Hello Tony,
Interesting figures! I have compared with my own measures (only done on a
sub-set of the Contestia modes). They are very close to yours.
Just a remark: I consider that a Word is 6 characters, so "Words Per Minute"=
Char/s * 10 (10=60 seconds/6 characters/word).
As a thumb rule:
For a same sub mode: Contestia has a double speed (+3 dB) but only 1.5 dB of
loss in term of minimum S/N compared to Olivia. So it seems to be a better
compromise.
73
Patrick
----- Original Message -----
From: Tony
To: digitalradio@yahoogroups.com
Sent: Friday, August 07, 2009 10:59 AM
Subject: [digitalradio] Olivia - Contestia Tone / Bandwidth Configuration
All,
It's interesting to see how the different Olivia mode configurations compare
when put through the HF path simulator.
I ran Contestia through the simulator this evening and these are the results.
Olivia 16/500 is shown for reference.
CONTESTIA 500Hz
Tones Bandwidth Char/s minimum SNR Words Per Minute
4 500 7.81 -6db
94
8 500 5.86 -9db
70
16 500 3.90 -13db
46
*16 500 2.00 -14db
24
32 500 2.44 -15db
29
64 500 1.46 -17db
17
128 500 0.85 -20db
10
*Olivia 16/500 mode
CONTESTIA 1000Hz
Tones Bandwidth Char/s minimum SNR Words Per Minute
4 1000Hz 15.6 -3db 187
8 1000Hz 11.7 -6db 140
16 1000Hz 7.8 -9db 94
32 1000Hz 4.9 -12db 59
64 1000Hz 2.9 -14db 35
CONTESTIA 250Hz
Tones Bandwidth Char/s minimum SNR Words Per Minute
4 250 3.91 -12db
46
8 250 2.93 -13db
35
16 250 1.95 -15db
23
32 250 1.22 -17db
15
64 250 0.73 - 20db
8.8
It's clear by looking at the chart that the slower the throughput, the better
the weak-signal performance. This no doubt has to do with symbol rate etc
(experts comments welcome). Reducing the number of tones by half will yield
1-to-4db better weak signal performance, but at the cost of slower wpm rate.
The nice thing about being able to change the configuration is that it lets
you try different combinations to squeeze the most out of the modes to suit
conditions.
The modes with the higher tones are extremely sensitive so the skies the
limit in terms of weak signal work as long as you don't mind the slow pace.
It pays to take a good look at each configuration and compare; for example;
Conestia 32/500 mode vs. Olivia 16/500.
The Contestia mode is 5 wpm faster and slightly more sensitive than Olivia.
This simple change lets you pick-up the pace without sacrificing weak signal
performance.
For those who are conscious about spectrum; take a look at Contestia modes
8/250 and 64/1000Hz.
They both have the same wpm speed and nearly the same sensitivity, but the
8/250 mode performance is the same and it does it in 1/4th the bandwidth.
Getting late here so will have to wrap it up and let the group look at the
figures and send some feed back.
Hope you all find it interesting...
Tony -K2MO
