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Message-ID: <006d01cd1f3d$7963c460$4001a8c0@lark>
From: "Alan Melia" <alan.melia@btinternet.com>
To: <rsgb_lf_group@blacksheep.org>
References: <747B7F1ACC2344CA812AF33D422316C0@AGB> <002d01cd1f1a$5abe8ae0$4001a8c0@lark> <8CE7B218E1414CCF948FDAAF7F315812@AGB>
Date: Fri, 20 Apr 2012 22:12:05 +0100
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Subject: Re: LF: Re: 136 propagation a QRO  secret  ?
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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" <g8fzk@g8fzk.fsnet.co.uk>
To: <rsgb_lf_group@blacksheep.org>
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" <alan.melia@btinternet.com>
> Sent: Friday, April 20, 2012 6:20 PM
> To: <rsgb_lf_group@blacksheep.org>
> 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" <g8fzk@g8fzk.fsnet.co.uk>
> > To: <rsgb_lf_group@blacksheep.org>
> > 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
> >
>
>