Our good friend Patrick Lindecker, has released a new version of his popular digital decoding software Multipsk. If you aren't familiar with this package, it is one of the best around. Many of the modes it handles are free in the basic version. For a low one time free you can add many more. It is the software package we use here on the radio ranch.
New release of MULTIPSK (4.40) - DSTAR
Pour les francophones: la
version en français de ce message se trouve sur mon site (http://f6cte.free.fr). Il suffit de cliquer sur
le lien "Principales modifications (courriel avertissant de la sortie de la
nouvelle version)".
Hello to all Ham and SWL,
The
new release of MultiPSK (4.40) is on my Web site (http://f6cte.free.fr/index_anglais.htm).
The
mirror site is Earl's, N8KBR: https://www.paazig.net/f6cte/MULTIPSK_setup.exe
The
MD5 signature of the downloaded MULTIPSK_setup.exe file to, possibly, check
(with WinMD5 for example), that the downloading works without error, is equal
to: 8c9e9cb83148cb228d949e74a263cfe8
Multipsk associated to Clock are
freeware programs but with functions submitted to a licence (by user
key).
The main improvements of MULTIPSK 4.40 are the
following: DSTAR decoding/transmission
"DSTAR" is
the acronym for "Digital Smart Technologies for Amateur Radio". This mode has
been developed by the Ham Japanese association (JARL). It is used in VHF and
in UHF, mainly for voice communication but also for data communication
(included during voice transmissions). It is spread in a world net by using,
among other means, repeaters and Internet. It is a mode for amateurs but
professionally developed, at equipment level. It is considered as a
professional mode for Multipsk (but the decoding is not
limited).
There are two sub-modes:
· the "DV" one (Voice + data) at 4800 bauds for communications between Hams and
between Hams and DSTAR repeaters,
· the "DD" one
(Data only ) at 128000 bauds for communications between DSTAR net pieces of
equipment.
Only the "DV" sub-mode is here considered and only the
data communication. So it is excluded the voice communication decoding which
needs an AMBE Codec (under a proprietary licence).
For Hams
and SWL, the DSTAR signal can be received:
· either
from the discriminator output of a classical VHF/UHF FM receiver via a direct
connection to the PC sound card. However, the receiver must have a large
reception bandwidth due to the high
modulation
speed, or with a SdR receiver (FunCube Dongle, RTL
SDR,..) and directly demodulated by Multipsk. It is the simplest
solution.
Here is the WEB address where you can know where all
DSTAR repeaters are located, with their frequencies, for each country (so as
to monitor one or more): http://www.dstarusers.org/repeaters.php
In
transmission, the following functions are compatible with the
ICOM transceivers:
· transmission of 20 characters
maximum messages, beacon,
· "parrot" (repeats valid DSTAR frames,
without any processing).
A small interface is proposed. See
the paper: "HOW_TO_DO_DIRECT_DSTAR_BETWEEN_HAMs_Rev_A.pdf" paper located
in the
http://f6cte.free.fr/DSTAR.ZIP
file.
This mode is in freeware, so without time
limitation.
See general specifications further
on.
Other modifications
· For
the users having a Multipsk licence, by clicking on the "Mode" button, it
will be found the new option "Modes selection" which goal is to select the
sole modes really used by the user. The panels
of modes (amateur and
professional) will, hence, propose a choice among the
sole selected
modes. Note that at each new Multipsk version, the selection panel will
display again with all the modes.
Note about translation of
Multipsk.exe and Clock .exe: the 4.39.4 version of Multipsk has been
translated to Spanish by Joachin (EA4ZB), from French.
See: http://f6cte.free.fr/Translation_files.htm.
73
Patrick
Description
of the DSTAR mode
There are two
sub-modes:
· the "DV" one (Voice + data) at 4800
bauds for communications between Hams and between Hams and DSTAR
repeaters,
· the "DD" one (Data only ) at 128000
bauds for communications between DSTAR net pieces of equipement.
Only
the "DV" sub-mode is here considered and only the data communication. So it
is excluded the voice communication decoding which needs an AMBE Codec (under
a proprietary licence).
Description :
Baud rate:
4800
Modulation : the NRZ logic signal (1/-1) directly modulates,
through a GMSK filter (to reduce the bandwidth needed), the VHF or UHF
frequency in FM (on about +/- 3 KHz). So this signal is received in base band
after FM demodulation.
Reception mode:
FM
Character set : on 8 bits (but only ASCII is
used)
Shape of pulse : GMSK (BT
product=0.5)
Bandwidth : about 6
KHz
Synchronization : automatic using the
signal
Detection code: yes on 15 bits.
Convolution
code: FEC R=1/2, k=3 on the header
Interleaving : yes on the
header
Scrambling: yes
Each DV DSTAR frame
contains:
· a 64 bits minimum training sequence
for synchronization,
· a sequence of 15 bits for
the frame detection,
· a header of 660 bits
containing different control pieces of information and 4 call
signs.
· a certain number of pair of 96 bits, each
pair containing either a "Voice slot" (72 bits) + a "data slot" (24 bits) or
a "Voice slot" + a synchronization flag,
· an end
frame flag.
For more details, see at the Internet address: https://www.jarl.com/d-star/shogen.pdf
Multipsk
transmission of messages compatible with the ICOM 20
characters messages
In addition, the DSTAR transceivers (mainly ICOM)
can transmit and receive a 20 characters message. It appears that these
messages are transmitted in "clear text" after a scrambling of each data slot
(24 bits). The packeting is simple but remains proprietary (so it is not
described).
Multipsk permits the transmission of such small
messages according to a protocol described in the document "Multipsk
specifications relative to the DSTAR DV mode rev. A.pdf" located in the http://f6cte.free.fr/DSTAR.ZIP file.
