[RTTY] uh, what about spectrum?

[Mike]

Hello Bill,

The more I thought about it, I'm not so sure about the sidebands 
being a problem when looking at the 200 Hz bandwidth limit.  You will 
always have sidebands, it's a matter of how far down from the 
fundamental, in this case two fundamentals 170Hz apart.  I've seen 
bad RTTY signals that are 170 Hz shift producing noticeable sidebands 
on the spectruim more than 200 Hz wide.  Yeah, they're probably AFSK 
generated.

I'm planning on using the 200 Hz region unless the FCC dictates the 
sideband values below a level unattainable by the average amateur 
equipment should  the ARRL's wachy bandplan be adopted.

No, I haven't done the math as the last time was 45 years ago as an 
undergrad.  Don't plan on drudging up old memory cells to do the math 
as I've got to get the amplifier working better plus build another 
for the second radio.

How's the amp. coming along, Bill?

At 06:59 AM 1/16/2006, Mike wrote:
>Hello Bill,
>
>Thanks for pointing it out.  That's why I put it as a question.
>
>At 12:00 AM 1/16/2006, Bill Turner wrote:
>>ORIGINAL MESSAGE:
>>
>>At 08:10 PM 1/15/2006, Mike wrote:
>>
>>>Since I use 170 Hz shift (bandwidth) and the DX stations I have
>>>contacted in and out of contests are also 170 Hz shift, the ARRL
>>>proposal should not impacting my operation in the 3520 - 3525 KHz
>>>area and below 7030 KHz and below 3580 KHz.  Am I not reading it
>>>correct?  Is there another ARRL or FCC document/proposal I should be
>>>looking at?
>>
>>
>>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>
>>Shift is not the same as bandwidth, as the mathematicians among us 
>>will be quick to point out. RTTY is a form of FM, and FM produces 
>>sidebands. The bandwidth is a function of both shift and baud rate.
>>
>>I'll leave it to the pros to calculate exactly, but somewhere 
>>between 250 - 350 Hz is required for 170 Hz shift.
>>
>>Bill, W6WRT
>
>         73,
>         Mike, K4GMH

         73,
         Mike, K4GMH