FreeDV modulation on VHF

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Víctor José Sánchez Escribano

Jun 24, 2021, 9:14:46 AMJun 24
to digitalvoice
Hi everyone.

I have a little doubt about FreeDV 2400B mode in VHF band (or another FreeDV mode in this band) with a Yaesu FT-857. Which modulation should I use: FM, DIG (SSB-based AFSK) or USB? I've try to receive with a near FM handheld: if I TX in FM the FM HT hardly or not receive (squelch is open) but if I TX in DIG or USB I can hear noise in the HT.

I've read the documentation but I only see that in HF bands it should be LSB for <10 MHz and USB for >10 MHz (as usual) but I cannot find any information about modulation in VHF band.


Mooneer Salem

Jun 24, 2021, 1:22:32 PMJun 24
Hi Victor,

2400B is intended for use with FM. Some radios (like the FT-817) have a specific "PKT" mode as well that is preferred, but it's definitely not required. From what I remember, the FreeDV application will detect whether you're in FM if 2400B is selected and you have Hamlib set up. Note that volume levels with FM may be different than with SSB, which may also explain what you're observing.


-Mooneer K6AQ

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Víctor José Sánchez Escribano

Jun 25, 2021, 2:26:34 AMJun 25
to digitalvoice
Thanks for your help, Mooneer.

I'll review the volume levels in FM if it could be the issue.

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