last updated: Sunday, August 18, 2002 09:10:17 AM

Call sign Servers

Solar Sites

 (see also AMTs HF page)

Digital Modes

HSMS is short for High Speed Meteor Scatter which is a computer operated mode used for VHF and UHF communication and is designed to take advantage of the few milliSeconds of reflection supported by an under-dense meteor 'ping'. In HsMs, full calls and grids e.g. "W6MT CM87 VE5UF C062" are exchanged in a mS or two (!). It has to be that fast because the mode of propagation. Generally, both parties transmit on a tight schedule. Believe me, taking your little computer-recorded 'blip' of a signal and post processing it until recognisable content appears will really get your propeller turning!

PSK31 (31 state Phase Shift Keying) is a narrow (<50Hz!) mode used primarily on HF (around 14070). It is a GREAT QRP mode and very useful for DX due to the great carrying power of the narrow signal combination. It also has the advantage of being fairly easy to tune in using any of the myriad available modem software. Its major limitation stems from the very narrowness: when the PSK31 signal suffers much doppler, excessive phase ambiguity is introduced to the signal rendering it uncopyable even though the signal itself may be strong enough.

MFSK16 addresses these problems by creating the premier DX mode using almost all the tricks in the book: Viterbi and Hamming encoding, nice non-linear tolerant FSK modulation, full character set, etc... all in about 300 Hz BW. Goes over the pole nicely, is narrow anough, fast enough and remarkably robust in the presence of other signals and deep fades). Nothing is magic... well, LTI is (see below).

  • MFSK16 (that musical stuff at 14080 USB)
    • ZL1BPUs MFSK16 Documents page (great starting place for MFSK16 software and reference).
    • Stream software. The original MFSK16 software. Also does PSK31.
    • HamScope Software - does RTTY (using MMTTY) in some ways better then MMTTY, PSK31, MFSK16 and takes a shot at CW. I (w6mt) like it. 

LTI is the acronym for Long Term Integration. In theory, you can collect photons for long periods and 'average out' the ones that are random (noise). Tthe longer the period, the more the random photons cancel each other and the desired ones add up. Well, if you REALLY knew the frequency that the other station is transmitting on and REALLY knew when the other station was there, and the other station used REALLY long transmit times, you could REALLY narrow your effective received bandwidth (like to fractions of a Hz!). Well, people ARE.

  • W7PUA and his close associates have created this page as entree into the DSP-10 world. The DSP-10 project is a 2M transceiver largely based upon a DSP IF subsystem. It permits complete control of modulation and demodulation; when interfaced into stable (GPS based) frequency and time-domain peripherals, one can create, well, QSOs like 5W 1296 EME. Let THAT roll over your tongue for a bit... It means that ANY DSP-10 station and a small satellite array is EME capable to another station just like it! It can decode its own echos. This is not a stunt, but rather the future. See you in a decade when lots of people will be doing backyard EME with solid state GPS stabilized VHF/UHF equipment.
  • JT44 is a more flexible, easier to implement LTI approach.  W1JT took W7PUAs work and implemented it under Windows.  Super easy to use, super workable.  Folks are using it for both Moonbounce (EME) as well as long haul tropospheric (tropo) paths and having lots of fun in the process.  Please see the Meteor Scatter page for links to the latest JT44 scheduling as well as software acquisition information.  See you on the mode!!  Also see W0SM's excellent power point presentation on WSJT (almost 3 megs).

Interfacing your radios to your computers

  • After you've listened enough and want to transmit you'll need a RigBlaster (to interface your radio to the computer for TX). Do it once, do it right.

Modifying your radios to get the most from them

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Copyright August, 2002 AMT ARC
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