Tuesday, 18 August 2015

Meteor scatter getting easier???

If all this looks complicated, there is a nice homely message at the bottom...

Just as I have been working on a review of data modes, everything gets thrown into chaos.

Lots of progress has been made bringing together WSJT modes into an integrated suite. Gradually WSJT-X has morphed from being a JT65 and JT9 HF type chat mode into a multi-mode platform. It isn't finished yet. WSJT-Suite brings together the development stages here. In there you find trial versions of WSPR4.0, WSJT-X 1.6.1 and WSJT10. In the one package by KI7MT, you have the latest HF data modes, meteor scatter, low power beacon modes and so forth, but beware --- this approach is still in development.

But that same time, Joe Taylor himself has packaged up a slightly different version of WSJT-X with WSPR and some new variants of the JT9 HF mode and offered it for trial on his Princeton University site. The version of WSJT-X he is offering is version 1.6.1 "development version" (1.6.1devel) and you can find it here. There are some words of explanation from Joe here.

Of interest to me is a fast mode called JT9H. Joe has always made the distinction between his slow modes (WSPR, JT65) and his fast ones (FSK441 and JT6M). The slow ones are for HF, and the fast ones for VHF. Basically that holds except for moon bounce, which is more like HF as there is not so much fluctuation as you get on terrestrial VHF - the moon stays pretty well in the same place over the duration of a QSO, and it moves gradually. Meteorites move pretty quickly from our perspective, by comparison.

So he has taken JT9, a very good low power HF mode, and adapted it for uses like meteor scatter. There are a lot of variants, but I decided to try JT9H. Immediate result:-
An easy 6m QSO with San, DD3SP, at a time of day when meteor scatter usually struggles. Good result.

There are a few issues with JT9H and WSJT-X 1.6.1 devel. As its name suggests it is still under development and there will be bugs and issues. For instance it lacks the "hot" beam angle calculator in the other meteor scatter programs, and it needs some way of adding a working frequency to the CQ call. But no doubt these things will come in due course.

I really like JT9 as an HF mode, and now I have JT9H for VHF meteor scatter. At first acquaintance it looks terrific. Better than JT6M I bet.

And now for the homely bit of reassurance. If all this looks too complicated, please do not give up on data modes. Just try Ham Radio Deluxe. Have a go at PSK and have a few QSOs. Even RTTY, not a mode I love, but reliable. Or WSPR: the nice simple WSPR 2.21 version is a good place to start. Just connect your computer to the rig and have a play.

After that, all ths meteor scatter or moon bounce stuff can come later (or not, if you don't need it).

I make it sound complicated, when it isn't really.

Just like I do with everything else.

73

Jim
GM4FVM

4 comments:

  1. Hello!
    I use WSJT-X r5889 on 50 MHz Meteorscatter either JTMSK or JT9H mode. What is the difference between the performance of the decoding settings fast - deep?

    73 OH7TE Juhnai "Yussi"

    ReplyDelete
  2. Yussi
    Thanks. Well, these words in "JT" modes usually mean -
    1) "Fast" - uses less computer processor power and looks for individual characters.
    2) "Deep" - uses more computer power and does "deep search" for groups of characters.

    So maybe on a very weak signal fast would show no decode, but deep might find it. Deep would look for bits of message (for example, bits of callsign) and compare that with its database. So some people say "deep search" is not fair as it takes part of a callsign and says you have heard it, when in fact you only heard a bit of it.

    I do not know which is best. Deep search is not worse than me doing CW and picking up parts of signals. For example, if I hear a bit of "73" I know what it is. It is OK, I think, to hear a part of "73", compare that with my brain database, and say I heard "73".

    But I like "fast" because when "fast" shows up a contact it usually means I can be sure you received all of it.

    It is up to you which on you use. I use "fast", but I only have a certain amount of computer power. So unless I buy a bigger computer, "fast" is best for me. "Deep" can slow down my PC.

    JT6H and JTMSK are very good modes anyway, so I stick with "fast".

    Hope I explained this well.

    73

    Jim
    GM4FVM

    ReplyDelete
    Replies
    1. oooops.

      I could have been clearer there.

      "Fast" and "Deep" settings only affect the processing of a received signal. They do not make the received signal any better, they only mean that the signal data you received will, or will not, go into more processing to be compared with more database entries.
      I believe that even "fast" may do some of this, but "deep" does a lot more.

      Jim

      Delete
    2. Thank you Jim.

      Maybe deep decoding goes to the time and because I have an old PC as good decoding setting may be 'normal'

      73 & tnx agn OH7TE "Yussi"

      Delete