Hi Graham there was a fair amount of skepicism about the possibility in
those days :-))
Yes VK is going to be quite difficult from the UK. You have extra problems
at the antipodes as signals can arrive many ways so lotsa fading
possibilities...Western VK may not be too bad but it is still much more
difficult from the UK than further East.
There was no "switch from CW"! QRSS, as it is now called, was used from
the
very early days on 73Khz when Andy worked Peter Martinez, with very low
power levels. Peter Dodd, Mike Dennison and the two Dave's were alsoactive
on 3 sec dot mode as soon as waterfall s/w became generally available.
Andy
had used a PIC ADC and written the FFT in cooperation with Peter who was
using a top-end Motorola DSP board. The first FFT I came across for the
Soundblaster 16 was actually written for EME and required a paid-for
registration of $35 (FFTDSP4 I think) and I think that was Win3.1 :-))
S/N is an interesting point, I have no doubt people like Andy may have
more
knowledge, but LF noise is not like other radio noise it is very "spikey"
and "bursty" (I believe the last term is actually an approved definition
:-)) A lot of tests assume it is random Gaussian and I dont really believe
that, though I have no data to dispute it.
I dont think you need worry about the "spirit" it seems to me that there
is
an abundance of the "lets try see if it works" attitude in the
Group....long
may it continue.
Best Wishes
Alan
G3NYK
----- Original Message -----
From: "Graham" <[email protected]>
To: <[email protected]>
Sent: Friday, April 20, 2012 7:46 PM
Subject: Re: LF: Re: 136 propagation a QRO secret ?
R Alan,
Yes a lot of myths linked to the 'Bright light's' of 136 , but I think
the
UK/VK full decode is yet to be achieved ? ive seen wiggles and
squiggles down under , bit like starting a old vintage engine, spark
plugs in the oven, that sort of thing , but not firing on all
cylinders yet ?
I did know about the previous tests , must of taken some setting up
as
well , we could do with a little of that old time pioneering spirit
now, but I assume the same arguments must of accompanied the
change
from cw to slow ?
The Op beacon and QSO mode ( 15 chrs 120 second tx -20 dB s/n)
,is
certainly taking a can opener to the established norm's round s/n
measurement and propagation observations at VHF and MF/LF , for
example
the day light path decodes from PA/RA on 136 , I for one always
assumed , you needed near total darkness , not 3 or 4 hours of
daylight in the path ! sure wspr would do the same thing , but thats
not a MKC mode (Morse key compatible), using the 'Peoples Beacon'
anyone can join in and get a set of results with any set up and
with
the longer tx times , the s/n is considerably lower , OP2 is about the
same as wspr , with -3 db for every X2 in time , OP8 is -6 dB
lower,
and that's a lot of PA amps saved ! (power amps)
USA stations are running on 145 MHz over a 250 mile path, using the
OP0.5 (30 seconds) mode with good results as well. (showing as 70
MHz
on the psk map, to prevent confusion , until a frequency can be defined)
s/n 'mode' comparative measurements also are not always
indicating
the observed performance either , may be linked to the pulsed nature
of
the transmission , everything is referenced to 'average' in the Op
system, the s/n reading is calibrated to the sim-path propagation
software and takes the average of ' all ' the received data pulses
,
so if you loose 50% then the s/n is reported -3dB lower , its
reporting the path usability rather than the max/min signals (ROS
Hf
+
MF) gives a s/n and margin , which is the fade difference, between
the
lower and higher levels , ie two values are presented.
4 months in and it looks quite stable , number of false decodes
are
quite low , usually linked to 500 Khz operation , which sort of
confirms , its a noisy place for some reason! at least its given a
good
justification for the experimental 500 licence as development for
ROS-MF and Opera where both initiated by the 500 band allocation
and
operations !
73 -G..
--------------------------------------------------
From: "Alan Melia" <[email protected]>
Sent: Friday, April 20, 2012 6:20 PM
To: <[email protected]>
Subject: LF: Re: 136 propagation a QRO secret ?
> Hi Graham you may not be aware that the only modes that were available
in
> the early days when the 1st TAs were achieved was QRSS3. Robert Horne,
> author of Spectrogram saw now use or reason for a slower
> waterfall.....remember he is a biologist and this suite was written for
> recording and analysing animal and marine mammal sounds. The results
were
> obtained in a period or high geomagnetic activity just after the peak
> of
> the
> last Solar max (Geomag activity trails sun-spots by about a year) We
have
> just had the quietest minimum for years and the level of activity is
> relative to the last max still quite low.
>
> The modern digital modes are around 20dB more sensitive than QRSS3
> this
> accounts for the difference between 100s watts and less that 10 watts,
> even
> allowing for quieter conditions. I think this is what you usually call
> "progress" :-))
>
> Alan
> G3NYK
>
>
> ----- Original Message -----
> From: "Graham" <[email protected]>
> To: <[email protected]>
> Sent: Friday, April 20, 2012 11:32 AM
> Subject: LF: 136 propagation a QRO secret ?
>
>
> Have the high power operators on 136 been keeping the real
potential
> of 136 propagation a secret ? writing you name in neon light is
one
> thing , but behind the glow of the sign , previously un seen, the
data
> recording Op beacon system is starting to reveal some interesting
> features of this band.
>
> Results from the first 'plug and play' 'peoples' beacon, seem to
> show , DX operation on 136 is not quite as difficult as was
perhaps
> made out , from the first TA decode of OP8 , using a
> Parasol-on-a-Stick , with a few hundred watts , to RA3AGC long wire
> to
> the trees , with similar power and PA0A 'small array' .. 2000 Kmtr
> +
> decodes are showing up on a quite regular basis , may be more than
> that
> offered by 500 KHz ?
>
> VK 136 operators have expressed interest in setting up sked's to
> make, what could be the first full call sign decode , to down
under,
> but to date, it seems there are no transmit takers this side ,
>
> Technically, the processing gain of OP32 , is very close to the
> estimated -40 dB path loss , EU-VK and should require 16 mins
of
> carrier above the s/n threshold in 32 mins to decode ...
>
> Anyone tempted to make a sked ?
>
> G,,
>
> 24 hour usage from http://pskreporter.info/pskmapn.html
>
> Txmtr Rcvr Band Mode Distance Time (UTC)
> 7L1RLL 7L1RLL 2200m OPERA 0 kms 09:54:58
> PA3BHT PA3BHT 2200m OPERA 0 kms 09:53:41
> PA0WMR PA0WMR 2200m OPERA 0 kms 09:45:35
> JH1ARY JH1ARY 2200m OPERA 0 kms 09:43:42
> UA0SNV-1 UA0SNV-1 2200m OPERA 0 kms 09:36:19
> JP1ODJ JP1ODJ 2200m OPERA 0 kms 09:34:55
> JF1PSS JF1PSS 2200m OPERA 0 kms 07:38:29
> UA0SNV UA0SNV 2200m OPERA 0 kms 07:33:19
>
