On February 16, the EDGE Research Lab team launched EDGE4 (flight summary), a relatively light flight designed to inform infrastructure decisions for our research project. The flight lasted almost 5 hours, reached a max altitude of 106,504 feet, and traveled 165 miles downrange. Of particular interest to this community is the head-to-head test that we did comparing the reliability and performance of the 9xTend (our standby radio for years - starting well before the formation of the EDGE team) against the recently released RFD900 (originally announced here on DIYDrones: RFD900 - New long range radio modem). A full writeup of the testing scenario, configuration, and the results can be found on our report page, but here's the short version: from a link speed and reliability perspective, the RFD900s are amazing. Here's a side-by-side comparison of the GPS tracking information that we received (xTend on the left, RFD900 on the right):
This was captured from two different chase vehicles at the same location, about 41.5 miles line-of-sight from the balloon at the time. The advantages of the built-in diversity and filtering on the RFD900 are clearly evident. Also, in case you're wondering, ground-based testing of the two payloads side-by-side indicated no substantial difference in the noise floor reported by either of the receiving stations with the other radio on, so they're not interfering with each other.
Big kudos to Seppo and his team at RFDesign; they've put together a phenomenal radio. We went into this test expecting to come out with a clear choice to stick with the xTends for our operations, but this result has us seriously reconsidering. On top of all of the performance goodness, these radios operate on the same SiK open-source firmware as the 3DR 900MHz radios!