[SFDXA] Are You Frequency Confused with RTTY?

Kai Siwiak k.siwiak at ieee.org
Wed Mar 7 18:44:38 EST 2012 

Right, that's the narrative, now go to the actual Rules and regs where 
they tell you what they mean by those two modulations. Specifically see:
97.305 (c) and 97.307 (f) 14 (i).
"Data ............ 2K80J2D ............... USB (for example, PACTOR-III)
RTTY.......... 60H0J2B ............... USB (for example, PSK31)"

Notice the "for example"?   and the phrase "except that the use of a 
narrower
necessary bandwidth is permitted" ?

Kai

Bill wrote:
> "Effective March 5, 2012  the FCC has permitted CW, USB, and certain 
> digital modes on these frequencies. The National Telecommunications 
> and Information Administration (NTIA) is the primary user of the 
> 60-meter band. The NTIA has specifically requested that amateurs 
> restrict digital operations on 60 meters to PSK31 and PACTOR III /only/. "
>
> Get there anyway you like...
> See you at the meeting...
> Bill
>
> On 3/7/2012 5:21 PM, Kai Siwiak wrote:
>> That's not correct Bill, the permitted data bandwidth on the 60m band 
>> channels is 2.8kHz. Ya gotta read the actual rules, not what W7AY says.
>> That's what the "2K80" part of the emission designator means. Of 
>> course anything less than 2800 Hz is also OK as explicitly stated in 
>> the rules.
>>
>> Once again, PACTOR-III the other RTTY (i.e., automatically received) 
>> data mode occupies around 2,200 Hz bandwidth. FCC says "OK!"
>>
>> W7AY's "correct frequency" is correct ONLY if you use the 2150 tone 
>> for Mark and only in LSB.
>>
>> 73
>> Kai, KE4PT
>>
>> Bill wrote:
>>> Yes maybe it was complex.
>>>
>>> The article was simple. It was about posting the proper frequency on 
>>> Clusters. That's it.
>>>
>>> Band with for 60 meter digital is 60 hz wide meaning all that is 
>>> allowed is PSK. W7AY brought up the other possibility for 60 m.
>>>
>>> All the article was about once again was about posting the correct 
>>> frequency.
>>>
>>> BTW the quote was not mine you referred to but W7AY. Take it up with 
>>> him if you disagree.
>>>
>>> Once again I respect your technical prowess. I long ago decided 
>>> Electrical Engineering was not for me after too many all nighters 
>>> doing DC Lab reports.
>>>
>>> But I do post Mark frequency on the Clusters.
>>>
>>> Bill
>>>
>>>
>>>
>>> On 3/7/2012 12:02 PM, Kai Siwiak wrote:
>>>> Hi Bill,
>>>> You've complicated simplicity itself! But discussion on this is indeed
>>>> needed.
>>>>
>>>> Ham-RTTY, that is, 170 Hz shift 45.45 baud signaling has an occupied
>>>> bandwidth of just under 250 Hz no matter what way you generate the
>>>> signal. See the definitions and methods of computing  occupied 
>>>> bandwidth
>>>> for the various modes are in US Title 47 Code of Federal Regulations:
>>>> 2.201 -- 2.202, as well as in the international recommendations (ITU-R
>>>> Recommendation SM.1138, 1995), which Part 97 references.  By 
>>>> "Terman" I
>>>> presume that you means Caron's rules for determining approximate
>>>> bandwidth, which is 2x(deviation + mod. freq). In ham-RTTY the 
>>>> deviation
>>>> is +/- 85 Hz, and the modulation frequency is the 45.45 Hz baud 
>>>> rate, or
>>>> 2X(85+45.45) = 261 Hz. The FCC/ITU-R "occupied bandwidth" formula 
>>>> gives
>>>> 250 Hz. Close enough. This agrees with Terman and others.
>>>>
>>>> I don't care how you generate your ham-RTTY, but to do it in the way
>>>> that complies with FCC/NTIA desires on the 60m band channels you 
>>>> need to
>>>> use recipe I gave below so that you can monitor for upper SSB 
>>>> voice. We
>>>> can discuss the reason if you want. Its really simple.
>>>>
>>>> "Official Observers" will observe complete compliance.  An OO will not
>>>> be able to tell whether you generated ham-RTTY using "FSK", or "AFSK"
>>>> using upper or lower SSB.  The OO will see only the two tones 
>>>> separated
>>>> by 170 Hz and occupying a necessary bandwidth (see the FCC 
>>>> definition of
>>>> necessary bandwidth) of 250 Hz. I don't know where the bogus focus 
>>>> on 23
>>>> Hz comes from. I plan to operate under the PACTOR-III data example.
>>>>
>>>> The "FCC bandwidth" for data in the 60m band channels is 2,800 Hz or
>>>> less. In their example,   PACTOR-III occupies about 2,200 Hz in its 
>>>> high
>>>> speed mode, but less than 1,000 Hz in the lowest speed mode. Their
>>>> second example PSK31 occupies less than 62 Hz.  Both are, in the words
>>>> of the FCC "examples of permitted data modes". The ham-RTTY we know 
>>>> and
>>>> love occupies 250 Hz which is certainly "2,800 Hz or less". So no 
>>>> problem.
>>>>
>>>> It really is that simple. One thing that may help is to think of 
>>>> the SSB
>>>> audio bandwidth (upper or lower, it doesn't matter) as the last IF in
>>>> your receiver, because in "AFSK" that is exactly what happens!
>>>>
>>>> 73,
>>>> Kai, KE4PT
>>>>
>>>> Bill wrote:
>>>>> Tell that to all the 1000's of  RTTY DXers, Contesters and the 
>>>>> writers
>>>>> and those commenting on the article. While this can be done, it is
>>>>> complicated on a regular basis and not popular. Having been a digital
>>>>> RTTY DXer for 32 years and having used some 10 different TNC's and at
>>>>> least 15 different software programs, I'll stay with conventional
>>>>> operations. Reading the article and from years of experience LSB, not
>>>>> USB is  common practice on RTTY when using AFSK. USB is not
>>>>> conventional in AFSK because of high/low tones. Too complicated a
>>>>> discussion for most including me. You are welcome to run your station
>>>>> in any way you like of course.
>>>>>
>>>>> To be specific on 60m, not very much digital activity on there at 
>>>>> this
>>>>> point. Cutting it close, as it is a very narrow range, is not for me.
>>>>> Official Observers are out in force monitoring the strict rules for
>>>>> 60m. There has been much discussion of 60m digital, on several 
>>>>> lists I
>>>>> follow. I do not plan to use any digital modes on 60m myself hi.
>>>>>
>>>>> Here's why, from W7AY just a couple of weeks ago. (more of my 
>>>>> comments
>>>>> below Chen's)
>>>>> "23 Hz shift MSK (Minimum Shift Keyed) will likely fit into the 
>>>>> FCC passband.
>>>>> But check your output spectrum before you transmit 23 Hz shift FSK 
>>>>> (Frequency Shift Keyed) on 60m.  Your FSK keying sidebands might 
>>>>> make your bandwidth greater than what the FCC permits.  If you are 
>>>>> using AFSK, *and* the AFSK waveform is wave shaped, you *might* be 
>>>>> able to get away with it.  See the last two figures here
>>>>>
>>>>> http://www.w7ay.net/site/Technical/K3/Content/digital.html
>>>>>
>>>>> to see what kind of keying sidebands are produced by a typical 
>>>>> rig's FSK generator and what a wave shaped AFSK looks like.  Just 
>>>>> eyeball the horizontal axis to match 23 Hz shift to get an idea.  
>>>>> Remember that the decay of the sidelobes remain the same since we 
>>>>> are still talking 45.45 baud keying sidebands.  I.e., don't just 
>>>>> squish the horizontal axes; instead, cut out a 147 Hz chunk at the 
>>>>> center of the signal.
>>>>>
>>>>> Remember your Terman?  The bandwidth of an FM signal comes from 
>>>>> two components.
>>>>>
>>>>> You can interoperate between MSK and 23 Hz shift RTTY by setting 
>>>>> up the FSK transmitter for 23 Hz shift, but a true MSK modulator 
>>>>> has the correct wave shaping to keep the signal narrow and the FSK 
>>>>> modulator does not.  The MSK symbol baud rate is also related 
>>>>> synchronized to the shift -- in addition to proper wave shaping of 
>>>>> the amplitudes, that also keeps the transmitter's keying sidebands 
>>>>> in check (that is an aspect of MSK that is shared with PSK31).
>>>>>
>>>>> Practically speaking, if you look at the aforementioned figures, 
>>>>> placing the center of RTTY tones tones at exactly the middle of a 
>>>>> 2.8 kHz channel on 60m should present very little QRM to the next 
>>>>> channel, even if we use standard 170 Hz RTTY shifts.  But we are 
>>>>> dealing with legal rules and regulations and not with 
>>>>> mathematics.  Further, the FCC might be looking out for the 
>>>>> primary users of the 60m band -- imagine if we spread out RTTY 
>>>>> signals on the band like what happens during a heavy split pileup 
>>>>> -- there is no way for the primary user to tell us to clam up when 
>>>>> they need the spectrum, except to illegally interfere with the DX 
>>>>> by transmitting commands over the DX station.
>>>>>
>>>>> Speaking of which, I did not come across any verbiage in the new 
>>>>> rules prohibiting cross channel ("split") communications -- can we 
>>>>> transmit on a PSK31 channel while receiving on a different 
>>>>> channel? Other than being uncivil, that is.
>>>>>
>>>>> All that said, during selective fading conditions (read:NVIS), you 
>>>>> will not be able to take advantage of an ATC anyway when you use a 
>>>>> 23 Hz shift.  So there is less reason to use 60m.
>>>>>
>>>>> Now, if we use a very wide shift, and place the Mark and Space 
>>>>> tones at the center of individual, adjacent 60m channels, you will 
>>>>> get very nice frequency diversity to counter selective fading    
>>>>> (Disclaimer: don't do this, I am joking!)
>>>>> 73
>>>>> Chen, W7AY"
>>>>>
>>>>>
>>>>> As I mentioned too complex for me and probably others.
>>>>>
>>>>> A full read of the eham article and comments covers frequency 
>>>>> readouts and why. I also only use FSK personally. On the Icom Pro 
>>>>> III it is the way to get access to Twin PBT filters which are 
>>>>> spectacular on RTTY, Particularly in RTTY DXing. Just my preferences.
>>>>>
>>>>> Life is too short for me to get around all the various software's, 
>>>>> and reconfigure them. Since I run FSK I don't have to. PSK and 
>>>>> other digital modes are a different story and AFSK is norm. Most 
>>>>> are too slow and splatter sensitive for contesting and DXing. RTTY 
>>>>> is used for those activities, simply because it is faster. Not 
>>>>> character transfer faster, but on/off faster as in Full break in 
>>>>> CW vs No break in or even semi.
>>>>>
>>>>> The article was a good reminder for those posting DX using USB 
>>>>> frequencies and LSB frequencies and wondering why they have 
>>>>> trouble locating posts on Telnet themselves. It shows them how to 
>>>>> do it according to convention, that's all. I hope you enjoyed it.
>>>>>
>>>>> Once again you and all hams are welcome to set your station up, 
>>>>> and run it in any way you like. My comments are to the Norms.
>>>>> 73,
>>>>> Bill Marx W2CQ
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On 3/7/2012 10:06 AM, Kai Siwiak wrote:
>>>>>> Hi Bill
>>>>>> The main distinguishing feature of that article is that it is wrong
>>>>>> because it assumes a specific set of tone frequency offsets from the
>>>>>> dial frequency.
>>>>>>
>>>>>> For example:
>>>>>> To operate ham-RTTY (170 Hz shift, 45.45 baud) in the 60 m band 
>>>>>> channels
>>>>>> the proper radio setting is upper SSB, radio dial set to the 
>>>>>> upper SSB
>>>>>> dial frequency for that channel, and RTTY operated in "AFSK" 
>>>>>> mode. You
>>>>>> would then select the two tone offsets as 1415 Hz and 1585 Hz.  
>>>>>> Thus,
>>>>>> fulfilling  the FCC/NTIA requirements that:
>>>>>> (1) you must monitor the channel for upper SSB voice 
>>>>>> transmissions, and
>>>>>> (2) the data signal must be centered in the 60m band channel.
>>>>>>
>>>>>> You can do this using the popular MMTTY software by editing the
>>>>>> Mmtty.ini file so that the line "Mark= ..." includes 1415 Hz.
>>>>>> Then in the main panel choose MARK=1415, and "Rev".  The radio 
>>>>>> must be
>>>>>> in upper SSB.
>>>>>> Since "Rev" is selected the MARK frequency is actually 1415+170 = 
>>>>>> 1585,
>>>>>> while the SPACE frequency is actually 1415 with respect to the 
>>>>>> upper SSB
>>>>>> radio dial frequency.
>>>>>> [Note: that is a nomenclature problem in MMTTY when the radio is 
>>>>>> set to
>>>>>> upper SSB]
>>>>>> On the air, the two tones will be 1500 +/-85 Hz. above the 
>>>>>> published 60m
>>>>>> band channel, or as required by the FCC and NTIA, dead center in the
>>>>>> channel. Said another way, if you monitor the band with a spectrum
>>>>>> analyzer you will find the two RTTY tone +/-85 Hz from the channel
>>>>>> dead-center frequency - just what the FCC/NTIA want.
>>>>>>
>>>>>> You can operate RTTY this exact same way ("AFSK", upper SSB, 
>>>>>> "mark=1415"
>>>>>> in MMTTY (Mark will actually be 1585), and "rev") on any ham band 
>>>>>> where
>>>>>> data is permitted. Then your RTTY "spotting" frequency will be your
>>>>>> upper SSB dial frequency plus 1585. That is the frequency that hams
>>>>>> traditionally "spot".
>>>>>>
>>>>>> Yes, its that easy to do RTTY, and to "know your RTTY frequency", 
>>>>>> and to
>>>>>> set up for operation on the 60m band channels
>>>>>>
>>>>>> 73
>>>>>> Kai, KE4PT
>>>>>>
>>>>>>
>>>>>> Bill wrote:
>>>>>>
>>>>>>> Frequency Readouts For RTTY...
>>>>>>>
>>>>>>> http://www.eham.net/articles/27625
>>>>>>> ______________________________________________________________
>>>>>>> South Florida DX Assoc. Reflector
>>>>>>> SFDXA WebSite: http://qsl.net/k4fk
>>>>>>> SFDXA Repeater 147.33+ 103.5 Tone
>>>>>>> DX Net Wed 7:33 PM Repeater
>>>>>>> To Post: mailto:SFDXA at mailman.qth.net
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>>>>>>>
>>>>>>> This list hosted by: http://www.qsl.net
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>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>> ______________________________________________________________
>>>>>> South Florida DX Assoc. Reflector
>>>>>> SFDXA WebSite: http://qsl.net/k4fk
>>>>>> SFDXA Repeater 147.33+ 103.5 Tone
>>>>>> DX Net Wed 7:33 PM Repeater
>>>>>> To Post: mailto:SFDXA at mailman.qth.net
>>>>>> Info:http://mailman.qth.net/mailman/listinfo/sfdxa
>>>>>>
>>>>>> This list hosted by: http://www.qsl.net
>>>>>> Please help support this email list: http://www.qsl.net/donate.html
>>>>>>
>>>>>>
>>>> ______________________________________________________________
>>>> South Florida DX Assoc. Reflector
>>>> SFDXA WebSite: http://qsl.net/k4fk
>>>> SFDXA Repeater 147.33+ 103.5 Tone
>>>> DX Net Wed 7:33 PM Repeater
>>>> To Post: mailto:SFDXA at mailman.qth.net
>>>> Info:http://mailman.qth.net/mailman/listinfo/sfdxa
>>>>
>>>> This list hosted by: http://www.qsl.net
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>>>
>>>

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