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.