Alan,
If you saw the 70 MHz wspr tests I did with Gary last year .. I
don't think frequency stability is a issue with Joe's software !
In test's on 500 over the years, the original MFSK system out performed
the other systems tested , olivia came a close second, but needs a
linear system due to the envelope shaping ..pity as the receive software
has the ability to seek and decode the signal ... still waiting for
some one to add a real arq function to one of the modern data packages,
but 'they' all seem to be locked into a disaster email delivery
system's .. what a disaster for the casual chatter ....... not that some
of 'us' have not sent error corrected emails on 500 .. sorry could not
resist it :)
Im not involved with Rogers project as such , other than I was looking
through the back posts to the ref and noticed the reference to 'wspr'
,the files are uploaded to the uk500khz group, but I notice there is not
a 'G3XBM' page .. that may be a useful addition to link the files
together ...
73 - G ..
--------------------------------------------------
From: "ALAN MELIA" <[email protected]>
Sent: Wednesday, December 09, 2009 10:32 PM
To: <[email protected]>
Subject: Re: LF: 500kHz simple 5W TX/RX transverter >>DATA MODES<<
Sounds good Roger and Graham... what it the stability like the problem
with transverters/upconverters normally is that while ok for some modes
they are often not stable enough for the very weak signal modes. These
are modes where you need to know the frequency of a station very
accurately because you will not hear it, or it will only pop above the
noise for short periods.
Alan G3NYK
--- On Wed, 9/12/09, Graham <[email protected]> wrote:
From: Graham <[email protected]>
Subject: LF: 500kHz simple 5W TX/RX transverter >>DATA MODES<<
To: [email protected]
Date: Wednesday, 9 December, 2009, 22:13
All
This latest
addition to the
HF / MF tx convertor opens the door
to data
communications on 500 ... ranging from
'all' the K1JT systems
through to the single carrier
multi tone
systems of
MFSK , DOMINO and THOR .. even
the almost
forgotten Amtor-arq and Packtor modes , anyone
still have
there pk232
listed are
data modes that may be used with
non-linear systems :-
http://groups.google.com/group/uk500khz/web/meat-grinder-comms
G..
From: Roger
Lapthorn
Sent: Tuesday, December 08, 2009 12:20 AM
To: [email protected]
Subject: LF: 500kHz simple 5W TX/RX
transverter
Dear All,
My WSPR tx up-converter has now been modified to
a full TX/RX tranverter suitable for WSPR, QRSS and
CW in a
very simple way, making use of the FT817 split
facility which allows you
to RX on 500kHz and TX on 28MHz. By adding a series LC
between the TX PA and the
FT817 input/output RF connection (with back-to-back diodes
at the L and C
junction, this allows "pass through" from the
500kHz ATU to the FT817 on RX
(tuned to 500kHz). On TX, the diodes conduct and the C part
is in parallel with
the first cap in the TX low pass filter. This scheme is now
working really well
with good RX sensitivity and no change in TX power out.
Schematic of the
transverter is on my blog at http://g3xbm-qrp.blogspot.com/
. My
attempt to add it as an attachment to an email here earlier
failed.
This more or less concludes my 500kHz experimenting, apart
from
getting a few more CW QSOs in the log. It's been great
fun all the way with lots
of support from folks here. I was going to try 136kHz, but
think I will now give
this a miss for now.
73s
Roger G3XBM
--
-------------------------------------------------------------
http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
G3XBM
GQRP 1678 ISWL G11088
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