SU383198A1 - DEVICE FORMING SIGNALS WITH MULTIPOSITIONAL FREQUENCY MANIPULATION - Google Patents

Description

one

The invention relates to radio engineering, in particular to modulators, intended to form signals with multipositional frequency shift keying, and can be used in apparatus for transmitting discrete information using frequency shift keying according to an arbitrary law.

Signal generating devices with multi-position frequency shift keying are known, comprising a reference oscillator, a binary frequency divider, a multi-input switch and an output frequency divider.

However, the known devices have large distortions of the output signal and side oscillations, since the formation of signals in them is carried out at low frequencies using phase quadrature modulators.

The aim of the invention is to provide smooth phasing of adjacent and extreme frequencies of the output signal.

For this, the second output of the binary frequency divider is connected via an additional controlled frequency divider with several outputs to the inputs of the multi-position switch.

FIG. 1 shows a block diagram of a device for generating signals with a multi-position frequency shift keying; in fig. 2-

FM output waveform; in fig. 3 - the spectrum of the signal at the output of the phase manipulator.

A shaping device with a multi-position frequency manipulation (see Fig. 1) contains an oscillator / reference oscillations, a binary divider 2 frequencies, phase manipulators 3 and 4, filters 5 No. 6 harmonic oscillations, phase shifters 7 harmonic oscillations, a multi-input switch 8 with temporary distributor, controlled frequency divider 9, consisting of binary divider lines 10 and 11, circuits 12 and 13 "And, circuits 14 I1 15" OR, decoder 16 control signals and frequency divider 17.

The proposed device operates as follows.

The voltage from the oscillator 1 of the reference oscillations with the frequency / o goes to the binary divider 2 frequencies and the phase manipulator 3, to another input of which a square signal is fed with the frequency F from the output of the divider 2 frequencies. At the output of the phase manipulator 3, a spectrum is formed that is shown in

FIG. 3. The spectral components are extracted in 5 No. of filters used to obtain output frequencies. One of the components is supplied to the phase arm 4 as a carrier, after which in a similar way

The next group of frequencies is distinguished using filters 6. The use of the spectrum of a phase-shift keyed signal, in which the carrier and even components are suppressed, eases the filter requirements.

At the output of the filters, we get n frequencies / 1, / 2, ... fn, according to the number of positions of the FM signal with spacing F. After the phase shifters 7, these oscillations go to a two-way switch 2, where there is a time distributor, by which the oscillations are switched by a divider controlled by the external signals of the decoder 16. In this case, the switching takes place at times determined by the clock frequency .yt (Ku is an integer), synchronized by the reference oscillator 1, which determines the discreteness of the cycle duration of the multipoint oh frequency manipulation (speed). At the switch output, there is a FM signal with frequency spacing between the steps, where D / s is the specified frequency spacing of the steps. This signal arrives at a frequency divider 17 with a division factor t, at the output of which we obtain the desired multi-position FM signal. The frequency is chosen in such a way that the number t is integer (better binary).

The absence of phase breaks when changing frequencies is ensured as follows: the phase shifter 7 of frequency / 2 establishes the equality of phases when changing the oscillations fi by / g, the phase shifter frequency / h - the equality of phases when changing / h to / 4, etc. These equalities remain if for the modulation period 7c (see Fig. 2) an integer number of frequency periods / 1, / 2, ..., etc., is laid down, then

. U. ts- / - I /., ... ts- / „- K„, (1)

here UE - integers.

When phase fn is changed to / h, only phase conditions can be set if

(/ „- / J- u-l u. (2J

where Yc is an integer, i.e. with the whole index for extreme frequencies.

It is easy to see that equality (2) follows from equality (1). In addition, it is easy to see that the index of a single step may not be an integer.

Equality (1) implies the condition that the division factors / Cy divider 9 frequencies must satisfy

l

1 vi

kyi

With frequency divider 9, condition (3) is automatically met for all discretely controlled transmission rates.

Frequency divider 9 contains a controlled linear serial binary divider 10 and an auxiliary ruler of binary divider //.

The division factor of the ruler of binary dividers 10 is changed by external signals from the decoder 16 (AND | 3men1 cycle duration - transmission rate) and automatically when commands from the auxiliary ruler of binary dividers 11 are received (by changing the duration of one of the steps).

The change of the division factor is carried out using circuits 12 " And connected to the outputs of binary dividers through circuits 15 " OR. Circuit 12 "And through circuit 14" OR resets all binary dividers 10 upon receipt of a predetermined number of input pulses.

At this time, the AND circuit, which receives the potential from the decoder of 16 input control signals and y, is working (see Fig. 2). Each of the 12 "And schemes corresponds to a certain transmission rate.

To set the speed precisely — decreasing the discreteness of its change, the duration of one of the steps of the FM signal is changed by the required number of periods of the input frequency using 1'– OR schemes controlled by an auxiliary ruler of binary dividers 11 and 13 ”I. At the output of circuit 1 ", the signal appears at the beginning of the required stage. This signal with the help of the corresponding circuit 15 И.. AND changes the division ratio of the binary delntel 10, which ensures the setting of the duration of this stage 7 s, and consequently, the exact setting of the cycle duration - the transmission speed.

Subject invention

A device for generating signals with a multiple-positioned frequency shift keying containing a series-connected reference oscillator, a binary divider

frequencies with two outputs, of which one through two phase manipulators connected in parallel to the input, filters and phase shifters are connected to a multi-pass switch, the output of which is connected to the input

The second frequency divider, in addition, the output of the oscillator oscillator is connected to the second input of the first phase switch and one of the inputs of the switch, and one of the filters of the first phase switch

connected to the second input of the second phase switch, characterized in that, in order to ensure smooth phasing of the adjacent and extreme frequencies of the output signal, the second output of said binary frequency divider is connected via an additional controlled frequency splitter with several outputs to the inputs of said switch. l-

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