is a MFSK mode designed for blind or partially sighted Hams and SWL's,
derived from Olivia, so it is robust. The minimum ratio Signal-to-Noise
ratio is about - 14.5 dB which makes it very sensitive. The tuning is
tolerant (+/- 157 Hz). It is designed for a 500 Hz CW filter. All
received characters can be pronounced.
This mode is included into the software MULTIPSK by Patrick F6CTE, there is the description of this mode as well as the specifications coming from his software :
Creator : Patrick Lindecker (F6CTE) in 2006
Click on the copy of the screen in order to
listen to the corresponding audio signal.
Baud rate : 21
Speed : about 2 characters/sec so 20 wpm
FSK 8 tones (3 bits arranged in a Gray form), with a shift between
tones of 21 Hz (168 Hz bandwidth). A block is composed of 32 symbols of
3 bits (in other words it is a matrix of 32 columns (following the
time) on 3 lines). Each of the 3 block lines of this block corresponds
to a character which has been encoded, on a 32 bits vector, using a
Walsh-Hadamard transform to provide a high level of redundancy.
implicite used matrix is 64x32 dimension, the 32 first lines are the 32
standard orthogonal combinations of the Hadamard matrix. The 32 next
lines are their opposite. So any couple of lines are either orthogonal
(scalar product=0) or biorthogonal (scalar product<0).
Reception mode : sensible to the side (USB or LSB), USB is recommended
Shape of pulse : specific shape (between a Hanning window and a rectangular window)
Character set : ASCII 6 bits (64 characters) but only 61 are usable.
Bandwidth : 168 Hz
Synchronization : automatic using the signal
Correction code : no
Convolution code : no
Interleaving : yes, spreading of 3 bits "vertically" in the block,
Scrambling : yes, with a 32 bits sequence applied on each line of the block but with a delay of 13 bits between two successive lines.
Drift tolerance : 10 Hz/mn (depending on signal the signal-to-noise ratio)
Pmean/Ppeak : 0.76
Lowest S/N : – 14.5 dB
Repetition of characters
This mode being done for blind or partially sighted Hams or
SWL's, all received characters can be repeated. So a received character
will be displayed on the screen and it could be, in the same time,
repeated in an audible way.
To take profit of this function, the output plug of the sound card must
be connected to an amplified speaker in parallel to the transceiver
Important: as the amplified speaker is going to be also active during
transmission, not to collapse the output signal, the ideal would be to
use the sound card "Speaker" output instead of the "Line out" output.
If your sound card does not have this type of low impedance output, it
must be checked that the sound card output can supports the amplificed
speaker and the transceiver input, by looking, on a voltmeter, at the
signal delivered by the sound card, which must not fluctuate. If it
fluctuates, the only solution is to do an interface to "open" the
circuit to the amplified speaker when the program is Txing (see the
second example in the RS232_EN.DOC file, but replacing the relay on the
diagram by an inverted relay, so as to open when Txing). Furthermore,
this interface will avoid to hear the modulation when TXing.
Any AF frequency (200 to 4000 Hz) must be able to be used.
However, it is considered a standard central AF frequency of 1000 Hz
for this mode, to simplify tuning. Furthermore, the "Freq. search"
function permits to localize any Voice transmission in a 480 Hz band.
So the ideal would be to set ON the XCVR 500 Hz CW filter and to tune
the HF frequency on the XCVR instead of tuning the AF frequency on the
Note: this mode is directly derived from the 8 tones, 62.5 bauds Olivia
mode (Pawel Jalocha SP9VRC) but with a 32 bits vector instead of a 64
bits vector, a different set of characters and a different speed.
this mode is directly derived from the 8 tones, 62.5 bauds Olivia mode
(Pawel Jalocha SP9VRC) but with a 32 bits vector instead of a 64 bits
vector, a different set of characters and a different speed.