to both carrier frequencies will be large. In this case, the differential activation of the relay should

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reduction of pomelo from atmospheric times3. By itself, the presence of a recording frequency during the pauses between the telegraph Jpp%

--.- 3 signs of unwanted interference due to the manifestation of "self-limiting or rather self-regulation of receivers.

4. The essence of the method leads to the use of filters with a very narrow frequency band in the telegraph channel. The use of a minimum frequency band should also reduce the effect of extraneous interference.

5. It is not difficult to assemble the circuit of the receiving part so that at least one of the manipulation frequencies will be sufficient for the relay to operate.

All these considerations, arising from the use of two very closely spaced frequencies for the telegraph channel, lead to the conclusion that when used in the transmitter used in the system described, anodic modulation, the reception quality of the telegraph channel will be higher than the reception quality of the same transmitter used for conventional telegraphy undamped oscillations.

The same considerations suggest that the reception stability of the telegraph channel when using grid modulation in a transmitter will be closer to the reception stability of a conventional telegraph transmitter with the same rated power of the generator tubes than follows from a simple power comparison.

With short waves, the reception of a telephone channel may be accompanied by telegraphic interference in those cases. when one of the carrier frequencies drops out at selective fading. By establishing an appropriate amount of constant auto-adjustment time for the strength of the reception of the telephone channel, this interference can be reduced. How much they will reflect on the quality of telephone reception can only be established by experience.

Any well-stabilized telephone transmitter can be used to work on the proposed radio transmission method.

The telephone channel does not require any changes in the scheme of the transmitting device. It is only necessary to introduce, according to the above considerations, a filter that protects the modulation

device from audio frequencies below 400 per / sec.

For telegraph operation, the transmitter circuit must be supplemented by a frequency manipulation device.

In those cases when the transmitter has a master oscillator with parametric stabilization, the frequency can be manipulated in the master oscillator itself, by connecting with the help of a telegraph relay in parallel with the oscillating circuit of the appropriate value of the neutral current resistance.

The degree of frequency manipulation with the width of the spectrum used in the telegraph channel of 400 lane. should be - 200 per. (in this case, the most favorable conditions are obtained for the separation of the frequencies of manipulation in the receiver).

In quartz-stabilized transmitters, the frequency can be manipulated by the method Shchukin used in his two-wire wiring system.

After the buffer stage, a frequency manipulator is introduced into the transmitter, one of the possible schemes of which is shown in the accompanying drawing (Fig. 2).

There are a high-frequency transient cascade A, assembled according to the Carson balanced scheme, and an auxiliary oscillator that is frequency-controlled in frequency. To the lamp grids Л и, 77ц

in the same phase, the voltage of the frequency f generated by the quartz and in the opposite phases the voltage of the frequency j is supplied from the generator B. At the same time, in the anode circuit of the LC there are current currents of frequency I, "+ / i". If the frequency / j. is large enough, then the appropriate setting of the LC circuit can distinguish one of these frequencies.

Manipulating the frequency of the oscillator / 7, connecting to its circuit using a small capacitance C telegraph relay, leads to the corresponding

manipulating the operating frequency of the transmitter. The value of the latter, as already mentioned, should be 200, hence the degree of manipulation of the frequency of the generator D A 200t is determined. , -, :::.:

 where “is the value of the total frequency used in the transmitter .-:; ;

The choice of frequency of the optional local oscillator depends on the operating frequency of the transmitter. It should be large enough so that there are no difficulties in isolating the anode contours of the fifth frequency manipulator and the cascades closest to it with the difference or total frequency we need. Excessive Magnification - Astrotes. lowers the chat

transmitter stability, since rerterator B can be stabilized

only parametric .. -. ;:

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Kovolnovyh transmitters lies in the range of 14-2 10 lane / s, for long-wavelengths - 1-l5 10 lane / s. , /

It goes without saying that the modulation amplitude must be carried out in one of the transmitter stages, where the modulated frequency is fully Eter separated. ; ,:, In the methods of frequency manipulation of the transmitter frequency disassembled, the telegraph relay acts directly on the oscillator circuit. At the same time, the transition from the frequency of pressing to the frequency of pressing and back to the back (almost instantly, which leads to a wide range of side frequencies, which can in some cases interfere with telephone work. Limiting this spectrum can be achieved by some slowing down the transition from one frequency to Another, the simplest way, such manipulation can be carried out by changing the grid potential of the auxiliary lamp, which its anode circuit takes along the oscillatory circuit of the generator. By switching to the grid circuit of this telegraph filter lamp, the transition time from one frequency to another can be increased (E ± i need y. ESHG; ™; - ,, -, - - .., .., j

The reception of the body of the body, is carried out by any body of the receiver. TrebovSH ShG T. on him a strong post-pulse impulse to lower to zero CBdJo sensitivity of .9 to the useful signal. If the differential fx cxigMa has an effect in relation to: atmospheric interference, the elimination from the circuit of an element that can be deduced from this interference is completely desirable. - Auditory control of telegraph work can be conducted after the filter ///. To ensure constant frequencies applied to filters III, IV, when the circuitry is only possible, stable operation of the circuit is used, an automatic adjustment of the local oscillator frequency is used. the resistance of the anode circuit of the lamp L. This resistance can be varied in wide variations by varying the voltage across the lamp. Thus, the frequency generated by the local oscillator depends ultimately on the grid potential of the lamp L. - V -. The part of the circuit circled by the dotted line serves to affect the potential of the grid of the lamp L, to add to the Change “LO Frequency, returning the beat frequency to the outcome - H -f-- f (or rather, the original) value. This is the control of concurrency .. - -r;, ...:,:; j: t.ch -: - -y .-. G-. , . ,, aKS32K. ± ::: viirt: Gl is carried out in the following manner. Reinforced low-frequency currents through the filters V, VI, VU are supplied to the grids of the lamps L, L. Filter V (€ W about the manipulation frequency. Filters VI, U, represent the failure of the resonant circuits with a small angle. One of them is tuned to the Frequency, but a few (about 50 front) frequency of spin; the setting of the second is the same and shifted in the same direction relative to the frequency of pressing. By matching the mixes on the grids of the lamps L and L, the circuit is adjusted so that the currents of these lamps are equal. At the same time, the potential difference between points a, b is equal to 0. If now, for some reason, either the manipulation frequencies are shifted relative to the initial values, then for example The voltage on the grid of the lamp L changes and the balance of the circuit is disturbed. The potential difference between points a and b arising in this case is fed to the grid of the lamp L by controlling its internal resistance. A satisfactory operation of the frequency regulator is possible only if the voltage applied to it is constant. In order to ensure this constant, an automatic adjustment of the low-frequency amplifier gain is introduced using the anode current of the lamp L. The question of the time constant of the frequency regulator is essential. It is necessary that during short term fading, leading to the loss of one or both of the manipulation frequencies, the controller does not have time to change the frequencies of the local oscillator. Adjusting the frequency for a large amount of time constant will not adversely affect, as the frequency fluctuations are fairly smooth. By selecting resistance R and capacitance C, the value of a constant time should be set within 10-15 seconds. The subject matter of the invention. A radio transmission method, characterized in that for the telegraph message, the carrier frequency of the transmitter is changed, modulated in amplitude for telephone or a number of other telegraph messages. . spectrum — frequencies that it should evenly pass, remain the same as in conventional telephony, since for a band of 6 kilocycles, the spreading of the spectrum by several hundred periods in our case does not play a significant role. Receiving a telegraph channel requires the addition of a receiver circuit with a device for frequency separation. For shortwave reception, this device should include a device for automatically adjusting the local heterodyne frequency by the incoming signals. With long waves, the need for such a device is eliminated, since the possible oscillations in the frequency of the transmitter and the receiving local oscillators are not large, they occur very smoothly and can therefore be compensated for by manually adjusting the receiver. In all other respects, the schemes of additional devices in both cases coincide; therefore, it is possible to restrict ourselves to considering the more complicated case of receiving short waves. To receive a telegraph channel, either a telephone channel receiver can be used, or if a telephone channel is not received at this point, a conventional frequency-converted telegraph receiver. The scheme of the additional device for the case of shortwave reception is shown in the attached drawing (Fig. 3). The operation of the circuit proceeds as follows. The intermediate-frequency currents amplified by the receiver through a band-pass filter 7, designed to pass a spectrum of -2 kilocycles, are fed to a detector lamp L. A second local oscillator is connected to the same g lamp. ijjl Frequency of beats by setting the local oscillator (set at about 2500 lane / s for the pressing frequency and 2700 lane / s for the spinning frequency (relatively high frequencies are taken here in order to eliminate the possibility of G being between the heterodyne frequency and the lateral P1 telephone modulation frequencies that can make further frequency separation impossible.) .ag.ai-.V ..,. sB3ia-iB5ia s Ssssisipi - - ". - J, .S," Jt - / k "-t H-5eH- - - "and-; Next, these two frequencies, pass through a filter // with a band of 2300-2900 are amplified by a low-frequency amplifier 11 and through band-pass filters ///, fV water to the grids is rectifying: lamps L, Lou. Filter I / g Passage Only press frequency, filter only tap frequency. Changes in the anode currents of lamps Л and J7 at the manipulation of the transmitter create current pulses through the windings of the relay P leading to a series of In the case of a transmitter, when a transmitter emits a carrier frequency pressing on the resistance, a portion of the anode battery voltage drops, which leads to the charge of the capacitor Cj. IMPULS zap dna o current, pro; move through the winding relay, throws it measles. Spanning the key at the transmitter leads to the appearance of current in the anode circuit of the lamp L and charging the capacitor Cg. The anchor of the relay in this case flips in the opposite direction. If for some reason the release frequency (for example, due to selective fading) is not caught by the receiver, the relay measles will still be thrown back by the discharge current of capacitor C, Thus, at least one of the manipulation frequencies is enough to trigger the relay. In those cases when the pulses of atmospheric nofiex with equal amplitudes simultaneously hit the grids of the Jf and A lamps, the relay, due to its differential switching circuit, will not be transferred. The absence in the circuit of the telegraph output of the limiter requires no explanation. In this case, it is not needed, since in the above scheme, all the direct impulses through the relay correspond to the same magnitude of the reverse pulse. 4f6; 7 ej sraeT J overstrain and, atysh U1ppampon n tory C and the elimination of the limiter gives an account | great advantage. All Kommersant body has a property when vozdeis