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Tuesday, October 2, 2012

Garmin’s GDL-39 ADS-B Receiver


ADS-B for under $1,000


By Bill Cox
Most of the time, you won't be able to do that with the ADS-B product, because the information is delivered via line-of-sight from the same ground stations that provide TIS. XM is heaven-sent, just like GPS. I departed Compton on one flight with the 696 indicating all the local weather before takeoff; then, watched the iPad weather depiction begin to fill in the screen as I passed through 1,500 feet.
In conjunction with Communication, Navigation and Surveillance (CNS) technologies, ADS-B is the key to air-traffic management in the future.
Uncharacteristically, Los Angeles was ringed by thunderstorms dredged up from the Gulf of California, so there was plenty to paint. By the time I passed 3,000 feet, both XM weather on my 696 and the GDL-39 readout on my iPad provided good depictions of the storms, with frightening shades of red and purple scattered across the screens.

There's little question that ADS-B will provide a major improvement when it's fully implemented in 2020. In the meantime, it's frustrating that the government apparently feels it necessary to partially degrade the current system of traffic alerts simply to encourage participation in ADS-B.

GPS With A Russian Accent
GLONASS, the Russian equivalent of our GPS, became operational on a limited basis in 1995 and was recently expanded to its full 24-satellite universe in 2011. GLONASS actually offers a few advantages over our Navstar system, but it's unfortunately not compatible with our cockpit-mounted GPSs.

GLONASS, an acronym for Globalnaya Navagatsionnaya Sputnikovaya Sistema (ask at your next hangar flying session to see if anyone else knows the derivation), does essentially the same job as GPS and offers another 24 satellites with the same navigation features. GLONASS orbits at 11,900 miles, 1,000 miles farther out than our system, and offers a lightning fast refresh rate of 10 times a second, twice as quick as our GPS. That's position accuracy to about every 35 feet for a 200-knot aircraft.

Though GLONASS doesn't participate in the ADS-B system, Garmin recently produced a wireless receiver to add GLONASS satellite signals for interpretation by your iPad. Put the two systems together, and you have the ingredients for a very comprehensive navigation system that could conceivably provide positional information well beyond that of your standard GPS.

Garmin's GLO receiver was also announced at Oshkosh and has a list price of only $99. Buy the full package, including a cockpit mount, power cables and Garmin Pilot six-month subscription, and you'll pay $129. Remember, this will only play through an iPad, Android or other laptop computer device, not a standard portable or panel-mount GPS unit.


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Labels: Avionics, Cockpit Gadgets, Features, Pilot Supplies, Pilot Gear, Gear
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