Hello Wes and all, I tried here Multipsk versus Mixw at -9 dB of S/N in RTTY 45 (I have not TRUETTY but they seem to be equivalent).
I tested with a text and the Multipsk decoding was better than the Mixw one . However, in RTTY the ITA2 set of character is used so it is difficult to compare because figures instead of letters can be seen as bad whereas there are good in fact (simply due to a random switching) . So I tested with C8C8C8C8C8C8C8C8C8C8 to avoid not this problem. I confirmed that the Multipsk RTTY decoding is better than the Mixw one (I don't think to have a partial opinion, I hope so...). But Multipsk could work better on this particular characters, so I tried with 1A2B3C4D5E6F7G8H9...which is a diversified sequence. I got 135 characters OK with Multipsk and 107 on Mixw. In both softs, I set the AFC Off and I tested with a confortable level (about 40 % of the maximum in average, taken on the Multipsk level), same exact AF frequency (830/1000 Hz). Note 1: I used a sound blaster sound card to send the signal which was decoded by both softs (input plugged with the output). Note 2: the decoding on Multipsk and Mixw is almost perfect (only few errors) at about -5.5 dB. 73 Patrick ----- Original Message ----- From: Wes Cosand To: [email protected] Sent: Thursday, January 21, 2010 3:05 AM Subject: Re: [digitalradio] Comparison of RTTY software sensitivity On Wed, Jan 20, 2010 at 8:06 PM, Dave AA6YQ <[email protected]> wrote: Thanks Wes. WinWarbler uses MMTTY as its RTTY engine; thus MMTTY can be configured to achieve the same performance as that shown for WinWarbler. Yes, I certainly did not mean to construct a test to show MMTTY at a disadvantage. I assumed folk would realize that the engine is the same in the two packages. I wanted to see if there was a difference between the Hyper Sensitive profile (which exists as a predefined profile only in WinWarbler) and the Standard profile which is the default in both packages. I was surprised after the tests to see the significant difference in performance made by inserting the notch filter between the mark and space frequencies. TrueTTY would seem to deserve wider attention. I have used UA9OV's CW Get for a number of years to zero beat my CW and perhaps I should keep a copy his TrueTTY running as a second receive modem when I work RTTY. Wes, WZ7I
