SU1145492A1 - Call tone receiver - Google Patents

Abstract

The TONE SIGNAL RECEIVER, containing a series-connected amplifier-limiter, a counting trigger and a filter for the lower hours: one, as well as the first and second threshold units, an inverter and a performance unit, with the output of the low-pass filter connected to the inputs. The first and second threshold units, characterized in that, in order to increase the noise immunity, a KS-trigger and an OR-NOT element are introduced in series, as well as a delay unit, the output of the first threshold unit being connected to the unit input of the RS-trigger, and the output of the second the threshold unit through the serially connected delay unit and the inverter is connected to the input of the zero -RS setting of the trigger; ementa Hilti NOR Kotoshi cerned third input connected to the output of the inverter.

Description

This invention relates to telecommunications technology and can be used to receive single frequency tones. A known receiver of tone signals contains a preamplifier, the output of which is connected through a series-connected limiting amplifier, a resonant amplifier, an amplifier, a direct current to a sjyuchyovy device, and the element I is connected to the input of an executive unit, the output of the preamplifier is connected through a serially connected detector and a threshold unit with the second input element I 1. However, the well-known receiver of tone signals is characterized by insufficient noise immunity, the possibility of false triggering of high harmonics contained in the input signal of a resonant amplifier. The closest to the invention is a receiver of tone signals containing a successively connected limiting amplifier, counter trigger and lower filter frequencies, as well as the first and second threshold blocks, the inverter and the executive block, with the output of the low-pass filter connected to the inputs of the first and second thresholds 21's blocks disadvantage of receiver tones is the low noise immunity induced perturbation NOSTA actuation of signals the frequency of which is less than a predetermined lower limit frequency band receiving object of the invention - povshenie noise immunity. k, .. The goal is to ensure that the receiver of tonal signals, containing a series-connected amplifier-limiter, has a counting trigger and a low-pass filter, as well as the first and second signal blocks, the inverter and the control unit, and the low-pass filter is connected to the inputs of the first and second threshold units, the US-trigger and the OR-H element as well as the delay unit are entered in series, and the first threshold block is connected to the installation input of the unit R5 three times, and the output of the second thresholds th block via series connected delay unit and an inverter connected to the setting input of zero RS-flip-flop, an output of YUTI is coupled to the input of executive unit, an output of the second threshold unit connected to the second input of OR-NB element, a third input coupled to an output of the inverter. FIG. 1 shows a structural electrical circuit for a tone receiver; in fig. 2 a .o timing diagrams explaining the operation of the tones receiver. The tones receiver comprises a limiting amplifier 1, a counting trigger 2 and a low-pass filter 3, the first threshold unit 4, the second threshold unit 5, the RS flip-flop 6, block 7 delay, the inverter 8, the element OR NOT 9, the Executive unit 10. The receiver of the tone signals works as follows. With the help of limiting amplifier 1 and counting trigger 2, the input signal is converted into a sequence of pulses, the duration of which depends only on the frequency of the input signal and does not depend on its level in a wide dynamic range. The filter parameters 3 are selected so that the reception frequency band is located at the cutoff of the amplitude-frequency characteristic brought to the device input, and the threshold levels U "v and Ufif of the first and second threshold blocks 4 and 5 are set so that the first threshold block 4 operates at frequencies below the lower frequency ,, and the second threshold unit 5 is below the upper frequency of a given reception frequency band. FIG. 2a shows time diagrams for the case when the frequency of the input signal is less than the lower limit of the receiving frequency band. In this case, the amplitude of the output signal at the output of the filter 3 exceeds both threshold levels. Uni and {) nf of the first and second threshold blocks 4 and 5. Due to the finite rate of change of the output signal Uj of the filter .3, the leading edge of the pulse 1 / one to the output of the second threshold block 5 occurs earlier and the falling edge later than the corresponding edges of them

pulse output of the first threshold unit 4. The output signal Oj of the second threshold unit 5 is fed to block 7, which provides a fixed delay of the falling front, not changing the temporary position of the leading edge (this unit can be implemented, for example, in the form of series-connected peak detector and threshold unit ). Since the output signal of block 7 is fed to the input of the setting of the RS RS-trigger 6 through the inverter 8 (signal Ug), by the time the pulse Uy appears at the output of the second threshold block 5, the output signal Uj, RiS trigger 6 is zero. The arrival of pulse U4 at the output of the first threshold unit 4 indicates that the output signal Uj of filter 3 has exceeded the threshold Uni of the first threshold unit 4, which occurs only when the frequency of the input signal is less than the lower limit of the receiving frequency band . At the same time, the output signal L / of the first threshold unit 4 sets T1 $ trigger 6 to one. The output signal of the UeP-S trigger 6 is equal to one until a pulse Ug appears at the output of the inverter 8, therefore the output signal Ug of the element OR NOT 9 arriving at the execution unit 10 remains equal to zero, i.e. in that case, the input signal will not be received.

FIG. -2 o are given temporary

l

diagrams for the case where the frequency of the input signal is within a given prim frequency band. The output signal U of the filter 3 in this case does not exceed the threshold level UM of the first threshold unit 4, the output signal. From which remains zero. Only the second threshold unit 5 is triggered, at the output of which a 1/5 impulse appears. RS-trigger 6 can name its state only during that time interval, as long as there is a high signal level. Oh is at the output of block 7, and the output signal, U $ is zero and does not affect

BS trigger 6. However, over a specified period of time, the output signal

The center of the first threshold unit 4 also remains zero, therefore the RS-trigger 6 remains in the same state as it was before the second threshold block 5, i.e. in zero, because in the absence of a pulse Uj at the output of the second threshold unit 5, the unit at the output of the inverter 8 acts on the input 1 of the setting zero RS-trigger O 6. Therefore, in a period of time the melody is at the falling edges of the pulses. Uj at the output of the second threshold block 5 and J at the output of block 7, all input signals of the element OR NOT 9

5 (Uj-, Ufc and Ug) are equal to Yul, and at the output of element 11ТШ-НЕ 9 a pulse Ug appears, the duration of which is equal to a fixed value of delay 5 introduced by block 7. The sequence of pulses from the output of the element OR-HE 9 is fed to the input of the executive block 10, where it is transformed into a given shape.

5 Thus, the input signal is received.

If the frequency of the input signal lies above the upper limit of the set value; reception bandwidth, or input

0 of the receiver of the tone signals is not given a signal at all, then the output signal of the filter 3 does not exceed the threshold level Ufii- of the second threshold block 5 5 whose output signal is 5 and, therefore, the output signal of block 7 is equal to zero, and the output signal of the inverter 8 is one, therefore, the output signal of the element OR NOT HE is equal to zero, i.e.

no input signal is received.

Thus, in the proposed receiver, the tone-signals at the input of the executive unit 10 appear only when the frequency of the input signal lies within a predetermined polo. sy reception frequency. Otherwise, the input signal of the executive

block 10 is zero.

The proposed receiver of tone signals has a high noise immunity, since it completely eliminates the possibility of false alarms from signals whose frequency is less than the lower limit of the rear receive band.

Claims (1)

A TONE SIGNAL RECEIVER comprising a serially connected amplifier-limiter, a counting trigger and a low-pass filter, as well as the first and second threshold blocks, an inverter and an executive block, the low-pass filter output being connected to the inputs of the first and second threshold blocks, characterized in that , in order to increase the noise immunity, a series-connected trigger AND element OR-NOT, as well as a delay unit are introduced, and the output of the first threshold block is connected to the installation input of the HS unit-trigger, and the output is The threshold threshold unit is connected through a series-connected delay unit and the inverter is connected to the zero-input input of the -RS trigger, the output of the IPI-NOT element is connected to the input of the executive unit, the output of the second threshold block is connected to the second input of the IPI-NOT element / third input of which. The horn is connected to the inverter output. U1 FIG. 1> 1 1145492 2