[Boatanchors] ALERT: AM Under Attack - WA3VJB

Gary Schafer garyschafer at ATTBI.COM
Fri Jun 20 23:50:11 EDT 2003

Colburn wrote:
>>>        Now 2.8KHz for SSB and 5.6 KHz for AM are now equivalent audio
>>>bandwidths. 6KHz is more appropriate.
>>With a proper BFO setting a 2.8 kHzx BW for SSB would be
>>transmitted audio freqs of 300 to 3100 Hz. Thus the proper
>>AM BW would be 6.2 kHz to get up to 3100 Hz in the audio
>>response.  John  KK6IL
> I agree that 2.8 is lots easier to listen to than 2.4! (Even though QRM
> frequently makes 2.4 necessary.) A max of 3.0 would allow for a little
> breathing room.
> Please explain why an AM signal (DSB with carrier) would require so much
> more than double the same bandwidth to duplicate SSB.  I really do not
> know.
> If the numbers really work that way then for the sake of boatanchor ops
> we need 3.0KHz SSB and 6.2KHz AM in the proposal.  [Just in case the FCC
> takes this seriously we should make the argument for reasonable specs.
> We dare not wistfully assume they won't!]
> Thanks! & 73, doc  kd4e
Copied from another of kd4e posts on the subject:
"-- though I will be recommending 3.0 and 6.0 KHz as more reasonable."

Well yes, what John says is correct about the frequency response. In SSB
it is essentially removed from the low end and added to the high end on
SSB when the carrier is moved to one side of the filter.

Without trying to be malicious I would suggest that there other aspects
of ham radio that you also do not understand.

How can you "recommend 3.0 and 6.0 KHZ as more reasonable" when you do
not understand what it means or what the difference is between AM and
SSB bandwidths?

Why not petition the FCC to channelize all the bands? That would
certainly assure that there would be no adjacent channel interference
wouldn't it?

There are probably many other restrictions that we could ask for to help
out with interference. But wouldn't that be very short sighted on our part?

Maybe you don't remember that there were at one time certain forms of
digital transmission that were not allowed on the bands. It took a lot
of years to get approval.

Why would we want to see restrictions added that may some day limit a
new mode that may be just around the corner? Or to limit experimentation
of modes that could be developed to better ham radio.

In the early days of SSB on the ham bands the AM guys put up a fuss
about how wide the SSB guys where and how much interference they caused.
(and if you listen to SSB on an AM receiver it does interfere with an AM
signal) Should SSB have been outlawed way back then? Maybe we would not
have the problems we have today if it were. :>)

Gary  K4FMX

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