Bob
No, I was not being derisive at all. If this effect is there, my first thought is that it is due to strong RF signals being picked up and rectified in the analogue audio stages of the phone or whatever device was used for recording.
Wrapping the device completely in aluminium foil will create a Faraday screen around the device and considerably attenuate any incoming RF signals, thereby reducing, if not removing the problem.
On a different note, it looks as though the OP (MothBall) has not been here since Saturday.
It would be nice to know if he has a solution, or it was just a bit of a wind-up.
JimB
No, I was not being derisive at all. If this effect is there, my first thought is that it is due to strong RF signals being picked up and rectified in the analogue audio stages of the phone or whatever device was used for recording.
Wrapping the device completely in aluminium foil will create a Faraday screen around the device and considerably attenuate any incoming RF signals, thereby reducing, if not removing the problem.
On a different note, it looks as though the OP (MothBall) has not been here since Saturday.
It would be nice to know if he has a solution, or it was just a bit of a wind-up.
JimB