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DJ1IJ > CLOVER 02.11.95 18:34l 96 Lines 4215 Bytes #-11041 (0) @ WW
BID : 02B517DB0DNI
Read: DL2MEL DF7ML DL5MHK DK2PV DJ1JV DL1RBR DL2DUL DL2MAI DL6MAA GUEST
Subj: No Hal-Clover Chaos!
Path: DB0AAB<DB0KCP<DB0MWS<DB0RBS<DB0LX<DB0SEL<DB0ZDF<DB0SRS<DB0FP<DB0DNI
Sent: 951102/1614z @:DB0DNI.#NDS.DEU.EU [Salzgitter JO52DD TheBox ] $:02B517DB0
de DJ1IJ @ DB0DNI.#NDS.DEU.EU (Hans)
to CLOVER @ WW
The clover tones. A chaos?
Hello!
Recently I found DF7ML's file in a mailbox about the mark and space
tones used by the P38 clover board from HAL. As I understand it more
a question than a statement I want to give the answer.
The P38 clover board has been developed by the radio amateurs at HAL.
It offers those of us who are interested in the new mode a chance to get
a cheap but powerfull HF DSP MODEM for clover AND for amtor, pactor and rtty.
As you surely know the TOR-modes use 2 tones, mark and space. In the US
and other parts of the world the HIGH tones are used while in Europe some of
us prefer the LOW tones.
Here is a list of the tones frequencies , the shift and the (centerfrequency).
HIGH TONES (Hz) LOW TONES (Hz)
Mark Space Shift (Center) Mark Space Shift (Center)
Amtor/ 2125 2295 170 (2210) 1275 1445 170 (1360)
rtty
Pactor 2110 2310 200 (2210) 1260 1460 200 (1360)
It is an agreement that the TOR-modes and rtty use the mark tone to give
the correct frequency where to find a station. I must underline that this agree-
ment was made for practical purposes only and not because of a physical law.
From the physical point of view it would have been the same when we would
use the space frequency or the (Center) of the mark and space frequency to
define the exact location of a station. In fact commercial stations use the center
frequency only because it will not be changed when the shift is changing.
In contrary clover uses 4 tones. For this reason there are NO mark and space
tones . The tones have a distance of 125 Hz and fit in a window of 500 Hz
at - 50 db.
Here are the tones frequencies:
F1 = 2062.5 Hz F(tone pulse #1)
F2 = 2187.5 Hz F(tone pulse #2)
F3 = 2312.5 Hz F(tone pulse #3)
F4 = 2437.5 Hz F(tone pulse #4)
Fc = 2250.0 Hz F(center)
Clover is compared to the TOR modes and rtty a totally different system and
has no relationship to them.
When in clover mode the P 38 board can ONLY be used for clover, having
the filters for the 4 tones and sending 4 tones. When you switch to amtor,
pactor or rtty it is a modem for ONLY these modes, using 2 tones (mark and
space). Under this condition it cannot read or send clover signals.
Maybe it is easier to understand that a P38 clover board contains 2 systems
one for clover and the other for the TOR modes and rtty.
I am often asked which advantages clover offers. Here are some examples:
- Clover uses duplex date transfer. Both stations send data during each
transmission cyclus, no OVER command, no acknowledgement.
- Files transfer is done in the 'background.' As the data transfer is much
faster as one can write most of the time is used for files transfer but the
qso has priority. During a qso files may be transfered in both directions.
- Transfer of text, binary data like exe.files and colour photographs with
different compression methods. Colour photographs can be compressed by
30:1 or even more which means very short transmission times.
- Transfer of sketches (drawings) at real time. For this vector graphics
is used similar to paintbrush.
- During the first contact with a new station small colour pictures of
the operators are exchanged in both directions which appear on the screen
each time you link that station.
- Transfer of voice. You hear your qso partner speaking.
- Radio control (scanning of frequencies.)
- Indication of SNR, phase dispersion and frequency deviation in 1 hz steps
to the other station on the screen.
- Mailbox with (store and foreward).
- Automatic logbook...
If you need more information about clover please contact the radio amateurs
at HAL. Mike, W9KVF or Mark, WB9HFK via FAX (217) 367 1701 or send Andrew
an internet mail. He has the following address: k9cw@prairienet.org
Remember: Christmas will come soon. Your xyl / yl will be happy when you
tell her that there are very fine DSP modems from different makers
now on the market.
73, Fred, DK4ZC
04:14:27 PM Thu Nov 2, 1995 73 Hans in Salzgitter H33
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