Glider Electronics Experiment #1 - electrical crosstalk demonstrated

On Saturday, May 2, 2020 at 4:32:04 PM UTC-5, wrote:
On Saturday, May 2, 2020 at 9:41:54 AM UTC-4, Richard Livingston wrote:
Nice demo of cross talk. Last year I fixed a problem in our glider where the microphone wires were not completely shielded, as in your demo, and were picking up signal from the radio speaker wires, also not completely shielded. The result was intermittently the radio would squeal during transmit due to feedback from the speaker back into the microphone. It was intermittent due to the wires shifting slightly every time the canopy opened/closed. Shielding both the speaker and microphone wires fixed the problem.

Rich L.

Such feedback could only occur if the radio had the (mis)feature of echoing the signal from the mic to the speaker. Kind of lets you know you've got the PTT pressed and it's all working, but not really necessary. With that happening, you may also get acoustic feedback, from the speaker back into the mic, even without crosstalk in the wiring. Maybe that feature can be turned off somewhere in the radio's settings?

That's called the "sidetone", and many radios have an adjustment for that. It is also possible (likely even) that the feedback was from the RF back into the microphone wires. Connectors are notoriously leaky, and even coax can leak a little bit. If that RF signal gets into the microphone input it can be rectified by the transistors in the amplifier and produce feedback that will cause a squeal.

Rich L.

On Saturday, May 2, 2020 at 2:22:55 AM UTC-7, Richard Lancaster wrote:
Thanks all for the positive comments.

Got asked on the UK glider forum for a description of what the video was about. So in case anyone is debating whether to sink their time into it, here's a quick abstract:

"Electrical crosstalk is a type of interference where the signals carried in
one set of wires "talk across" into another set of wires. This video sets
up a simple glider electrical harness, talks about how crosstalk might
occur in it, demonstrates it occurring and illustrates the magnitude of the
consequences to the pilot."

Best regards,

Richard

Great YouTube when is the next one on shielding.

Richard
www.craggyaero.com

On Saturday, 2 May 2020 16:20:40 UTC+1, Richard Pfiffner wrote:
Great YouTube when is the next one on shielding.

Am attempting to film the next one tomorrow (Sunday), then hopefully edited by the end of the week.

Richard

On Friday, May 1, 2020 at 10:17:03 AM UTC-7, Richard Lancaster wrote:
Hi all,

I got a bit bored and started filming some glider electronics experiments. I am attempting to pitch them to be interesting and understandable even if you don't know much about electronics.

First up:
Glider Electronics Experiment #1 - electrical crosstalk demonstrated

Available he
https://RJPLancaster.net/

Best regards,

Richard

Well done. I'm looking forward for your next installment. Thank you!
Craig

Nicely done.