FreeFlight Unveils Radar Altimeters that Mitigate 5G Effects

 - January 28, 2021, 7:07 PM

FreeFlight Systems has unveiled a new series of radar altimeters with “redesigned RF circuitry built to withstand 5G interference.” The new Terrain Series RA 5500, RA 6500, and RA 7500 are optimized for heavy rotorcraft, turboprops, business jets, and military aircraft and will be available in October.

Radar altimeters are facing interference problems from 5G terrestrial broadband datalink systems, such as new 5G products. According to FreeFlight, “Decades ago, when the original specification was created for the radar altimetry, the radio frequency (RF) environment was protected.” That is no longer the case with new products such as 5G.

In November, an RTCA Special Committee issued a report about the frequency spectrum assigned to 5G applications and warned they could interfere with aircraft radar altimeters. According to the report, the frequency spectrum from 3.7– to 3.98-GHz, which the Federal Communications Commission (FCC) has assigned to upcoming flexible 5G telecommunications applications, may “introduce harmful radio frequency (RF) interference to radar altimeters currently operating in the globally-allocated 4.2– to 4.4-GHz aeronautical band."

FreeFlight’s new radar altimeters are designed to withstand 5G interference, including from 5G systems by Ligado that the FCC has approved.

The RA 6500 is designed for Part 29 heavy rotorcraft and features an Arinc 552 interface for integration with older analog indicators. It can also be paired with FreeFlight’s RAD45 standalone indicator. For most installations, the new radar altimeters can connect to existing antennas. 

Terrain Series radar altimeter specifications include a 25-Hz update rate, frequency-modulated continuous-wave at 4.3-GHz center frequency, altitude range of 20 to 2,500 feet, antenna response angles of up to ±20 deg pitch and ±30 deg roll, and a service ceiling of 55,000 feet. The RA 6500 has received FAA and EASA technical standard order approval and is design-assurance level B-rated, as well as meeting DO-160G environmental and DO-178C software standards. 

“The design represents the forward-thinking, future proof technology that FreeFlight Systems is known for,” said FreeFlight Systems president and CEO Tim Taylor. “The Terrain family is designed for robust operation in future environments and platforms while offering a simple retrofit path for replacement of older less capable altimeters in service today.”