Barely Works
Technology
Metric and Awards
How about just using an extension below the axis of RST?
Readability
is just the number of Sigmas in your statics, if properly
controlled. 5 or 6 sigma is believable to anyone. My EME2
outing was 4.2 Sigma. Q-4 is awards grade. "Minimums" is
Q-2. Is 2-Sigma too low for "minimums?"
Signal strength: The accepted standard is 50 microvolts is -73
dBm for S9. This puts S0 at 0.1 microvolt or -127 dBm. This
is kind of the threshold for noisy FM, but on CW and even SSB you can
have Q-3 below that in a typical 600K front end. My EME2 outing
was S "-10" We just need a way to say that. "S minus
ten?" Or just drop the minus when the context is understood to be
this. Or give it a different name like "U" for "Under S0" so it
would U10. Then the system would be RUT. We're way in a RUT.
Tone. Nobody has evaluated tone in my time as an amateur, even on
the rare occasions when they needed to and it would have made a
difference to some poor guy. But, here it could be a metric of
how well you stayed on frequency or got on frequency compared to what
was needed. In my EME2 outing I didn't need to be on frequency
except relative to myself but I did need to stay on frequency with
respect to myself for the five second intervals. Let's say you
were in a 2.3 Hz bandwidth like I was. The transmissions were for
two seconds implying a needed guard band of 0.5 Hz. On both
sides, that leaves that I need to be in 1.3 Hz to contain everything to
the first keying lobe. I actually saw power in the +/- 1 bins
which could have something to do with the keying sidebands. So,
anyway, how stable was I compared to 1.3 Hz? I don't know.
I know I have a ppm offset which is 100-150 Hz. This may wander
around by a few Hz and I have no way to see it.
What if we didn't make it need relative but made it Allan Variance
relative. PPM stability over the integration interval would be
T6, that is 10^-6. So, my setup would be T6 absolute and T8
relative, as proven by the EME2 success. GPS disciplined could
achieve absolute T10 or T12.
So, my EME2 outing RUT would be 4 10 8 R where the R means
Relative. And this is more or less equivalent to an RST of 4 -10
8 for the loopback application.
This is the first iteration of
thinking on this, untouched:
The metric needs to be
- easy to understand (like DXCC or contest points but less arbitrary)
- independent of antenna or transmitter power
- like Larkin's 5 W. 1 hour single antenna detection but
normalized
- physically meaningful, not like "miles per watt"
- compare to existing CW and SSB as a reference point
- independent of time -- we're admitting that we're patient
- thus, probably needs to be in Joules, not watts or rewards
Joules rather than watts
- maybe it's certainty relative to some reference dBm
Mine was 4.2 Sigma -- 50,000:1 is 47 dB Sigma at -186 dBm
So maybe it's level - certainty (that is, level / certainty)
How about this for the metric:
sig dBm + sigma dB + time dB
This gives an equivalent to dBm signal levels. The sigma is
sigmas of the peak out of noise bins; smaller is weaker. Time is
the integration time or inverse bandwidth. More time is a weaker
signal. More bandwidth is stronger.
My EME2 was -187.36 dBm + log( 4.2 ) + log( 10952 seconds ) = -140.73
N6NB Q-3 at 12 WPM is -145.6 + log( 3 ) + log( 0.1 Hz ) = -151
Q-1 SSB is -150 + log( 1 ) + log( 1/2000 Hz ) = -117
Q-5 SSB is -130 + log( 3 ) + log( 1/2000 Hz ) = -157
this isn't right yet - needs more thought and work
The award system
- uses the metric to reward performance in the noise rather than big
station
- but also rewards scaling up (i.e., my demo says EVE is
possible then somebody else does it by scaling up, we both get an award)
- starts at 10 dB below CW
- can also compare to ZRO Test Z-8 contest at AMSAT maybe
- needs to encourage algorithms and equipment optimizations
last
updated 2007 July 7, cbd