[pskmail] Re: pskmail thread in WL2Kemcomm yahoo-group
- From: Rein Couperus <rein@xxxxxxxxxxxx>
- To: pskmail@xxxxxxxxxxxxx
- Date: Tue, 11 Sep 2007 14:07:21 +0200
> Thats my observation too! The receiving signal is possible too weak for clear
> decoding. When fldigi reads a frame, significant parts of it are missing or
> wrong (i.e. OEcxTJ instead of OE7FTJ). A human can interpret it correct ->
> fuzzy-logic!
> I'll try to read the imd and s/n value in the fldigi window next time, when
> receiving a longer text.
> When I send out an APRS-beacon I get back an 'QSL' immedeatly, but when I try
> to connect - no success.
>
If only 1 bit in a block is faulty the whole block will be thrown into the bin.
Once the connection has been made the block size will be reduced by the qrm,
increasing the chance
of success..
I have started to define a shorter connect/connect ack block, but could not
get the work done because of other priorities, I need a winter holiday for that
:)
> Perhaps a longer wire with optimized match could help to increase the
> rx-signal quality. But I have to ask some other hams with more knowlegde in
> hf and hf-antennas.... ;-))
What you are looking for is not signal strength but improved signal/noise
ratio. If lengthening the
antenna also produces more noise you are not gaining anything. Your signal
seems to be strong
enough at the servers. One problem is multi-path, as you are living in a
mountainous area, and I can
see quite some qsb on your sigs.
I have had some difficulties in Spain and Montenegro with that and I plan to
take along some
extra stuff to enhance reception next time.
As the problem is mainly in receiving, you should try to kill the noise. I
would start by using a
small vertical receive loop (a screened magnetic loop made of coax e.g.), which
at 30 meters is
a square with sides of max. 1,5 m. Anything smaller is ok, but signal strength
diminishes with the 4th power
of the area enclosed.
You will gain immediately 3 dB by picking up only half the noise. The mag loop
diagram is donut shaped,
with clear nulls broadside which you can point to kill the main noise source.
When you screen the loop it will only receive the magnetic component of the
signal, most of the noise is in the elctrical field.
I can give you more info if you want.
>
> @Rein:
> You should come to visit Innsbruck and give a lecture about pskmail ;-)
I am giving a lecture in Bern (Switzerland) on October 6th. Insbruck is not too
far from there,
we plan a few days vacation before or after that event...
Next time I will be in your area is around end of June 2008.
So let me know if you can arrange something.
BTW, we will also install a pskmail server in Bern during that weekend...
73,
Rein PA0R
--
http://pa0r.blogspirit.com
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