This article is the result of my frustration trying to get good upload speeds for video from the UAS to transmit back to the Emergency Operations Center (EOC) or Command Post (CP). I talked about dealing with video transmission in my article for AOPA.
Let me say I am not a radio frequency engineer, although a great Ph.D. brainiac, Mike Barts, from the Wireless Research Center, did lend some assistance in better understanding the issues and bandwidth available with the more advanced hotspot I tested. I also had the support and assistance of Wake Forest Fire Department Assistant Chief Darryl Cash who is a communications guru.
In public safety aviation, a significant bottleneck in sending live video back to others is the video upload speeds we can achieve. I care less about download speeds.
And while this article is about the Verizon hotspots, it’s just what we use as a department. I did not test any other providers service. Heck, this testing of just the Verizon hotspots took many, many miles over a series of days.
Currently, my department uses the Verizon Jetpack MiFi 7730L hotspot. There have been times I unable to find adequate upload speed from this unit to send video from the UAS to the EOC or CP.
Verizon released the new Verizon Jetpack MiFi 880L which is ” the first CAT 18 LTE Mobile Hotspot with 2, 3 and 4 carrier CA and LAA technologies.”
The unit has not been without growing pains and complaints from some. People have had issues with the unit restarting on its own. I also experienced some of those issues as well but they were not that frequent.
To understand more about the technology, you can watch this awesome video from the Mobile Internet Resource Center.
I’m sure a white-coated scientist would be able to poke all sorts of holes in my testing regime. All I can do is use the tools at hand and two iPhones in conjunction with the service from Speedtest.net to measure performance.
By the way, the United States ranks 35th in the world in cellular data speeds. The average download speed is 33.45 MBs and upload is 9.9 MBs.
Below you will see a map of the upload speeds achieved with the different units in different configurations.
I conducted tests in a rural area, along a major highway around Raleigh, and in our primary service area surrounding Wake Forest, NC.
You will find a number of layers in this map and by turning off a number of them you can focus on the results for a specific area of interest.
In addition to hotspot testing, I also included the testing of an external Multiple-Input Multiple-Output (MiMo) antennas which receive targeted radio frequency across the cellular data bandwidth.
The antennas I used were two Proxicast 8 dBi High Gain External Magnetic Antennas that were mounted more than 22″ apart on the roof of the Tahoe. I also found a noticeable speed difference if one antenna was oriented 90 degrees different than the other. Any reference to antenna versus no antenna is regarding this antenna.
One more point, around Wake Forest, our primary department service area, the testing configuration was the 8830 unit with the external antenna versus the 7730 without the antenna as it is primarily used now.
And Now the Results
The 8830 unit uses more bands to download and upload data. It has a feature called carrier aggregation and that’s how it jams more data through the pipe. Here are the various Verizon carrier bands and frequencies used. Look at NAR for U.S. based frequencies.
If you match the primary bands in the U.S with the frequency response of the Proxicast antennas you will see they are a good fit.
In my testing, to maximize speed is not only dependent on the type of hotspot where you operate but also the available cell towers in your area. Not all cell towers are equal. In more rural areas the older 7730 unit had faster upload speeds but in suburban and urban areas with more advanced cell towers the 8830 blew it away.
In our daily operational area, the 8830 unit with external antennas had an upload speed that was 37.9% faster than the naked 7730 unit. For me, that extra 5.7 MBs of upload speed can make the difference between a smooth high definition video transmission and a choppy one.
In rural areas, the 7730 unit performed better with uploads. The 7730 with the external antennas was 25.2% faster. The difference was 3 MBs but again, more speed is always better.
By the way, you will need an adapter to connect the external antennas to either Jetpack. These are the ones I used. They provided a much better connection than others I tried before.