[RTTY] USOS Question

[Richard Ferch]

W6WRT wrote:

> To the best of my knowledge, when it is enabled it
> is automatically enabled for both your TX and RX.

Sorry Bill, but that turns out not to be the case, at least for MMTTY.

The "UOS" button on the MMTTY main window affects only receive. It 
simply treats received text as if there were a LTRS character after 
every space. Overhead: none. It has no effect on transmitted text.

In the MMTTY Setup window under the TX tab, in the top centre "TX" pane, 
the first check box is labelled "UOS". When this is checked, MMTTY will 
send a FIGS character whenever a FIGS case character is to be sent 
immediately following a space. Overhead: 1 extra FIGS character inserted 
into every "<number><space><number>" combination. Incidentally, the 
description of this TX UOS option in the MMTTY Help file is inaccurate; 
it suggests that LTRS is also inserted into the transmit string between 
a space and a letter, but a bit of experimenting demonstrates that this 
is false - the only extra characters inserted by this option are FIGS 
characters before numbers.

With respect to Phil's combinations, the state of USOS RX on the sending 
station and USOS TX on the receiving station don't matter. The correct 
table is:

Sending Station              Receiving Station

USOS TX off                  USOS RX off
USOS TX off                  USOS RX on
USOS TX on                   USOS RX off
USOS TX on                   USOS RX on

The difficulty in deciding what to do about USOS rests mainly with the 
TX side. The RX side costs nothing, you can turn it on and off in an 
instant, and most software lets you see the other case more or less 
easily. On TX, you have to make the decision as a setup decision; you 
can't easily change it on the fly.

Since you can eliminate the extra character in the 
"<number><space><number>" situation by changing that to 
"<number><dash><number>", the best all-round option appears to be to 
leave TX USOS on and adjust your macros accordingly, depending on the 
balance you wish to achieve between speed and reliability. Between 
numbers, dash is slightly faster but space is slightly more reliable in 
most situations. Between letters, dash is considerably slower but only 
slightly more reliable, and it's unnecessary if the receiving station is 
using USOS.

If you want to cover all the bases, use TX USOS and try "599-123 123"; 
i.e., include a dash after the signal report, plus at least one space 
elsewhere in the exchange string.

73,
Rich VE3KI