By Jack Cauldwell. Arvin Systems, Inc.
The most crucial parameter of any CATV system is the complete system alignment. Presently each amplifier is aligned by hand using a Field Strength meter or a simultaneous sweep system and, consequently, takes a number of days to complete the entire system alignment. The only problem is that the system alignment does not remain stable over periods of time due to temperature changes, voltage variations, and component degradation.
There are several ways to detect the condition of system alignment, but all require going through the system by hand with a Field Strength meter to make corrections. Usually an alignment problem shows up as a poor picture on a customer's TV set. After a few complaints are made, the system operator determines that it is time to realign the amplifiers. There have been several attempts to curb the variations in system alignment, but none have proven good enough to eliminate periodic system alignments.