[UK-CONTEST] Data contest - apologies

[g3ory at lineone.net]

Graham,

An entirely different suggestion from me which focuses on the 

operating and not the propagation. Are your PSK macros long enough to 

allow the AFC of the station you are calling to 'lock on' to your 

signal?

73 Bob
G3ORY

>----Original Message----
>From: 
g3yyd at btinternet.com
>Date: 07/03/2012 8:35 
>To: "UK-
Contest at contesting. com"<UK-Contest at contesting.com>
>Subj: Re: [UK-
CONTEST] Data contest - apologies
>
>Graham
>
>I was not in the contest 
so no axe to grind but I do a lot of data
>contesting.
>
>PSK is a very 
poor mode for 80m during the winter/early spring evenings. The
>reason 
is that 80m suffers form a lot of multipath propagation and Doppler

>shift. The result of this is that the phase of any signal can change 
very
>quickly in fact so fast that PSK31 becomes useless as it relies 
on the phase
>on the incoming signal being reasonably stable over one 
bit time (32
>milliseconds). I suspect this is what you were really 
suffering from.
>
>You would have found that RTTY on the other hand is 
a different kettle of
>fish. This relies on frequency shift rather than 
phase shift. Phase change
>does not make a lot of difference to FSK. 
What destroys FSK using MMTTY is
>multipath causing one of the tones to 
disappear (selective QSB) and this
>does happen. It is a implementation 
failing of MMTTY as it is possible to
>copy on just one tone. The other 
thing that rarely destroys FSK is multipath
>with very long propagation 
delays causing the signal to be overlaid but
>later. If this delay 
reaches about 10milliseconds or more and is about the
>same strength as 
the main signal then it can and does confuse FSK decode. 
>
>The sound 
card in your laptop unless it has gone faulty, which I very much

>doubt, is perfect for these modes. There is no need to use an external 
one.
>The only reason to use an interface box of some sort between your 
rig and
>the FT1KMP is to reduce the amplitude of the audio out to the 
correct level
>and if you have a problem remove hum loops by the use of 
small transformers.
>However do not put small transformers near any 
power supplies especially
>linear ones as the mains transformer 
magnetic field could make things
>interesting.
>
>I used to use a 
FT1KMP and I found that for RTTY the ideal mark tone
>frequency was 
990Hz when using the two 250Hz xtal filters on the SSB mode.
>This was 
with the shift centred. Your optimum frequency may be slightly

>different as it depends on the individual filters. PSK optimum was 900 
to
>910Hz. I found a lower frequency is useful as it makes tuning in by 
ear
>easier. However do not overdrive the rig as on FSK you will create 
audio
>harmonics with QRM to other band users. On PSK also get IMD 
products (make
>sure the processor is off and no ALC indicated).
>
>73 
David G3YYD
>
>
>
>-----Original Message-----
>From: uk-contest-
bounces at contesting.com
>[mailto:uk-contest-bounces at contesting.com] On 
Behalf Of G4FNL
>Sent: 06 March 2012 20:32
>To: uk-contest at contesting.
com
>Subject: [UK-CONTEST] Data contest - apologies
>
>I was active in 
the 80m RSGB contest last night. I had done a great deal of
>pre-
contest checks, over the past week or so,  to try and ensure that I had

>everything working and properly operational in readiness. I am still 
new to
>the data modes.  Before the contest, I was more confident with 
using the
>software (N1MM), and also with using the radio and N1MM 
filtering more
>effectively, along with shifting the IF pass-band to 
ensure that I could use
>a narrower (400Hz) CW filter etc. So, I was 
very disappointed with the end
>results. I ended up with just 52 Qs.
>

>I believe that my TX signals were probably OK - but it possibly 
appears that
>I was missing many stations calling me. If you were one, 
please forgive me
>not responding back to you. I obviously lost out, 
and I apologise for
>wasting your time. I am unsure of the cause of my 
inability to properly
>receive on PSK - because it seems that it was 
working OK for some QSOs but
>not for others.  I am suspicious that the 
problem could possibly be with my
>in-built soundcard on the laptop 
PC.  I intend to try and replace my current
>interface / soundcard set-
up and borrow another for the next contest. So, if
>I haven't been 
blacklisted on the data contest scene yet - please bear with
>me and 
I'd be grateful if you would try and work me again next time. I would

>like to know the size of the problem - and so, if you called me, and I

>didn't respond - please tell me.
>
>If anyone has any suggestions 
(that don't involve buying equipment) to
>overcome the problems, I be 
grateful for the advice. I currently use an
>FT1000MP, + ZLP DigiMaster 
ProPlus interface, an H-P laptop with built-in
>soundcard, and generate 
PSK and RTTY with audio tones (AFSK). As I say, it
>all seems to work 
OK for individual QSOs - but in the contest environment,
>it's poor.
>

>73 Graham G4FNL
>
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