[CQ-Contest] Handicap For Dirty Rigs

[David Gilbert]

I've often thought that a bit of SDR software might be able to 
accomplish this.  My thought was to use a sliding cursor on a spectrum 
(panadapter) display to center on a particular signal, "capture" that 
signal in a defined and reasonably narrow bandwidth (say 20 Hz for CW 
and 2 KHz for SSB), read a wider (say 20 KHz) window around that signal 
in narrow slices (maybe 20 Hz for both modes) to identify the energy 
bursts that time wise track track the cursor window.  It should be 
possible to separate the wideband trash from other signals by comparing 
the slice bursts to the average energy found in those segments when the 
cursor window is "quiet". I'm not sure how short in time the windows 
would need to be captured, but ideally they should be quick enough to 
properly capture and quantify key clicks.  I haven't totally convinced 
myself this process would be feasible for SSB due to the variations and 
complexity of human voice, but I think it should be quite practical for CW.

Once the spectrum was quantified, it would be possible to create a 
profile of the total transmitted energy and "negative weights" could be 
assigned to each analyzed segment based upon their magnitude 
(proportionate to the energy in the cursor segment) and their separation 
from the cursor frequency.  Neither the magnitude weight nor the 
separation weight need be linear factors ... they could have some kind 
of logarithmic curve to more strongly penalize stronger or further 
energy.   Add up the segments and the result would be a "value" that 
could be used to grade a signal.

The hardware required could be as simple as a Softrock feeding a decent 
computer soundcard.  The software would need to be written by someone 
more capable than I, but to be honest, I'm surprised that someone has 
not already done so.  I'm pretty sure that the processing power is there 
for it.

Defining "goodness" for purposes of point deduction or disqualification 
is quite another matter, of course.  That becomes much more subjective, 
but it could be as simple as using the ratio of energy within/without a 
defined bandwidth as a multiplier for scores.  If 30% of your energy was 
outside a predefined limit, your score might be reduced by 30%.  Just 
thinking out loud here ...

A useful aspect of this technique is that it could be applied to any SDR 
file ... it wouldn't need to be performed in real time.

73,
Dave   AB7E



On 10/18/2014 6:06 PM, Randy Thompson K5ZD wrote:
> It is true that some rigs (depending on how they are operated) can produce
> signals that appear wider than normal.  Can you think of a way to express
> this in technical terms rather than using a K3 as a reference.  Contesting
> needs to have a dialog around what is the accepted standard for signal width
> or "cleanliness".
>
> What test equipment would some use to evaluate their own signal in the
> shack?
>
> What would be a good test standard for someone listening to capture the
> essence of the signal quality?
>
>
> Randy, K5ZD
>
>> -----Original Message-----
>> From: CQ-Contest [mailto:cq-contest-bounces at contesting.com] On Behalf Of
>> Jim Brown
>> Sent: Sunday, October 12, 2014 4:57 PM
>> To: cq-contest at contesting.com
>> Subject: [CQ-Contest] Handicap For Dirty Rigs
>>
>> In my study of the TX Noise produced by current transceivers, I noted the
>> significant advantage enjoyed by users of dirty rigs by pushing other
>> stations away from their TX frequency, and making it difficult (or
>> impossible) for stations to S&P near them. Consider the lineup of
>> hundreds of NA stations in the 15 kHz 160M JA window, and comparable
>> conditions from east coast to EU. One FTDX5000D burns five K3 channels;
>> one ICOM 7800,7700, 7600, burns three. I run a K3 and a Ten Tec Titan,
>> which is quite clean. I've established a run frequency for JA only to run
>> off by a guy with a dirty power amp 700 Hz away.
>>
>> Competitors using these dirty rigs should pay the price competitively. I
>> propose a scoring penalty of 15% to the users of FTDX5000 and other Yaesu
>> rigs in that family (study ARRL data to understand why that's valid), and
>> 10% to users of IC7800, 7700, 7600. KE1B, who uses a 7600 to drive a
>> solid state amp, wipes out 10 kHz of whatever band he is on for me on CW,
>> more on SSB. I'm not a WRTC competitor, but K6XX is, and his dirty TX
>> hurts Bob worse than me. By contrast, Bob and I, with K3s and tube amps,
>> can work 500 Hz apart and barely know the other is there. And Bob is
>> three miles closer than KE1B.
>>
>> Is this fair? I contend that with the right to run high power comes the
>> responsibility to produce the CLEANEST signal consistent with the state
>> of the art. K3 has established the state of the art, and preliminary data
>> from the mfr suggest  that Flex 6000-series may be as good. Kenwood
>> TS590S is 10 dB worse, at a very modest price. I contend THAT is state of
>> the art, and that ICOM and Yaesu fail to meet it.
>>
>> Yes, I'm saying that users of these dirty rigs need to replace them with
>> cleaner ones. In 2008, I sold a pair of loaded FT1000MPs at significant
>> loss to be replaced by K3s. I did this because I could see from specs
>> that I needed to do that to coexist with my neighbors. Before that, I
>> owned a pair of TS850s and K2s. All sold.
>>
>> And remember -- this is ARRL's data, not mine. :)
>>
>>   From my days in the civil rights movement of the '60s and '70s -- "if
>> you're not part of the solution, you're part of the problem!" I've dumped
>> my dirty rigs -- how about YOU?
>>
>> 73, Jim K9YC
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