Loading ...
Sorry, an error occurred while loading the content.

Re: [MT63] Wide band MT63

Expand Messages
  • Karl Larsen
    ... Reading the information on the web page of ZL1BPU I agree with the above figures. I get slightly faster WPM if you assume the average word has 5 charaters,
    Message 1 of 8 , Jun 4, 2004
    • 0 Attachment
      On Fri, 4 Jun 2004, Tomi Manninen wrote:

      > On Fri, 2004-06-04 at 17:22, Omar Shabsigh wrote:
      >
      > > for the 2000 Hz width and with the 200 bps rate, you have a spread factor of
      > > (roughly speaking) 2000/200 =10. Which is a good spread in a way.
      >
      > BTW the real data rates for MT63 are 35, 70 and 140 bps for 500, 1000
      > and 2000 Hz modes respectively.
      >
      > (7 bits per symbol at 5, 10 and 20 baud.)
      >
      Reading the information on the web page of ZL1BPU I agree with
      the above figures. I get slightly faster WPM if you assume the average
      word has 5 charaters, but that may not be correct.

      MT63 is designed to use a 7-bit ASCII character which is further
      encoded into 64 bits using the Walsh/Hadamard function. My question is,
      could we re-write MT63 so it used a 8 bit ASCII character? What would we
      loose if this was done? I am thinking of using Hoffman on the run
      arciving of the data before it's processed by MT63. This will run the
      speed of data transmition up by about half again as fast as without
      arciving. Pactor email went to this when pactor 1 tnc's were found to
      handle 8-bit ASCII. Alas the cheap ones from MFJ are 7-bit ASCII.

      Thanks for your input Tomi. It's easy to error with the
      information available.

      >

      --

      - Karl Larsen k5di Las Cruces,NM Az ScQRPions -
    • Walt DuBose
      I think that you can classify MT63 as OFDM modulation which the FCC has classified as not being SS. They did this in approvial of a Canadian Firm who put
      Message 2 of 8 , Jun 4, 2004
      • 0 Attachment
        I think that you can classify MT63 as OFDM modulation which the FCC has
        classified as not being SS. They did this in approvial of a Canadian
        Firm who put forward the use of IEEE 802.11G on the 2.4 GHz Part 15
        band. They said that it wasn't SS but met the usage criteria for the
        Part 15 use of 2.4 GHz.

        I believe that perhaps WB8WKA(?) might have the details on this.

        Walt/K5YFW

        Disclaimer...realizing that the FCC doesn't speak for the rest of the
        world. Hi Hi.


        Karl Larsen wrote:
        >
        > On Fri, 4 Jun 2004, Omar Shabsigh wrote:
        >
        > > I agree with you Karl. On my side of the world no PACTOR or for that any
        > > other mode affect my reception of MT63 signals. And you got it right. The
        > > wider, the better immunity to interference. This is not a general statement.
        > > It is a statement concerning MT63 which in my opinion is a kind of SPREAD
        > > SPECTRUM.
        >
        > Hi Omar, it was sure an experiance using the wide mode. I do not
        > think 2000 Hz constitutes enough spread to be classed Spread Spectrum. I
        > think it works so well because it is such well designed HF software.
        > Tomi Mannion thinks the symbol rate is too slow for HF conditions. I
        > think it might be why MT63 works so well...:-)
        >
        > >
        > > Omar YK1AO
        > >
        > >
        > > **********************
        > > ----- Original Message -----
        > > From: "Karl Larsen" <k5di@...>
        > > To: <MT63@yahoogroups.com>
        > > Sent: Friday, June 04, 2004 6:33 AM
        > > Subject: [MT63] Wide band MT63
        > >
        > >
        > > >
        > > > Don W1OER in Waltham MA and Karl K5DI in Las Cruces NM got
        > > > together with just fair signals and we were moved up 2.5 KHz to get away
        > > > from the darn pactor-pests. We started with the standard 1 khz and when
        > > > we got set up with names and QTH stuff I suggested we just switch to the
        > > > 2khz and see how it goes. So we did.
        > > >
        > > > We had no problems with synch or anything. The words went real
        > > > fast, twice as fast as when using 1khz. Don sent me a long thing that he
        > > > said later is 3 files. They zipped to my computer, and when Don sent it
        > > > back to me I said a few words and then sent it all back to Don. He said
        > > > what he got was an exact copy of what he sent!
        > > >
        > > > Now a little thought on what this means. We were able to send a
        > > > large file from the Southwest (50 miles north of Mexico) to MA and back
        > > > again for some time. There was a pactor-pest right in the center of our
        > > > 2khz signals but the QRM did nothing to harm our data. Don and I are
        > > > sure the wide band gets us away from lots of narrow QRM problems. The
        > > > 200 words/min is really fast.
        > > >
        > > > If there was a reason to send important data across the country
        > > > when all other means failed, MT63 wide mode will be my bet. As Tomi
        > > > says, he does not know why MT63 works so well. I can say now with the
        > > > Solar flux at 89 A=11 K-3 that MT63 gets through better than CW.
        > > >
        > > > --
        > > >
        > > > - Karl Larsen k5di Las Cruces,NM Az ScQRPions -
        > > >
        > > >
        > > >
        > > >
        > > > << Try MT63 on 80m - great fun!>>
        > > >
        > > > - The MT63 Reflector -
        > > > MT63@egroups.com
        > > >
        > > > (To unsubscribe. send email to
        > > > MT63-unsubscribe@onelist.com)
        > > >
        > > > Yahoo! Groups Links
        > > >
        > > >
        > > >
        > > >
        > > >
        > >
        > >
        > >
        > >
        > > << Try MT63 on 80m - great fun!>>
        > >
        > > - The MT63 Reflector -
        > > MT63@egroups.com
        > >
        > > (To unsubscribe. send email to
        > > MT63-unsubscribe@onelist.com)
        > >
        > > Yahoo! Groups Links
        > >
        > >
        > >
        > >
        > >
        > >
        >
        > --
        >
        > - Karl Larsen k5di Las Cruces,NM Az ScQRPions -
        >
        >
        > << Try MT63 on 80m - great fun!>>
        >
        > - The MT63 Reflector -
        > MT63@egroups.com
        >
        > (To unsubscribe. send email to
        > MT63-unsubscribe@onelist.com)
        >
        > Yahoo! Groups Links
        >
        >
        >
        >
      Your message has been successfully submitted and would be delivered to recipients shortly.