CN101136800B - Method for testing plate-carried LAN physical layer consistency performance - Google Patents

Abstract

The method includes following steps: (1) selecting the receiving end of difference pair signal (TX) sent by 100M network port to be tested as the test point; (2) using test set to test coincidence performance indicator in physical layer; (3) determining whether tested result satisfies requirement of prearranged guideline. The invention can determine coincidence performance indicator in physical layer of 100M Ethernet electrical port in board held local area network.

Description

The method of testing of plate-carried LAN physical layer consistency performance

Technical field

The present invention relates to the communications field, and especially, relate to a kind of method of testing of plate-carried LAN physical layer consistency performance.

Background technology

Along with developing rapidly of communication, the 100 m ethernet interface is widely used in communication system.Stipulated in " IEEE802.3-2005 " standard that 100 m ethernet electricity mouth uses the two pairs 5 class unshielded twisted pairs as transmission medium, based on 4B/5B signal encoding, the data rate interface as 100Mbps, its transmission range can reach 100 meters.In order to guarantee the good communication between ethernet device, the consistency of Ethernet electrical interface physical characteristic is very important, has therefore stipulated the method for testing and the index request of the physical layer of 100 m ethernet electricity mouth in " ANSI X3.263-1995 " standard.

According to " ANSI X3.263-1995 " standard, the step of at present general 100 m ethernet electricity mouthful physical layer consistency method of testing is: the first step, select test point, test point is placed on the transmitting terminal that tested 100-M network Ethernet sends differential pair signal (TX), as shown in Figure 1; Second step, by tester (such as the communication signal analyzer of the CSA7404B model of Tektronix) test physical layer consistency performance index, this index comprises differential signal amplitude, signal amplitude symmetry, rise time and fall time, rise time and fall time symmetry, Duty Cycle Distortion degree, shake and overshoot; The 3rd step: check whether test result satisfies index request, and this index request as shown in Figure 2.

Owing to stipulated 100 m ethernet electricity mouthful physical layer consistency method of testing in " ANSI X3.263-1995 " standard, so a lot of communication test instruments according to this standard integrated the testing software of Ethernet interface, thereby carry out the test of 100 m ethernet electricity mouthful physical layer consistency performance very easily.

Along with the integrated level of communication system is more and more higher, the design of 100 m ethernet electricity mouth is also had higher requirement, in this case, plate-carried LAN has just produced thereupon.The structure of plate-carried LAN as shown in Figure 3, the transmission medium in the local area network (LAN) between each Ethernet interface is printed circuit board (PCB) (PCB) cabling, can realize the function of local area network (LAN) on the veneer or between veneer by plate-carried LAN, and not need to pass through twisted-pair feeder.Along with the development of 3G all-IP communication system, it is very general that plate-carried LAN just becomes in communication system.

Can draw the difference of plate-carried LAN and traditional local area network (LAN) by comparison diagram 3 and Fig. 1.The transmission medium of plate-carried LAN is the PCB cabling, so just do not need being used among Fig. 1 to connect the Registered Jack-45 of 5 class unshielded twisted pairs and transformer; And the transmission medium of traditional local area network (LAN) is 5 class unshielded twisted pairs, so need between 5 class unshielded twisted pairs and the transformer be connected by Registered Jack-45.

Because the introducing of plate-carried LAN technology, for the Test Engineer, the problem of bringing is exactly how to test 100 m ethernet electricity mouthful physical layer consistency performance under the topology of Fig. 3.At present, common testing methods at plate-carried LAN, test according to a 100 m ethernet electricity mouthful physical layer consistency performance method of testing of introducing previously exactly, through facts have proved, find to satisfy the fault that the 100 m ethernet electricity mouthful of " ANSI X3.263-1995 " standard-required can not proper communication, and the 100 m ethernet that does not satisfy " ANSI X3.263-1995 " standard normal communication for a long time.

So far, a kind of technical scheme that can effectively measure the consistency performance of plate-carried LAN is not also proposed.

Summary of the invention

Consider the problems referred to above and make the present invention, for this reason, the object of the present invention is to provide a kind of method of testing of plate-carried LAN physical layer consistency performance, with the consistency performance of Validity Test plate-carried LAN physical layer.

According to embodiments of the invention, provide a kind of method of testing of plate-carried LAN physical layer consistency performance.

This method may further comprise the steps: first step, and the receiving terminal of selecting the differential pair signal (TX) that tested 100-M network Ethernet sends is as test point; Second step is by tester test physical layer consistency performance index; And third step, judge whether test result satisfies the requirement of desired indicator, wherein, the setting of desired indicator comprises: the index feature of the transmitting terminal of the differential pair signal that sends according to tested 100-M network Ethernet is provided with the desired indicator of the receiving terminal of the differential pair signal that tested 100-M network Ethernet sends.

Wherein, the consistency performance index comprises: differential signal amplitude, signal amplitude symmetry, rise time and fall time, rise time and fall time symmetry, Duty Cycle Distortion degree, shake, overshoot.

When the differential signal amplitude 380mv～1050mv or-1050mv～-scope of 380mv in the time, when rise time and fall time in the scope at 3.0ns～9.6ns the time, when in the scope of signal amplitude symmetry 98%～102%, when the rise time with when fall time, symmetry was in the scope of 0ns～difference＜0.5ns, when in the scope of Duty Cycle Distortion degree at 0ns～0.5ns, when in the scope of shake at 0ns～1.4ns or when having served as in the scope that is punched in 0ns～5ns, satisfy the desired indicator requirement.

By technique scheme of the present invention, can judge the physical layer consistency performance of the 100 m ethernet electricity mouth in the plate-carried LAN exactly.

Description of drawings

Accompanying drawing described herein is used to provide further understanding of the present invention, constitutes the application's a part, and illustrative examples of the present invention and explanation thereof are used to explain the present invention, do not constitute improper qualification of the present invention.In the accompanying drawings:

Fig. 1 is the Ethernet structured flowchart in " ANSI X3.263-1995 " standard;

Fig. 2 is the index request of the ethernet physical layer consistency performance quality in " ANSI X3.263-1995 " standard;

Fig. 3 is that schematic diagram is chosen in the test point position of plate-carried LAN physical layer consistency performance test of the present invention;

Fig. 4 is the flow chart according to the method for testing of the plate-carried LAN physical layer consistency performance of the embodiment of the invention;

Fig. 5 is the index request according to the plate-carried LAN physical layer consistency performance quality of the embodiment of the invention;

Fig. 6 is the sendaisle equivalent model of the tested network interface in " ANSI X3.263-1995 " standard;

Fig. 7 is a twisted-pair feeder amplitude attenuation schematic diagram.

Embodiment

Method embodiment

A kind of method of testing of plate-carried LAN physical layer consistency performance is provided in the present embodiment.

As shown in Figure 4, method may further comprise the steps according to an embodiment of the invention: step S402, and the receiving terminal of selecting the differential pair signal (TX) that tested 100-M network Ethernet sends is as test point; Step S404 is by tester test physical layer consistency performance index; And step S406, judge whether test result satisfies the requirement of desired indicator.

Wherein, the consistency performance index comprises: differential signal amplitude, signal amplitude symmetry, rise time and fall time, rise time and fall time symmetry, Duty Cycle Distortion degree, shake, overshoot.The signal of communication analyzer of CSA7404B model that preferably, can be by Tektronix is tested the physical layer consistency performance index.

As shown in Figure 3, test point is selected in the receiving terminal that tested 100-M network Ethernet sends differential pair signal (TX).

Fig. 5 shows the index request according to plate-carried LAN physical layer consistency performance quality of the present invention.As can be seen from Figure 5, when the differential signal amplitude 380mv～1050mv or-1050mv～-scope of 380mv in the time, when rise time and fall time in the scope at 3.0ns～9.6ns the time, when in the scope of signal amplitude symmetry 98%～102%, when the rise time with when fall time, symmetry was in the scope of 0ns～difference＜0.5ns, when in the scope of Duty Cycle Distortion degree at 0ns～0.5ns, when in the scope of shake at 0ns～1.4ns or when having served as in the scope that is punched in 0ns～5ns, satisfy the desired indicator requirement.

And the index feature of the transmitting terminal of the differential pair signal that sends according to tested 100-M network Ethernet is provided with the desired indicator of the receiving terminal of the differential pair signal that tested 100-M network Ethernet sends.

In fact, by the various parameters under Fig. 1 application scenario, can derive the parameter of the receiving terminal of the tested 100-M network Ethernet transmission differential pair signal (TX) under this situation, because it is consistent that tested 100-M network Ethernet sends the parameter request of receiving terminal of differential pair signal (TX) among Fig. 1 and Fig. 3, so some parameters of the receiving terminal that can come out deriving among Fig. 1 are applied to the receiving terminal of the tested 100-M network Ethernet transmission differential pair signal (TX) Fig. 3 application scenario under.

And EIA/TIA has stipulated the parameter of the double-legged line of the non-shielding of 5 classes: rate subtracts＜1.9267sqrt (f)+0.075 (f) (db of unit); Distributed capacitance＜330pf/100 rice (with the 1khz metering); D.C. resistance＜9.38 ohm/100 meters (20 ℃ of measurement update values), the parameter that can calculate the opposite end Ethernet receiving terminal that is connected with tested network interface according to these data has:

(1) receiving terminal differential signal amplitude

Because signal can be decayed to some extent when 5 class unshielded twisted pairs transmit, as shown in Figure 7,, can calculate through the single ended output voltage amplitude behind the twisted-pair feeder according to decay formula.

According to decay formula $r_{\mathrm{DB}}=20\log \left(\frac{V_1}{V_0}\right)$ Can obtain

$V_1={10}^{\frac{r_{\mathrm{DB}}}{20}}{\mathrm{<figure-callout\; id="0"\; label="V"\; filenames="S07179512120070302E000012.png,S07179512120070302E000031.png"\; state="\{\{state\}\}">V</figure-callout>}}_0={10}^{-\left(\frac{1.9267\sqrt{31.25}+0.075\&times;31.25}{20}\right)}\&times;475=190\mathrm{mV}$

Wherein, transmission frequency is 31.25MHz on the 100 m ethernet both feet line, and the ultimate range of transmission is 100 meters, so receiving terminal differential signal amplitude is 190 * 2=380 millivolt.

(2) receiving terminal rise time and fall time

Because 5 class unshielded twisted pairs are not desirable transmission line, so exist distributed capacitance on it, its equivalent electric circuit as shown in Figure 6, and because the existence of these distributed capacitance, make the edges of signals on the twisted-pair feeder slow down, and therefore worsened quality of signals.

According to the time delay at the 50% place formula that adds up $\mathrm{\&Delta;TD}=\frac{1}{2}{Z}_{0}C$ Can obtain

$\mathrm{\&Delta;TD}=\frac{1}{2}{Z}_{0}C=\frac{1}{2}\&times;50\&times;330=8.25\mathrm{ns}$

And the rise time and the fall time that can obtain receiving terminal thus are $\sqrt{5^2+8.25^2}=9.64\mathrm{ns}$

(3) signal amplitude symmetry

Because signal amplitude symmetry is the ratio of differential signal generating positive and negative voltage amplitude, and 5 class unshielded twisted pairs have decay to the voltage magnitude of differential signal, but because the amplitude of decay is consistent, so the signal amplitude symmetry parameter remains unchanged.

(4) rise time and fall time symmetry

Because the rise time and fall time symmetry be the difference of differential signal rise time and fall time, and 5 class unshielded twisted pairs are influential to the rise time and the fall time of differential signal, but the influence time be consistent, so the rise time and fall time the symmetry parameter remain unchanged.

(5) duty ratio

Because the difference of duty ratio is differential signal on time shaft a few periods, and 5 class unshielded twisted pairs are influential to the time shaft of differential signal, but since the time of influence be consistent, so duty cycle parameters remains unchanged.

(6) shake

Jitter parameter is that duty ratio and baseline drift are relevant, and 5 class unshielded twisted pair models are to the not influence of these two parameters, so the jitter parameter of differential signal remains unchanged.

(7) overshoot

The overshoot parameter is whether the impedance on the transmission channel is relevant continuously, and the impedance of 5 class unshielded twisted pair models is continuous, so the overshoot parameter of differential signal remains unchanged.

In sum, by technical scheme of the present invention, can judge the physical layer consistency performance of the 100 m ethernet electricity mouth in the plate-carried LAN accurately, thereby solve the incredible problem of result of the 100 m ethernet physical layer consistency test in the plate-carried LAN.

The above is the preferred embodiments of the present invention only, is not limited to the present invention, and for a person skilled in the art, the present invention can have various changes and variation.Within the spirit and principles in the present invention all, any modification of being done, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (9)

1. the method for testing of a plate-carried LAN physical layer consistency performance is characterized in that,

Comprise:

First step, the receiving terminal of selecting the differential pair signal (TX) that tested 100-M network Ethernet sends is as test point;

Second step is by tester test physical layer consistency performance index; And

Third step, judge whether test result satisfies the requirement of desired indicator, wherein, the setting of described desired indicator comprises: the index feature of the transmitting terminal of the differential pair signal that sends according to described tested 100-M network Ethernet is provided with the described desired indicator of the described receiving terminal of the differential pair signal that described tested 100-M network Ethernet sends.

2. method of testing according to claim 1, it is characterized in that described consistency performance index comprises: differential signal amplitude, signal amplitude symmetry, rise time and fall time, rise time and fall time symmetry, Duty Cycle Distortion degree, shake, overshoot.

3. method of testing according to claim 2 is characterized in that, when described differential signal amplitude 380mv～1050mv or-1050mv～-scope of 380mv in the time, satisfy the desired indicator requirement.

4. method of testing according to claim 2 is characterized in that, in the scope at 3.0ns～9.6ns the time, satisfies the desired indicator requirement when described rise time and fall time.

5. method of testing according to claim 2 is characterized in that, when in the scope of described signal amplitude symmetry 98%～102%, satisfies the desired indicator requirement.

6. method of testing according to claim 2 is characterized in that, when the described rise time with when fall time, symmetry was in the scope of 0ns～difference＜0.5ns, satisfies the desired indicator requirement.

7. method of testing according to claim 2 is characterized in that, when in the scope of described Duty Cycle Distortion degree at 0ns～0.5ns, satisfies the desired indicator requirement.

8. method of testing according to claim 2 is characterized in that, when in the scope of described shake at 0ns～1.4ns, satisfies the desired indicator requirement.

9. method of testing according to claim 2 is characterized in that, when described mistake is punched in the scope of 0ns～5ns, satisfies the desired indicator requirement.

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