IMHO, RTTY is like AM -- a classic mode which uses more bandwidth
than necessary, but is nice to keep around for nostalgia and to
relive history.
RTTY is not like AM in using more bandwidth than necessary. *ANY*
FSK signal will have a minimum bandwidth (as defined by ITU) of
(1.2 * shift + baud rate). For 45.45 baud, 170 Hz shift (traditional
RTTY) that works out to about 250 Hz
73,
... Joe, W4TV
On 11/27/2013 2:00 PM, Bill Frantz wrote:
I have a 250 Hz filter I use for PSK and RTTY. It helps when there is a
strong nearby station that overloads the AtoD converter between the K3
and my computer. During a RTTY contest, I found it helped, but the dual
frequency DSP RTTY filter was more than enough for most contacts.
When I use the filter with PSK, I lose the computer waterfall and the
computer noise reduction because of the narrow bandwidth. I use full
bandwidth to scan for signals and the 250 filter after establishing
contact. Usually a narrow filter works better than the computer noise
reduction.
I would worry about 200 Hz for RTTY. While the deviation is nominally
170 Hz, there is energy out wider than that which may be affected by the
skirts of the 200 Hz filter.
IMHO, RTTY is like AM -- a classic mode which uses more bandwidth than
necessary, but is nice to keep around for nostalgia and to relive history.
Cheers - Bill, AE6JV
On 11/27/13 at 9:58 AM, [email protected] (Dave Barr) wrote:
Which two of the 200/250/400 and 500 hz filters are best for digital
use, primarily RTTY, both contests and dx. I understand that for
JT-65 and PSK the standard ssb filter, or even the AM filter is
useable. I am concerned that the 200 hz might be too narrow for
RTTY. I work some CW but almost no ssb.
-----------------------------------------------------------------------
Bill Frantz | If the site is supported by | Periwinkle
(408)356-8506 | ads, you are the product. | 16345 Englewood Ave
www.pwpconsult.com | | Los Gatos, CA 95032
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
