Overview
This Error insertion application permits single, fixed, automatic, random, and burst error insertion into the incoming bit
stream. Bulk delay is an added feature in Error insertion application (applicable only to USB Analyzers), that allows users to
apply delay on the entire T1/E1 trunk (full multi-frame) of 1.544Mbps (T1) pipe or 2.048 Mbps (E1) pipe. This helps to
simulate network delay along the T1E1 links.
A block diagram is shown below. Before invoking this application, ensure that the analyzers framing format
configuration is set according to the input signal framing format. As shown in the diagram below, the input to the T1 Card
is fed back to the output after passing through the error insertion logic.
Error Insertion Modes:
Auto error insertion
The types of error insertions that are supported are single logic error, and multiframes. Single Logic Errors as stated
above can be inserted at a rate from 10-2 to 10-9.
In fixed or random insertions, the errors are inserted only in the timeslots that have been selected.
Multiframe Errors uses a multiframe mask file that was created by the Tx Multiframe application to insert errors. A rate of 10-2
means that the error multiframe will be inserted every 100th multiframe. It will be necessary to activate all timeslots. With
Continuous MFs insertion, the error multiframe mask is inserted into every multiframe that is transmitted.
Manual error insertion
For T1 & E1:
- Logic Errors
- Bipolar Violations
- MF Errors
- CRC Errors
For T1:
- Facility Data Link (FDL)
- Framing Pattern Sequence (FPS)
For E1:
- Extra bits
- Y bit
- CAS Multiframe
- National bits
- A bit
- International bit
Examples
Bipolar Violations
- Open Monitor T1/E1 line tabs on card2. Open the Error Insertion application on card1.
- Click on Bipolar Violations on error insertion. Observe that bipolar violation is inserted (turns red and then to yellow) and BPV
count increments on the 'Monitor T1/E1 line' tab.
MF error:
MF Errors or Fixed Error Injection allows you to insert errors in a very précised manner.
You can direct that an error will be inserted in the timeslot and bit position of their choice. It is also necessary to select all the
timeslots. If necessary, you can deactivate transmit timeslots that are being used by other applications.
- Start the application, Tx Multiframe.
- Click Reset MF and modify the multiframe by inserting desired values (such as 56).
- Click Save MF and save the multiframe mask to a file say "mf'.
- Open Error Insertion application on card1.
- Click Load MF Mask and Select the saved file mf.
- Click MF Error and observe that frame error turns red on Monitor T1/E1 line tab on card2 and the frame error count increases
on the monitor tab.
Bulk Delay (For USB Analyzers Only)
Bulk delay is an added feature in Error insertion application (applicable only to USB Analyzers),
that allows users to apply delay on the entire T1/E1 trunk (full multi-frame) of 1.544Mbps (T1) pipe or 2.048 Mbps (E1) pipe.
After selecting or adjusting the delay, the Delay will fill a buffer and begin transmitting the signal; this will cause the T1 or E1
multi-frame signal to briefly lose sync when applying the delay.
- Bulk delay can be applied in either Microseconds or Milliseconds units
- Delay can be varied from 0 to 169.77mS or 69 to 169845 µSec for T1 and 0 to 127.99mS or 46 to 128042µSec for E1 with
an accuracy of +/- 10µS.
- The delay resolution is based on the byte increments of T1 or E1 (8 bits at a time)
The bulk delay inserted can be verified using the precision measurement application.
The user can either enter the required delay value manually or can adjust the slider to choose the delay value. To observe
the delay set, in the precision measurement window as shown in the screen below the user has to check the Enable Bulk
Delay check box. The Precision Measurement window displays default delay difference of 0.04 for E1 card and 0.06 for T1 cards.
The delay set by the user using the Error Insertion application can be observed in the Precision Delay Measurement application.
