Skip, I agree with you.
My considerations to prefer in HF Contestia 250/4 format is related to
the idea to find some compromise for bpsk31 folk, Olivia light users,
and rtty folk when the propagation is not enough good for bpsk31 and rtty.
So Cnt 250/4 with 39wpm is the first alternative for bpsk and rtty folk
and the last alternative for Olivia hardusers ;)
The idea to use 250/4 format motivated also by fact that Cnt 250/4
signals are seen in wtrfl until the copy lost (-9dB). 250/8 is washed
out from wtrfl around -10dB. Both, psk31 and rtty users was wont to see
signals on wtrfl. To see signals is motivated also from QRM reducing
viewpoint.
The idea to make 2-step default switch from 250/4(-9dB) to 250/16
(-15dB) and so get additional snr -6dB is compensate 250/8 format
snr-advantage. Default shift need default procedure what/how to do when
the copy is lost.
WPM considerations
29wpm (250/8) is good speed from cw-viewpoint, but too less from
rtty/psk31 viewpoint. 39wpm (250/4) is somekind compromise between the
different speed/snr expectations.
vy73, Jaak
es1hj
10.05.2010 2:59, KH6TY kirjutas:
Hi Jaak,
Great idea to start a long test of Contestia 250/4!
Perhaps Contestia 250/8 can also be compared in actual practice to
Contestia 250/4. Contestia 250/8 is slower (at 29 wpm), but decodes 2
dB deeper into the noise, which may be important when there is QSB
(fading) and the signal is already near the noise level ( such as when
the band is going out). Although I can type over 50 wpm, my personal
feeling is that 29 wpm is fast enough for a QSO, but Contestia at 78
wpm (3 dB less sensitive) is more reasonable for passing traffic (if
conditions can support 3 dB less sensitivity). If not, then to be able
to pass the traffic at all, it has to be sent at a slower, more
sensitive speed, such as Contestia 250/4.
It all depends upon the average individual preference for typing speed
for QSO's vs conditions.This may become clear during your tests. I
hope the testers will make their minimum typing speed preferences
known, as well as how well the mode works.
73, Skip KH6TY
Jaak Hohensee wrote:
Hi everybody
* Contestia derived from Olivia.
* Contestia 250/4 is channelfree like psk or rtty. BW less than
rtty and same as psk125, 39wpm, snr -9dB.
* So Contestia 250/4 is good narrowband alternative for psk31 or
rtty folk, specially when propagtion is not for psk/rtty or
signals are too weak.
* Contestia 250/4 is good mode for mid- or high-latitude folk.
Many times there are disturbed propagation path not suited for
psk or rtty.
* Concept testing period to the end of year 2010. Everybody is
welcome.
More info contestia.blogspot.com <http://contestia.blogspot.com/>
--
vy73, Jaak
es1hj
--
Kirjutas ja tervitab
Jaak Hohensee
