[GreenKeys] FSK shifts

[Steve Garrison]

Maybe because the FCC seems to be narrow banding everything?  Just my guess.

Steve G./N4TTY

-----Original Message-----
From: greenkeys-bounces at mailman.qth.net <greenkeys-bounces at mailman.qth.net> On Behalf Of Duncan Brown
Sent: Sunday, August 22, 2021 8:47 AM
To: Green Keys <greenkeys at mailman.qth.net>
Subject: [GreenKeys] FSK shifts

I was surprised to learn that KPH is running 170Hz shift on RTTY and that is now the standard for commercial RTTY/SITOR/NAVTEX.

850Hz shift was the standard shift for a long time and gives some diversity assistance in TUs that can copy with just one tone. Hams using
850 Hz shift got some flack from CW operators because of their "wide" 
signal among the narrow CW signals.  That, plus the (once) crowded CW bands, forced the change to amateur RTTY switching to 170 Hz. (More stable TX & RX made narrower shifts more practical, but didn't require it.)

Other than narrower transmitter bandwidth, is there any advantage to 170 Hz shift over 850 Hz? When & why did the commercials change to 170 Hz? With assigned channels, they would not have the QRM problems that we have on the Ham bands.

Thanks,

Duncan
K2OEQ


______________________________________________________________
GreenKeys mailing list
Home: http://mailman.qth.net/mailman/listinfo/greenkeys
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:GreenKeys at mailman.qth.net

>>> Jordan Spencer Cunningham's GreenKeys Search Tool: 
>>> https://teletype.net/gksearch 2002-to-present greenkeys archive: 
>>> http://mailman.qth.net/pipermail/greenkeys/
>>> 1998-to-2001 greenkeys archive: 
>>> http://mailman.qth.net/archive/greenkeys/greenkeys.html
>>> Randy Guttery's 2001-to-2009 GreenKeys Search Tool: 
>>> http://comcents.com/tty/greenkeyssearch.html

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html Message delivered to steve.n4tty at gmail.com