[Flexradio] 5 days, made a little progress

[Brian Lloyd]

On Tue, May 5, 2009 at 5:15 AM, Lee A Crocker <lee_crocker at yahoo.com>  
wrote:
> if you choose the right mode you will not have to choose "reverse"
>
> CW does the same thing as far as following U/L band convention.  I  
> always use CWL
>
> You can set up profiles that store your favorite parameters and then  
> choose the "RTTY" profile or the "PSK" profile

One of the problems that people face trying to do RTTY is that there
are now two directions -- traditional and realistic. Traditionally
with RTTY the mark frequency is above the space frequency. But when
generated at audio (AFSK) the mark tone is *lower* than the space
tone. So in order to invert the tones when transmitting, one uses LSB
on the transmitter. This is the "traditional" approach that probably
came from someone a million years ago trying to do RTTY on the lower
bands, e.g. 160/80/40 and wanting to keep to the "tradition" of using
LSB on those bands.

But nowadays writers of software have opted to write code that just
puts the mark tone above the space tone so that it is just like the
transmitted signal, only translated in frequency. This requires
something like USB to transmit.

Radio manufacturers are a confused sort and aren't sure which way to
go so you need to know several things:

1. Does the software generate the tones with mark above space or space
above mark?

2. Does my rig have a RTTY mode and is it LSB (inverts the signal
before transmitting) or USB (does not invert the signal)?

3. Does my rig in RTTY mode display mark frequency or carrier frequency?

4. Does my software calculate mark, space, or center frequency for me?

I have discovered that most rigs that have a RTTY mode for AFSK use
LSB. That means that for most other digital modes, you need to run
RTTY reverse mode. PSK31 doesn't care but some modes, e.g. the MFSK
modes like MFSK and Olivia, do. You need to make sure that the radio
is NOT inverting the spectrum of the signal for transmission and
reception. This is why some of the newer software doing RTTY generates
the tones with the mark tone above the space tone. That way you don't
need to change modes on the radio when going from MFSK to AFSK. But it
sure is confusing the RTTY traditionalist.

So, bottom line, make sure you know what the radio AND the software
are doing so you can get them doing the right thing together.

73 de Brian, WB6RQN/J79BPL