Patton electronic 2701RC manual 22

2.Verify that the data terminal equipment is operating properly and can be used for a test.

3.Perform a V.52 BER (bit error rate) test as described in Section 5.3. If the BER test equipment indicates no faults, but the data terminal indicates a fault, follow the manufactur- er s checkout procedures for the data terminal. Also, check the interface cable between the terminal and the NetLink-E1.

5.2.2Operating Remote Digital Loopback (RL)

The Remote Digital Loopback (RL) test checks the performance of both the local and remote NetLink-E1™, as well as the communication link between them. Any characters sent to the remote NetLink-E1™ in this test mode will be returned back to the originating device (i.e, characters typed on the keyboard of the local terminal will appear on the local terminal screen after having been passed to the remote NetLink- E1™ and looped back).

		G.703/G.704 NTU				G.703/G.704 NTU
			Model 2701 RC			Model 2701 RC
	Serial			Internal		Receive	Ethernet
						Recover
				Clocking
Device						Clocking	Device
					Cable Span
	Clock/						Clock/
	Data					Data	Data
	Clock/						Data
	Data					Model 2701RC
			Model 2701RC
			RDL Initiated

Figure 8. Remote Loopback

There are two Remote Loops that can be initiated from the NetLink-E1 unit: (1) V.54 Loop, and; (2)CSU Loop. The user can select the type of loop that can be initiated from the System Diagnostics/Statistics screen or with Switch S2-1. Select c RDL Type and press the <spacebar> to toggle between the CSU loop and the V.54 loop. When a loopback is initiated this is the type of loop that the unit uses to loop up the remote unit. NOTE: The NetLink-E1 will respond to both loops regardless of the state of the RDL Type.

To perform an RDL test, follow these steps:

1.Activate RDL. This may be done in three ways:

a. Enter		b	Remote Loop from the System
Diagnostics/Statistics menu and toggle the <Spacebar>
until	RL		appears next to the		Remote Loop option.;
				b
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b.Activate the RL signal on the DTE. If you are not sure which lead is the RL signal, please refer to Appendix D.

c.Set the front panel switch to Remote .

2.Perform a bit error rate test (BERT) using the internal V.52 generator (as described in Section 5.3), or using a separate BER Tester. If the BER test indicates a fault, and the Local Line Loopback test was successful for both NetLink™s, you may have a problem with the twisted pair line connection.

5.2.3 CSU Loop

The NetLink-E1™ also responds to central office initiated loop com- mands. The NetLink-E1™ will implement the loop up command when it recognizes the pattern 10000 in the data stream for a minimum of 5 seconds. The loop down command is implemented by the pattern 100 in the data stream for a minimum of 5 seconds.

The NetLink-E1™ will respond to Universal Loopback De-activate to clear all central office loops.

5.3 BIT ERROR RATE (V.52) DIAGNOSTICS

The NetLink-E1™ offers three V.52 Bit Error Rate (BER) test pat- terns. These test patterns may be invoked along with the LAL and RDL tests to evaluate the unit(s) and the communication links.

When a 511, 2047, or QRSS test is invoked, the NetLink-E1™ generates a pseudo-random bit pattern of 511 bits, 2047 bits or 220 bits, respectively, using a mathematical polynomial. The receiving NetLink- E1™ then decodes the received bits using the same polynomial. If the received bits match the agreed upon pseudo-random pattern, then the NetLink-E1™(s) and the communication link(s) are functioning properly.

511	Initiates a built-in 511 bit pseudo-random
	pattern generator and detector.
2047	Initiates a built-in 2047 bit pseudo-random
	pattern generator and detector.
QRSS	Initiates a built-in 220 bit pseudo-random
	pattern generator and detector.
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