Dale, yeah but it would be even better if it WERE applied in real-time.
Let me join you, thinking outside the box on this topic... the variety
of comments got me thinking that it might be possible to develop a
"Quality of Signal" standard, based upon what is actually heard on the
air. Part of such a system is already in place, known as the Reverse
Beacon Network... at least for CW and RTTY signals.
As everyone knows, the RBN feeds an unbiased signal strength back to the
user (community) without regard to "who it is, what antennas they are
using, which direction they are beaming, or what equipment is on the
opposite end of the coax." I propose if a signal quality indicator
system was created that produced a numeric value between 1 to 100, that
QoS figure could also be reported.
In this scenario, maybe a "perfect signal" would score in the 90 to 100
range. "More dirty signals" would fall below that range. The impact
would be a lot of exposure and peer pressure to those who score low.
Many radios provide a menu adjustment for CW "attack" so an operator
could experiment with this value to get feedback on its effect. I am
always interested in the signal reports from the existing RBN and I
would (personally) be thrilled to know where my on-the-air signal would
appear on a QoS rating.
As has been mentioned, most fellows don't have the test equipment
therefore have no idea how their signal sounds on the air. I sold off
all my test gear so I am now sailing in the same boat! Normally I don't
get any complaints, but a while ago someone told me my RTTY signal
"sounded odd" to them, even though they could decode it without issue.
After hearing that report, I traced the problem to an audio cable, even
though I was using FSK to key the radio. I have no idea how long my
signal "sounded odd", but if there had been a QoS system in place, I
would have probably noticed this problem immediately. It definitely was
not apparent when listening to the radios built-in monitor.
Inserting a QoS value into the RBN distribution is most likely easier
than developing a QoS detection system. That said, I recall when the CW
skimmer and RBN were being developed, thinking to myself "Geez, it would
really be great if the someone would create an RTTY skimmer too." The
RTTY system is here now.
73 de Bob - KØRC in MN
------------------------------------------------------------------------
On 10/18/2014 10:17 PM, David Gilbert wrote:
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@contesting.com] On
Behalf Of
Jim Brown
Sent: Sunday, October 12, 2014 4:57 PM
To: cq-contest@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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