[RTTY] TinyFSK modem for 45 and 75 baud

[Robert Chudek - K0RC]

JFTHOI...  (just for the heck of it)...

I logged the Stop Bit Length on a variety of stations I worked the last 
few hours of this Markothen contest on 4 bands. If the entry below 
includes "jitter", that means the 2Tone reading was not solid, rather 
moving +/- several numbers. The majority were pretty stable, after the 
decoder locked in on the signal. It would be interesting to know how 
these stations generated their signal.

In my case, I am using N1MM Logger with MMTTY generating On/Off keying 
with EXTFSK through the parallel port of my Latitude C640 laptop which 
is running Win XP sp3. The LPT port keying is the single transistor switch.

I am using 2TONE 13.04a in a second decode window. (I had some issues 
with the newest 2Tone version freezing the display so I backed down to 
the previous version I have been using. I am not certain yet whether 
this is related to 2Tone or some other situation with the contest 
computer after recent MS updates to XP.)

73 de Bob - KØRC in MN

FWIW - unscientific as it is, here's the list...

K0RC       34

*10M*
ZL1G       46

*15M*
VE7CC      34
DM5TI      46 jitter
W4UEF      34
IK2DZN     46 jitter
EA8/RW3DO  34
KN5S       34
W7OM       46
CO2GL      34
K7OX       38
WA1GOS     34
K1MK       33
G8ORH      34
AE1T       34
K4GMH      42
AA5AU      34
VA2UP      42
W6SFK      40
K0GEO      44
K1DUQ      34
K6HGF      40 jitter
JG3FEA     46
W6SX       48
VE2EBK     47 jitter
VA7ST      38
KH6GMP     42
N2ESP      34
JA7BME     46

*20M*
K4HAL      34
VE3MGY     34
S53M       38 jitter
5C5W       42
PD2PVM     34
IK2DZN     44 jitter
PD1ALW     34
W4UK       34
DF9ZP      36
9A7C       48
K5LRN      44
W5LKB      34
KJ7GI      34
N7UVH      34
W1UE       46
PR7AR      34
KG4HF      34

*40M*
AA0AW      34

------------------------------------------------------------------------


On 10/12/2013 2:56 PM, Andrew Flowers wrote:
> Andreas wrote:
>> - if I did that right and the routine is accurate -
> That's a good point, Andy--we're all assuming that the stop-bit tracking routine in 2Tone is accurate.   You could always put a scope on the logical output if you really wanted to look at the waveform over time.  Then you could see jitter and anything else.
>
> I am also not sure that 2Tone will copy one stop bit.  If it's not printing correctly then the number being reported is meaningless. It looks like 46ms might be an upper limit, too....maybe David fails over into an "asynchronous" mode in this case....I don't know.  I do know MMTTY *will* copy one stop bit.  Fortunately, almost nobody sends that on ham bands since frame errors become much harder to recover from.
>
> For those keeping score at home, one bit = 22ms at 45 baud.  So 1.5 stop bits should 33ms, and 2 stop bits should be 44ms.
>
> Andy K0SM/2
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