DE1033725B - Arrangement for measuring and monitoring the residual loss of a communication link based on the principle of a loop measurement - Google Patents

Description

GERMAN

The invention relates to arrangements for measuring and monitoring the residual attenuation of a communication link according to the principle of a loop measurement, in which in the office at the near end of the connection a measuring transmitter and receiver is available and at the far end the forward and return lines have the correct level, especially over an attenuator, are connected to each other in such a way that the measuring transmitter, preferably with constant Level, generated level oscillation transmitted via the forward line via the return line to the measuring receiver got.

It is known that with regard to the security of the message transmission, the residual attenuation of Message channels may only deviate from the setpoint within certain limits. It must therefore from time to time be measured. Of the currently common methods, the individual channel measurement requires a transmitter and each Recipient in both offices. When measuring the speech circuit via a loop, which is achieved through interconnection at the correct level the outward and return lines at the far end, e.g. B. is formed via an attenuator, is only one sender and receiver required in one office. With this method, however, there are no measurement results Guarantee for correct leveling, as there are positive and negative attenuation deviations in the outgoing and return lines compensate for display. It is also known in circuit arrangements for operational monitoring of carrier frequency systems in which the channels of the two transmission directions in different Frequency areas are transmitted over the same line, an optionally switchable modulator arrangement provide through which the channels of the transmission direction in the frequency range of the channels of the reception direction implemented. This measure can be used in systems in which different frequency ranges are used for the two transmission directions, the simple low-frequency test method in interconnection be carried out by the transmitting and receiving part. With one on the same principle working known circuit arrangement for checking cables equipped with amplifiers at the far end, instead of a modulator, a non-linear switching element is provided, which consists of the incoming Vibration generates a vibration in the opposite direction and returns it to the transmission point.

The arrangement according to the principle of loop measurement is now improved according to the invention in that at the far end the outward and return lines are additionally via a non-linear network that consists of the level oscillation transmitted via the forward line, e.g. B. by distortion, at least one of its different oscillation, in particular the first harmonic, derives its The voltage depends non-linearly, preferably quadratically on the voltage of the level oscillation, in such a way

Arrangement for measurement

and monitoring of the residual damping

a communication link after the

Principle of a loop measurement

Applicant:

Siemens & Halske Aktiengesellschaft,

Berlin and Munich,
Munich 2, Witteisbacherplatz 2

Dipl.-Ing. Joachim Böhse, Munich,
has been named as the inventor

are connected to one another that in the measuring receiver both the level of the level oscillation transmitted via the loop as well as the level of the derived from it with the help of the non-linear network at the far end and over the return of the transmitted vibration can be measured selectively. This allows the residual attenuation in a loop circuit So measure with little equipment.

Compared to the previously known principle of measuring the residual attenuation in a loop circuit, however, this results the main advantage that the residual attenuation errors of the outgoing and return lines can be determined individually from the measurement result are. The residual attenuation errors of the outgoing and return lines could only be individually based on the principle the single channel measurement can be determined. With this method, however, as already explained in the introduction, a increased equipment effort required. In the method according to the invention it is initially assumed that

the residual attenuation of the channels in the transmission range for all frequencies, especially for those used for measurement frequencies used has the same value. Except for this ideal case of distortion-free transmission the principle can also be used advantageously if only small attenuation distortions in the Transmission path occur.

Further considerations within the scope of the invention show, however, that when creating a measurement criterion for the Elimination of the residual attenuation path, the measuring principle described can also be used if the prerequisite small attenuation distortions in the transmission path cannot be considered fulfilled. In further development According to the invention, the arrangement for measuring and monitoring the residual attenuation is designed in such a way that

809 560/325

that the non-linear network can be replaced for a further measurement by a modulator in which the additional Oscillation is generated by modulation, but the voltage of this additional oscillation is linear from the voltage of the level oscillation is dependent. The measurement is started one after the other at am far end connected, non-linear network (distortion) and then with the modulator connected carried out. From the measurement result, the

are connected to each other and the deviations of the level of an oscillation transmitted via the loop from the target value are measured at the broadcasting office. In Fig. 1, an arrangement is shown schematically, with which the monitoring and leveling of communication channels can be carried out according to the known principle of loop measurement. In the end office EA ₁ , the oscillation generated by the generator G is transmitted from the frequency f ₁ (e.g. 800 Hz), the voltage of which is CZ ₀ , in arrow residual attenuation errors of the outgoing and return lines individually io direction to the end office EA ₂ and there from which to be determined. It is useful, but not amplified channel amplifier KV _1. The output of the channel absolutely necessary that in the modulator through the amplifier KV ₁ is connected via the attenuator D with setting the same frequency from the level oscillation of the return line, so that a loop is formed, which is also derived in the non-linear network and from the generator G generated in the end office EA ₁ is caused by distortion. Likewise, the invention should not be limited to the oscillation via the return line, amplified by the fact that, in order to create the channel amplifier KV ₂ , it reaches the level receiver P in the final measurement criterion for the elimination of the residual office EA ₁ . In the level receiver P, the attenuation path is selectively measured by a modulator instead of the distortion deviation from the target level. The display is switched on, in which the additional oscillation of the level receiver P gives but no guarantee is generated so that the voltage of the additional 20 for a correct leveling of the path, since positive oscillation is linear from the voltage of the level oscillation attenuation errors in one direction negative who is dependent. Instead of the modulator, others could compensate, for example.

wise also a link for the derivation of the additional with those shown in Figs. 2 and 3 schematically

Vibration can be used, which no linear chip arrangements can, however, according to the following has voltage dependency. The type of voltage 25 described method according to the invention level dependence of the error of the outgoing and return lines for the second measuring process separately by a turned link must be determined by the type of voltage loop measurement. The one for the measurement Dependence of the required effort used for the first measurement process depends on up to which one Distinguish between the limb. Particularly useful degrees can be assumed that the residual damping However, as already mentioned, it is moderate for the second 30 of the channels in the transmission range at all frequencies, Measurement process a link with linear voltage-dependent, especially at the frequencies used for measurement to use. zen, has the same value. This ideal case distortion

In a manner known per se, it is also advantageous that free transmission should initially be assumed for the purpose of forming the necessary for the measurement to- According to FIG. 2, the channels are through at the far end

In addition to the additional oscillation, the frequency of the level oscillation 35 multiples, in particular doubles, a loop of an attenuator D ' and a nonlinear network NW lying parallel to this in the nonlinear network or in the modulator. For the type (distortion) linked together. The network should be used for the multiplication or doubling, any circuit arrangement, preferably the first harmonic of the measurement frequency, can be used. Also generate (f ₂ = 2 ^ ₁ ). Because the residual attenuation distortion

can be used for filtering out the at the far end of the 40 according to CCIF to f - 800 Hz, should f _x

Level oscillation derived additional oscillation = 800 Hz can be selected. The voltage U _t . the first

the known sieve means and also known for the selective measurement of the vibration at the monitoring station Measurement methods are used. For example, with the help of the non-linear network am far end of the level oscillation derived additional oscillation via a switching element that is only for this additional oscillation is permeable, can be given to the return line.

__ In the course of the progressive automation of the 50 displays of the target value (A χ for f _x , A y for f ₂ ) results

The described device can also be remotely controlled semi-automatically or fully automatically in a manner known per se are executed. The readjustment of the residual attenuation regulator can also be carried out on the basis of the measurement result be done manually or automatically. The processes and facilities required for automation, such as B. the use of a service connection number, possibly with suffix dialing of another code number, or independently rotating scanning devices that

To carry out several processes fully automatically in which there are 60 attenuation differences between f _x and f ₂ on the back position are assumed to be known. You are in charge, so it turns out

advantageously applicable in connection with the invention.

The invention is based on the in Fig. 1

known principle of loop measurement shown schematically, with reference to that shown in FIGS

Embodiments explained in more detail. The operational readiness of a message channel can

be checked in a manner known per se by am

at the far end, the four-wire terminals have the correct level with- 70 a _zl =

Harmonics at the output of the distortion unit should, for example, be a quadratic function _{of the input voltage CZ 1.}

At the end of the loop, the levels for f _x and f _{s are} measured selectively. The pointers on the display instruments are at the nominal value when the residual attenuation errors in the outward and return lines (a _u and a ₂₁ for f _x = 800 Hz, a _w for / 2 = 1600 Hz) are zero. From the deviations of the

a ₂₂ =

= Ay-Ax,
= 2 Aχ - Ay.

By regulating the channel amplifier KV ₁ and
A χ and A y can be made zero. This means that the residual attenuation errors of the two channels are individually zero.

The prerequisite for distortion-free transmission is generally not met in practice. Is a _r the rest

- Ay ~ \ -a _r , Ci ₁₁ -Ay - Ax - a _r .

If the channel amplifiers KV ₁ and KV ₂ are set so that Ax and Ay are - 0, the residual attenuation errors are errors

Ci ₁₁ = —a _r ,

For \ a _T , the maximum value for CCIF-like connections is given by the tolerance scheme. After that is

I «,

. = 0.25 N

a value that appears as an error in a residual attenuation measurement of course cannot be admitted. The actual residual attenuation errors will be much smaller.

A maximum permissible residual attenuation error in a channel results from the stability requirement. if It can be assumed that for the frequencies 800 and 1600 Hz the sum of the rate and the temporal Fluctuations in the residual damping the permissible limit is always within the permissible deviation, the method described here can be used to level a communication link.

If the requirement of small distortion a _r cannot be considered to be fulfilled, a further measurement criterion must be created for the elimination of the residual attenuation path. For this purpose, the loop can be supplemented by a modulator M , which is switched on by a changeover switch S in place of the non-linear network (distorter) Vz (FIG. 3). Like the non-linear network Vz, the modulator M also generates the frequency 2 f _v, however, the voltage at the modulator output is linearly dependent on the input voltage and not quadratically. If the residual attenuation deviations in the channels a _n and a ₂₁ for / \ = 800 Hz, ₂₂ for f ₂ - 1600 Hz, the following deviations from the nominal value displays of the level receiver or level meter P result

«21 = Ax for f ₁

* 11

«22 -

2 «

for

= Ay ₂ - Ay ₁

, Modulator

'Distortion

The measurement process is as follows: The level differences Ay (f ₂ ) are measured once for the modulator path and then for the distortion path. KV ₁ is adjusted so that Ay ₁ - Ay ₂ . Then a _n , the residual attenuation error of channel 1, is equal to zero. Ax (/ \) is then made zero by rules at KV _2. This means that the speech circuit for f _x = 800 Hz is correctly adjusted.

The described measuring method is electrically equivalent to any method that uses the 800 Hz tone to measure. It can therefore be used for leveling and regular control of a speaking group.

Compared to the usual level measurements, the method has the following advantages: The disadvantage that the Compensating for residual attenuation errors in the channels is avoided by the method described. Even there are significant simplifications compared to the duct measurement. Only one set of measuring devices (transmitter and recipient) used in the same office. For the accuracy of the display of the transmission and reception level The same requirements apply as for duct measurements. The concentration of the measuring instruments in one office is Of particular interest at the network group level, where all stub lines are monitored from a node office can be. Personnel trained in measurement technology are only required in one office (node office). The laying of the Loop in the distant office does not require any specialist knowledge.

Even when operating the switch for connecting the modulator, no mistakes can be made, since KV ₁ is regulated to the same deflections Ay, regardless of the switch position. Furthermore, all known methods of automation can be used. The equipment set required at the far end (decoupler, modulator, distortion, filter means and, if necessary, amplifier) is to be regarded as a measuring device, since the function of the loop formed with it depends on the ίο absolute value of the voltage. The equipment set must therefore be calibrated from time to time with the transmitter-receiver set of the node office or be provided with a calibration circuit.

Claims (4)

PATENT CLAIMS: 1. Arrangement for measuring and monitoring the residual attenuation of a communication link after Principle of a loop measurement in which in the office at the near end of the connection a measuring transmitter and -receiver is available and at the far end the forward and return lines have the correct level, especially over an attenuator so connected to each other are that the one generated by the measuring transmitter preferably at a constant level, via the forward line transmitted level oscillation reaches the measuring receiver via the return line, characterized in that that at the far end the outward and return lines are additionally via a non-linear network that is derived from the level oscillation transmitted via the forward line, z. B. by distortion, at least one of its different vibration, especially the first Harmonic derives, the voltage of which is non-linear, preferably the square of the voltage of the level oscillation depends, are connected to each other in such a way that in the measuring receiver both the level of the above the level oscillation transmitted by the loop as well as the level of the level oscillation transmitted by it with the help of the non-linear Network at the far end derived and sent via the return line, additional oscillation is selectively measurable. 2. Arrangement according to claim 1, characterized in that the with the help of the non-linear network Additional oscillation derived from the level oscillation at the far end via a switching element, which is only permeable for this additional oscillation, reaches the return line. 3. Arrangement according to claim 1 or 2, characterized in that the non-linear network for a further measurement can be replaced by a modulator in which the additional oscillation is implemented is generated, but the voltage of this additional oscillation is linearly dependent on the voltage depends on the level oscillation. 4. Arrangement according to one of the preceding claims, characterized in that the frequency the level oscillation in the nonlinear network or in the modulator is multiplied, in particular doubled will. Considered publications: German Patent No. 826 600;
German Auslegeschrift F 16436 VIII a / 21 a ² (published on March 8, 1956). 1 sheet of drawings