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last updated:
Sunday, August 18, 2002 09:10:17 AM
Call sign Servers
Solar Sites
(see also AMTs HF page)
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.
- PSK31 homepages (that din at 14070 USB):
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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