Patton electronic 2500 Series user manual CSU Loop, DSU Loop, V.52 BER Test Pattern Generator

CSU Loop

The CSU Loop is activated when the central office reverses the DC sealing current that flows between the TX pair and the RX pair. In this case, the Model 2500 Series recognizes this and loops signals on the RX pair back to the central office on the TX pair (see Figure 8, below). While the CSU Loop is activated by the central office, the TM light is illuminated.

Figure 8. CSU loop

DSU Loop

The DSU Loop is activated when the central office sends a DSU loop signal over the twisted pair wire. The Model 2500 Series senses this signal and loops the digital data back to the central office (see Figure 9, below). While the DSU Loop is activated, the TM light is illuminated.

Figure 9. DSU loop

5.4 THE V.52 BER TEST PATTERN GENERATOR

The Model 2500 Series has a built-in test pattern generator and detector. It can be invoked at both ends of a link simultaneously (using two operators) or it can be invoked in conjunction with the LAL or RDL tests (using one operator). The following example requires two operators–one to initiate and monitor the test at the local Model 2500 Series, and one at the remote Model 2500 Series. To use the V.52 BER test by itself, both operators should simultaneously follow these steps:

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1)Locate the “511/511E” toggle switch on the front panel of the Model 2500 Series and move it DOWN (see Note 1). This activates the V.52 BER test mode and transmits a “511” pseudorandom test pattern to the other unit. If any errors are received, the receiving CSU/DSU’s red “Error” LED will blink sporadically (see Notes 1 & 2, below).

2)If the test indicates no errors are present, move the V.52 toggle switch UP, activating the “511/E” test (see Note 2). The 511/E test transmits the 511 pseudorandom test pattern and injects intentional errors about once per second. If the test is working properly, the receiving CSU/DSU’s red “Error” LED will blink regularly.

A successful “511/E” test will confirm that the link is in place, and that the Model 2500 Series’ built-in “511” generator and detector are working properly.

Note1: The 511 BER pattern can also be activated using the software control port. Follow these steps: From a terminal, first go to the Main Menu and select item 3 to display the Software Switch Menu (Section 4.2) In the Software Switch Menu, select item “c” to go to the Send 511 Pattern Menu (see below). To send a 511 pattern, select item 1.

Note2: Control Port activation of the “511E” pattern isnot possible. The “511E” pattern may only be activated using the front panel toggle switch.

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