ARCATA-- Monitoring traffic cameras from a single location in a busy urban environment requires fast, robust links that don’t lose bandwidth over a “daisy chain” of microwave links. LongHaul ST, the new lightning-fast Ethernet bridge from Carlson Wireless, offers this kind of performance-- “head and shoulders above” the competitors, according to an independent field test.  

Jake Smith, a systems integrator at Cactus Computer in Central Texas, engineers and installs advanced traffic control systems for municipalities. For upcoming projects in five cities in the southern United States, Smith designed a complex, daisy-chain architecture, which communicates across point-to-point, microwave links of five or six repeaters off a fiber backbone.

After perfecting this design, he searched for radios that would work well in an urban environment and handle the throughput of video feed while minimizing bandwidth usage across the communication links.

When Kiely Cronin, sales engineer for Carlson Wireless, learned that Smith was looking for a better product than the ones he had tested at the time, Cronin put Smith in contact with the Carlson Wireless engineering team, headed by CEO Jim Carlson himself.

“I had heard about the outstanding work Carlson was doing in the wireless microwave industry, and I thought he might have a unique way to help with the project,” Smith said.

The Carlson Wireless engineering team went to work immediately to test LongHaul ST in the lab and soon reported back to Smith with the results, which he called “exciting.”

“It looked too good to be true,” Smith admitted. He needed to see for himself, so he decided to test the LongHaul ST, along with similar products from four other manufacturers, in as stringent an environment as he could create. This included setups in his office and in the field.

For the test, Smith demonstrated the radios in three cities in Texas, Fort Worth, Irving and Duncanville, and two in West Virginia, Huntington and Charleston. He tested the products by transmitting telemetry data and video. Representatives from each manufacturer were present at the demonstrations.

Among the tests was an experiment designed to determine how reflections and other interference would affect bandwidth. For the demonstration, Smith placed a unit on top of a parking garage and transmitted data to another unit located seven stories below, in an intersection surrounded by trees.

The multiple links are necessary in Smith’s application because of environmental obstacles, which range from tree-covered intersections where traffic cameras are located to tall buildings where the signal is received. 

Smith’s application is unique not only because it uses more links than usual but also because it demands exceptional performance. “Each link has to be extremely fast and the delay extremely short,” he said.

The performance of LongHaul ST exceeded Smith’s expectations, delivering data-transmission rates as much as three times higher than comparable equipment from competing manufacturers. Smith said he believes the performance and reliability of the LongHaul ST will enable him to connect as many as 12 links off the fiber backbone.

“LongHaul ST allows you to monitor clusters of intersections from a central point to a backhaul point and to backhaul the cluster,” Smith said, “and you can narrow the channels from 20 to 10 to 5 MHz without channel overlap.”

The competing products provided a maximum data-transmission rate of 22 Mbps under test conditions, while the LongHaul ST’s throughput ranged from 33 to 66 Mbps depending on the type of data that were sent (small file size with telemetry data, large with video).

“LongHaul ST performed exactly as the Carlson team said it would,” Smith said.

He also appreciated the personal service and customized engineering he received when working with Jim Carlson. “I was impressed that he is able to control every aspect of the product and optimize it to match an application,” Smith said.

With results like these, Smith is now planning applications in several other cities, some with as many as 12 links in a row.

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