[RTTY] Estimating increase in bandwidth/interfeerence from Winlink if RM11708 is approved

[RTTY]

The spectrum shown on SCS web site: http://www.scs-ptc.com/pactor/pactor
is 2.2 KHz if one ignores the -25 dB "ears".  Since the IMD from most
of the PACTOR III stations is worse than the -25 db (all knobs to the
right), I tend to ignore them.

73,

    ... Joe, W4TV


On 4/17/2014 11:10 PM, Terry wrote:
> Joe,
>
> I got the bw off the ARRL site (http://www.arrl.org/pactor-iii ) which says
> "The occupied bandwidth at the --40 dB points is 2.4 kHz".   I can make the
> 2.2 change if that's more accurate?
>
> Terry
>
>
> -----Original Message-----
> From: Joe Subich, W4TV [mailto:lists at subich.com]
> Sent: Thursday, April 17, 2014 9:03 PM
> To: rtty at contesting.com
> Cc: 'Dick Hanson'; 'Angelo Glorioso'; 'David Woolweaver'; 'Ted Rappaport';
> 'Mark'; 'Dan White'; 'John Robert Stratton'; Terry
> Subject: Re: [RTTY] Estimating increase in bandwidth/interfeerence from
> Winlink if RM11708 is approved
>
>
> Terry,
>
> One other issue ... PACTOR III is 2.2 KHz not 2.4 KHz.  That change will
> further increase the additional interference by at least 0.5 dB.
>
> 73,
>
>      ... Joe, W4TV
>
>
> On 4/17/2014 9:36 PM, RTTY wrote:
>> Thanks to inputs from Ted, N9NB, the model was changed where the
>> results are now in dB showing the additional interference if current
> Winlink stations
>> move to RM11708 max bandwidths of 2.8 KHz.    The average interference
>> across the modeled 40 meter spectrum is 3.4 dB.   And yes, interference is
>> the correct term since the stations are all automated and do not have
>> working busy frequency detectors.
>>
>> The new graph in dB can be seen at:
>> http:\\64.128.19.154\Images\RM11708-2.jpg
>>
>> Two new assumptions were added to the list:
>>       1. The model assumes a linear Power Spectral Density, PSD.  That
>> simplifies the model but it lowers the final results a bit
>>       2. Each 100 Hz frequency bin starts at a count of 1 (rather than
>> 0) which keeps the dB/power ratio math in check
>>
>> Terry  AB5K
>>
>>
>> ------------------------------------------------------------------
>>
>> Taking the existing Winlink stations and transmitting bandwidths and
>> changing the bandwidths to 2.8 KHz, we can get a idea on the future
> increase
>> in consumed bandwidth/interference if RM11708 is approved.   Here are the
>> steps used in this analysis:
>>
>>
>>
>> 1.  Take the published Winlink call/frequency/mode list.  Determine
>> the current bandwidth and convert it into a spectral density format
>> where we total the total number of stations transmitting every 100 HZ.
>>
>>
>>
>> 2.  Repeat step one using a 2.8 KHz bandwidth for each station.
>>
>>
>>
>> 3.  Import into Excel, sum from 7.060 to 7.100 MHz.
>>
>>
>>
>> The result is:   3.6 times more spectral bins used if 2.8 KHz becomes the
>> standard.     A graph displaying the results can be found at:
>> http:\\64.128.19.154\Images\RM11708-1.jpg
>>
>>
>>
>> The X axis is frequency and the Y Axis is the total stations
>> transmitting in each 100 HZ bin.
>>
>>
>>
>> Assumptions:
>>
>>       1. The processing was only ran against US Winlink stations.
>>
>>       2. Only Winlink frequencies were analyzed.   Other current and future
>> digital waveforms (ALE, etc)  are not included.
>>
>>      3.  Modulation is USB, no offset
>>
>>       4.  Current Winlink bandwidths are:  Pactor 4:  2.4,  Pactor 3:
>> 2.4, Pactor 2:  .6, WINMOR 1600:  1.6, WINMOR 500  .5, and  Robust
>> Packet: .5
>>
>>
>>
>> Terry AB5K
>>
>>
>>
>>
>>
>>
>>
>>
>>
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>
>