Graham,
I'm behind on ROS progress so have a few questions please, if you've time:
- How does ROS compare on a weak signal "effectiveness" factor with modes like QRSS3, 10 etc and with WSPR? Is there a "dB better than" estimate for ROS in its various forms?
- What sort of bandwidths does ROS occupy on these LF tests? I appreciate it is spread spectrum, so there's not much power at any time on any frequency.
- What sort of TX PA is needed - linear or non-linear?
- Is the software less clunky than when I looked a few months back?
- Is it going to be a serious contender for real QRP buffs like me?
73s
Roger G3XBM
On 20 June 2010 20:46, Graham <[email protected]> wrote:
''''for instance the French stn F5WK cannot
hear you'''''
Well , yes , that's the point of
it all , no noise, no trace just 100% pure
digital data rolling over the land , like the un-seen
fog of progress
IARU - R-1 plan .. 137.4 to 137.6 digital
modes , with the note that CW is 'not allowed'
I think the test and the
frequency went fully to 'to plan' and paves the way for
a magnitudinal increase in data use on 137 , to date limited
by bandwidth to psk31 , ros-mf by design occupying
on 50% of the allowable space on 137 and 99% of
the 100Hz allocations for 500K. and passing
via a non linear system , how long will it before
the first live data qso over the pond
?
G .
Sent: Sunday, June 20, 2010 6:30 PM Subject: Re: LF: Re: 137.500 kHz ROS beacon
Gary
There are too many variables with these experiments
for instance the French stn F5WK cannot hear you but you are S5 solid
on 137.5 here at my qth
The RX stations antennas need to be analyised
otherwise it misrepresents what you are doing.
Can u pse use frequencies below 136.5 kcs otherwise
there is a problem with EU and Russian stations using the area 137 - 137.778 kcs
for QRS acty.
also this is the DX window area for the USA and
others.
73 de mal/g3kev
----- Original Message -----
Sent: Sunday, June 20, 2010 4:31 PM
Subject: Re: LF: Re: 137.500 kHz ROS
beacon
Hi Mal,
Thank you for your report & comments. The mail you replied to gives
all the details of equipment in use for the test beacon.
I would like to be able to have a QSO using morse but I have to admit to
a complete loss of confidence as I have not used the mode for 25 years which
was one year after I passed the test in 1984. Looking back, letting it go was
a silly thing to do.
I do enjoy testing out these "weak signal" modes & in the report I
received from Michel F5WK last night he wrote that he could not hear the
signal or even see it on SpecLab but he got a complete decode. So as a weak
signal communication mode it works.
Just to elaborate on the antenna, it is a 12 metre base loaded vertical
with a small elevated inductor of 500uH at about 9 metres & a 1 x 3 metre
capacity top with a 120uH spiral inductor. In my small garden I have no space
to go outwards only upwards.
73,
Gary - G4WGT.
On 20 June 2010 13:48, mal hamilton <[email protected]>
wrote:
Gary
If that was you last nite on 137.5 kcs
you were strong enough for cw or qrs3 no need to struggle with decodes
from elswhere.
also I had a qso with G3XIZ this morning on
137.0 kcs and got 599, he was 569.
Not sure what antenna u were using but it
was putting out a fair signal to this qth. Your radiators are probably
acting as an antenna above earth.
de mal/g3kev
----- Original Message -----
Sent: Sunday, June 20, 2010 12:07
PM
Subject: LF: 137.500 kHz ROS
beacon
Having successfully bench & on-air tested a x2 harmonic amplifier
method of driving my G0MRF Class D LF transmitter, I ran a beacon last
night (Saturday 19th) on 137.500 kHz.
An extract from my previous e-mail description is shown at the
end.
Using the equipment & method described below, the ERP from my 12
metre vertical antenna was around 150mW. The mode was ROS MF-1, 100 Hz
bandwidth.
I received the following report from Michel, F5WK in JN18HP, a
distance of 410 miles (661 kilometres) in daylight.
>> Not even a faint trace on a QRSS3 spectrum
but:
>> RX1: 19:23 @ 5.9 Hz: 9 <STOP> -37
dB
>> RX1: 19:28 @ 5.4 Hz: O4WGT <STOP> -34 dB
>>
RX1: 19:33 @ 5.4 Hz: G4WGT <STOP> -31 dB
The x2 harmonic low level amplifier is a simple way of driving a
Class D type of transmitter which employs a divide by 2 drive chain. My
limitation with multi tone drive is that my DDS VFO will only produce 2
frequencies ie. the main frequency & a CW/Rx offset which has
previously limited me to 2 tones as with RTTY & DFCW modes.
Please bear in mind that it will not be suitable for modes like PSK
were tones are transmitted simultaneously.
At the moment the 2 small PCB's are precariously lying on the desk,
when I have cased them I will publish the circuit & pictures.
73
Gary - G4WGT.
***********************************************
After a few days experimenting & bench testing a method of
driving my
G0MRF Class D Tx on the 137.000 kHz band from my linear
transverter I finally
constructed a harmonic amplifier producing a
274.000 kHz signal from 137.000
kHz input. An "on-air" trial was
conducted resulting in a QSO with
Graham G0NBD on 137.000 kHz using
ROS data mode software.
My thanks to Graham for his ideas
& tests.
The mode used was ROS MF-7. The equipment used
for the QSO was as
follows. Kenwood TS-440 to my LF-MF linear
transverter producing the
137.000 kHz signal, followed by a tuned
harmonic circuit & buffer
amplifier whose output was 274.000 kHz
therefore at x2 drive for the Class
D Tx. The x2 signal is then
divided by the Tx driver chain in the
normal way to provide 137.000
kHz to the PA.
This method should also work well using WSPR
& other similar modes.
*********************************************
--
http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/g3xbm
G3XBM GQRP 1678 ISWL G11088
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