Connecting cameras/voice recorders etc to aircraft intercom
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Connecting cameras/voice recorders etc to aircraft intercom
Hello,
I am looking at connecting my GoPro camera to an aircraft intercom.
I realise an option is to simply use a small mic tucked away inside the earcup of a headset but I'd rather connect the camera directly to the intercom for better clarity, and also comfort.
From what I have understood from the feedback I've received here, and internet research, there are three main issues to overcome.
Firstly, is physically hooking up the camera to the audio source. That should be easy as I understand it, I guess I could just use something like this:
Pilot Avionics PA 80 Video/Audio Adapter Cable (GA Twin Plug)
From my limited knowledge, this kind of thing (available from many other pilot supplies retailers too) is simply a 6.35mm stereo plug extension with a 3.5mm plug extension connected in parallel, right? So I'm also assuming, as the 6.35mm is fairly standard/common, I don't have to look in a pilot shop for this kind of adaptor.
Secondly, is the issue of signal levels. I'm guessing the voltage used to drive beefy aviation headsets is a lot higher than that the camera will have been designed for? I did read (in my other thread) that some trial and error would be involved in solving this one, but I was wondering if there is a more concrete way to do it. Maybe matching impedance figures (again, totaly newbie here)?
Thirdly, and this is the one I'm totally clueless about, is the issue of a DC power source being present on some aircraft intercoms. This is referenced in the item description here:
AIRCRAFT INTERCOM RECORDING CABLE from Aircraft Spruce
It says that the DC supply can, at best, cause a high pitched squeal on the recording, or damage the recorder if the voltage is high enough. However, from looking here:
TRS connector - Wikipedia, the free encyclopedia
It seems the DC power supply, if needed, will only connect to the microphone (through the often unassigned tip on the TRS connector), and not to the headphones (with sleeve being common ground, and tip/ring being two audio channels). And as I understand it, the camera would be connected to the intercom's audio output (which connects to the headphones, and therefore without DC power supply), not to the microphone input (where there would be a DC power supply connected to the tip of a TRS connector inserted there).
So how is it that the possible DC power supply is at all relevant to recording to a camera? Am I right in saying that aircraftspruce have built in a useless feature, or have I (probably more likely) totally confused myself?
I'd massively appreciate any feedback on these.
Also, I understand I had started another thread on cockpit cameras, but with the specificty of these questions I thought it might be useful to start a new thread.
Thanks!
Odai.
I am looking at connecting my GoPro camera to an aircraft intercom.
I realise an option is to simply use a small mic tucked away inside the earcup of a headset but I'd rather connect the camera directly to the intercom for better clarity, and also comfort.
From what I have understood from the feedback I've received here, and internet research, there are three main issues to overcome.
Firstly, is physically hooking up the camera to the audio source. That should be easy as I understand it, I guess I could just use something like this:
Pilot Avionics PA 80 Video/Audio Adapter Cable (GA Twin Plug)
From my limited knowledge, this kind of thing (available from many other pilot supplies retailers too) is simply a 6.35mm stereo plug extension with a 3.5mm plug extension connected in parallel, right? So I'm also assuming, as the 6.35mm is fairly standard/common, I don't have to look in a pilot shop for this kind of adaptor.
Secondly, is the issue of signal levels. I'm guessing the voltage used to drive beefy aviation headsets is a lot higher than that the camera will have been designed for? I did read (in my other thread) that some trial and error would be involved in solving this one, but I was wondering if there is a more concrete way to do it. Maybe matching impedance figures (again, totaly newbie here)?
Thirdly, and this is the one I'm totally clueless about, is the issue of a DC power source being present on some aircraft intercoms. This is referenced in the item description here:
AIRCRAFT INTERCOM RECORDING CABLE from Aircraft Spruce
It says that the DC supply can, at best, cause a high pitched squeal on the recording, or damage the recorder if the voltage is high enough. However, from looking here:
TRS connector - Wikipedia, the free encyclopedia
It seems the DC power supply, if needed, will only connect to the microphone (through the often unassigned tip on the TRS connector), and not to the headphones (with sleeve being common ground, and tip/ring being two audio channels). And as I understand it, the camera would be connected to the intercom's audio output (which connects to the headphones, and therefore without DC power supply), not to the microphone input (where there would be a DC power supply connected to the tip of a TRS connector inserted there).
So how is it that the possible DC power supply is at all relevant to recording to a camera? Am I right in saying that aircraftspruce have built in a useless feature, or have I (probably more likely) totally confused myself?
I'd massively appreciate any feedback on these.
Also, I understand I had started another thread on cockpit cameras, but with the specificty of these questions I thought it might be useful to start a new thread.
Thanks!
Odai.
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You might avoid a lot of these problems with a "telephone pickup coil" attached to a headset can by its suction cap. The magnetic signal transfer might be less noisy than a microphone bumping about in the can. And you would not have to worry about voltages or impedances.
I actually bought one for about £8, meaning to try it, but I never got round to it.
I actually bought one for about £8, meaning to try it, but I never got round to it.
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No doubt you could match the level of the 1/4" jack headset feed to the minijack input on the camera, but finding the right lead would be the easy bit.
The headset feed is designed to drive the headset transducer at a moderate level, which would require (I'm guessing) a volt or two, whereas the camera input is designed for a mic feed, which would be of the order of a few millivolts.
You really can get perfectly good results by putting a lapel-type mic in the headset earpiece - it's not that uncomfortable.
The headset feed is designed to drive the headset transducer at a moderate level, which would require (I'm guessing) a volt or two, whereas the camera input is designed for a mic feed, which would be of the order of a few millivolts.
You really can get perfectly good results by putting a lapel-type mic in the headset earpiece - it's not that uncomfortable.
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Don't forget to consider the routing of a cable from your earpiece to the camera.
I plug in to the rear intercom sockets and have the camera in the back of the aircraft, or if it needs to be in the front, I use the pax sockets.
The prospect of a loose cable from my ear to the camera seems potentially awkward at best. Should you decide to try this, you may want to cable tie the mic lead to the headset lead to at least keep it tidy as far as the dash.
I plug in to the rear intercom sockets and have the camera in the back of the aircraft, or if it needs to be in the front, I use the pax sockets.
The prospect of a loose cable from my ear to the camera seems potentially awkward at best. Should you decide to try this, you may want to cable tie the mic lead to the headset lead to at least keep it tidy as far as the dash.
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The PA80 seemed to work OK with a GoPro - I've only tried it once so far and the sound is rather loud and a bit distorted at full volume, but at more reasonable levels seemed OK. What seemed more bizarre was the total lack of noise on the recording... In my experience with headsets on its usual to still hear some engine noise, but with the PA80 connected to the intercom and GoPro the only sound recorded was what comes from the intercom - no background noise at all... The recording sounds almost too quiet when there's no talking/communications going on.
Andy
Andy
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