PSK31 using data mode

[wa4ywm]

I have encountered a problem using PSK31 in data mode with my K2. I have
been successfully using PSK31 with a homebrew interface for several months
with the K2 in USB mode. I recently decided to use PSK31 in the data mode to
take advantage of its automatic selection of no compression and its DSP
selection of no noise reduction and no auto-notch while allowing me to have
my own bandwidth selections just for PSK31. My software is Digipan.

The problem that I noticed is that the receiving frequency of a station I am
watching on the waterfall is actually approximately 1 KHz higher than its
actual frequency. For example, a station could be transmitting on 7070.5 and
I will see its signal on 7071.5 and nowhere else (i.e. "ghosting" is not
occurring). I determined this by conducting a test with a nearby ham. I
assume that I am also transmitting on that same frequency (7071.5) although
we were unable to verify that. I am certainly not transmitting on the
correct frequency since I was never able to make contact with anyone over a
number of attempts. I have generally had no problems conducting QSOs with
anyone.

Has anyone else seen this problem or have a possible solution?

TNX & 73, Jim  WA4YWM



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[Don Wilhelm-3]

Jim,

If you have not set up the RTTY filters and BFOs (I think that you have not
from your description), then do that first and it should set things
straight.

I usually set the RTTY filters as follows:  FL1=OP1, with the BFOs set the
same as those for SSB (RTTY = LSB and RTTYr = USB).  FL2=1.00, FL3=0.80,
FL4=0.40 with the BFOs set to position the passband centered at 1000 Hz.

With those settings, tune the station of interest to (or near) 1000 Hz using
FL1, then when the station is selected, lock the transmit frequency in the
software.  Now you can narrow the filters by tapping XFIL if a strong
station comes on nearby and tries to take over the receiver AGC.

73,
Don W3FPR

> -----Original Message-----
>
> I have encountered a problem using PSK31 in data mode with my K2. I have
> been successfully using PSK31 with a homebrew interface for
> several months
> with the K2 in USB mode. I recently decided to use PSK31 in the
> data mode to
> take advantage of its automatic selection of no compression and its DSP
> selection of no noise reduction and no auto-notch while allowing
> me to have
> my own bandwidth selections just for PSK31. My software is Digipan.
>
> The problem that I noticed is that the receiving frequency of a
> station I am
> watching on the waterfall is actually approximately 1 KHz higher than its
> actual frequency. For example, a station could be transmitting on
> 7070.5 and
> I will see its signal on 7071.5 and nowhere else (i.e. "ghosting" is not
> occurring). I determined this by conducting a test with a nearby ham. I
> assume that I am also transmitting on that same frequency
> (7071.5) although
> we were unable to verify that. I am certainly not transmitting on the
> correct frequency since I was never able to make contact with
> anyone over a
> number of attempts. I have generally had no problems conducting QSOs with
> anyone.
>
> Has anyone else seen this problem or have a possible solution?
>
> TNX & 73, Jim  WA4YWM
>

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[list1]

Hi Jim and all,

Not sure what you mean but could the following be your problem?

Say you set the K2 to USB and configure FL4 centered on 1000 Hz when you are
configuring the filter.  Then when your VFO is set to a center frequency of
7070.5 (as seen on the LCD), your PSK signal will be seen at 7071.5.  That
is because with USB the signal is transmitted on the upper sideband which is
set for an offset of 1000 Hz higher than the center frequency.  With USB the
center frequency is not transmitted.

I run into the same problem testing PSKMail in the USA, which hopefully can
become an alternative for Pactor III.  Some one sets up a server on 40
meters and gives the frequency so others can try to connect.  The standard
is to specify the frequency of the upper sideband.  But many hams don't know
the difference and just give the frequency shown on their radio's LCD, and
no one can connect because the server is initially not transmitting and you
can't see a signal on the waterfall.  If you don't know the offset of the
filter on the guy's radio, even though you know the center frequency, you
don't know the exact frequency of the server (which is on the upper
sideband).

I hope I didn't confuse everyone on the list.  Its easier if you drawing it
on a piece of paper.  Or specify the frequency shown on the waterfall as
this takes into account the audio offset.

I have run the same test with someone running a PSKMail server.  When they
transmit for a second, and I see a signal about 1000 Hz higher in frequency,
I know they have specified the wrong frequency.

Steve, W2MY


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Checked by AVG Free Edition.
Version: 7.5.432 / Virus Database: 268.16.10/625 - Release Date: 1/13/2007
5:40 PM
 

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[Leigh L. Klotz Jr WA5ZNU]

If you have KIO2 and run gMFSK or fldig on Linux, or if you run any of
the similar Windows programs with rig control, the waterfall can show
you the frequency exactly.  But some hams don't use rig control because
their PSK PTT is done by the interface box using the computer's lone
RS232 port, and they don't know that rig control cam key the transmitter
instead, so they don't need two ports.

Also, with gmfsk and fldigi, you need to enable hamlib in the setup menu
to get the RF frequency to show on the waterfall.

Leigh/WA5ZNU
On Mon, 15 Jan 2007 6:34 am, Steven Pituch wrote:
> on a piece of paper.  Or specify the frequency shown on the waterfall
> as
> this takes into account the audio offset.
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