Weird High Pitched Sound in packet audio

Packet Commander
1

Hello All, I am using the DigiRig Lite and my Yaesu FTM-150 for some packet work. I made a video to show some club members and we noticed this weird high pitched sound with my data packet. It’s still working great but just wondering what it is?

Thanks,

Matt WV8MAT

2

The high-pitched sound you’re hearing is expected to be present in the audio stream coming out of the iPhone when using the internal packet modem.

Packet Commander uses a tone on the right audio channel to control PTT. That tone is typically around 12 kHz. The DigiRig Lite only sends the left audio channel to the radio, but some Yaesu radios are known to mix or bleed the PTT line into the audio path. That’s perhaps why you’re hearing the tone (not sure where in the chain you recorded the audio).

The tone shouldn’t interfere with normal operation. It’s filtered out by most radio circuits, but some leakage might still be audible.

Here’s the DigiRig Lite schematic if you want to see how the audio routing works:

The PTT tone frequency can be adjusted in Settings if necessary.

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