CS212625B1 - Connection for automatic control of coaxial cable impedance - Google Patents

Abstract

The invention relates to a circuit that allows to automate the process of measuring the wave impedance of coaxial cables and at the same time allows to measure the wave impedance values of coaxial cables faster, with the required accuracy and without great demands on the operator. The essence of the circuit lies in the fact that the coaxial relay, controlled by a delay control circuit, is connected by its first output to a capacitance comparator with a connected signaling control circuit, and the second output is connected by a high-frequency directional tap to which a pulse generator is connected, to a digital pulse propagation time meter. The capacitance comparator and the digital pulse propagation time meter are connected by a computing unit to which a display unit and a printer are connected, to a comparator unit with an out-of-tolerance value signaler.

Description

1 212625

BACKGROUND OF THE INVENTION The present invention relates to a connection for the automatic control of coaxial cable impedance by means of a comparative capacity meter, a digital pulse propagation meter and a computing unit. The connection makes it possible to automate the whole measurement process of one of the main parameters of coaxial cables - wave impedance. Several methods are currently used to measure coaxial cable wavelength at 200 MHz, where the measurement accuracy is within ± 2%, based on measurement of various variables. For example, the best practice method is based on measuring the diameter above the insulation (below the outer core), the diameter of the inner core, and calculating the wavelength impedance after fit into the appropriate relationship. Another method, suitable for higher frequencies, is based on the measurement of the inductance and capacitance of the coaxial cable and the subsequent calculation of the wave impedance value. One of the most commonly used methods of measuring the wave-impedance of coaxial cables, the permittivity of which does not change with frequency, is the resonance method. When measured by this method, a sample of the coaxial cable is connected to a high-frequency generator with an aperiodic indicator and the end of the measured cable is connected to a no-load or short-circuit. By changing the frequency of the generator, the periodic ment of the input impedance and the cable, the axis manifests itself as a periodic change in the deflection of the indicator. The wavelength impedance of the measured coaxial cable is then calculated from the difference in frequencies between the two minimums or maxima and the measured total capacity of the coaxial cable sample.

A common disadvantage of all of the above-mentioned methods of measuring the wavelength of the coaxial cables is their relative intensity, requiring qualified operators. The disadvantage of the most commonly used resonance method is also the relative long time needed to obtain the measurement result - up to 30 minutes, in other methods of time not as demanding, their inaccuracy.

The above drawbacks are eliminated by the involvement of the automatic control of the co-axial wavelength impedance by means of a comparative capacity meter, a digital pulse propagation meter and a computing unit according to the invention, wherein the coaxial, single-input, delayed control circuit is the first output a switched capacity comparator, the output of which is connected to the signaling control circuit, and the second output via the high frequency directional coupler, connected to the generator pulse input, coupled to a digital pulse propagation meter, with a capacitance meter and a digital pulse propagation time meter with its through outputs of the computing unit to the block of the comparison unit. The advantages of the proposed connection lie above all in considerable time and in the difficulty of measuring the qualified personnel. Another benefit of the proposed connection is its wide range of applications in the production of coaxial cables, both in terms of measurement, in-process control as well as continuous, as well as the ability to measure the wave impedance of each produced length, with a view to automating the entire measurement process, which guarantees a higher quality products. The wiring according to the invention also allows the control of the wavelength impedance of the coaxial cables without the need for their impedance matching and without the change in relative permittivity of the cable insulation in the calculation.

The invention is explained in the following by way of example, in conjunction with the accompanying drawing.

The figure shows a schematic diagram of the circuitry for automatic control of the coaxial cable wave impedance. Coaxially relay J., controlled by delay control circuit 11. is the first output coupled to the comparator 2 of the capacitance of which the signaling control circuit 22 is connected. The second output is coaxially to relay 1 via the high-frequency directional coupler 32. to which pulse generator 31 is connected, the switched digital meter and the time pulse propagation. The capacitance comparison meter and the digital pulse propagation time meter 2 are output through the calculation unit 4, with the printer outputs 42 and the display unit 41. to the reference unit 2 with the signaling device

Claims (1)

2,2625 2 rom 51 non-tolerance values. The connection according to the invention operates as follows: the measured coaxial cable 6 is connected to the coaxial relay 1, which switches the input of the coaxial cable 6 to the comparator of the capacitance meter 2, to which the signal control circuit 22 is connected. and signaling a possible imperfect connection of the measured coaxial cable 6 to the co-axial relay 11. Coaxially, relay J is controlled by a delay control circuit 11. which, in a few seconds, during which the total length of the measured coaxial cable 6 is measured, the input of the coaxial cable 6 switches to a block of the digital time pulse meter 2, where the pulse generator 31 emits pulses through the high frequency directional coupler to the connected coaxial cable 6, The pulse propagation time is fed to the digital meter via the high-frequency directional tap 32 and terminated at no-load or short-circuit. A computational unit is connected to the outputs of the comparative capacitance meter and the digital meter and the pulse propagation time, which makes a simple calculation, whereby it is connected by outputs to the display unit 41 and to the printers 42, the measured wave impedance values are calculated in the display. the digital form by the display unit 41 and written by the printer 42 on the prepared labels. The input unit 6 is connected by its input to a comparing unit which records the deviations of the wavelength impedance of the measured coaxial cable 6 from the allowed tolerance, and the non-tolerance value indicator 51 indicates the non-tolerance value. Connections for automatic control of coaxial wavelength impedance can be used in technical control departments and directly in production in large enterprises producing coaxial cables. DESCRIPTION OF THE INVENTION Involvement for automatic control of coaxial wavelength impedance using a capacity meter, a digital pulse propagation timer and a computation unit, characterized in that it coaxially relays (1), one input connected to a delay control circuit (11), the first output is switched to a capacity comparator (2), to which the signaling control circuit (22) is connected, and the second output is via a high-frequency directional coupler (32) connected to the pulse generator (31), the switched digital meter ( 3) the pulse propagation time, wherein the capacitance comparator (2) and the pulse propagation digital reader (3) are output via the calculation unit block (4) to the comparator unit block (5). 1 sheet of drawings Severografia. n. p., race 7. Most