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Carlson Simulcast & Commtech

Written by Law and Order Staff

Carlson Simulcast Expands Availability and Cuts Expenses for Public Safety
www.carlsonwireless.com

www.commtechradio.com

There simply are not enough channels to go around, especially for public safety use.   Agencies have been forced to apply for new channels and upgrade to very elaborate systems in order to communicate. However, thanks to analog simulcast, they can use the same channel to cover a wide geographic area, while continuing to use their existing mobile and portable units. Simulcast is more popular in the public safety field than anywhere else.

Although P25 digital communication is currently a major topic of discussion, it is also a big-ticket item that many rural entities cannot afford, which is another reason they turn to Simulcast analog communications instead. However, simulcasting requires the latency, or time delay, across the microwave backhaul to be fixed. P25 does not require fixed latency like analog systems do. Therefore, most P25 systems use IP backhaul. An IP-based data stream can also work if all you want is analog backhaul, as long as it is not contingent on critical timing. Conversely, if you’re using multiple sites, an IP-based system is not a viable solution because they vary too much.

CommTech, a division of Communications Group Inc., is a wireless communications provider in Nashville, Tenn. They provide complete communications infrastructure, which runs the gamut from building towers to outfitting the equipment at the base of the towers for radio systems to integrating into 9-1-1 centers when necessary.

The core of CommTech’s business is public safety entities throughout middle Tennessee.  Most of the customers they cater to are county agencies. As such, they do not have the financial resources most metropolitan agencies have. Therefore, CommTech delivers many simulcast radio systems with multiple towers transmitting at the same time.  Because these are analog systems, timing is critical and the latency cannot vary—which is why CommTech started working with Carlson over 10 years ago.

Brad Adams, Service Manager at CommTech said, “Carlson fits into our business because in multi-site systems, you need backhaul from tower to tower. Fixed latency is something that Carlson’s Trailblazer does that’s really important. The latency cannot change, it always has to be the same; and that is the primary reason that we use the Trailblazer.”

Affordability is another reason CommTech turned to Carlson for a simulcast solution. “Carlson was the least expensive solution and it met our needs better,” Adams said. “A lot of microwave solutions are way more than you really need for an analog application; whereas, with Carlson’s Trailblazer, which we use exclusively for these types of applications, is just enough, and not too much.”

Steve Rich, Vice President at CommTech stated, “Carlson is the only one in their price point/class that provides analog fixed latency. The next step up, you’re looking at a much higher tier radio system and you are into three to four times the price.  The Trailblazer is just a very good radio and very good quality for its price point.”

Here is an example of how CommTech’s Simulcast system solves a communications crunch. A county sheriff that is 30–50 miles outside the metropolitan area may not have millions to spend on a P25 radio system, so CommTech builds them a Simulcast analog system using Carlson’s Trailblazer for backhaul. The agency can keep all their legacy equipment in their cars as well as their portables, all the while improving their coverage. Ultimately, they are able to achieve the same goal even though they are still using analog. Hence, there is still a valuable place in the market for true TDM microwave.

“One of the other things that I like about the Trailblazer is it has the best of both worlds,” Adams commented. “We can have analog, true TDM, fixed latency, microwave, with a little bit of Ethernet. We only use a portion of the Trailblazer’s 512 kB bandwidth for connectivity to different sites to do diagnostics that require Ethernet.”   

CommTech has created as many as 10 Trailblazers at a site with almost no degradation.  CommTech has found a way to successfully eliminate localized interference by using the Trailblazer to spread the usage over various frequencies.

For those agencies that may consider P25 in the future, Carlson’s Trailblazer offers the perfect migration path because the system allows for both IP and TDM analog. If it was being used for analog simulcast and then the agency switched to P25, they could change over the bandwidth to IP and use it to migrate to P25. However, since most agencies that use an IP backhaul need higher bandwidth that can support extensive data such as video traffic cameras or other streams, Carlson also offers a LongHaul product for that purpose.

But for CommTech, the Trailblazer fits their needs to the “T”. 

“Carlson’s Trailblazer has found its niche in analog simulcast because it is a true TDM radio. It does exactly what it’s supposed to do,” Adams stated. “It does fixed latency backhaul for analog communications, and it does it quite well.”


Published in Law and Order, Sep 2012

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