Gents,
I decide to take the plunge and do some GoPro video and record cockpit audio separately and planned to use an old Samsung smart phone as my digital voice recorder.
I have a Garmin GTR200 radio that has audio output that typically goes to an audio panel but the manual says it can be used for external recording. The manual says the audio out (called receiver out in the manual) has an impedance of 600 ohms.
Yesterday I installed an audio out jack (isolated from the airframe ground) in my panel wired to the GTR200. I made an adapter cable to interface with the 4 ring connector the cell phones used. I did some test recording and wasn't happy with the results.
I tried recording on two of my phones, my S5 (currently the phone I use) and the Fascinate (5+ years old). I used the Samsung recording app on both phones. I had nothing else powered up on in the plane except the radio.
The recording on the Fascinate had a lot of what I call static or background noise. When I recorded the ATIS it was even worse. There was no background noise present in my headsets while recording. My voice (testing 1,2,3 etc) sounded very tinny.
The recording on the Samsung S5 had static and a small amount background noise. It too sounded tinny.
Doing some research on the Samsung phone mike interface I found that the phones expect to see an mike impedance of 1200-1600 ohms. Since the output impedance from the Garmin GTR200 is only 600 ohms, would the impedance mismatch cause the noise and tinny recording?
Since there are only two pins for the mike input to the phone is there a polarity to be concerned about?
Any insight would be appreciated.
I decide to take the plunge and do some GoPro video and record cockpit audio separately and planned to use an old Samsung smart phone as my digital voice recorder.
I have a Garmin GTR200 radio that has audio output that typically goes to an audio panel but the manual says it can be used for external recording. The manual says the audio out (called receiver out in the manual) has an impedance of 600 ohms.
Yesterday I installed an audio out jack (isolated from the airframe ground) in my panel wired to the GTR200. I made an adapter cable to interface with the 4 ring connector the cell phones used. I did some test recording and wasn't happy with the results.
I tried recording on two of my phones, my S5 (currently the phone I use) and the Fascinate (5+ years old). I used the Samsung recording app on both phones. I had nothing else powered up on in the plane except the radio.
The recording on the Fascinate had a lot of what I call static or background noise. When I recorded the ATIS it was even worse. There was no background noise present in my headsets while recording. My voice (testing 1,2,3 etc) sounded very tinny.
The recording on the Samsung S5 had static and a small amount background noise. It too sounded tinny.
Doing some research on the Samsung phone mike interface I found that the phones expect to see an mike impedance of 1200-1600 ohms. Since the output impedance from the Garmin GTR200 is only 600 ohms, would the impedance mismatch cause the noise and tinny recording?
Since there are only two pins for the mike input to the phone is there a polarity to be concerned about?
Any insight would be appreciated.