Jose, CT1BOH analyzed 109 bust spots out of 8114 DR1A spots, mere 1,34 % !
This is much better than humans 3 % average.
QSD I/Q images and harmonic relations are well known phenomena. BPF help
even single band Perseus as shown by M/M K3LR.
I enjoyed latest QEX long post-mortem story on AOR-7070 analog RX. Get used
to error-freer digital world asap - hi.
LP MMM S56A
-----Original Message-----
From: Brett Graham [mailto:vr2bg@harts.org.hk]
Sent: Sunday, July 21, 2013 11:28 AM
To: cq-contest@contesting.com
Cc: Marijan Miletic', S56A; ct1boh@gmail.com
Subject: Re: [CQ-Contest] Understanding the dynamic error free RBN algorithm
S56A4ZR said:
> Real life 0IF RX could achieve 60 dB unavoidable image rejection and
> this is not enough in contests. Our ham freqs are NOT channelized
> although one knows where the image is!
The most popular version of QSD receiver has EVEN HIGHER response at
harmonics of its LO than -60 dBc
This means those receivers hear signals FROM OTHER BANDS something around 30
dB LOUDER than the in-band I/Q gain/phase unbalance-caused spurious
responses of signals from the band the receiver is SUPPOSEDLY listening to
(that S56A4ZR goes on about).
Let's ignore all the mechanisms responsible for wrong-frequency RBN spots,
shall we?
> Direct HF sampling ADC RX like QS1R or Perseus with 16 bits has
> dynamic range over 100 dB with a single, clean XO and no inherent
> images. This is several orders of magnitude better then single bit QSD.
Too bad that in practice, skimmers using QS1Rs also say signals are on all
sorts of frequencies where they are not.
Instead of several orders of magnitude better - I suggest, like I did that
the wrong-freq RBN spot rate was some number of %... denied vigorously by
N4ZR & now essentially confirmed by CT1BOH who rather than just saying
things, looked at & worked with the data - it's roughly as bad as the QSDs.
> We are dealing with low error rates and further processing would
> reduce insertion mistakes while increasing omissions. I like to catch
> erronious ones - HI.
Human now making excuses for failure of machine to do better than humans are
capable of...
-ex-VR2BG/p.
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