PF14O Error Analyzer

Introduction: 

This guide is to help users of the test instrument to become familiar with the switches, settings, controls and outputs without the tedious reference to the handbook. However this guide is only a brief summary and for further detail the reader will have to go to the handbook. It is included as much as possible the explanations of any abbreviations used so that unfamiliar terms are clear. This will make this guide suitable for students of digital transmission. In association with this and other activities have compiled a dictionary of abbreviations and will be included.

About the Instrument:

The equipment is of German origin and is recognized as one of the best quality. The PF14O is a test set designed for use with Plesiochronous Digital Hierarchy (PDH) and Synchronous Digital Hierarchy (SDH - also originally known as SONET-Synchronized Optical Network). The carry handle is extendable and the lid can be clipped back on to the set in 3 ways, 2 of which during use. The help key, one of the 6: hard’ keys under the screen does not function. You are simply told to see manual’. There are 6 soft keys: F1~F6 beside the screen on the right which change their function according to what is displayed on the screen.

Switching on:

Sit the instrument upright with the screen toward you and the power cord at the top. Switch on using the small black switch at the top right near the power cord. “0” = off. There is a brief self-test and the instrument displays the settings used when the set was last turned off. Re-initialization can be performed by holding down the ‘clear’ key when switching on - but this resets the date and time to zero (1-1-94) and is better left alone unless there is a fault. 

Transmitting:

The set can generate signals from an internal clock (at PDH rates) or from an external clock source (for SDH) and transmit these in a range of selectable line codes (Coded Mark Inversion - CMI, Non Return to Zero -NRZ, High Density Bipolar 3 zeros - HDB3, Alternate Mark Inversion - AMI, and B3ZS).

Receiving:

The set can receive a wide variety of signals and decode them. In ‘framed’ signals the Frame Alignment Word is decoded and checked for errors and information, and the traffic can be demodulated’. The Auto conf (auto configure) key enables the receiver to work out for itself the speed and type of incoming signal.

Functional Test Program. 

Built into the set is a test program that the operator can use just to check that the set is working properly. It requires that two cords are used to connect jack 40 to jack 50 and also jack 42 to jack 53. By reading the printing on the panel layout it can be seen that this simply connects the output of the transmitter to the input of the receiver and also the clock output to the clock input. Start the test by pressing the Test/conf key just below the screen next to the numbers keypad. Then press F5 for ‘self test’. The screen changes to the self test screen and the function keys at the right of the screen allow the user some options - All tests, a single test, a range of tests, show all, Start test, and continue test Press Fl for ‘All’ and then F5 ‘start test’. The printer will give a result, and shown below is the sample for ‘no faults found.

“Paper feed” is the Stop/paper key. The user can experiment by disconnecting the input to output leads jacks 40 to 50 and see the resultant fault’ [fails test 21]. It is not often easy to determine when a test has finished, or if the set has stopped at a failed test. If the set has stopped at a ‘failed’ test, press F6 ‘continue test to continue with the remainder of the tests. The failed test number is printed on the printout.

To get out of any menu back to the one before it, or to simply get back to the start menu on the screen, press the esc (escape) key on the right, below the 6 function keys.

The user may want to change some of the basic setup of the screen (light or dark) or date and time, and this can be done from the test/conf key menu.

Applications

An ‘application’ is simply using the set for a test. Currently there are only two ‘applications’ available: Line Test and Monitor test. A line test is where a pattern is generated and transmitted through the equipment under test and then received and errors counted. A monitor test is where no signals are transmitted but the existing signals of a working system are checked for errors and information.

Setting up to perform a test

Press ‘appl’ key to bring up the ‘applications’ menu. It doesn’t matter where you are in the menus, the applications menu will be presented whenever the key is pressed. Select either ‘Line Test’ or ‘Monitor’ by using Fl or F3.

In order to ensure that the set is working, it is a good idea to connect a test cord from the transmitter to the receiver and make sure that signals are getting through. The ‘no signal’ LED at the left side under the screen should go out and the green LED ‘signal OK’ should come on. By pressing main menu and then Fl Tx (transmitter) setting, then moving the cursor down to the “Error insert” line which is usually ‘off, the operator can select ‘on’ by pressing F2 and then errors are injected at the rate chosen (eg 10^-3) or the operator can inject errors one at a time by pressing F4. When errors are inserted, a warning buzzer is heard and the display alters to indicate the number and other data such as percent (%) Error seconds (ES). Ensure that G.821 results are printed out by pressing F4 “measurement” from the main menu, then cursor down using the down arrow to “Analysis”, then press F2 for G.821. This will cause the printer to print out ES, SES, DM etc. This exercise should be performed by those new to the instrument and at many times during tests to ensure that the signal being examined is the signal required. The same technique is often used to test equipment. If 5 errors are injected then only 5 errors should be received.