Re: MMTTY DATA-A or FSK

[iw1ayd]

Hi all.
I strongly disagree with the words  that say DATA, thus AFSK - whistle
tones , is the better RTTY contest modes. There are, from my point of
several points against this theory.
Nor AFSK is the best non contest mode for RTTY. It's just for casual
operations, often with radio that doesn't have FSK or have false FSK
using two audio oscillators manipulated by the FSK external signal.
Luckily or beloved K3 is a real RTTY FSK radio, non a mimicker like
some other brands.

The main points I see against AFSK are:
1) Whistling the tones, even if the K3 have a TX ALC control much
better than other radios it's too much prone to the attention of any
operator, that could become low and low hour after our when in contest
1.a) this is true even if our K3 have a great approach to ALC control
when in digital modes
2) Tones IMD of the default AFSK emission is high, the generated BF
signal, worst when used more down than 2000 Hz, will affect the RTTY
signal to be on air
2.a) partial solution is to enhance the standard DSP filtering of the
MMTTY BF generated tones using MMTTY Setup - into the TX tab -
changing TxBPF/TxLPF to set, at least, TxBFP enabled and Tap to 512 -
this could affect performances on the low edged PC ... but look with
the "f" button, just nearby: what a difference! (it's just a picture
generated by tap number, but real life look like it)
3) since last year new firmware the K3 have a more and more pure
routines to generate the tones manipulation switching issue - this
syndrome affect any real FSK transceiver. The quality of the LSB
NORMAL tones is really now excellent and much better than any other
radio.

Giving at least those 3 points and their reversed effects I say that
FSK with the K3 is the better way to with it. More stable on AGC
control - that indeed isn't any more needed - more clear and crispy
tones even with low tones pair.

Anecdotally I could affirm than since the FSK FW changes I have much
more problems of other contester signals proximity even with the PA
and a lot of elements well high on the roof. East and North European
stations are gliding too near to me, times over times. This is
happening in both the main direction directions where I could aim the
aerials, a 16x3 and a 3 el. Quad. Thus when pointing JA I will pass
over East Europe but nevertheless a lot of East operators come well
into my tight RUN set-up filter, 400 Hz used a 500 Hz. This mean that
they don't have any serious problem with my signal, even with the PA
and what I consider a big gain aerial ... plenty of signal strength...
I have often to move out of the mess they are making with those near
and pesky signals into my filter. Driving roofing filter down to the
250Hz used at 350 Hz is not a viable option all the time. Better to
maintain the rate finding another QRG much clear.

So, I will vote for RTTY-L, never for DATA-A or AFSK forever with
those well known 3 conditions.

           73 de iw1ayd Salvo

PS BTW 2Tone already have the purest filters for AFSK audio tones
generation to whistle. The Author have already solved the worst tones
issues since the start. Also FLDIGI use strict DSP filtering, but also
add, as 2Tone - my memory - some other techniques to prevent tone IMD
since the Sound Interfaces signal generations. But not all Sound
Interfaces are the same. But all the radio are the quite the (out of
some native SDR) for TX filtering. The choice of high tones, > 2000
Hz, is anyway a must, even if clicking on RTTY signals with the mouse!
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