In the USA, an emergency locator transmitter (ELT) is required on a homebuilt with two or more seats, and certainly not a bad idea in a single-seater. While I think the old 121.5 MHz ELTs are still technically legal, they are no longer monitored by satellites and wouldn't do much good if you ever needed to be found. The new 406 MHz is much better and prices have come down to about $500 for a basic new installation. They are even more effective if you provide the optional GPS input so the beacon broadcasts your location in an emergency.
So, here's my question/suggestion. What's the cheapest (and ideally small and light) way to provide the GPS signal to the ELT? Of course if you've got some big Garmin glass panel then you're all set, but if you're flying something simple and maybe using a portable GPS or phone or tablet for navigation, I don't think there's an easy way to get that GPS signal to the wired connection on the ELT. Plus, it's probably better to make that a standalone function not dependent on your portable device.
I have looked around for an easy, off the shelf solution. The GPS data format needed by the ELT is very standard: NMEA 0183 at 1200/2400/4800/9600 baud. The components are cheap and avialable, you'd think someone would sell something like that all ready to go, but I haven't found any. Hobby electronics places like Adafruit and Sparkfun have all sorts of GPS modules, and it turns out that they are totally self-contained: apply power and they will start up, do their magic and then start spitting out the GPS data in the proper format, no other processor required. One I looked at also had a separate pin out for the "acquired" signal that you could rig to an LED on your panel to yet you know that it's up and running.
Even I can manage to solder a few wires and I think all you would need is some wire, a min DIN connector, a fuse, a 3.3v regulator, the GPS module, an external antenna if needed, an LED and a plastic enclosure. If you want to get fancy you could add a backup battery so that even total electrical failure would still provide the actual crash location to the ELT. Without it, the ELT would still have the spot where you were when the power went out.
Electronics gurus (definitely not me), what you you think?
Cheers,
Matthew
So, here's my question/suggestion. What's the cheapest (and ideally small and light) way to provide the GPS signal to the ELT? Of course if you've got some big Garmin glass panel then you're all set, but if you're flying something simple and maybe using a portable GPS or phone or tablet for navigation, I don't think there's an easy way to get that GPS signal to the wired connection on the ELT. Plus, it's probably better to make that a standalone function not dependent on your portable device.
I have looked around for an easy, off the shelf solution. The GPS data format needed by the ELT is very standard: NMEA 0183 at 1200/2400/4800/9600 baud. The components are cheap and avialable, you'd think someone would sell something like that all ready to go, but I haven't found any. Hobby electronics places like Adafruit and Sparkfun have all sorts of GPS modules, and it turns out that they are totally self-contained: apply power and they will start up, do their magic and then start spitting out the GPS data in the proper format, no other processor required. One I looked at also had a separate pin out for the "acquired" signal that you could rig to an LED on your panel to yet you know that it's up and running.
Even I can manage to solder a few wires and I think all you would need is some wire, a min DIN connector, a fuse, a 3.3v regulator, the GPS module, an external antenna if needed, an LED and a plastic enclosure. If you want to get fancy you could add a backup battery so that even total electrical failure would still provide the actual crash location to the ELT. Without it, the ELT would still have the spot where you were when the power went out.
Electronics gurus (definitely not me), what you you think?
Cheers,
Matthew