[RTTY] USB to Serial FSK experiment/observations

[WB2RHM - Ben Antanaitis]

All,

I am testing MMTTY's EXTFSK.dll capability to send FSK via a USB 
connection, for my own station use.

I have several USB to Serial adapter cables that are based on the Prolific 
chipset. These are really very cheap to buy from outlets like 
TigerDirect.com (~$9 to $15 depending on the rebates). Several 
manufacturers have Prolific based USB to Serial cables for sale there.

Prolific released a new set of drivers in 2004. They can be downloaded from the
Prolific web site http://tech.prolific.com.tw/visitor/v_fileBrw.asp and then
select the USB to Serial link to find the latest drivers for your system. 
These are a higher/newer level than those at any of the cable makers 
'download' areas that I've looked at. Windows, and the Prolific based USB 
to Serial cables, will accept generic Prolific update/replacement drivers.

I downloaded them, uninstalled the original ones that came with the cables, 
and installed the new ones on my WinME based system using the 'installer' 
program that comes inside the Prolific update package.

Using MMTTY alone with EXTFSK.dll. I found that I could now send FSK to my 
Orion after setting the Windows ME Start>Settings>System>Control 
Panel>Device Manager>Com Port>Properties settings to "5" Bits, 1.5 Stop 
Bits, No Flow Control, for the USB FSK COM port. The trick seemed to be to 
set the com port to what we need for RTTY. I used the EXTFSK USB option of 
MMTTY and it seemed to work.

Using Windows 'sound recorder', I recorded my radio's speaker 'output' via 
the Orion's 'monitor mode' and then I played it back into MMTTY which 
happily decoded everything correctly from the .wav file.

N1MM also seemed to work fine.

Unfortunately, Logger32 seems to do some kind of 'port polling' that chops 
up the FSK signal into many 'slices' that destroys the FSK 'keying' signal.

At ~$9 to $15/cable depending on the rebates, this is much cheaper than 
some of the latest USB keyer packaged solutions.

I didn't know if I should post my preliminary results on the RTTY contest
reflector yet, especially if I'm the only one who sees these results ;-( 
But Don suggested this may help others and spur some more tests.

73, good luck,
Ben Antanaitis
WB2RHM