[UK-CONTEST] Data contest - apologies

Wed Mar 7 12:39:23 PST 2012

Interesting comments from both re Data.

To be honest, I have not really found any advantage in using narrow filters
during an 80m Data contest .  In fact to be able to see many stations at
once can be a big plus. I am probably lucky in not having any really loud
local stations that might change my views on this.
I only ever use AFSK for both modes, and from past experience with the
oddities of MixW logging and macros (grrrr!) I have stuck with N1MM and
MMvari - ESM is wonderful!
I also found that conditions were pretty dire for psk but stayed with it for
the first half, I guessed phase problems might get worse in the latter part
of the contest. They did indeed appear to do that in the S.West.
I have only recently discovered the delights of using dual receivers and
VFOs on the FT1000D for Data contesting . Being able to run, and then
quickly hop off to S&P in either mode if necessary, is really useful.
I must apologise for my operating in the Data contest before last, as I had
not really discovered the full implications of having AFC activated -
suddenly finding I was calling CQ on top
of another station having jumped frequency without being aware of it
...whoopps! 

73
Robin
G3TKF
City of Bath
FT1000D/ Dipole at 50ft /MMvari/microHAM MKII

> -----Original Message-----
> From: uk-contest-bounces at contesting.com [mailto:uk-contest-
> bounces at contesting.com] On Behalf Of G4FNL
> Sent: 07 March 2012 19:11
> To: 'UK-Contest at contesting. com'
> Subject: Re: [UK-CONTEST] Data contest - apologies
> 
> Hi David
> 
> Thanks for the very helpful / useful feedback. Perhaps I will retain my
data
> modes gear after all - but I am intending to investigate an alternative -
just to
> see if there is any difference.
> I particularly found your comments re: the filter and tones etc for RTTY
> useful. I use AFSK to produce RTTY. That's because of the interface unit
that I
> have - and can switch from PSK to RTTY without needing to change cables on
> the rear of the radio. Anyway, I plan to test my receiving capability once
again
> on both PSK and RTTY - to ensure that I am match-perfect for next month's
> contest. Hopefully, I won't be as embarrassed and frustrated as I was on
> Monday eve......
> 
> Once again, thanks to everyone who has commented.
> 
> 73 Graham
> G4FNL
> 
> -----Original Message-----
> From: uk-contest-bounces at contesting.com
> [mailto:uk-contest-bounces at contesting.com] On Behalf Of David
> Sent: 07 March 2012 08:36
> To: UK-Contest at contesting. com
> Subject: 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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