SU65132A3 - Cordless telephone transmitter - Google Patents

Description

The present invention relates to radio telephone transmitters with a carrier and one side 1 GAL; axis 1 more specifically concerns the method and means of transmitting one side and carrier frequency.

There are several carrier transmission systems and one sideband. One of the methods consists in filtering MODULATED. Down the path and exit, which destroys one of the side lanes. Another method is filtering the amplitude-modulated sigpal in the low-power transmitter cascade and further amplifying the filtering signal, which is then either radiated or mixed with the oscillations of the second generator, after which the sideband is re-allocated.

The first method is not very effective and either leads to leakage of the suppressed sideband or to weakening of the carrier frequency.

The latter method does not allow for sufficiently efficient use of amplifiers, which, in addition to the necessary frequency band, must also read excessive frequencies.

One of the objects of the present invention is the development of efficient methods for producing a carrier wave and one sideband. Another object of the invention is a device for separately amplifying and subsequently shifting oscillations of a carrier wave to one of the sidebands.

A further object of the invention is a method of filtering out one of the sidebands from the amplitude modulated carrier frequency and mixing these oscillations with carrier frequency oscillations in the proper phase, resulting in a signal, and in carrier Hi of one sideband.

The invention is illustrated in the drawing, where the maf fig. 1 shows a general scheme of the device; FIG. 2 shows a diagram of a device with a system for shifting the carrier and sideband currents; ma FIG. 3 is a diagram of a balanced modulator; FIG. 4 is a schematic of an impedance converter and in FIG. 5 is a broadband filter circuit.

The carrier frequency generator 1 is connected to the input m. Amplifier A, the output of which is connected to the load 5 via an impedance converter 3. The load is also connected to the output of the second amplifier B, whose input is connected to the oscillator of one of the side frequencies 7.

The first Assistant should be set to class C mode, as with this. the greatest effect is achieved. The second amplifier B is brought to a cutoff and therefore remains locked in the absence of modulation by the sideband signal.

When the device is operated, the first amplifier A feeds the load of 5 kW of the carrier frequency through the impedance converter 3. The amplifier B has no effect on the load circuit, just as in the absence of a modulating signal only a surge voltage is applied to it.

When / sideband signals

applied to the second amplifier,

then the amplified high frequency k. glebans of the sideband fall

into the load circuit.

At some point, the voltage of the sideband oscillations will be in phase with the voltage of the carrier wave, as a result of which the carrier currents and side POL10C will add up to the load and the signal will increase at the output.

-Another moment of the phase, the carrier and sideband oscillations will be opposite, as a result of which the output signal will be reduced.

The transducer of the impedants causes undesirable interaction, and the operation of both amplifiers and, in addition, reduces the output signal of the amplifier A while reducing the load on the output.

During the period of oscillation, the plug A does not consume energy, and therefore the currents of the carrier and sidebands are amplified without distortion.

Although previously it was meant - a mode. 1THE ONLY one sideband, which in practice is very difficult to achieve, it is necessary to introduce another number of devices shown in

the circuit of FIG. 2, where the main generator, generating a relatively low frequency, is indicated by M.

Let, for example, the transmitter be designed for a television station and operate at a frequency of 63 MHz, with the sideband extending from 63 to 65.5 MHz.

Based on this assumption, select the frequency of the main oscillator equal to 3 MHz. The core generator 11 and the modulating voltage source 13 are connected to a balanced modulator 15. A filter 17 connected to the output of a balanced modulator 15 selects the upper sideband from 3 to 5.5 MHz and suppresses the lower sideband to 1, 5 MHz.

The oscillations of the upper sideband are brought to the second side of the modulator 19, which, in turn, is connected to the second generator 21, which generates a frequency of 10 MHz.

The output of the modulator 19 is attached to the filter 23, which passes: The upper sideband from 13 to 15.5 MHz and. suppresses the lower one from 7 to 14.5 MHz.

Filter 23 and the third generator 25, operating at a frequency of 50 MHz, are connected to a third balanced modulator 27, the output of which is connected to filter 31, which passes the lower sideband from 34.5 to 37 MHz.

The signal from the output of the filter 31 is supplied to the amplifier 33, to which, in the absence of modulation, the offset for the l: cutoff is applied. The output of amplifier 33 is supplied to antenna 35 or to some other load.

The main generator 11 is connected via a frequency multiplier 37 to a carrier frequency generator 39.

The output signal at the operating frequency of the oscillator 39 is fed through the phase shifter 41 to the input of the amplifier 43.

The offset supplied by the PA amplifier 43 is designed to operate the amplifier in class C. The output signal from the amplifier is supplied through

impedance transducer to antenna 35 1OR to another load.

In the system described above, the phase shifter 41, connected between the carrier frequency generator and the impedance converter, is used to maintain a proper phase relationship with respect to sideband oscillations.

It is easy to get that the carrier wave is synchronized with the master oscillator so that the corresponding phase relationships are maintained between the oscillations of the carrier frequency and the sideband.

Balance -module (Fig. 3) typical.

The impedance transducer is an E1 line C; wavelength V-l (Fig. 4) or an equivalent circuit composed of lumped parameters.

The bus-field filter (FIG. 5) consists of two or more coupled resonant circuits.

It will be understood that a different number of generators, balanced modulators and filters can be used.

The present invention is not limited to the described devices for producing currents of one sideband. For example, the source of one sideband shown in FIG. 2, the method described in E of d may be applied. g. with. Luck for Lo 248567 rt AOR / HP 1938. The name is Antenna Circuit Modulation Systems ("Modulation System in Antenna Circuits).

In some cases, it is preferable to prefer a double-balanced modulator of prn yizky modulating frequencies and the sequential switching on of filters (shown in Fig. 2) at higher modulating frequencies.

Both methods can be applied in combinations.

Patent Subject

A radio telephone transmitter operating at a carrier frequency and a DAY sideband, wherein the sideband amplifier is connected to the load directly and the carrier amplifier is connected to it through an impedance converter, in order to eliminate the effect of one amplifier on the other.

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FIG. 3

FIG. four

FIG. five

Output

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