Most current GNSS use the GPS constellation. However, with commercial use of GLONASS being promoted by Russia and with Galileo sloooowly emerging, will any existing Garmin Wonderbox navigation systems be capable of using systems other than GPS?
I note that EGNOS is supposedly able to improve the accuracy of my automotive Garmin using signals from Inmarsat (ID33) and Artemis (ID 37). However, in practice I've noticed no difference and the system rarely sees any EGNOS signal. Presumably aviation systems track EGNOS in Europe these days?