PSK 31-A NEW DIGITAL MODE

PSK31 Description

PSK31 is a new digital mode:

based on the RTTY mode of operation,
useful for live keyboard to keyboard QSO
that works at 31.25 bauds,
that uses varicode caracter coding what gives 50wpm,
easy to use and monitor,
that give very good copy under low Eb/No numbers and is thus suitable for QRP,
that instead of using FSK or on/off keying uses BPSK or QPSK with a Viterbi decoder,
that is available for free for many platforms, including Windows (c) with SoundBlaster type Soundcard,
and uses advanced DSP and narrow band (31 Hz!!) techniques.

PSK31 is not a digital mode that:

will make Pactor, Pactor-2, Clover-II or Gtor obsolete,
offers error free links,
can be used to transmit files or acces mailboxes...

HOW IT WORKS:

The newest of digital modes uses "Phase Shift Keying" to signal mark and space values. Instead of changing the frequency like RTTY, DSP is used to change the phase by 180 degrees when a switch from mark to space is needed. This is the same as instantly skipping half of the simple sine wave cycle of the single pure tone (called "a coherent signal"). The ear detects each transistion but then perceives it as the same tone as before (which it is). DSP analysis by the program instantly detects this "Phase Shift". The baud rate is 31 and it can use the full Ascii set like Pactor. The signals themselves are often found on 14069 KHz. Since the bandwidth is equal to the baudrate and the chosen baudrate is 31.25 we can now use a bandwidth of 31Hz and narrow CW filters can be employed. This is good news because it can work at much lower signal levels in the crowded digital bands. The normal bandwidth of other modes is in the order of 300-500Hz.
PSK31 has shown itself to be a real trouper in weak-signal situations. Some hams experimenting with PSK31 claim that it outperforms all other amateur modes for weak-signal work--including CW. It works on almost any kind of a computer/operating system, the sound card being the only requirement. There are versions that work with DOS, Windows 3.1, 95/98 and NT, and Linux.

Download PSK31SBW 1.08 .........size 178 KB

Download Logger 7.01.................size 1.90 MB

Links

Reccomended PSK31 frequencies:

- The plan for PSK31 activity has always been (since PSK31 started just 3 years ago) to concentrate activity starting from the bottom edge of the IARU RTTY bandplan, expanding upwards as activity increased. The exception is in the 10mts band in order to give non full privileges ham to meet. It was defined as 150 Hz above it. Keep in mind that all you need is about 100 Hz as channel separation.

1838.150
3580.150
7035.150
10140.150
14070.150
18100.150
21080.150
24920.150
28120.150

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PSK 31-A NEW DIGITAL MODE

PSK31 Description

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