Message-ID: <490E5A0F229D49678FFD0E84584FC7A1@AGB>
From: "Graham" <g8fzk@g8fzk.fsnet.co.uk>
To: <rsgb_lf_group@blacksheep.org>
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Date: Sat, 21 Apr 2012 15:46:27 +0100
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Subject: Re: LF: Re: 136 propagation a QRO  secret  ?
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R Alan,

Good point  on the  multi-path  to  VK , that's one of the un-anticipated 
advantages of the  Op system, as its only  1 carrier , on/off phase 
distortion is not a  problem along  with  Doppler, the coding allows  for  a 
random loss of upto 50% of the  data distributed along the time  line or in 
a block.

EU/VK  Dx fade patterns on  136 , tend to  show , there would be  sufficient 
signal to meet the  decode criterion  for OP32

DSP may be  one of the  best  uses  for  desk top  PC  processing power , 
that  side still  remains a bit of a  dark art ..

Ok on the  spirit, that  may be a little hung over from the celebrations  !, 
But at least Mal , gave the  system a  run  on 500  and Bob in NY achieved 
a  'Dual' west  coast de-code  USA west  coast and  Europe West coast at the 
same time , that's a  good trick !

Thinking  about it, the  GB4FPR  location  could  be a  good  place to 'go 
fly a kite' , there is a  Kite festival at Wallasey/New Brighton  9th & 10th 
June  ... may  be a  good place to  start .. only thing missing  is the  atu 
..

73 - G.

--------------------------------------------------
From: "Alan Melia" <alan.melia@btinternet.com>
Sent: Friday, April 20, 2012 10:12 PM
To: <rsgb_lf_group@blacksheep.org>
Subject: Re: LF: Re: 136 propagation a QRO  secret  ?

> 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
>> >
>>
>>
>
>