Hello all,

Another Patrick here.

For an honest comparaison, logically the result might be normalized to a 
standardized text throughput (based, for example, on BPSK31). For example, the 
Olivia 32-1000 has a throughput of 24.4 wpm. MFSK16 about the same as PSK31 (a 
little less than 50). This because, it is mechanical to improve a minimum S/N: 
if you decrease the speed transmission by 2 you have a gain of 3 dB on the 
minimum S/N (however in the reality it is only about 3 dB because the new 
parameters are not at the exactly same quality of "optimality").
Note: a word is a group of 6 characters.

In fact, it is not totally honest, because characters can be 6, 7 or 8 bits 
large and of course the more bits you have and better it is (with 8 bits you 
can transmitted accented latin characters or non-latin characters, when you 
can't in 7 bits and in 6 bits you cannot distinguish small or capital letters).

Now to normalize it is easy. For example, if the text throughput is half the 
normalized text throughput, the determined minimum S/N is increased by 3 dB and 
so on (10* log(ratio)).

73
Patrick (F6CTE)

  ----- Original Message ----- 
  From: Patrick Novak 
  To: digitalradio@yahoogroups.com 
  Sent: Saturday, July 12, 2008 9:06 AM
  Subject: Re: [digitalradio] Re: KV9U - Mode Sensitivity / Robustness


  Yes... that would be the ONLY proper test... the statistics would tell us...

  cheers
  P

  Tony wrote: 
Patrick,

  I for one would like to try different modes and compare them
under real conditions. There can be too many variables.
    
I agree, I think the simulator can tell a lot about mode performance, but it 
has it's limitations.

It might be a good idea to test modes according to type. Seems fruitless to 
compare a mode that's known to be extremely sensitive and robust against the 
"average" chat mode.

Good point about switching frequency when testing; need to mind the wide 
modes in the narrow band segments etc.

There was a lot more activity along these lines when sound-card modes were 
first introduced. Wonder if anyone recalls digital beaconing?

Station S59DOR had one on 10 meters that would transmit the different 
Hellschreiber modes.

Macros allowed the software (IZ8BLY's Hellschreiber) to switch modes 
automatically. Have a screenshot of the beacon if anyone is interested.

Glad to see the enthusiasm Patrick! It's the stuff that keeps the hobby 
alive.

Tony, K2MO
Kings Park, NY





----- Original Message ----- 
From: "Patrick Novak" <[EMAIL PROTECTED]>
To: <digitalradio@yahoogroups.com>; <[EMAIL PROTECTED]>
Sent: Friday, July 11, 2008 11:09 PM
Subject: Re: [digitalradio] Re: KV9U - Mode Sensitivity / Robustness


  Hi Tony and it is good to see your posting to the group.

I for one would like to try different modes and compare them under real 
conditions. There can be too many variables. I understand it is impossible 
to do it exactly but how about this scenario:

We will start a contact and send a short file in one mode, then switch to 
a different mode (close/same  frequency/band) and send the same file 
again.
Try several modes and then compare the number of errors in each mode.
If we have a large sample set we will be able to make an educated guess at 
the mode which performs best.
There could be a group or individual who will keep the results table, or 
each or OF us (experimenters) will keep own statistics.
What do you think? What everybody thinks?

regards es 73
Patrick
VK2PN



Tony wrote:

 Rick,

 >Has anyone compared Domino EX with the top modes that get
 >through the worst conditions and, if so, what have you found?

 I've compared a variety of sound card modes for sensitivity and 
robustness using an HF path simulator (see below).

 I first tested each mode for sensitivity by finding the lowest 
signal-to-noise ratio that would still produce 100% decode. These were 
direct-path simulations with no ionospheric disturbance.


 For what it's worth, DominoEX 11 baud, had about the same sensitivity as 
MT63 and Olivia 500/4. DominoEX 4 baud had about the same sensitivity as 
MFSK16.

 Olivia 500/16/8 were more sensitive than DominioEX 11 as well; Olivia 
mode sensitivity would increases with an increase in the number of tones.

 Things got interesting while testing for robustness with the ionospheric 
simulator. The Domino EX modes fell short to the point where they would 
not decode at all with certain disturbances regardless of SNR.

 The DominoEX modes seemed sensitive to frequency spread found on the more 
disturbed ionospheric paths, especially polar and low-latitude paths.

 I think it's important to remember that these are simulations and on-air 
testing may show different results. There are no static crash simulators 
with Pathsim so it's hard to simulate things like mode recovery time etc.

 If anyone is interested in path simulation, it's important to normalize 
the audio before it's feed into the simulator. Normalizing keeps the audio 
at the same level so one mode is not any louder or weaker than another.

 Tony, K2MO
 Kings Park, NY

 ______________________________________________________


 Sensitivity Test ( lowest SNR that will produce 100% decode)
 (DIRECT PATH - NO IONOSPHERIC DISTURBANCE)

 RTTY 45...................  -5db
 Feld Hell.....................-6db*
 DominoEX-11........   -8db
 MT63 1K.................   -8db
 Olivia 500/4.............. -8db
 Olivia 500/8..............-10db
 PSK31...................   -10db
 Olivia 500/16 .......... -12db
 MFSK16....................-14db
 DominoEX-4 baud...-15db

 * Simulated quiet band condx. Good contrast between text and white 
background.


 ______________________________________________

 Sensitivity Test SNR -12db
 (DIRECT PATH - NO IONOSPHERIC DISTURBANCE)

 MFSK16.....................Perfect Copy
 Olivia 500/16..............Perfect Copy
 DominoEX 4 baud....Perfect Copy
 Oivia 500/8..................90%
 Olivia 500/4.................90%
 DominoEX 11 baud...90%
 PSK31.........................90%
 Feld Hell......................Faint Text *
 MT63 1K.....................No Copy
 RTTY 45 baud............No Copy

 * Feld Hell somewhat readable at this SNR under extremely quiet condx.

 _______________________________________________________

 Sensitivity Test SNR -15db (faint signal in waterfall)

 (DIRECT PATH - NO IONOSPHERIC DISTURBANCE)

 DominoEX 4bd..........100% Copy
 MFSK16.......................95% Copy
 Olivia 1K/32.................90% Copy
 Olivia 500/16...............90% Copy


 Olivia 500/8................. <50%
 THE QUICK BROWN FOX :UMPS OB$[T,3AZY DOG
 T.`8 dIC `"N FSX JUd VCR g&?GZY 1PaOlj/== BROWZ+_
 /|mu_S R pHB\7JY 9OG

 Olivia 500/4...................No Copy


 DominoEX 11bd...............50%
 tTHE QUICK BDOWN FOXGUMPSLiVER IE LA ' Y BCI
 THQUICK) ROWN FOX JU S OVCu THE LAZY DOG
 TH QUo  OWN FN0 ZUMLx OGR THE tZY DOa? L

 PSK31...........................<50%
 E QUIhK BRO FOs  J.MPS OVEC THE s
 -t( a OGTr �ITBRO N Ft uJU0PbtaVEXE LAZY t
  OpHE uPIOK BROWN FtoMPS OT0R li0 LA rY Ctep

 MT63..........................No Copy
 Feld Hell.....................No Copy
 RTTY 45....................No Copy

 _______________________________________________________________


 High-Latitude Path Simulation

 (Moderate High-Latitude Disturbance, 3ms path delay, 10hz frequency 
spread, SNR -8db)

 (3ms path delay, 10hz frequency spread, SNR -8db)

 MFSK16......................Perfect Copy
 Olivia 500/16...............Perfect Copy
 Olivia 500/8..................Perfect Copy
 Olivia 500/4..................90%
 Feld Hell........................90%*
 DominoEX 4bd..........No Copy
 DominoEX 11bd........No Copy
 PSK31.........................No Copy
 RTTY45........................No Copy
 MT63............................No Copy

 * Text to background contrast marginal but readable.

 _______________________________________________________


 Mid-Latitude Path Simulation

 (Storm condition Mid-Latitude Disturbance, 2ms path delay, 1hz frequency 
spread, SNR -8db)

 MFSK16......................Perfect Copy
 Olivia 500/16...............Perfect Copy
 Olivia 500/8..................90%
 Olivia 500/4..................90%
 DominoEX 4bd............90%
 MT63 1K.......................90%
 Feld Hell........................<90%*

 *Good text contrast, missing characters

 DominoEX 11bd
 THE QUIRK BROWN FOX JUMPTYOFttT3G LAZY DOG
 THE QROWN FOiRJUMPtJeoER TLAZY DOG
 THE QUICK NNOWOXlrUMPS OVER ti8AZY DOG

 PSK31
 THe  EaoICK BROWN F Jto c OTeR THE LAZY DOG
 THE Q4Icš BROWN MOX p HMPS OVIRHE LAZY DOG
 Tr4 QUICK BROWNa o e o JUMPS r  -ER THE LY

 RTTY45
 XMXSPYUIVK BRGWN FOKGDUMHR KZ4 ZILAZYHDOG
 OVZHE QUFKH?492,6FF JINQ QOCSKQ0/6&)'6 BMXDQ
 NQ QUICK YBRTZNLFMY JUVHS OVER PHE )-+6 DOG

 ______________________________________________________________

 Low-Latitude Path Simulation

 (Storm condition Low-Latitude Disturbance, 6ms path delay, 10hz frequency 
spread, SNR -8db)

 MFSK16...................Pefect Copy
 Olivia 500/16............Perfect Copy
 Olivia 500/8..............90%
 Olivia 500/4..............90%
 Feld Hell....................Poor Copy*
 DominoEX 4bd .......No Copy
 DominoEX 11bd......No Copy
 MT63 1k....................No Copy
 PSK31......................No Copy
 RTTY45.....................No Copy

 * Feld Hell letters were diffuse (spread) making it difficult to read.





-- 
~~~~~~~~~~~~~~~~~~~~~
Patrick VK2PN
QF56pe
Sydney Australia

 
    

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