[CQ-Contest] Understanding the dynamic error free RBN algorithm

[Brett Graham]

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.