CN201811996U - System for testing performance of network isolating transformer - Google Patents

Abstract

The utility model discloses a system for testing performance of a network isolating transformer, which is applied to the field of communication. The system comprises a two-port network analyzer, a balancer and the network isolating transformer, wherein the balancer consists of a first balancer and a second balancer; the single-end port of the first balancer is connected with the first port of the two-port network analyzer; the differential port of the first balancer is connected with one end of the network isolating transformer, and the other end of the network isolating transformer is connected with the differential port of the second balancer; the single-port of the second balancer is connected with the second port of the two-port network analyzer; and the first balancer and the second balancer are transformers with transformer ratio being 1:2. The system can utilize network testers at two ends to test the insertion loss and the return loss of the network isolating transformer.

Description

A kind of system of test network isolating transformer performance

Technical field

The utility model relates to the performance test of the ethernet communication equipment of the communications field, relates in particular to a kind of system of test network isolating transformer performance.

Background technology

Network isolation transformer is to be applied in the ethernet device (as switch, router etc.), for fear of influencing each other of each network equipment power-supply system, needs to use network transformer to realize with the electrical isolation that outreaches equipment.Simultaneously the antijamming capability that isolating transformer can elevator system and reduce system electromagnetic interference (EMI) (electromagnetic interference, EMI).

When selecting network transformer, its some frequency domain characteristics are key indexs of network transformer type selecting, as return loss and insertion loss, and concrete being defined as follows:

(1) return loss, the circuit connection diagram of the return loss of Measurement Network equipment as shown in Figure 1, wherein, the formula of concrete calculating return loss is:

${\mathrm{RL}}_{\mathrm{dB}}=20\·{\log }_{10}\left|\frac{\mathrm{Vb}1}{\mathrm{Va}1}\right|$

Wherein, Va1 is the signal incident voltage; Vb1 is a signal reflex voltage; RL is a return loss.

Signal reflex is owing to the place of transmission signals in the impedance sudden change, part signal is reflected and returns to cause, so return loss represents that ability that isolating transformer correctly mates the both sides impedance (coupling is meant that the impedance on both sides equates) is (among Fig. 1, ZREF is called reference impedance, and ZLOAD is called loaded impedance).

(2) insert loss, the circuit connection diagram of the insertion loss of Measurement Network equipment as shown in Figure 2, the formula that loss is inserted in concrete calculating is:

${\mathrm{IL}}_{\mathrm{dB}}=20\·{\mathrm{LOG}}_{10}\left(\frac{V_{\mathrm{OUT}}}{V_{\mathrm{IN}}}\right)$

Wherein, VOUT is the output voltage of isolating transformer; VIN is the input voltage of isolating transformer.

Network isolation transformer is the transmitted in both directions device, also sets up after signal source and the load transposing among the last figure.Decay when signal is represented in the insertion loss through isolating transformer.

As depicted in figs. 1 and 2, network isolation transformer is the transmitted in both directions device, also sets up after signal source and the load transposing.

In existing Ethernet, the input and output of isolating transformer are not shown in Fig. 1 and Fig. 2, negative (-) port ground connection, but positive and negative port all is the differential pair that connects signal source, and two signal source signal amplitudes of differential pair are identical, and phase place opposite (concrete syndeton as shown in Figure 3).Like this, make that network transformer is four port devices, test needs to use the network analyzer test of four ports.And the network analyzer of four ports very expensive (generally about 1,000,000), if so carry out frequency domain test in the prior art, then need spend huge testing cost.

The utility model content

The utility model provides a kind of system of test network isolating transformer performance, can be with the insertion loss and the return loss of the network tester test network isolating transformer of two-port.

The utility model provides a kind of system of test network isolating transformer performance, comprise: the two-port network analyzer, evener and network isolation transformer, evener comprises first evener and second evener, the single-ended port of described first evener connects first port of two-port network analyzer, the difference port of this first evener connects an end of network isolation transformer, the other end of this network isolation transformer connects the difference port of second evener, the single-ended port of second evener connects second port of two-port network analyzer, wherein, described first evener and second evener are the evener of 1 to 2 no-load voltage ratio;

The reception voltage that the incident voltage that described two-port network analyzer sends according to first port and second port receive is determined the insertion loss of described network isolation transformer from first port direction to second port direction; Perhaps

The reception voltage that the incident voltage that described two-port network analyzer sends according to second port and first port receive is determined the insertion loss of described network isolation transformer from second port direction toward first port direction.

First port of described two-port network analyzer and second port are determined the return loss at network isolation transformer two ends respectively according to incoming signal that sends and the reflected signal corresponding with described incoming signal that receives.

The single ended line impedance of described first evener and second evener is 50 Europe, and the differential lines impedance is 100 Europe.

A kind of system of test network isolating transformer performance, comprise: the two-port network analyzer, evener and network isolation transformer, evener comprises first evener and second evener, the single-ended port of described first evener connects first port of two-port network analyzer, the difference port of this first evener connects an end of network isolation transformer, the other end of this network isolation transformer connects the difference port of second evener, the single-ended port of second evener connects second port of two-port network analyzer, wherein, described first evener and second evener are the evener of 1 to 2 no-load voltage ratio;

First port of described two-port network analyzer and second port are determined the return loss at network isolation transformer two ends respectively according to incoming signal that sends and the reflected signal corresponding with described incoming signal that receives.

The single ended line impedance of described first evener and second evener is 50 Europe, and the differential lines impedance is 100 Europe.

The beneficial effects of the utility model are: system provided by the utility model has all designed signal path at the two ends of measured device, not only can realize one-sided return loss test, and the return loss that can test two ends simultaneously; The system that provides of the utility model has also realized inserting the test of loss in addition.

Description of drawings

Fig. 1 is the definition and the test model synoptic diagram of network isolation transformer return loss in the prior art;

Fig. 2 is definition and the test model synoptic diagram that network transformer inserts loss in the prior art;

The structural representation that Fig. 3 connects for the network transformer differential pair;

Fig. 4 is the structural drawing of the system of a kind of test network isolating transformer of the utility model performance;

Fig. 5 is the monolateral return loss test structure of a utility model embodiment network transformer synoptic diagram;

Fig. 6 implements the bilateral return loss test structure of network transformer figure for the utility model;

Fig. 7 is the insertion loss test structural drawing of network transformer among the utility model embodiment.

Embodiment

The utility model provides a kind of system of test network isolating transformer performance, comprise: the two-port network analyzer, evener and network isolation transformer, evener comprises first evener and second evener, the single-ended port of described first evener connects first port of two-port network analyzer, the difference port of this first evener connects an end of network isolation transformer, the other end of this network isolation transformer connects the difference port of second evener, the single-ended port of second evener connects second port of two-port network analyzer, wherein, described first evener and second evener are the evener of 1 to 2 no-load voltage ratio; The incident voltage that described two-port network analyzer sends from first port receives reception voltage at second port after by first evener, network isolation transformer and second evener, and the two-port network analyzer is according to this incident voltage and receive voltage and determine the insertion loss of described network isolation transformer from first port direction to second port direction; The incident voltage that perhaps described two-port network analyzer sends from second port receives reception voltage at first port after by second evener, network isolation transformer and first evener, and the two-port network analyzer is according to this incident voltage and receive voltage and determine the insertion loss of described network isolation transformer from second port direction toward first port direction.

As shown in Figure 4, concrete structure of the present utility model is:

First port of two-port network analyzer 401 (or being called the A port) connects the single-ended port of first evener 402, and the difference port of this first evener 402 links to each other with network isolation transformer 403 (this network isolation transformer can be an isolating transformer in the utility model);

In ethernet communication equipment, utilize the evener of 1: 2 no-load voltage ratio just can realize of the mutual conversion of single-ended port to the difference port, the single ended line impedance Control of described evener is 50 Europe, the differential lines impedance Control is in 100 Europe.

The utility model utilizes evener a single-ended port translation to be become the function of a differential interface, follow the port of two-port network analyzer to connect the single-ended port of evener, the differential interface of evener is connected with isolating transformer, finish of the conversion of the single-ended port of two-port network analyzer to isolating transformer difference port.

The other end of described network isolation transformer 403 connects the difference port of second evener 404, and the single-ended port of described second evener 404 connects second port (or being called the B port) of described two-port network analyzer 401.

In the utility model, described two-port network analyzer 401, first evener 402, network isolation transformer 403 and second evener are connected into a ring.

As shown in Figure 5, when the system that using the utility model provides tests the return loss of network isolation transformer, comprising:

A port with the two-port network analyzer is that example describes in the present embodiment, and the B port is similar.

Second evener converts two-port network analyzer B port internal driving to 100 Europe impedances as loaded impedance (ZLOAD), utilize first evener to convert the differential interface of network transformer to single ended interfaces, the A port internal driving of two-port network analyzer has promptly constituted test circuit shown in Figure 5 as reference impedance (ZREF) simultaneously.

The A port of two-port network analyzer sends test signal (being incident voltage), test signal converts differential signal to through evener and arrives isolating transformer, influenced by the characteristic impedance sudden change of isolating transformer, part signal can be reflected (being reflected voltage), through getting back to the A port of two-port network analyzer behind the evener, the two-port network analyzer can and send incident voltage according to the reflected voltage that receives and calculate return loss value reflected signal again.

In the application of reality, the S11 in the two-port network analyzer (A port) test item is exactly the computing of taking the logarithm (LOG10) of the ratio of test reflected voltage of each port and incident voltage.Therefore utilize the return loss that the S11 of two-port network analyzer can test network transformer A port.If the B port (S22) of two-port network analyzer also is connected to second evener, promptly can test simultaneously every the return loss (as shown in Figure 6) that becomes two ends.

As shown in Figure 7, when the system that using the utility model provides tested the insertion loss of network isolation transformer, concrete method comprised:

The internal driving of two-port network analyzer A port is as ZREF, and the internal driving of B port is as ZLOAD, and two eveners convert the differential pair of network transformer to single ended interfaces, promptly constitute the test model that inserts loss.

The A port of two-port network analyzer sends test signal (being incident voltage), test signal through first evener after, convert differential signal to and arrive isolating transformer, this moment, a part of signal was because the impedance sudden change turns back to the A port of two-port network analyzer, after part signal passes isolating transformer, convert the B port that single-ended signal arrives the two-port network analyzer to through evener, promptly receive voltage.The reception voltage that incident voltage that the two-port network analyzer sends according to the A port and B port receive calculates, and draws the insertion loss of isolating transformer.

The S21 test item of two-port network analyzer is exactly take the logarithm (LOG10) that test A port sends signal and the ratio of B port received signal.Insertion loss when therefore Fig. 7 can the test network transformer transmits signal from left to right.In like manner, if the B port signals, A port received signal, the insertion loss when transmitting signal of can the test network transformer turning left of the S12 test item of two-port network analyzer from the right side.

Because can distinguishing accurately, each port of two-port network analyzer sends signal and received signal, therefore the utility model can be tested S12, S21, S11 simultaneously, S22, i.e. the insertion loss of the return loss at the two ends of network transformer and two different direction of transfers.

Evener of the present utility model can adopt the 0300BB of North hill, and the two-port network analyzer adopts Agilent E5071B etc.

System provided by the utility model has all designed signal path at the two ends of measured device, not only can realize one-sided return loss test, and the return loss that can test two ends simultaneously; The system that provides of the utility model has also realized inserting the test of loss in addition.

The system that utilizes the utility model to provide, the two-port network analyzer (its price has only about half of four ports) of use two-port is promptly finished the return loss and the insertion loss test of the differential interface of network transformer, has saved testing cost greatly.

The foregoing description only is the preferred embodiment of stating for explanation the utility model; certainly; the utility model also can have other embodiment; under the situation that does not deviate from the utility model spirit and essence thereof; those of ordinary skill in the art work as can make various corresponding changes and distortion according to the utility model, but these corresponding changes and distortion all should belong to the protection domain of claim of the present utility model.

Claims (2)

1. the system of a test network isolating transformer performance, it is characterized in that, comprise: the two-port network analyzer, evener and network isolation transformer, evener comprises first evener and second evener, the single-ended port of described first evener connects first port of two-port network analyzer, the difference port of this first evener connects an end of network isolation transformer, the other end of this network isolation transformer connects the difference port of second evener, the single-ended port of second evener connects second port of two-port network analyzer, wherein, described first evener and second evener are the evener of 1 to 2 no-load voltage ratio.

2. the system as claimed in claim 1 is characterized in that, the single ended line impedance of described first evener and second evener is 50 Europe, and the differential lines impedance is 100 Europe.

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