I'm starting to think about upgrades on my RV-9A, inching toward IFR capabilities. One of the first things I'd like to do is add a second COM. Now, I like to tinker and sometimes I come up with ideas that should never see the light of day. My current idea might be one of those so I thought I'd put it out there for comment.
The first problem that comes up with the second COM (and a future NAV radio) is the need for an audio mixer or panel. As we all know, audio panels are painfully expensive. Mixers are much less feature rich and more reasonable in price. Here is my idea - using a Raspberry Pi, a whole lot of relays (26) and a small LCD touch screen I could build an audio panel. The Pi would present the various selector buttons (RX COM1/COM2/NAV, TX COM1/COM2) and drive the relays for simple connections from my radios to my headsets and from my mics/PTT to my radios. This isn't all that complex and would cost less than 10% of a new audio panel. The relays are bundled on small cards, 8 at a time. I would design it so that my COM1 is connected via normally closed circuits so that if I lose this contraption I still have COM1 working in both directions.
The second opportunity here is for a COM controller. The MGL V16 comes as a remote unit and you can add a variety of heads to operate it. Their interface is published and very well documented and if you can connect RS232, you can control it. Now, I've had some success with connecting RS232 to a Raspberry Pi - I know I can do that. Writing the little bit of code to make a front end interface for the radio is well within my experience. This could go on the same Raspberry Pi and same small touch screen as the audio panel. This comes with no incremental costs (I already have the DB9-USB dongle for the serial connection) and would save a few hundred dollars as well.
All told, this project could save me 2 AMUs. It would all be for backup avionics so I could tolerate complete failure. Anyone have any reasons that this might be too crazy? Or that something that I described would not work?
Bonus material - any reason that I wouldn't want to install my second COM antenna under my wing, maybe 3' out behind the fuel tank? Just aft of the inboard access plate?
I know, too much time on my hands.. Thanks for any 2 cents out there.
The first problem that comes up with the second COM (and a future NAV radio) is the need for an audio mixer or panel. As we all know, audio panels are painfully expensive. Mixers are much less feature rich and more reasonable in price. Here is my idea - using a Raspberry Pi, a whole lot of relays (26) and a small LCD touch screen I could build an audio panel. The Pi would present the various selector buttons (RX COM1/COM2/NAV, TX COM1/COM2) and drive the relays for simple connections from my radios to my headsets and from my mics/PTT to my radios. This isn't all that complex and would cost less than 10% of a new audio panel. The relays are bundled on small cards, 8 at a time. I would design it so that my COM1 is connected via normally closed circuits so that if I lose this contraption I still have COM1 working in both directions.
The second opportunity here is for a COM controller. The MGL V16 comes as a remote unit and you can add a variety of heads to operate it. Their interface is published and very well documented and if you can connect RS232, you can control it. Now, I've had some success with connecting RS232 to a Raspberry Pi - I know I can do that. Writing the little bit of code to make a front end interface for the radio is well within my experience. This could go on the same Raspberry Pi and same small touch screen as the audio panel. This comes with no incremental costs (I already have the DB9-USB dongle for the serial connection) and would save a few hundred dollars as well.
All told, this project could save me 2 AMUs. It would all be for backup avionics so I could tolerate complete failure. Anyone have any reasons that this might be too crazy? Or that something that I described would not work?
Bonus material - any reason that I wouldn't want to install my second COM antenna under my wing, maybe 3' out behind the fuel tank? Just aft of the inboard access plate?
I know, too much time on my hands.. Thanks for any 2 cents out there.