| Quick Field Instructions For
Federal Communications Commission Proof Testing on the Tektronix®
2714 Cable Television Radio Frequency Analyzer
A Condensation by George Stantial
Introduction The typical spectrum analyzer in use for cable
television purposes is a swept-tuned or scanning radio-frequency analyzer. This
means that instead of displaying signal amplitude as a function of time as is
done by the oscilloscope, the spectrum analyzer will use the frequency domain
as the x-axis on its graphical display.
This allows radio energy signals differing in frequency to be examined
for their proper attributes. The
technician using this field guide should already be aware of this basic
information along with the uses and limitations of spectrum analysis. The basic information presented in this
quick field guide is not meant to substitute for the proper understanding and
operation of the Tektronix® 2714 CATV Analyzer.
Indeed, the instructions assume the technician already has some familiarity
with this analyzer. Additionally, the
technician should have a basic understanding of the tests required by the
Federal Communications Commission (FCC).
The purpose of this field guide is to allow experienced technicians to
quickly perform certain required measurements without the need to search and
summarize the supplied manual. This guide is neither supplied nor
endorsed by the manufacturer of Tektronix® equipment. To use the Tektronix® analyzer for purposes other than those
outlined below, it is recommended the Tektronix® provided manual be consulted. The finger controls on the Tektronix® spectrum analyzer will allow the user to move and zoom (in terms of frequency and amplitude) on the displays of the received signals of interest. Other controls will allow certain operating parameters on the analyzers such as "bandwidth" and "scan rate" to be changed. Properly setting the parameters will not only increase the accuracy of measurements, but may allow anomalies to be seen that could not be seen otherwise. Yet more controls allow the software-driven manipulation of the previously mentioned controls to perform automated multi-step testing. A spectrum analyzer is a versatile testing
and troubleshooting device whose accuracy limits must be respected. The user
must be aware of the specifications of the analyzer and be able to determine if
it meets the needs for its intended purpose.
As an example, many times, the frequency display portion of a spectrum
analyzer is a reference only and not an accurate depiction of frequency. The
analyzer must have a built-in frequency counter to read actual frequency. For FCC testing, the counter must have a
high enough accuracy for that purpose. The amplitude reading is also subject to
accuracy ratings. Furthermore, some tests may require signal amplitudes to be
within a specific range to reduce the uncertainty of the result of those tests.
In all cases, refer to the owner’s manual for the specifications or consult
with the manufacturer. Setup Instructions for the Tektronix® 2714 CATV Analyzer For the purposes of the instruction listed
below, labels in capital letters are for menu items on the display and will be
preceded by a “Select” command. Labels
in bold capital letters are for physical buttons on the analyzer and will be
preceded by a “Press” command. Press POWER Allow the analyzer to warm up 15 minutes before use. Due to the variety of older machines in use, the following instructions are based on analyzer firmware Version 06.05.92. The firmware should be upgraded when the analyzer is sent in for calibration. To check the version of firmware in use perform the following steps: Press UTIL in the button grouping labeled “MENUS” Select 4 SYSTEM CONFIGURATION Select 9 INSTALLED OPTIONS DISPLAY The version number (date) will read under the INSTALLED OPTIONS heading Press any “MENUS” key to exit the utility menu To check/modify the test setup perform the following steps: Press CATV/APPL in the button grouping labeled “MENUS” If the menu heading does not read CATV MEASUREMENTS, Select 9 to leave its current menu Select 5 CARRIER TO NOISE to enter that menu (Select 9 MORE if required first) Select 5 CARRIER TO NOISE SETUP to enter that menu If needed, Select 5 NOISE NORM’D BW, Press 4 and Press MHz mSEC mV on the keypad for 4.0 MHZBW Select 0 INTERACTIVE to place the C/N test in interactive mode Do not select 1 AUTO as firmware older than 01.05.95 will violate FCC parameters Do not select 2 AUTO (PAUSE FOR CARRIER OFF) as firmware older than 01.05.95 will violate FCC parameters Press BSKP as needed to return to the CATV MEASUREMENTS menu Select 6 HUM/LFD to enter that menu If needed, Select 5 POWER LINE FREQ, to toggle the line frequency to 60Hz Press BSKP as needed to return to the CATV MEASUREMENTS menu Select 5 CTB/CSO to enter that menu (Select 9 MORE if required first) Select 5 CTB/CSO SETUP to enter that menu Select 0 INTERACTIVE if it is desired to manually select the beats to measure Do not select 1 AUTO as CTB cannot be measured without carrier removal Select 2 AUTO (PAUSE FOR CARRIER OFF) for a slow measurement with better accuracy Select 3 SINGLE SWEEP for a speedy measurement with good accuracy The AUTO TEST LOCATIONS should read: 4 +1.250 MHZ (OFFSET) 5 +750.000 MHZ (OFFSET) 6 + 0.000 MHZ (OFFSET) 7 -750.000 MHZ (OFFSET) 8 -1.250 MHZ (OFFSET) Optionally, the lowest offset may be deleted if the upper band-edge of the lower adjacent channel creates false CSO To delete it, Select 8 –1.250 MHZ (OFFSET), Press W=DELETE Press BSKP as needed to return to the CATV MEASUREMENTS menu Select 7 IN-CHANNEL RESPONSE to (Select 9 MORE if required first) Select 5 IN-CHAN RESP SETUP to enter that menu Select 0 INTERACTIVE for manual placement of the high/low markers on the headend injected multiburst pulses Select 1 AUTO for the recommended automatic placement of the high/low markers on the multiburst pulses Press BSKP as needed to return to the CATV MEASUREMENTS menu or any “MENUS” key to exit Setup for these tests is now complete Test Instructions for the Tektronix® 2714 CATV Analyzer To Tune to the Channel Desired for Test: Press channel number(s) desired on KEYPAD Press W on KEYPAD
To Test Carrier to Noise: Press CATV/APPL in the button grouping labeled “MENUS” If the analyzer is in a test mode other than the one desired, Select 9 to leave If needed, Select 5 CARRIER TO NOISE to enter that menu (Select 9 MORE if required first) Select 0 RUN CARRIER/NOISE INTERACTIVE For unmodulated carrier, on MOVE MARKER TO NOISE prompt move marker near channel center (+/- 2MHz) Press W to continue For modulated carrier, on MOVE MARKER TO NOISE prompt first remove carrier, then move marker as above Press W to continue Record the displayed results Tune to the next channel desired and repeat the steps listed above
To Test CTB/CSO: Tune to the channel desired Press CATV/APPL in the button grouping labeled “MENUS” If the analyzer is in a test mode other than the one desired, Select 9 to leave If needed, Select 5 CTB/CSO to enter that menu (Select 9 MORE if required first) Select 2 RUN CTB/CSO to run the test in the mode selected during setup When prompted, turn off the carrier Press W to continue and follow any further prompts depending on test mode The display will show the worst case Press CATV/APPL Select 2 DISPLAY RESULTS All results for both both CTB and CSO will display Record the displayed results (only worst case for each of CSO and CTB is required) Press W to continue Press any “MENUS” key to exit Tune to the next channel desired and repeat the steps listed above
To Test Hum and other Low Frequency Disturbances: Tune to the channel desired Press CATV/APPL in the button grouping labeled “MENUS” If the analyzer is in a test mode other than the one desired, Select 9 to leave If needed, Select 6 HUM/LFD to enter that menu (Select 9 MORE if required first) Remove modulation (recommended) for a system Hum/LFD reading Leave modulation for a reading of all LFD (source video may influence reading) Select 0 RUN HUM/LFD Record the displayed result This test is only needed on one channel at each test location To Test In-Channel Response: Tune to the channel desired Press CATV/APPL in the button grouping labeled “MENUS” If the analyzer is in a test mode other than the one desired, Select 9 to leave If needed, Select 7 IN-CHANNEL RESPONSE to enter that menu (Select 9 MORE if required first) Select 0 RUN IN-CHANNEL RESPONSE Inject the multiburst test signal when prompted Press W to continue Remove the multiburst test signal when prompted Press W to continue Record the displayed result Tune to the next channel desired and repeat the steps listed above
Tektronix® is a registered trademark of Tektronix Inc.
Copyright © 1998-2008 G. Stantial |