Ethernet Surge Protector, PoE surge protection device parameters Testing (Part I) — The basic concept of be confused
1. Data speed and signal bandwidth
Ethernet transmission must first distinguish “signal bandwidth” and “data rate” two concepts, can distinguish from the unit, one is MHz, one is Mbps. RJ45 cat5/5e network Ethernet cable (the original cat5 line standards have been scrapped, now mentioned cat5 line refers to the super cat5e line), RJ45 cat6 Network Ethernet cable can run gigabit data, only cat5e and cat6 itself signal bandwidth, perform protocol type difference. For example, how much a road width, and how fast the car can run on the road, are the two concepts, but there is a certain correlation, when the car more and want to run fast, that is way more wide.
- cat5e line 100 MHZ maximum signal bandwidth, the highest data can run 1000 Mbps.
- cat6 line signal bandwidth of 250 MHZ, highest can run 5 Gbps data.
Achieve data through different protocol type speed changes.
Our daily said MB network gigabit network surge protection device are index according to the rate of MB and gigabit.
2. The standard Ethernet transmission
Gigabit Ethernet standard focuses on three types of transmission medium, single-mode fiber; The long wave on the multimode fiber laser (called 1000 base LX) and shortwave multimode fiber laser (called 1000 base SX);1000 base CX medium, the medium can be in equilibrium shield 150 ohms on copper cable transmission. IEEE802.3 z committee simulated 1000 base-t standard allows Gigabit Ethernet in cat5e and cat6 UTP twisted-pair expand the transmission distance of 100 meters, making the most of building internal wiring of building with cat5e of UTP twisted-pair cable, ensure the user previously investments in Ethernet, fast Ethernet.
1000 base-t and 100 base-t transfer using the same clock frequency, but with a more powerful signal transmission and encoding/decoding scheme, this scheme can be on the link twice as more than 100 base-t transmission of data.(from Baidu encyclopedia)
Visible test gigabit networks can be on the 100 MHZ or 250 MHZ signal bandwidth ran out of the 1000 Mbps. All kinds of cable types are listed in the table below the corresponding data speed.
Various application standard protocols corresponding data speed, cables, signal width (from FLUKE technical manual)
Each application standards are the rules of the limit value of the test, the selected standard is selected to determine the basis.
Common 100Mbps Ethernet surge protector (surge protection device) use 2 of line protection, should choose cat5 100 base-TX, testing 80MHz frequency band, test data speed is 100Mpbs.
Common 1000Mbps Ethernet surge protector (surge protection device), using 4 pairs of line protection, firstly confirm jumper is cat5e or cat6, and then choose the corresponding cat5e line: cat5e 1000 Base-T, testing 250 MHZ frequency band, test data speed is 1000 Mbps; cat6 line: cat6 1000 Base-TX, ATM-1.2G, FC1.2G, testing 250 MHZ frequency band, test data speed is 1000 Mbps. Gigabit net are using 4 pars line protection.
In addition to the application of standard, but also the test by the standard of different countries or regions, such as IEEE802.3; GB/T50312-2016 standards such as cat 6/5e CH several standard test Ethernet, corresponding types in standard protocol, for example, attenuation, return loss and crosstalk.
3. Test jump line selection
Ethernet SPD is in series to the CHANNEL, so it need jump line. According to T568A or T568B jumpers use different rules for using, the following figure. Select the correct RJ45 cable of Ethernet SPD accord with the requirement of the target application.
100Mbps network, gigabit network surge protection device should be distinguished by cat5e or cat6 cable types, cat6 lines generally use isolation frame, single strand wire diameter is more thicker, and do it according to the different environment choice: UTP without blocking; ScTP\FTP outer shield; STP whole block (line to outer shield) can refer to the following diagram.
As a third party testing agencies, should with STP cat6 jumper, as test spare jump line. Will response all the test result for Ethernet surge protection device sample itself, rather than jump line.
Anyhow, 100M/gigabit Ethernet communication parameters of surge protector device is not in the 100/1000 MHZ band width under test attenuation, return loss and crosstalk, even not with balanced non-equilibrium converters on the vector video network analyzer test, this is the basic concept of confusion.
Ethernet Surge Protector (Power over Ethernet PoE surge protective device) parameters Testing (Part II) — The impact of lightning protection device on high-speed link parameters
(Here do not mention the issue by the distributed capacitance and other routine of the problems of surge protection device components)
Ethernet surge protector affect three core transmission parameters in Ethernet link.
It is the insertion loss IL; Crosstalk between line and line NEXT or FEXT, and return loss RL. Since Ethernet SPD interrupt into the Ethernet line, to use jumper wire connections. The device is not only joined the parallel components, at the same time, due to the printed circuit board can only get the line is straight line, line width, line of cross-sectional area and the original cat6 and cat5e cable, a stark impedance transformation.
(1) Insertion loss formed by the resistance of the electrode between SPD, the wire diameter also has certain influence. Since joined the surge protector, to form two new RJ45 connection point, points of contact resistance and effect in the insertion loss. This is the whole loop resistance increase. If the insertion loss is too big, then the signal will not be able to spread very far, wiring is impossible to achieve the desired future project budget
Figure 1 – impedance distribution of surge protective device
(2) Crosstalk between line and line, originally using twisted pair, the line of isolation between skeleton, increase the wire diameter, increase the rate of kinky, even line for shielding to achieve high-speed transmission. However, in the surge protector circuit board, it is impossible to twisted-pair, helpless joined many parallel lines and reduce the rate of kinky. In high speed transmission line, the general requirement is solved not more than 13 mm in length, so as to run high speed network, but the surge protector can’t only 13 mm PCB wiring. For crosstalk is one of the most concerned in high-speed network indicators, generally at the time of crystal head lineup, short of a few millimeters, parallel wiring will be critically considered among the crosstalk, let alone a surge protector.
Figure 2 – printed circuit board for SPD
Printed circuit board, although can’t achieve the result of twisted pair, but still reasonable design can satisfy the use requirement
(3) the return loss, is the result of damage to impedance continuity. It is different from this impedance and the impedance of the “Part I” we mentioned, here basically to transfer characteristic impedance, general is 100-120 Ω twisted-pair cable, the cable body of the ratio of inductance and capacitance. Surge protector is parallel to the circuit board wiring described above, the whole circuit impedance continuity of a serious damage (as shown in Figure 2 – printed circuit board for SPD). Introduction of lines in the connector, also requires small solder joints as far as possible, surge protector, circuit board of the solder joints and didn’t notice the size of the problem, a discharge tube pin for more than 2 mm. The solder joints directly damage the line capacitance. Reflected back in the loop, the greater the echo of that the greater the resistance mutation.
Characteristic impedance formula
According to characteristic impedance formula, we can see as long as the shape of the transmission channel change, characteristic impedance will change
After discussing the above three core parameter, also should pay attention to another parameter, called SNR ( Signal to Noise Ratio ) ACR. Signal-to-noise ratio can be used as a correction to the previous three parameters, to determine means of comprehensive analysis. Signal strength is determined by the insertion loss. Noise intensity is determined by the crosstalk and echo. Crosstalk noise and echo is strong, but the insertion loss of small signal intensity is high, the overall signal transmission of signal distortion, not as a signal to noise ratio is small, can be judged as qualified. On the other hand, the insertion loss is small, but the echo of crosstalk, the signal-to-noise ratio is big, line transmission will not qualified.
Figure 3 – signal-to-noise ratio
Surge protector will also bring another problem, that is the line imbalance. The Cross-sectional area of line and the long and short of line, these are all made of the wiring circuit board. Because, the receiver is differential-mode amplifier, that is, between the two lines of differential mode signal is amplified and their common mode signal to the ground, regardless of the amount of interference, the offset will be amplifier. External interference signal is the role of the two line online at the same time, the two lines after the same disturbance, on the common mode interference signal is the same, on the differential mode receiver will be offset. Two wires, however, if the length is different, different degree, the wiring system is different, the distance that is relative to foreign signal is different, so the two line, produced by the common mode interference signal is the difference between the high and low, reach the differential mode signal receiver will not be completely offset, form the interference signal. Standard committee of experts seem to balance parameters, particularly interested in, because it represents the most anti-interference ability.
Figure 4 – line to line imbalance causes interference can’t equivalent offset
Generally, for surge protection, artificially increased the super point of failure. In the eyes of a network engineer, surge protection device is not support high-speed link. When acceptance of the entire network, as long as the speed run fast, check firstly whether install SPD or not. Has become a routine for inspection. In the eyes of SPD engineers, their Ethernet SPD through a variety of professional design and excellent communication parameters. Excellent but this is only for surge protection device itself, relative to a one hundred – meter channel acceptance, surge protection device takes up a lot of network resources.
Figure 5 – Qualified SPD also take up network resources
So, all test parameters of surge protection device, at the same time of attaches great importance to the test result is qualified, attention to connect into the whole channel qualified to judge how many allowance? The greater the margin after installation of the whole project acceptance, will tend to be more qualified.
Ethernet Surge Protector (PoE surge protection device) parameters Testing (Part III) — Gigabit Ethernet surge protector testing
1. Test preparation
(1) The preparation before the test, to test of jump line, general surge protection device manufacturers will be equipped with a jump line, used to connect a surge protective device construction and the line is interrupted. The next issue will be special. We use the test equipment test equipment standard test line.
(2) We choose the test jumper wire to a meter or two meters or so commonly, so we connect the surge protection device, after the formation of the channel parameters test to be accurate, because the connecting cables are too short can cause some parameter test values, the return loss, for example, will be larger because of the lines are too short.
(3) Select test standard, choose commonly used standard 1000 base-t and national standard GB50312-2016. Applied standard 1000 base-t is in view of the special application of standard 1000 Mbps, cat 5e GB50312-2016 as a cat 5e types of Ethernet cabling standards, at the time of acceptance, the standard rate range of 1000 m – 2.5 Gbps, surge protection device if access to acceptance of the link, by this standard. Finally GB50312-2016 cat 6 support link speed more wide: 1000 m – 5 Gbps, basic surge protection device. So the surge protector manufacturers must be clear, meet according to the standard of gigabit net 1000 base-t, or satisfy the whole line transmission Gigabit.
The test values of surge protection device under different standard results the same, each standard change in different letters with the limit of the frequency point determination value.
2. The gigabit network surge protection device test parameters.
To apply the standard 1000 base-t and GB50312-2016 cat 5e CH contrast test.
(1) The insertion loss
Two of standard insertion loss IL compare
|2||GB50312 CAT 5e||21.5dB/100MHz||2.5dB/100MHz|
From the point of analysis, four lines of all the insertion loss can satisfy the requirements of the standard, less than the standard limit judge the value of the red line, to pay attention to the allowance of insertion loss of 21.5 dB, this value in the engineering installation in the future, to link length is of decisive importance. Insertion loss is a unified requirements, even different standard limit.
Besides, surge protection device manufacturers often labelled Ethernet surge protector insertion loss as follows: 0.5 dB and 0.5 dB/100m, nominal highly specification, the test won’t have such a result, the next issue we only test jump line can be seen, a 1 meter long quality jump line insertion loss is 0.5 dB/100 MHz, even surge protector device. so suggest manufacturers can table 0.5 dB/10 MHz or 2.5 dB/100 MHz.
(2) The crosstalk at near-end NEXT
Two of standard near-end crosstalk NEXT compare
|2||GB50312 cat 5e||-2.8dB/12.4MHz||37.2dB/51MHz|
Qualified gigabit Ethernet surge protection device, all near-end crosstalk in limit for determining value above the red line. Unqualified Ethernet SPD, some lines of more than, the judgement of red line. We must pay attention to the test results, the parameters of the allowance for the whole channel. No.2, 12,4MHz frequency point and 2.8dB (the value less than 3dB), here need comprehensive signal-to-noise ratio to determine ACR test result.
(3) Return loss RL
Return loss RL compare
|No.||Standard||Limit value||Allowance||Minimum value|
|2||GB50312 cat 5e||10dB/100MHz||-0.6 dB/100MHz||9.4dB/100MHz|
We can see that No.2, also in 100MHz frequency point and 0.6dB (the value less than 3 dB), here also need comprehensive signal-to-noise ratio to determine ACR test result.
Qualified to judge the line position is different, different judgement of the same samples, for GB50312-2016 is not the three problems will directly determine the unqualified transmission parameters, try this kind of product and we completely different lightning protection product testing, and using the principle of transmission channel 3 db, this parameter testing SNR, as long as the signal to noise ratio meet the requirements, the principle of 3 db will automatically apply, of course the whole process of comprehensive judgement is to remove the operator cognitive effects.
(4) Signal to noise ratio ACR-N/F
Visible signal-to-noise ratio SNR test result is very good, can be identified as the NEXT and RL noise signal is big impact to the signal of the information, so the transmission within 3 db problem can determine three parameters for critical through.
(5) The wiring of diagram of Network cable
The wiring diagram of test results use different network cable
In addition we see the wiring diagram. Correlates of existing conventional lightning protection device, used mostly for two on the line, 1/2, 3/6.Using two old cat5 on line. Two pairs of line is completely run high-speed, medium-speed and high-speed link now, we will try to use four pairs of line protection and four keep high-speed transmission design of line.
Shielding layer. Surge protection device is a metal case for shielding, should choose shielding interface, in tapping the outer metal shell good grounding, shielding real impact, open the transmission lines will have corresponding anti-interference ability. When testing, surge protection device shall be earthed at the same time, the transmission test again.
Ethernet Surge Protector (PoE surge protection device) parameters Testing (Part IV) — Special quality evaluation of Ethernet jump line
1. The quality of jump line is ignored by SPD Manufacturer
Let’s talk about the short network cable which connect Ethernet surge protector. Previous we mentioned a lot of Ethernet SPD’s transmission parameters of design and test problems. Describe the bad design of surge protection device caused the network transmission bottleneck. In addition, there is still a parts to easy bring parameters limitation, it is that cable which SPD manufacturer provided, show as below.
The cable which SPD manufacturer provided
It is convenience if there is a jump line when installation, but bad quality jump line will bring some trouble.
2. The quality of different brand jumpers
In these device under test (DUT), generally there is a jump line which provided by SPD manufacturer, the label marks cat6 or cat7 on the line. We purchase some other brand line for run this test.
The table of jump line from different manufacturers
|1||AMPCOM||CAT 7 BK|
|2||PHILIPS||HIGH PERFORMACE CAT6|
|3||UGREEN||CAT6 FLAT CABLE|
|4||SPD manufacturer provide||UTP CAT6 4R-6AG VERIFIED|
Kinds of jump line from different manufacturers
We compare the three key parameters of transmission, jump line according to the type of cable cat6 national standard GB50312-2016 cat6 CH to test, test results are list as below, only the jump line (cable) which SPD manufacturer provided is unqualified.
Let’s see the waveform figure of three key transmission parameters
Insertion loss IL compare
|4||SPD manufacturer provide||20.1dB/106.5MHz||2.4dB/106.5MHz|
The jump line which SPD manufacturers provided that appear the worst value at 100 MHz, it will bring serious problems to 1000 Mbps rate transmission.
Near-end crosstalk NEXT compare
|4||SPD manufacturer provide||19.1dB/15.5MHz||72.6dB/15.5MHz|
Return loss RL compare
|4||SPD manufacturer provide||-1dB/124MHz||10.7dB/245MHz|
This jumper wire has filled the return-loss parameters of 100 m channel resources, no any allowance. Of course there are other such as SNR, signal-to-noise ratio, total power near-end crosstalk total power, etc. Between these parameters and three key parameters, have corresponding relationship, here we do not repeat the analysis.
By the test as you can see, one of the most cheap UGREEN brand jumper wire, under the cat6 national standard test, show good results than imported brand. Originally a very simple accessories, why SPD manufacturers are so difficult to do the qualified configuration? or SPD manufacturers did not inspect and test these jump wire which purchased from marketplace. This issues is very worth to think about.
3. The affect by the unqualified jumper wire when testing SPD
Once use the unqualified jumper wire, installed SPD in the channel, is also a serious impact, even if Ethernet SPD through the careful design, up to the requirements of gigabit network speed, will make the parameter results change due to use this jumper wire.
Below for a standard 1000 base-t test to apply critical qualified gigabit Ethernet SPD, when using qualified jump wire and unqualified jump wire to test, it will cause critical qualified and unqualified two final acceptance. To the same three transmission parameters, for example, the following lists the test comparison of the graphics.
Insertion loss IL
|1||Qualified jump wire||22dB/100MHz||2dB/100MHz|
|2||SPD manufacturer provide||19.8dB/100MHz||4.2dB/100MHz|
Unqualified under the gigabit speeds. at the 100MHz – 3db insertion loss.
Near-end crosstalk NEXT
|1||Qualified jump wire||0.2dB/15.4MHz||30.7dB/100MHz|
|2||SPD manufacturer provide||-19.8dB/16.3MHz||16.8dB/87.3MHz|
Near-end crosstalk test results of the most obvious difference, since the SPD with jump wire test is a mess, crosstalk between 3/6-4/5 is fully unqualified.
Return loss RL
|1||Qualified jump wire||3.8dB/100MHz||11.8dB/100MHz|
|2||SPD manufacturer provide||-2.7dB/52MHz||7.7dB/69MHz|
we can see from the compare figure, it is obvious that two tests are from qualified to unqualified. It should be clear: SPD manufacturer’s jump wire as part of SPD, must join SPD test together, regardless of SPD or jump wire as long as the connection channel parameters is unqualified, will ultimately determine the SPD is unqualified. So SPD manufacturers must inspect and test the jump wire which purchased from marketplace.
LSP can be able to provide qualified Power over Ethernet PoE Surge Protection Device DT-CAT 6A/EA, and it was certificated by TUV Rheinland.