General Rule Of Thumb Sweep Information

General rule of thumb information.
By Kevin Custer

The first thing you will want to do before attempting to sweep a system is to ensure the basic levels of the channels are flat and at the level they should be. This may mean having to go to the antenna site and balancing the levels to ensure basic flatness. Although absolute level flattening is not important in newer sweep methods like the Wavetek Stealth Sweep system, it is important that the levels of the carriers, especially the pilot(s) be accurate. This will aid in the rough setting of the amplifiers output before sweep balance is done. Since many newer meters allow the addition of several channels in the "tilt" mode, basic flatness can be seen. The pilot channels should employ the use of quality equipment to allow the system to be be stable. If you are sweeping in the "Sweepless" mode, channel accuracy affects overall response accuracy. The use of Demod-Remod processing for off air signals is a plus. Scientific Atlanta produces good modulators for satellite channels that stay put for several weeks on end. This lessens the need to normalize the reference and allows more time for actual sweep production. I always go the the antenna room and verify the equipment being used before sweep is started. I recommend equipment replacement when necessary. This is also a good time to ensure A-V carrier delta, visual modulation depth, and audio deviation. Just these few steps will make a difference to what the subscriber sees and hears. After you sweep and repair problems, and possibly increase usable bandwidth, the subscriber will see a good quality picture, not something dark, loud, or horrible.

In a system employing amplifiers or LE's that have bi-directional test-points, it is a good practice to look at the basic flatness in the tilt mode before balancing to see if there are any gross response problems. Since the Wavetek (WWG - Acterna - JDSU) Stealth allows 9 channels to be seen in the "tilt" mode, the meter can indicate if the systems response is grossly out of whack. The meter will not "hit on the line" so to speak. This is an indication of response problems in the occupied bandwidth and the amplifier should not be set up until the problem has been resolved, or possibly the amplifier balanced via a directional test point.
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