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RTTY vs PSK for DATA A question K3

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KD8NNU

RTTY vs PSK for DATA A question K3

Dear Group,

RTTY is supposted to be LSB and PSK on USB.

If you have the K3 in DATA A mode does it matter. Once you tune into
the signal and my system decodes I would suspect that I am fine.

From what my brain is telling me is that a RTTY signal that is posted
if you are in DATA A and its in USB then all I need to do is turn lower
in FRQ to find the signal and all shoud be good.

What am I missing if anything with the RTTY. Will it have a big effect
on RX decode or TX to someone else.

The reason that I am asking is I just realized the LSB issue yesterday
and now I am thinking that may be part of my problem where I have poor
RTTY decode and ability to make weak contacts. Other digital modes
like PSK and JT65 work just fine with the system.

I am using the HRD suite of software with DM780 in case that matters.

Otherwise everything works fine, so its more of an education issue for
operator not a K3 problem.

Cheers have a great weekend.

Don

~73
Don
KD8NNU
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Joe Subich, W4TV-4

Re: RTTY vs PSK for DATA A question K3

> If you have the K3 in DATA A mode does it matter. Once you tune into
> the signal and my system decodes I would suspect that I am fine.

If you are using DATA A for RTTY you will likely find the signals are
"upside down" (reversed) unless your software compensates. Most RTTY
software expects the lower audio tone to me MARK - which is correct
for normal LSB FSK.

The other issue with DATA A (USB) is that the display (dial) frequency
will be the suppressed carrier - not the actual RTTY frequency which
will be "VFO + MARK TONE (the higher of the two tones)"

73,

... Joe, W4TV

On 4/22/2012 7:59 AM, [hidden email] wrote:

>
> Dear Group,
>
> RTTY is supposted to be LSB and PSK on USB.
>
> If you have the K3 in DATA A mode does it matter. Once you tune into
> the signal and my system decodes I would suspect that I am fine.
>
> From what my brain is telling me is that a RTTY signal that is posted
> if you are in DATA A and its in USB then all I need to do is turn lower
> in FRQ to find the signal and all shoud be good.
>
> What am I missing if anything with the RTTY. Will it have a big effect
> on RX decode or TX to someone else.
>
> The reason that I am asking is I just realized the LSB issue yesterday
> and now I am thinking that may be part of my problem where I have poor
> RTTY decode and ability to make weak contacts. Other digital modes
> like PSK and JT65 work just fine with the system.
>
> I am using the HRD suite of software with DM780 in case that matters.
>
> Otherwise everything works fine, so its more of an education issue for
> operator not a K3 problem.
>
> Cheers have a great weekend.
>
> Don
>
> ~73
> Don
> KD8NNU
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> 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:[hidden email]

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Please help support this email list: http://www.qsl.net/donate.html

KD8NNU

Re: RTTY vs PSK for DATA A question K3

In reply to this post by KD8NNU

Hi Joe,

If I use DATA A REV will that make it correct? I am guessing yes from
what I remember from reading in the past that changes from USB to LSB.
Or would I be better off to use a REV setting in the software??

Time to read the manual again. :-)

~73
Don
KD8NNU

On Sun, Apr 22, 2012 at 8:54 AM, Joe Subich, W4TV wrote:

>> If you have the K3 in DATA A mode does it matter. Once you tune into
>> the signal and my system decodes I would suspect that I am fine.
>
> If you are using DATA A for RTTY you will likely find the signals are
> "upside down" (reversed) unless your software compensates. Most RTTY
> software expects the lower audio tone to me MARK - which is correct
> for normal LSB FSK.
>
> The other issue with DATA A (USB) is that the display (dial) frequency
> will be the suppressed carrier - not the actual RTTY frequency which
> will be "VFO + MARK TONE (the higher of the two tones)"
>
> 73,
>
> ... Joe, W4TV
>
>
> On 4/22/2012 7:59 AM, [hidden email] wrote:
>>
>> Dear Group,
>>
>> RTTY is supposted to be LSB and PSK on USB.
>>
>> If you have the K3 in DATA A mode does it matter. Once you tune into
>> the signal and my system decodes I would suspect that I am fine.
>>
>> From what my brain is telling me is that a RTTY signal that is
>> posted
>> if you are in DATA A and its in USB then all I need to do is turn
>> lower
>> in FRQ to find the signal and all shoud be good.
>>
>> What am I missing if anything with the RTTY. Will it have a big
>> effect
>> on RX decode or TX to someone else.
>>
>> The reason that I am asking is I just realized the LSB issue
>> yesterday
>> and now I am thinking that may be part of my problem where I have
>> poor
>> RTTY decode and ability to make weak contacts. Other digital modes
>> like PSK and JT65 work just fine with the system.
>>
>> I am using the HRD suite of software with DM780 in case that matters.
>>
>> Otherwise everything works fine, so its more of an education issue
>> for
>> operator not a K3 problem.
>>
>> Cheers have a great weekend.
>>
>> Don
>>
>> ~73
>> Don
>> KD8NNU
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> 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:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

Don Wilhelm-4

Re: RTTY vs PSK for DATA A question K3

In reply to this post by KD8NNU

Don,

Your problem may just be HRD/DM780. I no longer use it, but I do recall
it did not handle the K3 Data sub-modes correctly.

I would suggest using AFSK-A sub-mode for RTTY rather than DATA A. It
does default to LSB, allows use of the dual-tone filter, and indicates
the mark frequency on the dial.

MMTTY will work just fine if you want something more simplistic than
DM780 for RTTY.

73,
Don W3FPR

On 4/22/2012 7:59 AM, [hidden email] wrote:

> Dear Group,
>
> RTTY is supposted to be LSB and PSK on USB.
>
> If you have the K3 in DATA A mode does it matter. Once you tune into
> the signal and my system decodes I would suspect that I am fine.
>
> From what my brain is telling me is that a RTTY signal that is posted
> if you are in DATA A and its in USB then all I need to do is turn lower
> in FRQ to find the signal and all shoud be good.
>
> What am I missing if anything with the RTTY. Will it have a big effect
> on RX decode or TX to someone else.
>
> The reason that I am asking is I just realized the LSB issue yesterday
> and now I am thinking that may be part of my problem where I have poor
> RTTY decode and ability to make weak contacts. Other digital modes
> like PSK and JT65 work just fine with the system.
>
> I am using the HRD suite of software with DM780 in case that matters.
>
> Otherwise everything works fine, so its more of an education issue for
> operator not a K3 problem.
>
> Cheers have a great weekend.
>

Richard Ferch

Re: RTTY vs PSK for DATA A question K3

In reply to this post by KD8NNU

Don,

The choice of sidebands depends more on your software than on the mode.
If you are using software that was written to support a wide variety of
digital modes, and particularly if it does not support FSK keying, it is
likely that this software expects the radio to be in upper sideband,
whether you are in RTTY or any other digital mode. This kind of software
quite likely also expects the radio's displayed dial frequency to be the
suppressed carrier frequency, not the actual transmitted frequency.

To put it another way, with this kind of software and with many
transceivers, the expectation is that the radio is in USB mode. On the
K3, you should use DATA A sub-mode for this kind of software. DATA A is
upper sideband and the dial displays the suppressed carrier frequency,
the same as in USB, but in DATA A compression and equalization are
turned off and the microphone is muted (using the normal audio input
configuration settings). The exact same default software settings that
work with other radios in USB should also work with the K3 in DATA A.

On the other hand, if the software was written for RTTY only, and
especially if it also supports FSK keying, then it is likely that this
software expects the radio to be in lower sideband, and it is likely
that it also expects the radio's displayed dial frequency to be the
actual transmitted mark frequency. With this kind of software, the
appropriate sub-mode on the K3 is AFSK A (unless you are using FSK
keying, of course, in which case it is FSK D).

With either kind of software, it is usually possible to select the
opposite sideband (often with a switch or button called "Reverse"). Note
that if you are using the wrong sideband for RTTY, you will not decode
anything meaningful at all. If you get even scraps of sensible-looking
text or callsigns, you are almost certainly using the correct sideband.

If you are having poor decode when using AFSK A with software that is
set to expect the correct sideband, the next thing to look at is whether
your audio frequency settings in the software and on the radio are aligned.

In DATA A, the K3's filter bandpass is centred on 1500 Hz, so you should
use audio frequencies near this value (a centre frequency of 1500 Hz in
USB corresponds to mark/space frequencies of 1585/1415 Hz). In AFSK A,
you can set the K3's expected Mark frequency to be any one of 2125 Hz,
1445 Hz, 1275 Hz or 915 Hz. The DSP filter bandpass settings are
automatically adjusted to match this choice, so that the filter bandpass
centre is at 2210 Hz, 1530 Hz, 1360 Hz or 1000 Hz respectively. You
should choose an audio frequency in your software that is consistent
with the K3's mark pitch and filter settings.

Until you are familiar with how to use these software capabilities, you
should also avoid using AFC and clicking in the waterfall to tune in
RTTY signals, because either of these moves the software's audio
frequency away from the optimal frequencies near the centre of the
filter bandpass. If the audio frequencies are near or beyond the edge of
the filter bandpass, your software's ability to decode will be degraded,
especially on weaker signals.

The convention for spotting amateur RTTY signals is to spot the actual
mark frequency. In AFSK A, this is the same frequency that is displayed
on the K3's dial. In DATA A, on the other hand, the actual mark
frequency is higher than the displayed dial frequency by an amount equal
to the audio mark frequency (e.g. 1585 Hz if the audio centre frequency
is 1500 Hz). Many software programs are capable of doing this arithmetic
for you automatically, provided the software is configured correctly for
the particular sub-mode and sideband you are using.

73,
Rich VE3KI

KD8NNU wrote:

> RTTY is supposted to be LSB and PSK on USB.
>
> If you have the K3 in DATA A mode does it matter. Once you tune into
> the signal and my system decodes I would suspect that I am fine.
>
> From what my brain is telling me is that a RTTY signal that is posted
> if you are in DATA A and its in USB then all I need to do is turn lower
> in FRQ to find the signal and all shoud be good.
>
> What am I missing if anything with the RTTY. Will it have a big effect
> on RX decode or TX to someone else.
>
> The reason that I am asking is I just realized the LSB issue yesterday
> and now I am thinking that may be part of my problem where I have poor
> RTTY decode and ability to make weak contacts. Other digital modes
> like PSK and JT65 work just fine with the system.
>
> I am using the HRD suite of software with DM780 in case that matters.
>
> Otherwise everything works fine, so its more of an education issue for
> operator not a K3 problem.