CN115189786A - Method for measuring noise of device under test and measuring apparatus - Google Patents
Method for measuring noise of device under test and measuring apparatus Download PDFInfo
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- CN115189786A CN115189786A CN202110362716.6A CN202110362716A CN115189786A CN 115189786 A CN115189786 A CN 115189786A CN 202110362716 A CN202110362716 A CN 202110362716A CN 115189786 A CN115189786 A CN 115189786A
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- 238000012360 testing method Methods 0.000 title claims abstract description 68
- 238000000034 method Methods 0.000 title claims abstract description 33
- 230000005540 biological transmission Effects 0.000 claims abstract description 39
- 238000005259 measurement Methods 0.000 claims description 46
- 238000012545 processing Methods 0.000 claims description 6
- 238000012549 training Methods 0.000 abstract description 14
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B17/00—Monitoring; Testing
- H04B17/30—Monitoring; Testing of propagation channels
- H04B17/309—Measuring or estimating channel quality parameters
- H04B17/345—Interference values
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R29/00—Arrangements for measuring or indicating electric quantities not covered by groups G01R19/00 - G01R27/00
- G01R29/26—Measuring noise figure; Measuring signal-to-noise ratio
Abstract
The invention provides a method and a measuring device for measuring noise of a device under test, wherein the device under test is connected to a link partner device through a cable, and the measuring device is respectively coupled to the device under test and the link partner device. The method can comprise the following steps: controlling the link partner device to transmit a remote data sequence to the dut according to the transmission data; controlling the device under test to recover the transmission data to generate an auxiliary data sequence according to the transmission data, wherein the auxiliary data sequence is used for counteracting with the received remote data sequence to generate a counteracting result; generating a first noise value and a second noise value in a first training stage and a second training stage respectively; and estimating noise from at least one circuit according to the first noise value and the second noise value.
Description
Technical Field
The present invention relates to noise measurement, and more particularly, to a method and apparatus for measuring noise of a Device Under Test (DUT).
Background
When the ethernet transceiver transmits data to the outside through the digital-to-analog converter, a part of the noise on the data bounces back from the cable. In measuring such noise, the related art typically stops the other end of the cable from transmitting data (i.e., the ethernet transceiver under test does not receive a signal from the other end of the cable) to ensure that the detected noise includes only the measured bounce noise and no extra signal (e.g., data or noise from the other end of the cable) is mixed therein.
However, when the other end of the cable (for example, the link partner device connected to the ethernet transceiver under test through the cable) transmits data to the ethernet transceiver under test, the load of the output terminal of the ethernet transceiver may be changed, thereby affecting the amount of the bouncing noise. As can be seen from the above, the measurement method in the related art cannot accurately know the amount of the rebound noise in actual use. Therefore, there is a need for a novel method and related measuring device to solve the problems of the related art with no or less side effects.
Disclosure of Invention
Therefore, one objective of the present invention is to provide a method and a measuring apparatus for measuring noise of a Device Under Test (DUT), so as to solve the problems of the related art.
At least one embodiment of the present invention provides a method for measuring noise of a device under test connected to a link partner (link partner) device through a cable. The method can comprise the following steps: controlling a pseudo noise (pseudo noise) generator in the link partner device to generate a remote data sequence according to transmission data and transmitting the remote data sequence to the device under test through the cable; controlling a virtual noise descrambler (descrambler) in the device under test to restore the transmission data according to the received remote data sequence to allow a virtual noise generator in the device under test to generate an auxiliary data sequence according to the transmission data, wherein the auxiliary data sequence is used for offsetting the remote data sequence received by the device under test to generate an offsetting result; obtaining a first noise value according to the cancellation result in a case where the link partner device transmits the remote data sequence to the device under test and the device under test does not substantially transmit any data to the link partner device; obtaining a second noise value according to the cancellation result when the link partner device transmits the remote data sequence to the device under test and the device under test simultaneously transmits the auxiliary data sequence to the link partner device by using at least one circuit therein; a difference between the first noise value and the second noise value is calculated to estimate noise from the at least one circuit.
At least one embodiment of the present invention further provides a measuring apparatus for measuring noise of a device under test, wherein the device under test is connected to a link partner device through a cable, and the measuring apparatus is respectively coupled to the device under test and the link partner device. The measurement apparatus may include a storage device for storing program codes and a processing circuit coupled to the storage device and configured to control the measurement apparatus to transmit control signals to the device under test and the link partner device, respectively, according to the program codes. For example: the measuring equipment controls a virtual noise (pseudo noise) generator in the link partner device to generate a remote data sequence according to transmission data, and transmits the remote data sequence to the device under test through the cable; the measurement equipment controls a virtual noise descrambler (descrambler) in the device under test to restore the transmission data according to the received remote data sequence so as to allow a virtual noise generator in the device under test to generate an auxiliary data sequence according to the transmission data, wherein the auxiliary data sequence is used for offsetting the remote data sequence received by the device under test so as to generate an offsetting result; the measurement apparatus obtains a first noise value according to the cancellation result when the link partner device transmits the remote data sequence to the device under test and the device under test does not substantially transmit any data to the link partner device; the measurement equipment obtains a second noise value according to the cancellation result under the condition that the link partner device transmits the remote data sequence to the device to be tested and the device to be tested simultaneously transmits the auxiliary data sequence to the link partner device by utilizing at least one circuit therein; the measurement device calculates a difference between the first noise value and the second noise value to estimate noise from the at least one circuit.
The method and the measuring apparatus provided by the embodiment of the invention can obtain the data and the noise from the link partner device when the transmitting end of the device to be measured does not start to operate, and then subtract the noise from the measurement result obtained after the transmitting end of the device to be measured starts to operate, so as to accurately obtain the noise amount rebounded when the transmitting end of the device to be measured sends data during actual use.
Drawings
Fig. 1 is a schematic diagram of a transceiver connected to a link partner device via a cable according to an embodiment of the present invention.
Fig. 2 is a schematic diagram of a measurement apparatus for measuring noise of a device under test (e.g., the transceiver shown in fig. 1) according to an embodiment of the invention.
Fig. 3 is a diagram illustrating some configurations of the transceiver shown in fig. 1 during a test flow according to an embodiment of the present invention.
Fig. 4 is a diagram illustrating some configurations of the transceiver shown in fig. 1 in a test flow according to an embodiment of the present invention.
Fig. 5 is a diagram illustrating some configurations of the transceiver shown in fig. 1 in a test flow according to an embodiment of the present invention.
Fig. 6 is a flowchart of a method for measuring noise of a dut according to an embodiment of the present invention.
Fig. 7 is an example of the workflow based on fig. 6 according to an embodiment of the invention.
Detailed Description
Fig. 1 is a schematic diagram of a transceiver 10 (e.g., an ethernet transceiver) connected to a link partner device 50 via a cable 20, wherein the transceiver 10 is connected to the cable 20 via a port 100 therein, and the link partner device is connected to the cable 20 via a port 500 therein, according to an embodiment of the present invention. As shown in fig. 1, the transceiver 10 may include, but is not limited to, a digital-to-analog converter (DAC) 110, an analog front-end (AFE) circuit, an analog-to-digital converter (adc) 130, an adder 140, an equalizer (equalizer) 150, a parser (slicer) 160, a pseudo noise descrambler (descrambler) 170, an echo canceller (echo canceller), a pseudo noise generator 190M (e.g., a master virtual noise generator), and a pseudo noise generator 190S (e.g., a slave virtual noise generator). It is noted that the transceiver 10 and the link partner device 50 may have the same architecture (e.g., the link partner device 50 may be an ethernet transceiver having the same architecture), and thus the link partner device 50 may also include the above-mentioned components, such as the digital-to-analog converter 510, the analog front-end circuit 520, and the virtual noise generator 590M (e.g., the main-end virtual noise generator). Other components of the link partner device 50 will not affect the overall operation in the following embodiments, and therefore are not shown in the drawings for simplicity.
In the case where both the transceiver 10 and the link partner device 50 operate in compliance with the specifications of the ethernet standard, one of the transceiver 10 and the link partner device 50 is set in a master (master) mode, and the other is set in a slave (slave) mode. For example, when the link partner device 50 is set in the master mode, the transceiver 10 is set in the slave mode, wherein the transceiver 10 uses the virtual noise generator 190S (e.g., the slave virtual noise generator therein) to carry the data to be transmitted to the link partner device 50 in the data sequence to the digital-to-analog converter 110, and the digital-to-analog converter 110 converts the data sequence from the digital format to the analog format for transmission on the cable 20. For another example, when the link partner device 50 is set in the slave mode, the transceiver 10 is set in the master mode, wherein the transceiver 10 uses the virtual noise generator 190M (e.g., the master virtual noise generator therein) to carry the data sequence to be transmitted to the link partner device 50 to the digital-to-analog converter 110, and the digital-to-analog converter 110 can convert the data sequence from the digital format to the analog format for transmission on the cable 20. For simplicity, this and subsequent embodiments are described only for the case where the link partner device 50 is set in the master mode and the transceiver 10 is set in the slave mode, and so on for the case where the link partner device 50 is set in the slave mode and the transceiver 10 is set in the master mode.
In this embodiment, the link partner device 50 may utilize the virtual noise generator 590M (e.g., the master virtual noise generator therein) to carry the data sequence to be transmitted to the transceiver 10 to the digital-to-analog converter 510, and the digital-to-analog converter 510 may convert the data sequence from a digital format to an analog format to generate an analog signal that may be transmitted via the cable 20. When the transceiver 10 receives the analog signal, the analog front-end circuit 120 may process the analog signal (e.g., filter the analog signal through a filter therein and/or amplify the analog signal through a Programmable Gain Amplifier (PGA) therein) to generate a processed analog signal, and the adc 130 may convert the processed analog signal from an analog format to a digital format to obtain the received data sequence.
In some embodiments, the transceiver 10 is transmitting signals to the link partner device 50 at the same time as receiving signals from the link partner device 50, and a portion of the signals transmitted by the transceiver 10 to the link partner device 50 will bounce back off the cable 20 and be received by the analog front end circuit 120. Therefore, the echo canceller 180 can generate a cancellation sequence according to the data sequence to be transmitted to the link partner device 50 at present, and the adder 140 can add the received data sequence and the cancellation sequence to eliminate the data component caused by the signal transmitted by the bounce of the cable 20 from the received data sequence to generate a cancelled data sequence. The state or waveform of the received data sequence may be unstable due to inter-symbol interference (inter-symbol interference) during data transmission, and it is difficult to determine the exact value. For example, if the cancelled data sequence originally expected to represent a logic value "1" at +9 volts (V) and a logic value "0" at-9V, it may be difficult to determine whether the cancelled data sequence should be +9V or-9V at a certain time point because some channels may jump between +9V and-9V at a certain time point in response to, for example, inter-symbol interference. Therefore, the equalizer 150 can perform an equalization process on the canceled data sequence to eliminate or reduce the jitter (jitter) or drift (drift) caused by the channel responses, thereby allowing the parser 160 to correctly interpret the value of the canceled data sequence. The parser 160 may then send the interpreted result to the virtual noise descrambler 170 for restoring the data to be transmitted by the link partner device 50. It should be understood by those skilled in the relevant arts that the details of the implementation of the various components in the transceiver 10 under the specification of the ethernet standard can be understood from fig. 1 and the above description, and are not described herein for brevity.
Fig. 2 is a schematic diagram of a measurement apparatus 30 for measuring noise of a Device Under Test (DUT), such as the transceiver 10, according to an embodiment of the invention, wherein the measurement apparatus 30 is coupled to the transceiver 10 and the link partner device 50, respectively. The measurement apparatus 30 may include a storage device 30S, and a processing circuit 30P coupled to the storage device 30S, wherein the storage device 30S may be used for storing a program code 30C, and the processing circuit 30P may be used for controlling the measurement apparatus 30 to transmit a control signal to the transceiver 10 and the link partner device 50, respectively, according to the program code 30C.
In fig. 3 to 5, for the sake of understanding, the components and signal paths shown in solid lines are enabled (enabled), and the components and signal paths shown in dotted lines are disabled (disabled).
In the embodiment of fig. 3, the measurement apparatus 30 may control the transceiver 10 and the link partner device 50 to operate in a first training phase TP1, wherein in the first training phase TP1, the measurement apparatus 30 may control the devices operating in the master mode to transmit data to the devices operating in the slave mode while the devices operating in the slave mode avoid transmitting any data to the devices operating in the master mode. First, the measurement apparatus 30 can control the virtual noise generator 590M in the link partner device 50 to generate a remote data sequence according to the transmission data TXdata and transmit the remote data sequence to the transceiver 10 through the cable 20. As shown in fig. 3, the far-end data sequence can be transmitted through a data path formed by the digital-to-analog converter 510, the port 500, the cable 20, the port 100, the analog front-end circuit 120, and the analog-to-digital converter 130, so that the adder 140 can obtain the received far-end data sequence, wherein the echo canceller 180 is disabled (disabled), so that the adder 140 can directly transmit the received far-end data sequence to the equalizer 150. Then, the measurement apparatus 30 can control the virtual noise descrambler 170 in the transceiver 10 to recover the transmission data TXdata according to the received far-end data sequence. Specifically, the measurement apparatus 30 may control the equalizer 150 in the transceiver 10 to perform an equalization process on the received remote data sequence to generate an equalized remote data sequence, and control the parser 160 in the transceiver 10 to obtain a restored remote data sequence according to the equalized remote data sequence, so that the virtual noise descrambler 170 restores the transmission data TXdata according to the restored remote data sequence. Since the virtual noise descrambler 170 can recover the transmission data TXdata, the virtual noise generator 190M in the transceiver 10 can generate an auxiliary data sequence (labeled as "auxiliary data" in the drawing for simplicity) according to the transmission data TXdata.
In the embodiment of fig. 4, the measurement apparatus 30 may control the transceiver 10 and the link partner device 50 to continue to operate in the first training phase TP1. It should be noted that after the tx data TXdata is recovered, the virtual noise descrambler 170 may be disabled and the echo canceller 180 may be enabled. In addition, the virtual noise generator 190M in the transceiver 10 may have the same structure as the virtual noise generator 590M in the link partner device 50, so that the virtual noise generator 190M may generate the same data sequence according to the same transmission data TXdata (i.e., the auxiliary data sequence generated by the virtual noise generator 190M may be substantially identical to the remote data sequence generated by the virtual noise generator 590M). Based on the above characteristics, the auxiliary data sequence can be used to cancel the received remote data sequence in adder 140 to generate a cancellation result. It should be noted that the echo canceller 180 is enabled if the SNR of the equalized far-end data sequence exceeds the first predetermined threshold SNR _ eye _ open, so that the cancellation result is generated if the SNR of the equalized far-end data sequence exceeds the first predetermined threshold SNR _ eye _ open. Since transceiver 10 and link partner device 50 operate in the first training phase TP1 (link partner device 50 is set in the master mode and transceiver 10 is set in the slave mode), measurement apparatus 30 can obtain the first noise value P1 according to the cancellation result when link partner device 50 transmits the remote data sequence to transceiver 10 and transceiver 10 avoids transmitting any data to link partner device 50, wherein the cancellation result is avoided from being equalized by bypass (bypass) equalizer 150 (denoted EQ =1 in fig. 4 for ease of understanding), so that the cancellation result is directly transmitted to analyzer 160 for calculating the first noise value P1. Accordingly, the first noise value P1 may include a noise value provided by the link partner device 50 (which may be referred to as a power value P (noise _ far) of the far-end noise _ far) and a noise value provided by a transmission path of the far-end data sequence (which may be referred to as a power value P (noise _ rx) of the transmission noise _ rx). It is noted that the first noise value P1 is calculated in case the signal-to-noise ratio of the cancellation result exceeds the second predetermined threshold value SNR _ EC _ done.
In the embodiment of fig. 5, the measurement apparatus 30 may control the transceiver 10 and the link partner device 50 to operate in the second training phase TP2, wherein in the second training phase TP2, the measurement apparatus 30 may control the device operating in the master mode to transmit data to the device operating in the slave mode and also transmit data to the device operating in the master mode. As shown in fig. 5, the digital-to-analog converter 110 may be enabled. Unlike the operation defined by the ethernet standard, although the transceiver 10 is set in the slave mode, the digital-to-analog converter 110 obtains the auxiliary data sequence from the virtual noise generator 190M. As such, the data sequence transmitted by the transceiver 10 to the link partner device 50 is the same as the data sequence transmitted by the link partner device in order to measure the amount of noise. Since the transceiver 10 and the link partner device 50 operate in the second training phase TP2 (the link partner device 50 is set in the master mode and the transceiver 10 is set in the slave mode), the measurement apparatus 30 can obtain a second noise value P2 according to the cancellation result when the link partner device 50 transmits the remote data sequence to the transceiver 10 and the transceiver 10 simultaneously transmits the auxiliary data sequence to the link partner device 50 by using at least one circuit therein (e.g. the digital-to-analog converter 110), wherein the cancellation result is prevented from being equalized by the bypass equalizer 150 (denoted EQ =1 in fig. 5 for easy understanding), so that the cancellation result is directly transmitted to the parser 160 for calculating the second noise value P2. Accordingly, the second noise value P1 may include a noise value provided by the link partner device 50 (which may be referred to as a power value P (noise _ far) of the far-end noise _ far), a noise value provided by a transmission path of the far-end data sequence (which may be referred to as a power value P (noise _ rx) of the transmission noise _ rx), and a noise value that the auxiliary data sequence is bounced back when transmitted to the cable 20 through the digital-to-analog converter 110 (which may be referred to as a power value P (noise _ near) of the near-end noise _ near).
Thus, after obtaining the first noise value P1 and the second noise value P2, the measurement device 30 may calculate a difference between the first noise value and the second noise value to estimate the noise from the at least one circuit (e.g., the noise that the auxiliary data sequence bounces back when transmitted to the cable 20 through the digital-to-analog converter 110, such as the near-end noise _ near). The near-end noise value P (noise _ near) obtained in the above manner is measured when a signal is transmitted at the other end of the cable, so that the method can be closer to a real situation, and the problem of the related art is solved.
Fig. 6 is a flowchart of a method for measuring noise of a device under test that is connectable to a link partner device (e.g., link partner device 50) via a cable (e.g., cable 20), according to an embodiment of the invention. The workflow of the present embodiment can be applied to the measurement apparatus 30 shown in fig. 2, and the transceiver 10 shown in fig. 3 to 5 can be taken as an example of the device under test. It should be noted that one or more steps may be added, modified or deleted from the workflow shown in fig. 6 as long as the overall result is not obstructed, and the steps do not necessarily have to be executed completely in the order shown in fig. 6.
In step S610, the measurement apparatus 30 may control a virtual noise generator in the link partner device to generate a remote data sequence according to the transmission data, and transmit the remote data sequence to the device under test through the cable.
In step S620, the measurement apparatus 30 can control the virtual noise descrambler in the device under test to recover the transmission data according to the received remote data sequence, so as to allow the virtual noise generator in the device under test to generate an auxiliary data sequence according to the transmission data, wherein the auxiliary data sequence is used to cancel the received remote data sequence to generate a cancellation result.
In step S630, the measurement apparatus 30 may obtain a first noise value according to the cancellation result under the condition that the link partner device transmits the remote data sequence to the dut and the dut avoids transmitting any data to the link partner device.
In step S640, the measurement apparatus 30 obtains a second noise value according to the cancellation result when the link partner device transmits the remote data sequence to the dut and the dut simultaneously transmits the auxiliary data sequence to the link partner device by using at least one circuit therein.
In step S650, the measuring device 30 may calculate a difference between the first noise value and the second noise value to estimate the noise from the at least one circuit.
Fig. 7 is an example of the workflow based on fig. 6 according to an embodiment of the invention. It should be noted that one or more steps may be added, modified or deleted from the workflow shown in fig. 7 as long as the overall result is not hindered, and the steps do not have to be executed completely in the order shown in fig. 7.
In step S700, the measurement apparatus 30 may perform initial setting on the device under test and the link partner device. For example, the device under test is set in the slave mode, and the link partner device is set in the master mode. In addition, the device under test and the link partner device may be connected with a cable of, for example, 100 meters, and the measurement apparatus 30 may synchronize the frequencies of the device under test and the link partner device.
In step S710, the measurement apparatus 30 can link the device under test and the link partner device in a first training phase TP1 (i.e., control the two devices to operate in the first training phase TP 1), and set the gain of a programmable gain amplifier (e.g., a programmable gain amplifier in the analog front end circuit 120) according to the length of the cable (e.g., 100 meters). The dut may now operate according to the normal first training phase TP1 procedure, and the measurement apparatus 30 may monitor the SNR _ SL measured by a profiler (e.g., profiler 160) within the dut.
In step S720, the measurement device 30 can determine whether the signal-to-noise ratio SNR _ SL exceeds a first predetermined threshold SNR _ eye _ open (denoted as "SNR _ SL > SNR _ eye _ open. If the determination result is yes, it indicates that the equalization process performed by the equalizer 150 on the received remote data sequence is completed (the signal is stabilized), and the flow proceeds to step S730; if the determination result is "no", the process returns to step S710.
In step S730, the measurement apparatus 30 may maintain the link partner device in the first training phase TP1 and reset the equalizer in the device under test (e.g., set to the bypass mode, denoted as "EQ = 1"), then turn on the echo cancellation operation in the device under test that matches the data (e.g., TXdata) transmitted by the link partner device, and monitor the SNR _ SL measured by the parser (e.g., parser 160) in the device under test.
In step S740, the measurement apparatus 30 may determine whether the signal-to-noise ratio SNR _ SL exceeds a second predetermined critical value SNR _ EC _ done (denoted as "SNR _ SL > SNR _ EC _ done. If the determination result is yes, it indicates that the echo cancellation operation is completed (the signal is stable), the process proceeds to step S750; if the determination result is "no", the process returns to step S730.
In step S750, the measurement device 30 may calculate the noise power P1 received by the parser, where P1= P (noise _ far + noise _ rx), where P (noise _ far + noise _ rx) may be used to represent the total power of the far-end noise _ far and the transmission noise _ rx.
In step S760, the measurement apparatus 30 sets the link partner device and the device under test in the second training phase TP2, then outputs transmission data TXdata using a digital-to-analog converter (e.g., the digital-to-analog converter 110) in the device under test, and monitors a signal-to-noise ratio SNR _ SL measured by a parser (e.g., the parser 160) in the device under test.
In step S770, the measuring device 30 can determine whether the SNR _ SL exceeds a second predetermined threshold SNR _ EC _ done (denoted as "SNR _ SL > SNR _ EC _ done.
In step S780, the measuring device 30 may calculate the noise power P2 received by the parser, where P2= P (noise _ far + noise _ rx + noise _ near), where P (noise _ far + noise _ rx + noise _ near) may be used to represent the total power of the far-end noise _ far, the transmission noise _ rx, and the near-end noise _ near.
In step S790, the measurement apparatus 30 may calculate the noise power of the digital-to-analog converter in the device under test, for example, calculate the power value P (noise _ near) = P2-P1 of the near-end noise _ near from the digital-to-analog converter.
In summary, the embodiments of the present invention can remove the influence caused by far-end noise, channel noise, non-ideal effect of the equalizer, etc. through the control of the measurement process, so as to calculate the near-end noise value under the condition that there is a transmitted signal at the other end of the cable, thereby being closer to the real situation and solving the problems of the related art.
The above description is only a preferred embodiment of the present invention, and all the equivalent changes and modifications made according to the claims of the present invention should be covered by the present invention.
Description of reference numerals:
10: transceiver
20: cable wire
50: link partner device
30P: processing circuit
30S: storage device
30C: program code
30: measuring device
100. 500: port(s)
110. 510: digital-to-analog converter
120. 520, the method comprises the following steps: analog front-end circuit
130: analog-to-digital converter
140: adder
150: equalizer
160: dissector
170: virtual noise descrambler
180: echo canceller
190S, 190M, 590M: virtual noise generator
S610, S620, S630, S640, S650: step (ii) of
S700, S710, S720, S730, S740, S750, S760, S770, S780, S790: step (ii) of
Claims (10)
1. A method for measuring noise of a device under test connected to a link partner device by a cable, the method comprising:
controlling a virtual noise generator in the link partner device to generate a remote data sequence according to transmission data, and transmitting the remote data sequence to the device under test through the cable;
controlling a virtual noise descrambler in the device under test to restore the transmission data according to the received far-end data sequence so as to allow a virtual noise generator in the device under test to generate an auxiliary data sequence according to the transmission data, wherein the auxiliary data sequence is used for counteracting with the far-end data sequence received by the device under test so as to generate a counteracting result;
obtaining a first noise value according to the cancellation result in a case where the link partner device transmits the remote data sequence to the device under test and the device under test does not substantially transmit any data to the link partner device;
obtaining a second noise value according to the cancellation result when the link partner device transmits the remote data sequence to the device under test and the device under test simultaneously transmits the auxiliary data sequence to the link partner device by using at least one circuit therein; and
a difference between the first noise value and the second noise value is calculated to estimate noise from the at least one circuit.
2. The method of claim 1, wherein the virtual noise generator in the device under test has the same architecture as the virtual noise generator in the link partner device.
3. The method of claim 1, wherein:
the first noise value includes a noise value provided by the link partner device and a noise value provided by a transmission path of the remote data sequence; and
the second noise value includes a noise value provided by the link partner device, a noise value provided by a transmission path of the far-end data sequence, and a noise value that the auxiliary data sequence bounces back when transmitted to the cable through the at least one circuit.
4. The method of claim 1, wherein controlling the virtual noise descrambler in the device under test to recover the transmitted data according to the remote data sequence received by the device under test comprises:
controlling an equalizer in the device to be tested to perform equalization processing on the remote data sequence received by the device to be tested so as to generate an equalized remote data sequence; and
and controlling a parser in the device to be tested to obtain a restored remote data sequence according to the equalized remote data sequence, so that the virtual noise descrambler restores the transmission data according to the restored remote data sequence.
5. The method of claim 4, wherein the cancellation result is generated if the signal-to-noise ratio of the equalized remote data sequence exceeds a predetermined threshold.
6. The method of claim 4, wherein the cancellation result is avoided from equalization by bypassing the equalizer to be directly sent to the parser for calculating the first and second noise values.
7. The method of claim 6, wherein calculating the first noise value and the second noise value is performed if a signal-to-noise ratio of the cancellation result exceeds a predetermined threshold.
8. A measurement apparatus for measuring noise of a device under test connected to a link partner device through a cable, the measurement apparatus being coupled to the device under test and the link partner device, respectively, the measurement apparatus comprising:
a storage device for storing program code; and
a processing circuit, coupled to the storage device, for controlling the measurement apparatus to transmit control signals to the device under test and the link partner device, respectively, according to the program code;
wherein:
the measuring equipment controls a virtual noise generator in the link partner device to generate a remote data sequence according to transmission data and transmits the remote data sequence to the device to be tested through the cable;
the measuring equipment controls a virtual noise descrambler in the device to be tested to restore the transmission data according to the received far-end data sequence so as to allow a virtual noise generator in the device to be tested to generate an auxiliary data sequence according to the transmission data, wherein the auxiliary data sequence is used for counteracting with the far-end data sequence received by the device to be tested so as to generate a counteracting result;
the measurement apparatus obtains a first noise value according to the cancellation result when the link partner device transmits the remote data sequence to the dut and the dut does not substantially transmit any data to the link partner device;
the measuring equipment obtains a second noise value according to the offset result under the condition that the link partner device transmits the remote data sequence to the device to be tested and the device to be tested simultaneously transmits the auxiliary data sequence to the link partner device by utilizing at least one circuit therein; and
the measurement device calculates a difference between the first noise value and the second noise value to estimate noise from the at least one circuit.
9. The method of claim 8, wherein the virtual noise generator in the device under test has the same architecture as the virtual noise generator in the link partner device.
10. The method of claim 8, wherein the first noise value comprises a noise value provided by the link partner device and a noise value provided by a transmission path of the remote data sequence; and the second noise value comprises a noise value provided by the link partner device, a noise value provided by a transmission path of the far-end data sequence, and a noise value that the auxiliary data sequence bounces back when transmitted to the cable through the at least one circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110362716.6A CN115189786A (en) | 2021-04-02 | 2021-04-02 | Method for measuring noise of device under test and measuring apparatus |
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