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drowe67 / freedv-gui

GUI Application for FreeDV – open source digital voice for HF radio
https://freedv.org/
GNU Lesser General Public License v2.1
193 stars 49 forks source link

[Question] IF Filter & FreeDV #701

Closed Nokia808 closed 6 months ago

Nokia808 commented 6 months ago

Hello again !

What is ideal & most suitable IF Filter band width ?

tmiw commented 6 months ago

~3 KHz is likely fine for most uses, especially since it allows you to easily pick up other users regardless of what mode they're using. We haven't done much official testing with narrower filters.

However, it's possible that narrower filters may help in certain situations; IIRC the narrowest mode (700D) only needs around 1-1.1 KHz bandwidth.

Nokia808 commented 6 months ago

@tmiw

Does IF Filter BW = 3 KHz make something bad for 700D mode ?

tmiw commented 6 months ago

Does IF Filter BW = 3 KHz make something bad for 700D mode ?

It shouldn't as it's much wider than the ~1 KHz of bandwidth that it requires. The wider bandwidth is preferred mainly due to the other modes being wider than 1 KHz (thus reducing the need to continually adjust the filters).

Nokia808 commented 6 months ago

@tmiw

Many thanks ! Question answered !

@tmiw & @tyrbiter I welcome sked with you if you like & if you have a time !