The Affinity allows each TV location desired to access digital cable as well as the modulated signals by providing an easy way to switch between the two feeds. Essentially, one can think of this product as a remote-controlled A/B switch.

Video Modulation over Digital Cable

Jack Urrutia | Channel Vision

Channel Vision's Affinity
Breathes New Life into
Video Modulation over Digital Cable

By Jack Urrutia,

The Affinity allows each TV location desired to access digital cable as well as the modulated signals by providing an easy way to switch between the two feeds. Essentially, one can think of this product as a remote-controlled A/B switch.

Channel Vision Technology


Over six years ago, I took my very first technical support job working for a company that made RF modulators. About the same time, many cable providers were in the various stages of upgrading their infrastructures and just beginning to offer digital cable services. These new services required the cable providers to utilize channel ranges above their basic analog programming. Traditionally, this had been the range that custom installers had used to insert modulated channels.

Having had the opportunity to speak to countless custom installers, it was easy to see and understand the progression of this new technology. It was as if I were working for the Centers for Disease Control and watching the spread of a new deadly virus. In the years since the beginning, the virus has become an epidemic that has consumed nearly all of the channel space that was once available for in-house modulated channels. This epidemic needed a cure and Channel Vision has finally provided one.

Before we talk about the solution, we should understand the progression of the problem. It's important to understand what modulators do and why they are often necessary. In short, an RF modulator allows a regular audio/video signal (such as a signal from a DVD player or security camera) to be displayed on a standard TV channel. When they were first introduced in the 1980's, modulators quickly became an easy way to display multiple CCTV cameras on all the TVs in one's home. The cameras displayed on the TV just as if they were additional channels provided by the cable company. One might ask the question, "Why do I need to modulate when I can just distribute the composite video feed from my security cameras?" Well that may be true, but in order to distribute composite video, one must have a dedicated coax for each video feed, and splitting the composite video requires a powered device that is much more costly than a standard RF TV splitter. Quite simply, modulation is a very efficient way to distribute multiple video signals.

When digital cable services first began to spread, custom installers would call for tech support and say, "I've had your modulators installed in several of my customers' homes for years and they've been working fine, but now all my customers are calling to say that the modulated channels look 'snowy'." The first question I would ask in return was, "Is your customer subscribing to digital cable services?" Most of the time the answer was, "no" so to solve this problem, we would simply sell the customer a low pass filter that would block out all of a certain digital cable frequency range, thus eliminating the interference that had caused the problem.

In the early days of digital cable, cable companies would typically broadcast over a limited space, usually between analog cable channels 78 - 117. When a customer needed to modulate on a digital cable system, we would suggest a low pass filter that eliminated any interference above these channels. This was often challenging because it only left a few open channels available for modulation.

Before long, we started to receive complaints that these less invasive low pass filters were blocking out important digital cable channels and it soon became clear that the cable companies' services had moved beyond channel 117. In response to customer complaints, we began offering notch filters that could delete a group of channels below analog channel 78. These filters provided a reasonable compromise, but required the customer to sacrifice a handful of analog TV programming in order to allow room for their modulated channels - which made it unpopular with homeowners.

Eventually, we began focusing on educating installers and encouraging them to install two runs of coax to each TV location. This would allow a dedicated coax to digital cable TV programming and the other coax to in-house RF modulation. This is a great solution, but only works for new systems where two cable runs are possible. We still needed to find a solution for existing homes with only one coax running to each TV location. These are the circumstances that inspired the new Channel Vision P-0321 Affinity™ Digital Cable Combiner, making video modulation over cable TV once again a true reality.

The Affinity allows each TV location desired to access digital cable as well as the modulated signals by providing an easy way to switch between the two feeds. Essentially, one can think of this product as a remote-controlled A/B switch. The system utilizes Channel Vision's IR over coax technology, which allows the home owner to simply switch between the cable or modulated channels, selecting which signals are being delivered to the TV set. This ensures that there will never be an interference problem because the Affinity allows only one signal over the coax at a time.

Channel Vision's Affinity is now available in kit form and includes everything needed to complete the system including a modulator and can be customized based on system configuration needs.

Although the Affinity has only been on the market for a short time, the initial response has been very positive. It has given installers a viable solution that makes their clients happy.

Jack Urrutia is an Applications Engineer for Channel Vision Technology


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