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For more than 20 years security installers have used RF modulators to quickly and easily distribute video sources such as security cameras throughout their customer's homes over unused broadcast TV channels. In recent years, the continued evolution of digital cable services has limited the availability of channels with which to modulate. For this very reason, many installers have either found ways around it or have simply given up.
But modulation is alive and well! Though many now shy away from the old method that sacrificed hundreds of digital channels, it still is a valuable tool in the arsenal of the security dealer. As digital technology continues to change the way you must do business, despite these changes, modulation can still be a valuable tool that can be utilized in your installations. It will allow you to continue keeping your CCTV customers happy for another 20 years.
"Modulation has been the best way for our CCTV customers to get the most out of their home surveillance systems," states Lucy Wilson of HSS Security in Downey, CA. "We continue to use it despite some of the service issues that we encounter with digital cable."
In order to better understand how digital cable services have been a culprit in the demise of modulated channels in many homes, you must first look back to the days when modulation was the norm. Before the implementation of digital cable and related services, there were simply analog channels. Basic cable services sat on channels 2-78 and 95-99. In some isolated regions, digital cable services did exist, though usually in test areas and only above Channel 78. Modulation thrived in these times.
Once the cable companies began upgrading their networks and further expanding their services to offer more channels and broadband cable services, the analog channels were sacrificed. Since cable companies could offer more channels by utilizing the digital spectrum in the same area as analog, they began converting these channels over to digital.
As these digital channels spread, they began interfering with the analog channels that had been filtered out for modulated video feeds. Where customers were once able to view their security cameras with no issue on their modulated channels, they began seeing distorted channels in its place.
To solve this, installers utilized low-pass filters to simply create a "white space" by removing the analog channels and inserting the modulated channels with little flexibility. Though some channel loss could be expected, customers were aware of this and could determine which channels they would not receive. Dealers could offer up to 19 channels of modulation with the low-pass filter.
With further expansion of digital cable service, the low-pass filter became less and less effective. No longer could a broad range of modulated channels be offered. In came the Notch Filter — a filter that would allow specific channel ranges to be blocked. With a series of notch filters, you could offer up to 5 modulated channels in the analog broadcast range, though an increasing number of cable channels also were sacrificed.
"The changes in digital cable have greatly affected our business," states Tim Wilcox, president of Dijisys, a San Clemente, CA based dealer integrator. "We can't recommend modulation to all customers because in some areas the service would simply be wiped out with the use of filters. Our older customers are less than patient with the changes and don't really care that we can't do it, they want us to find a way that does not cost them a whole lot more money."
Today, the expanded digital cable spectrum is used to hold hundreds of channels and additional services including those for HDTV, Programming on Demand, Pay Per View, Broadband services and Voice Over IP. Utilizing the old filtration methods no longer works effectively because many of those added service features are layered on top of and in between channels. To filter channels out, as in the days of filters, would likely mean the loss of hundreds of digital channels and services, if not all.
Eventually, industry insiders and manufacturers started recommending future-proof wiring adjustments be made to all new homes. It was recommended that two coax runs be installed to each TV location so that one could be dedicated to digital cable TV programming and the other could be utilized for in-house RF modulated signals.
This was an easy solution for new home builds, yet did not address the existing home with only one coax running to each TV location. In retrofit situations, where running a second coax was either cost prohibitive or simply not an option, there still remained no solution to address this need.
You may wonder, why not simply distribute the composite video from the security cameras? Yet, in order to distribute the composite video from the cameras, you must have a dedicated coax cable for each video feed, and splitting the composite video requires a powered device which is much more costly than a standard RF TV splitter.
The other solution is one that is being addressed by Channel Vision Technology, which has developed the Affinity Digital Cable Combiner.
"Nearly 90 percent of calls into our technical support team are questions regarding modulating on digital cable," comments Darrel Hauk, president & CEO of Channel Vision Technology. "Our U.S.-based engineering team developed the Affinity to address this growing issue that is becoming a real industry-wide problem."
The Affinity provides a way for the modulated video signals to coexist with a digital cable system without the need for RF filters. Affinity allows homeowners to easily switch between cable and modulated channels with its included remote control while sharing both on a single coax cable to one TV.
"The Affinity product is simple and will be a great tool for us to incorporate into our CCTV business," says Wilcox.
author: By Angie Tucker