[WL-USERS] FSK Stop Bit Setup
Michael C. Joens
Sun, 20 Jun 1999 21:35:13 -0400
Wayne has fixed the stop bit issue and I have tested it with a scope, a
local friend and in the ANARTS contest. I also called 4l1BR a couple times
with the revised version of Rttyrite, and he could copy me fine (he's the
one who had the problem copying me with the short stop bit most recently).
I found that the fix works fine. I don't know why Wayne and Ron haven't
posted the revised version of Rttyrite yet, so I'll leave it up to them to
help you further. I don't want to bypass them by posting the URL on the
reflector - it is their program.
On Sunday, June 20, 1999 7:40 PM, John Lockhart [SMTP:email@example.com]
> Good Catch Michael!
> I don't use WriteLog much as I "grew up" using DOS applications (first
> then MSDOS). I've experimented with WriteLog using FSK (I never use
> here and it seemed to be OK in limited trials with stateside stations.
> Please post a note to the reflector if Wayne fixes the stop bit
> John W0DC
> -----Original Message-----
> From: Michael C. Joens <firstname.lastname@example.org>
> To: email@example.com <firstname.lastname@example.org>
> Date: Friday, June 04, 1999 03:56
> Subject: [WL-USERS] FSK Stop Bit Setup
> >I'm using FSK to transmit RTTY in Writelog. Works beautifully with my
> >Icom IC-745, and I enjoy being able to use the RTTY setting for the
> >bandpass filtering for the high tones, including a 250Hz wide filter (I
> >could copy 4L1BR while someone in my town was working OM3NY only 1 kHz
> >away, with an S9+50dB signal).
> >I also like the fact that the FSK generated signal is very clean. In the
> >IC-745 it is generated by shifting the oscillator on the 9MHz IF, and
> >rig allows continuous duty at 100W. None of the splatter problems when
> >using AFSK. I understand that not all new rigs generate true FSK even
> >so labeled.
> >There is only one problem: the signal is too fast, resulting in some
> >stations not being able to copy me. They can hear me, but can't decode.
> >Most stations have no problem, but 4L1BR for example could not copy me.
> >When I switched to AFSK, he called me!
> >People have reported that the diddle sounds too fast, and measurement
> >an oscilloscope confirms that the total character length is only 154 ms.
> >45 baud (really 45.45 baud, i.e. bit length of 22ms), that amounts to 1
> >start bit, 5 information bits and 1 stop bit. Each bit is 22ms long, as
> >should be. However, according to the teletype standard, the stop bit
> >be at least 1.4 bits long. I've set the serial port to 1.5 stop bits
> >is not available in PC's) and to 2 stop bits in both the Win95 setup and
> >Writelog.ini, but the character length remained 154ms no matter what. If
> >could slow the signal down to 1.5 or 2 stop bits, the output would be
> >"perfect". Also, distant stations would probably get a more stable
> >reception if the stop bit length meets the minimum requirement (it can
> >infinitely long - there was no diddle in the old mechanical machines).
> >I have tried several serial ports. COM 1 and 2 are the built-in ports
> >the COM/LPT/Floppy do-it-all controller chip) and COM 4 is a true 16550
> >chip. I also tried a true 16450 chip, same problem on all chips. I seem
> >have the same problem with the demo version of the RITTY progam by
> >too. RITTY apparently tries to "fake" the 1.5 stop bits by alternating
> >between 1 and 2 stop bits, although that may be caused by the com port
> >hardware, not the software (I cannot distinguish that).
> >Of course, I could use AFSK, but I MUCH prefer the FSK method,
> >if I could get the stop bit problem solved. I would be very happy to
> >for 2 stop bits, i.e. 176 ms character length. True 1.5 stop bits (not
> >alternating 1/2) would generate near-perfect 165ms character length.
> >Has anyone experienced the same problem? How can I get WriteLog /
> >to give me a longer stop bit?
> >Any help would be appreciated.
> >Michael, K1JE