FMの復調機能の追加を行った．
AMの復調ができているので，それを少しモディファイするだけでOK.
つまりAMは振幅を求めるがFMは位相を求めて微分すればよいので，下図のような構成になる．
tan の逆関数は安直にテーブル参照にした．math ライブラリのatanやatan2関数は処理が重くて使えなかった．
今のところSGからのFM信号はうまく復調できている．リミッタを深く効かせた通常のFM復調と違ってノイズは多め．この方式はI,Q信号の瞬時値から位相を計算するため，リミッタが使えないから仕方ない．
もう少しテストが必要かもしれないが，とりあえず SSB(USB/LSB)，CW，AM，FM モードの受信が可能になった．
Tj Lab 
Dear Uebo, it is a great design, but I couldn’t find any Software of this project. There is the receiver schematic but any source code. Is there a reason or I failed in finding it (just found the coefficient computing)? I already made your SSB TX modulator and your VFO, and they work great, I am courious to test your receiver project and learn from it. Thank you
いいねいいね
I am confirming the operation and the function of the receiver.
For now I don’t think it has satiable performance for AM and FM.
The AGC function is also in trial and error.
That is why I have not released the firmware.
For the time being, I will release the firmware for SSB in a couple of days.
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Many Thanks Uebo, take your time, your works are very instructive and useful, I’ll wait.
Have a great day.
Antonio (Rome, Italy)
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I have released the source code of SSB receiver.
The link is described in the latest blog article.
いいねいいね