AALogic ViewPC User's Guide - Signal Trace Capture
Options - New Capture Trace
AALogic ViewPC can process new signal capture trace sessions in several ways.
Overwrite
New capture trace session overwrites the currently displayed capture trace session. You are not prompted to save data with this setting.
Autosave
You will be prompted to save the currently displayed capture trace session when starting a new capture trace session. The autosave folder is used as the default location for files.
Set Autosave folder
This is the default folder location for saving files. Set this location to the folder you most often use. You will be able to navigate to a new folder and specify a filename before AALogic View actually saves the file.
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Real-time Capture Trace
Real-time capture trace requires the ADMpc to be connected to a line and connected to the PC via the USB port.
Refer to the AAlogic Viewpc connection diagram or the ADMpc documentation for additional connection information.
Capture Trace Configuration
You must set the desired configuration options properly before starting a capture trace session.
The options include the scale, span, and trigger type. The trigger options may also require parameters.
The table below explains each of the settings.
Scale | There are four scales, two DC and two AC. Use the DC scales to evaluate the DC line voltages and timing of actions such as off-hook and on-hook. You will also be able to evaluate the line voltages for idle and busy. Use the AC voltages for evaluating dial-tone, ring signal, DTMF digits, carrier, and data. You should use the lowest scale that provides a trace that does reach the maximum or minimum limits. If you are not sure, use the largest scale first. |
Span | Span refers to the length of time the trace will record. The time starts from the trigger and extends for the length of time specified. The options are 5, 10, 15, or 20 seconds. Start with a 20 second traces and use the results to refine your settings. |
Trigger Type | The trigger refers to the action required to start the trace. Four trigger options are provided -- dial tone, DTMF, ring back, and voltage.
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Capture Trace
Click the Capture Trace button after setting the trigger options. AALogic ViewPC sends the appropriate commands to the ADMpc. The commands set the configuration options and enter the signal trace mode on the ADMpc.
The End Trace button can be clicked to end the current trace session. The status bar below the graph window shows the ADMpc is waiting for the trigger to occur.
The ADMpc will send voltage and timing measurements to AALogic View as soon as the trigger criteria is met.
Note: The dial tone trigger is designed for 380Hz and 440Hz while the ring back is designed for 440Hz and 480Hz. Some systems may not use these frequencies and the triggers may not work properly.

AC Trace Results
This example shows a 300bps credit card transaction. The trigger was set to dial tone and the span was 20 seconds. The cursor is positioned at the start of the communications session and the maximum amplitude of the signals.
The cursor information is displayed in the green box within the information window. It indicates the cursor position, the beginning of the communications, is l0.63 seconds after dial tone was detected and the peak amplitude of the signal is .47 volts AC.
Other measurements are made by moving the cursor or by using the marker.
Other trigger options allow you to delay the start of the trace to later points in the transaction. The ring back trigger can be used to start the trace at a point just before the host answers. You can also manually start the trace by using the voltage trigger and start the transaction by clicking the Capture Trace button at the desired point while listening to the sounds from the ADMpc speaker. This is a useful technique but may take practice to determine the correct trigger point.
The Snap to trace option can be selected to force the cursor to follow the voltage of the signal. The cursor snaps to the positive side of an AC signal and follows the trace for DC signals.
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AC Trace Analysis
Analyzing the trace information may require some knowledge of the transaction components. The various parts of the previous trace are identified and labels in this figure.
You will notice that clicks create spikes in the trace. The spikes labeled Host Pickup, Host Hang up, and Terminal Hang up are examples.
Using the marker and the cursor, the duration of any of the segments can be easily determined.

Adjusting Voltage Trigger
The voltage trigger line extends across the graph window while it is being adjusted. This makes it easy to set the trigger in relation to a trace.
Click and drag on the the T----- and the line is extended. The current voltage value of the trigger is shown in the Voltage window to the left and updated as you drag the trigger line.
The example shows a voltage setting that will trigger on dial tone, DTMF dialing, and the data communications but not ringing. The user listens to the ADMpc during the transaction and click the Capture Trace button when the first ring back is heard. The ADMpc will then start the trace when the data communications starts.

Adjusting Voltage Trigger Results
The span was changed to 10 seconds after the trigger was adjusted. This provides a better view of the data communications.
The resulting trace provides a view of just the data communications and the end of the transaction.
Note: the final spike is caused when the telephone network recognizes the on hook condition.

DC Trace Results
This example shows a DC trace of a 300 bps credit card transaction. The scale is set to 60V DC, the span is 20 seconds, and the trigger is set to Voltage at -24V DC.
To see the idle voltage, the trigger was set and then the line connected to the ADMpc. This triggered the ADMpc as the measured voltage changed from 0V DC to -47.6V DC, crossing the -24V DC trigger.
The transaction was immediately started to see the off hook and on hook transitions at the beginning and end of the transaction.

DC Trace Analysis
Analyzing the DC trace information may may also require some knowledge of the transaction components. The various parts of the previous trace are identified and labels in this figure.
You will notice that there is a small change in the DC voltage level after the terminal went off hook This is called ringing and is normal as long as it is not excessive in amplitude or duration.
Using the marker and the cursor, the duration of any of the segments can be easily determined.

Using the Marker - AC
You can set a marker at any location in the trace. Position the cursor where you want to place the marker and double click the left mouse button.
The blue marker is placed at the beginning of the data transmission segment in the example. The information window in the lower left of the screen indicates the cursor position in green, the difference between the marker and the cursor in white, and the marker position in blue.
The marker automatically snaps to the voltage amplitude. This marker is set to 12.64 seconds from the trigger point and the voltage is 0.494 Vpp. The cursor is set to the point when the host disconnects, 17.45 seconds from the trigger and the typical voltage of the signal is .34 V peak.
The difference from the marker to the cursor is 4.81 seconds, displayed in the white section. This is the actual time required for the terminal and the host to exchange information for the transaction. The voltage difference is .093 V peak but this is not significant in this example.

Using the Marker - DC
The marker is used with the cursor to analyze the DC voltage for a line.
The blue marker is placed at the point that the terminal went off hook The idle voltage is -32.230 VDC using the data in the information window.
The cursor is positioned at an arbitrary point after the line is made busy. The cursor voltage is -7.9 V DC as indicated by the data in the green area of the information window.
The difference information in the white section shows a voltage change of 24.344 V DC from idle to busy.
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Disk Files
File save and open operations follow conventional Windows application norms.
You can save the current trace session to disk by clicking the diskette icon on the toolbar or selecting File from the menu and then Save or Save As. You can also save data by pressing Ctrl+S. The default folder is the Autosave folder but you can navigate to any folder on the PC or a network and save files.
You may also be prompted to save a file. This occurs when there is captured trace session displayed that has not been saved and you select an operation that will clear the session.
To open a file, use the File, Open menu option.
Data is stored in a proprietary file format that is only useful to AALogic Viewpc.
Printing
Printing is completed in the same way as most other Windows applications. You must have an installed printer to be able to print.
Your are encouraged to use File, Print Preview, to see how the data will appear when printed. The output will vary depending on the capabilities of the printer selected.
The example shows a typical print preview. The page header includes the session information. The events are printed in the same format as displayed on the screen.