[CQ-Contest] Band Edge

Edward Sawyer EdwardS at advanced-conversion.com
Sat Nov 14 06:53:26 EST 2020

Since the topic of Band Edge has come up.  I am interested in what people think the band edge is on SSB.

I believe the FCC provides some guidance in Part 97.  They define the width of an SSB signal I believe as 36dB down from the signal on the center frequency.  This allows a "clear signal" to be closer to the band edge and still be sufficient.  Rather than a "broad brush answer" of 3khz away.  In fact, 3khz away isn't far enough if you are splattering 10 - 15khz wide with signal energy above -36db.

I am assuming that most countries don't define the band edge other than center frequency given that you always hear Europe on frequencies like 7199.9, 3799.9 and 14349.9.

I personally use 0.5khz above on USB and 2.8khz below.  I periodically get the "you are out of band" quips from the khz cops that think 3.0 is written in Part 97 somewhere.  Its not.  -36db is.  And 3khz comes from a "rounded up" answer to how far away do you need to be to insure that the properly modulated SSB signal is -36db down form the center frequency.

Ed  N1UR

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