JPH02111140A - Line simulator - Google Patents

Abstract

PURPOSE:To realize an operation while observing a displayed pattern and to improve operability by integrating an operation section for parameter setting to generate noise able to be produced in a communication line based on a random number and a display section displaying a random number or the like. CONSTITUTION:The circuit of a line simulator 1 is housed in the inside of a casing 2. The upper half of the upper face of the casing 2 is occupied by a display screen of a display device 3 and the lower half is formed as an operation section 4 having various operation keys or the like arranged. Moreover, plural connectors 5 to be connected to a device to be tested are arranged to one side face of the casing 2. In the case of using the line simulator, the line simulator 1 is connected to a device A to be tested, the simulator 1 applies the processing to give noise to a transmission signal (communication data) and the resulting signal is sent to the device A to be tested, thereby checking the operation of the device A to be tested. In this case, while the initial value of the random number, the present value of the random number and the elapsed time after the operation start are displayed on the display device 3, the operation section 4 applies the operation such as the input of the random number initial value and the start and stop of noise addition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a line simulator that simulates noise that may occur on a communication line for purposes such as performance testing of communication equipment.

[Prior Art] In recent years, with the development of digital communication technology, communication devices including LSIs with built-in seed (communication element) III'l have been developed. To test and evaluate LSIs, it is necessary to incorporate phenomena that may occur in actual communication channels.

In particular, noise is inherent in actual communication channels, and errors due to noise occur on the communication lines. Therefore, a device is known that applies a certain amount of noise to a prototype communication device and measures the error rate (occurrence rate).

[Problems to be Solved by the Invention] However, in conventional error rate measuring devices, the noise applied to the device under test is analog noise generated by an electrostatic noise generator, and its pattern is fixed to a constant value. Therefore, there was a problem in that it did not reflect the noise that could actually occur on the communication line, and it was not possible to measure error rates for various types of noise.

In order to solve this problem, the present inventors have developed a line simulator that simulates noise, signal waveform distortion, etc. that can occur on communication lines (Patent Application No.
No. 138376), this method variably sets parameters for generating noise and waveform distortion that may occur in communication lines, generates an error signal determined by the parameters from random numbers generated by a random number generating means, and generates an error signal determined by the parameters. While the noise is occurring, the noise determined by the above parameters is added to the externally input signal and output. It has become possible to test the behavior and performance of communication equipment in response to communication failures.

In order to make the above-mentioned line simulator more practical, the present invention aims to provide an easy-to-use line simulator that allows easy operations such as setting initial values of random numbers that generate reproducible noise. do.

[Means for Solving the Problems] The present invention is a line simulator that generates noise based on random numbers on one communication line, and includes an initial value of the random number, a current value of the random number, and an elapsed time after activation or equivalent thereof. A display section for displaying a value, a random number initial value input means for inputting an initial random number value, and a start operation means for starting an operation of adding noise to a communication line.

and an operation section including a stop operation means for stopping the operation.

The present invention also provides a parameter setting means for variably setting parameters for generating noise on a communication line, a scatter generation means for generating random numbers, and a parameter setting means for generating random numbers from the random numbers generated by the random number generation means. a signal generating means for generating an error signal determined by a set parameter; and a signal generating means for adding noise determined by the parameter set by the parameter setting means to an externally input signal while the error signal is being generated. a display means for displaying an initial value of the random number generated by the random number generating means, a current value of the generated random number, an elapsed time after startup, and a parameter set by the parameter setting means; and an initial value of the random number. and operation means for executing the input of the noise adding operation and the start and stop of the noise adding operation.

[Function] In the line simulator of the present invention, the display section displays the initial value of the random number, the current value of the random number, and the elapsed time since the start of the operation, while the operation section allows input of the initial random number value, start of the noise addition operation, and The operator who performs operations such as stopping can therefore know how much noise has been generated within a certain period of time, and can accurately perform a performance test on the device under test. Also, if the initial value of the random number is recorded, communication tests using the same noise generation can be repeated over and over again. Furthermore, the test can be started/stopped at any time.

In a line simulator equipped with a parameter setting means for variably setting parameters for generating noise on a communication line, an error signal determined by the parameters set by the parameter setting means is generated from random numbers generated by the random number generation means.

While this error signal is generated, noise determined by the parameters set by the parameter setting means is added to the externally input signal and output. During such a noise adding operation, the initial value of the random number, the current value of the random number, the elapsed time after startup, and the setting parameters are displayed on the display means, so that it is easy to input the initial random number value and start and stop the noise adding operation using the operating means. can be carried out accurately.

[Example] A line simulator 1 shown in FIG. 1 houses a circuit constituting the simulator inside a rectangular parallelepiped-shaped casing 2. The upper half of the upper surface of the casing 2 is occupied by a display screen of a display device 3 that displays as will be described later, and the lower half is configured as an operation section 4 on which various operation keys, etc. described below are arranged.

Further, on one side of the casing 2, a plurality of connectors 5 for connection to a device under test are arranged.

When in use, as shown in FIG. 2, the line simulator 1 of the present invention is connected to the device under test A, and the simulator 1 performs processing to add noise to the transmission signal (communication data). Send it to JA.

By checking the operation of the device under test A, it is possible to check the behavior and performance against communication failures.

Next, the display device 3 provided in the embodiment of FIG. 1 is composed of a liquid crystal display device, and has a 15-line display section as shown in FIG. 3 within its display screen. Of these, the top three lines are a monitor section that displays actual measured values measured by the simulator, and consists of the following items.

Tame: Displays the total 311 elapsed time (time elapsed after startup) in hours, minutes, and seconds (maximum display time range is 24 hours)
However, the display method is not limited to this, and numbers or characters corresponding to the elapsed time may be displayed.

Line: Displays the disconnection state of the communication line.

If the communication line is connected "==±======J is displayed, ! /J If it is disconnected, "r===X===" is displayed.

Bit Error Counts: Displays the number of bit errors that have occurred since the start of measurement.

BER: Bit error rate calculated using the above Bit Error Counts value.
or Rate).

RND: Displays the current random number value.

This monitor section is a section that cannot be written to by key operations on the operation section 4, and even after the power is turned on, a total of J11
Only the title is displayed while it is not running.

The fourth and subsequent lines are sections that display various measurement operation conditions that can be set by key operations, and are comprised of the following items ① to ＠.

■Line 5elect: Communication line standard (e.g. R5422, R5232C, T
TL).

■Baud Rate: Displays the selected communication data transfer rate. The selectable range is, for example, 1 Mbps to 300 bps.

■Pulse Width: Displays the error pulse width of a bit error that occurs at one time 0 The range of pulse widths that can be selected is, for example, IJLS-
It is assumed that selection can be made in 100 ms at intervals of 1, 2, and 5×10.

■Error Mode: Displays the type of bit error that occurs. The error type refers to how the communication data is changed by adding an error, and the contents are as follows, and one of them is selected.

Thru: Do nothing.

High: Forcibly save data by the width of the error pulse.
1”.

Low: Forces the data by the width of the error pulse to
”.

In5ert: Invert the data by the width of the error pulse.

■Initial RND: Bit errors are generated by random numbers and added to communication data, but the initial values input to create the random numbers are displayed here. Since the initial value of the random number can be set, it is possible to reproduce the simulated operation.

This random number initial value is input as an 8-digit hexadecimal number using the 16 keys, unlike other setting items. At the end of the input,
It is necessary to operate the rENTRJ key, which will be described later, and the input data becomes valid only when this key is manually operated. However, rEN
If you operate the rSTRTJ key (described later) before pressing the TRJ key manually, it will be assumed that an ENTRJ input has been made, and the value displayed on the screen will be valid.

■Err Trig Rate: This is the reciprocal of the value (number of bits) that indicates how many bits an error will occur once in, and the frequency at which a bit error will occur is displayed on this display. The range that can be selected using the key operations described below is, for example, 1.49XIO-8 to 9.78X.
10-4, which can be set at intervals of 1/22.

■Duty: Displays the duty ratio of communication data. The range of duty ratios that can be selected is, for example, 6.25% to 93.75%, and can be selected at 3.125% intervals.

■Trigger 5source: Displays the measurement start trigger. This can be selected from the following:

Key: Start measurement by pressing the rsTRTJ key on the operation unit.

RXCP-Edge: Measured by positive edge of communication data. Start measurement.

RXCN-Edge: Total due to negative dispute over communication data. Start measurement.

EXT P-Edge: Positive edge of external trigger signal Start the measurement with .

EXT N-Edge: Negative edge of external trigger signal Start measurement with .

No matter which measurement start trigger listed in L is selected, it is necessary to press the rSTRTJ key before the trigger signal arrives. If “Key” is selected as the trigger, rS
Measurement starts simultaneously with the input of the TRTJ key. Also,
In any case, when the ``5TOPJ'' key is pressed or when a stop signal is input from the outside, measurement stops immediately.

■RXC5source: Displays the communication data synchronization signal. This can be selected from the following:

Int P-Edge: Same as Positive Edge for communications data. Start-stop synchronous communication.

Int N-Edge 2 Same as negative dispute over communication data. Start-stop synchronous communication.

EXT P-Edge: Positive effects of external synchronization clock Synchronous communication by

EXT N-Edge: Negative effects of external synchronization clock Synchronous communication by

6 IJitter: Displays the amplitude of jitter (waveform fluctuation) added to communication data. The values are 0%, ±3.125%, ±6.25
You can choose from %. 0% is when no jitter is added.

oBER = This is the actual error trigger rate (Err
Trig Rate), error pulse width (Pulse
This is an item that is automatically calculated and displayed by the simulator from Width) and Baud Rate, and cannot be input by key operation. The value displayed here is called the "pit error rate" and corresponds to the probability that one bit of communication data will become an error per second.

Weird 5ave or Load no: Operation section 4
The test conditions set by key operations are stored in the simulator's storage device and can be retrieved and used whenever necessary. This test condition can be stored for example up to 9
The number of files to be saved or retrieved is set in advance. The set file number will be displayed here.

Next, the operation unit 4 is comprised of the following keys marked with D in order from the left side in FIG.

(→"0" to "9" and "A" to "F" are keys for inputting the initial random number 4fi kJ of 16il numbers.

``rsAVE'' and ``rLOAD'' These are keys for storing and retrieving the aforementioned test conditions.

@rENTR" This is the key operated when setting the initial random number value as described above.

(d) Four "Δ" keys with different orientations. These keys are used to move the cursor on the display screen up, down, left, and right. Two "Mu" keys with different orientations are used to display the contents of each selection item mentioned above on the screen. Regarding the contents of the six selection items that are keys, pressing the "M" key will display the next one, and pressing the "M" key will display the previous one.

■rcUTJ This key is used to disconnect and disconnect communication lines.

Every time I press this, the line is disconnected! A continuations are performed alternately.

(sec rERORJ During measurement, the pulse width of the error that occurs is the key to forcibly generate one error if necessary.
The value set in "(7) rPulse Width" above is 〒.

■rsTOPJ Key to stop measurement. By pressing this key, measurement can be stopped regardless of the measurement start trigger described above.

(T) rsTRTJ Pressing this key enters the state of waiting for the measurement start trigger described above. Then the rT r i gg6r
Measurement starts when the trigger selected in 3sourceJ is input. If rKeyJ is selected, measurement starts at the same time as this "5TRT" key is input.

In addition to the operation keys mentioned above, the operation unit 4 also includes a power switch 4.
A and a display section 4b that lights up when an error pulse occurs are also arranged.

As a general rule, the line simulator 1 of the embodiment displays the initial value of the random number (Initial) in the display screen on the top surface of the casing.
RND), the current value of the random number (RND), the elapsed time after the start of the operation (Time), etc. are displayed on the operation unit 4.
Operation means for inputting initial random numbers (cursor movement keys, 0
~9 and A-F 16+-1rENTRJ keys), an operating means to start the noise adding operation (rsTRTJ key), and an operating means to stop the noise adding operation (the 5T
OPJ key), it is possible to know how much noise has been generated within a certain period of time, making it possible to accurately perform performance tests on the device under test. Furthermore, by storing the initial value of the random number, communication tests with the same noise generation can be repeated over and over again, and the tests can be started and stopped at any time.

Next, the casing 2 houses a circuit that constitutes a line simulator according to the above-mentioned patent application. Its structure and operation are as follows.

First, as shown in FIG. 4, the circuit of the line simulator includes a parameter setting section 6, a control section 7, an error signal generation section 8,
It consists of a claw generation section 9 and a line section 10.

The parameter setting section 6 is a means for setting parameters such as bit error rate for generating noise that may occur in the communication line, and in the wooden embodiment, it is constituted by the keys of the operation section 4.

The control unit 7 holds the parameters input from the parameter setting unit 6, sends a display signal for causing the display device 3 to display the necessary information, and uses a random number generation circuit, which will be described later, based on the parameters set as described above. This is a part that performs operations such as selecting a generated random number and generating a pit error signal, and is composed of a CPU equipped with the following various registers as a holding means for holding parameters set in the parameter setting section 6. Ru. That is, the CPU generates a random number initial 4
+ti setting register 11, pit error rate, immersion chamber register 12. Bit error pulse width setting register 13,
It has a pit error mode setting register 14, a rising delay setting register 15, a falling delay setting register 16, and a line interruption register 17.

The random number initial value setting register 11 is a register for setting an initial value of a pseudo random number generation circuit 21, which will be described later. By writing an initial value to this register, you can directly preset the pseudo-random number generation circuit 21. Also, by setting a certain initial value in this register, the same bit error pattern can be generated from the pseudo-random number generation circuit 21, so it is possible to test This is effective when repeating.

The bit error rate setting register 12 is a register for setting the bit error rate, and the bit error rate is approximately 10 per line.
-3 to 10-8 times/bit error can be set. Each line generates bit errors at the same pit error rate.

The bit error pulse width setting register 13 is a register that sets the pulse width when a bit error occurs, which will be described later.

The bit error mode setting register 14 sets the type of bit error (Thru, High, Lov, Inve) to be added as noise to the communication data signal as described later.
This is a register for setting rt). This is “Th”
When set to "ru", the communication data signal does not change even when a bit error occurs, which will be described later. However, when set to "old gh", the input signal changes to H level "1" when a bit error occurs. Output from line section 4, “Low”
”, when a bit error occurs, the input signal changes to L level “0” and is output. Also, “Inv
ert'', the input signal is inverted and output when a bit error occurs.

The rise and fall delay setting registers 15 and 16 are registers for individually setting the rise time delay and fall time delay that occur in the actual communication path.

If the frequency generated by the clock generation circuit 9 is set to, for example, 16 times the baud rate, a delay of 1716 data beats or 2 beats can be set.

The line disconnection register 17 is a register for disconnecting communication to the line unit, and can make the output from the line unit 4 high impedance.

Next, the error signal generation section 8 is a section that generates an error signal for simulating phenomena that may occur in an actual communication line, and includes a pseudo random number generation circuit 21, a bit error generation circuit 22, and a bit error pulse width generation circuit. circuit 23
Consists of.

The pseudo-random number generation circuit 21 includes an Excl.
Pseudo-random numbers are generated by intervening a sive OR circuit E1"'E13 and varying the outputs X32-x1 of each of the flip-flops D32-D. A pseudo-random number generating circuit having such a configuration is known per se. It is.

In this pseudo-random number generation circuit 21, in order to set the initial value of the random number to be generated, each of the D flip-flops D1 to D32 has a set terminal, into which the output signal of the random number initial value setting register 11 is inputted. This puts the D flip-flop in the set state. That is, by writing an initial value into the random number initial value setting register 11, the register output is applied to the set terminals of the D flip-flops D1 to D32, and the initial value of the pseudo random number generation circuit 21 can be preset.

As shown in FIG. 6, the bit error generation circuit 22 includes a decoder 31 that decodes the bit error signal from the pit error rate setting register 12, and a signal generated by the pseudo random number generation circuit 21 from the decoder 31. It consists of a data selector 32 that outputs only the signal to be used from among the generated pseudo-random numbers, and an AND circuit 33 that outputs a bit error occurrence signal when all the signals output from the data selector 32 are H. As a result, if the number of random number signals selected by the data selector 32 is n, then 17
A bit error occurrence signal is output with a probability of 2''.

The bit error pulse width generation circuit 23 includes a timer 34 and an RS flip-flop 35, as shown in FIG. During operation, as shown in FIG. 8, the output from the bit error generation circuit 22 (bit error generation signal) is used as a start signal to start the timer 34, and the RS
The flip 70 knob 35 is set to generate a bit error pulse. After counting the pulse width set in the bit error pulse width setting register 13, the timer 34 resets the RS flip-flop 35. This results in a bit error of the set pulse width. The pulse width is n - n + 1 g for the set value n
sec. If the next signal comes before the bit error pulse ends, the pulse width is further extended by the set value from that point onwards.

The clock generation circuit section 9 has a constant frequency (for example, 16MH).
The output signal from the crystal oscillation module (z) is frequency-divided to generate lock signals necessary for each of the above-mentioned circuits.

Next, the line section 10 is a section that processes the input signal according to the parameters given from the simulator main body 3 and outputs it, and also performs connection and disconnection of the line.

Specifically, as shown in FIG. 9, the line section 10 includes a receiver 41 that converts the level of a signal input from a transmission line, a rise detection circuit 42 that detects the rise of the input signal, and timers 43 and 44. It includes a fall detection circuit 45 that detects the fall of an input signal, an RS flip-flop 46, a noise addition circuit 47, and a driver 48 that converts the level of its output signal and outputs it to a transmission line. Each detection circuit 42
45 is a D flip-flop, and each of the timers 43 and 44 is a down counter.

During operation, the detection circuits 42 and 45 detect the rising edge of the input signal,
When the falling edge is detected, timers 43 and 44 are started. Each of the timers 43 and 44 changes its output after a delay time determined by the signals (rise and fall delay values) sent from the rise and fall delay setting registers 15 and 16 of the control unit 7, respectively. The RS flip-flop 46 is set by a change in the output of the rise delay timer 43 and reset by a change in the output of the fall delay timer 44. This allows the first
As shown in FIG. 0, a signal having a preset rise and fall delay is output.

In this way, the detection circuits 42, 45 and the timers 43 and 44
and RS flip-flop block 46 are waveform conversions that can delay the rise time and fall time of a signal input from a transmission line within a range of less than 1 bit time (until just before the next signal change). It constitutes a circuit. Assuming that the set value is n and the period of the clock used in this circuit is T, the 8 total time is nT to (n+1)T.

The clock signal supplied to the timers 43 and 44 is as follows:
Typically, a frequency of 16 times the baud rate is used, but a clock with a lower frequency can also be used to create longer delays. In this case, the rising delay time is until immediately before the next rising edge, and the falling delay time is until immediately before the next falling edge.

The waveform conversion circuit described above can change the duty ratio of the input signal by individually setting rise and fall delay times. Furthermore, by changing each delay value, jitter (waveform fluctuation) can be caused.

The noise output circuit 47 applies an error mode (Thr.
When no bit error occurs (when the bit error pulse is L), the input signal is output as is regardless of the error mode. When a bit error occurs (when the bit error pulse is H), the input signal is changed and output according to the error mode.

In other words, when the error mode is Low, the output is output regardless of the input while a bit error occurs.
and if the error mode is High, the output is unrelated to the input (High) while a bit error occurs.
become. Similarly, when the error mode is Invert,
While a bit error occurs, the output is the inverse of the input. When the error mode is Thru, the input signal is output as is (no noise is added) even if a bit error occurs.

The output signal from the above noise adding circuit 47 is as follows.

The signal is level-converted by the driver 48 and output to the transmission line, but the driver 48 is closed by the line disconnection signal from the line disconnection register 17 described above. In other words, line intermittent register 1
7 outputs a line disconnection signal, the output side of the driver 48 becomes high impedance, and the transmission line can be substantially disconnected.

As described above, the illustrated embodiment uses parameters such as random numbers on the display screen in a line simulator that generates bit error pulses based on random numbers and can also simulate waveform distortion and line disconnections that may occur in communication lines. In addition to displaying the parameters, the parameters can be set variably using the keys on the operation panel.When using this to perform sex tests on communication devices, the operator can operate the keys while looking at the display screen. It has the advantage of good operability and ease of use.

Although the present invention has been described above with reference to embodiments, the present invention is not limited thereto, and the circuit, display section, and operation section constituting the line simulator may use any means as long as it has the above functions. It can be configured as follows.

[Effects of the Invention] As described above, according to the present invention, parameters for generating noise that can occur in communication lines are set, and noise based on random numbers is generated, thereby improving the performance of three-channel LSIs, etc. You can test the device under test without connecting it to an actual communication line. In addition, since it incorporates a display section that displays random values, etc. and an operation section for parameter settings, when using it, you can operate it while looking at the screen that displays random values, etc., improving operability and ease of use. A good effect can be obtained.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the external appearance of an embodiment of the present invention, Fig. 2 is a diagram showing a state in which the line simulator of the present invention is connected to the device under test, and Fig. 3 is a display example of the display screen and the configuration of the operation section. FIG. 4 is a block diagram showing the circuit configuration of the embodiment. FIG. 5 is an explanatory diagram of a pseudo-random number generation circuit, and FIG. 6 is a configuration diagram of a bit error generation circuit. FIG. 7 is a block diagram of a bit error pulse width generation circuit, and FIG. 8 is a diagram showing input signals and output signals of the error pulse width generation circuit. FIG. 9 is a configuration diagram of the line section, and FIG. 10 is a waveform diagram showing signals input to the waveform conversion circuit of the line section and their output signals. l-111 line simulator. 2-111 casing, 3--m-display device, 4
--- 1 operation section, 5 --- connector, 6 ---
-parameter setting unit, 7----control unit. 8--m-error signal generating section, 9--1-clock generating section, 10--1 line section. Figure 1 Patent applicant: Yamatake Honeywell Co., Ltd. Agent
Patent attorney Susumu Hori (and 1 other person) Figure 2

Claims (2)

[Claims] (1) A line simulator that generates noise based on random numbers on a communication line, which includes a display section that displays the initial value of the random number, the current value of the random number, and the elapsed time after startup or a value equivalent to that, and the initial value of the random number. A line simulator comprising: a random number initial value input means for inputting a value; a start operation means for starting an operation of adding noise to a communication line; and a stop operation means for stopping the operation. (2) A parameter setting means for variably setting parameters for generating noise on a communication line, a random number generation means for generating random numbers, and a parameter set by the parameter setting means from the random numbers generated by the random number generation means. a signal generating means for generating a determined error signal; and a means for adding noise determined by a parameter set by the parameter setting means to a signal input from the outside while the error signal is being generated, and outputting the resultant signal. and a display means for displaying the initial value of the random number generated by the random number generation means, the current value of the generated random number, the elapsed time after startup, and the parameters set by the parameter setting means; and input of the initial random number value, noise. 1. A line simulator comprising: operation means for starting and stopping additional operations.