Sample Emulate CSU/NIU Test

The purpose of this test mode is to emulate a CSU or NIU. The test set will terminate the T1 line, and a loop-up code sent from the far end will cause this test set to enter a loopback state. Conversely, a loop-down code sent from the far end will cause this test set to exit the loopback state.
If you are using ESF, configure the appropriate ESF Loop Code on the Setup menu.
In this example, you use the emulate CSU/NSU test mode to have the test set emulate a CSU or NIU at the near end. In this mode it is possible for the far end to place this test set into loopback mode. The T1 circuit is not available for service during loopback. Loopback tests are normally limited to the CSU since NIU loop codes are normally suppressed at the central office. When the test set is in a loopback state, AIS is present at the Secondary Tx jack. When not in loopback state, the Primary Rx signal is routed to the Secondary Tx jack and the Secondary Rx signal is routed to the Primary Tx jack.
NOTE: Avoid having a hard loop in the Secondary channel as it will cause a constant loop condition to exist.
You may want to emulate the functionality of a CSU/NIU if trouble is suspected in that equipment. The wireless technician will often be interested in only the CSU mode. The functionality of a CSU is emulated in this mode and the test set will respond to loop codes received at the Primary Rx input.
 The test set has the capability to emulate the functionality of a CSU/NIU.
The test set will respond only to the type of loop code selected on the setup screen. Be aware that when the test set is not in loopback mode, the source of data on the Primary Tx jack is the Secondary Rx jack, and the source of data on the Secondary Tx jack is the Primary Rx jack. If B8ZS is selected on the test set, then the signal (or no signal - which is decoded as all zeros) will be translated to B8ZS format.
 The following table provides the data source for primary Tx and secondary Tx during loop-up and loop-down states in emulate mode.
 Data Source in Emulate Mode
Jack
 		Loop Up
 		Loop Down
Primary Tx
 		Primary Rx
  • AIS when no signal present at Secondary Rx
  • Secondary Rx
Secondary Tx
 		Secondary Rx
  • AIS


Sample Emulated CSU/NIU Test:

Step
 		Notes
1
 		Connect the BSTS to the DSX panel
 		Refer to the Measurement Guide
2
 		[Mode]
3
 		[Backhaul]
4
 		[T1 Analyzer]
5
 		Select a test mode.
  1. [Get Started/ Test Mode]
  2. [Emulate CSU/NIU]
  3. [Emulate CSU]
Choose this to emulate a CSU.
6
 		[Setup]
 		Select this to display a list of setup choices that apply to this test mode.
7
 		Setup Rx input.
  1. [Rx Input]
  2. [Terminate]
This assumes the test set is connected into a jack that interrupts the circuit.
8
 		Setup line code.
  1. [Line Code]
  2. [B8ZS]
This assumes the circuit is designed for B8ZS.
9
 		Setup framing.
  1. [Framing]
  2. [ESF]
This assumes that the circuit has been designed for ESF.
10
 		Select a pattern.
  1. [Pattern]
  2. Use the up and down buttons to select.
  3. QRSS
  4. [Select]

11
 		Setup Tx LBO.
  1. [Tx LBO]
  2. [0 dB]
This is a typical level found at the customer demarcation point.
12
 		[More 1 of 2]
 		Displays the rest of the Setup options.
13
 		Setup the loop code.
  1. [Loop Code]
  2. [ESF Data Link]
Configures what type of loop code this test set will respond to. Requires a Datalink loop code for this test set to enter loopback mode.
14
 		[Display]
 		Enables the Display options on the buttons on the right.
15
 		Setup the results display.
  1. [Results]
  2. Use the up and down arrows to select.
  3. Make a selection.
  4. [Select]
Enables a list of results information that can be displayed in the Results pane. Make a selection based on the need of the application.
16
 		[Control]
 		The selection enables several soft keys on the right that control choices specific to each test mode.
17
 		[Pattern]
 		Select a pattern.
18
 		[Self Loop Up]
 		Forces the test set to enter loop-up state.
19
 		[Self Loop Down]
 		Forces the test set to enter loop-down state.