MultiPSK 4.15 is uit
Er is een nieuwe versie van het populaire data mode programma MULTIPSK gereleased met als extra mogelijkheid MIL-STD-188-110A, ook wel bekend als STANAG 4539 of FED-STD-1052.
Patrick F6CTE schrijft daarover (en ik geef het maar even onvertaald weer vanwege de vele technische termen):
Hello to all Ham and SWL,
The new release of MultiPSK (4.15) is on my Web site (http://f6cte.free.fr).
The main mirror site is Earl's, N8KBR:
http://www.eqth.info/multipsk/index.html (click on "United States Download Site").
Another mirror site isTerry's:
Multispk associated to Clock are freeware programs but with functions submitted to a licence (by user key).
The main modifications of MULTIPSK 4.15 are the following:
1) Decoding of the MIL-STD-188-110A ("110A") + 110A beacon. This mode (MIL-STD-188-110A/B) is named also FED-STD-1052 or STANAG 4539. It is used mainly by professionals (the text being mostly encrypted) but also, rarely, by Hams.
The 75 bps sub-mode in TX (beacon) is proposed by Multipsk.
Several sub modes (75 to 4800 bps) and two different interleaving (short and long) are proposed. All modes are fixed frequency, except a 75 bps (bits per second) sub-mode which is transmitted in "frequency hopping". It is not decoded in this soft.
The receiver should be in USB mode. The bandwidth must extend from 300 to 3300 Hz (at -30 dB) with a relatively flat frequency response between 600 and 3000 Hz. The central frequency is, in this case, equal to 1800Hz. It can be selected a 1500 Hz central frequency for Ham receivers.
The soft automatically decodes the speed (75, 150, 600, 1200, 2400 or 4800 bps) and the interleaver (short or long), in different character formats.
The radio-amateur frequency proposed for this mode is 14104 KHz (adjusted on the transceiver).
Important: in USA, 110A text transmission is forbidden. PSE, check if it is allowed in your country.
This mode is available for licencied copies, only (otherwise, the decoding is stopped after 5 minutes). However the 75 bps sub-mode in format 8N1 (RX/TX) is free.
See specifications further on.
2) RS ID, Call ID (Prop ID)
These identifiers are now permanently monitored in background, by default (the CPU load being weak). The management of these identifiers has been improved.
For Call ID and "Prop ID" ("Propagation ID"), it is proposed four frequencies bandwiths for transmission and monitoring.
3590, 7040, 10148, 14075 KHz (to adjust on the transceiver).
All the minimum AF band, i.e. from 200 Hz to 2500 Hz can be used. These frequencies can be favourably scaned ("Transceiver" button).
3) Improvements of
– the SdR mode and frequency management,
– the ARQ FAE mode (in ALE or ALE400),
– the JT65, GMDSS and SELCAL modes.
Baud rate: 2400.
Modulation: 8PSK (not differential, the exact phase being determined through known data) with a central frequency of 1800 Hz
Reception mode: USB
Character set: different synchronous or asynchronous formats are proposed (5 ITA2, 7 bits ASCII or 8 bits (ASCII+ANSI))
Shape of pulse: raised cosine
Bandwidth: about 3 KHz (300 to 3300 Hz)
Synchronization: automatic using the known data
Convolution code: except in 4800 bps, yes. The constraint lenght is equal to 7 bits,
Interleaving: except in 4800 bps, yes. Two interleavings are proposed: short or long. However, it is expected the possibility not to use interleaving.
Pmean/Ppeak: about 0.76 (specific to Multipsk in TX) Lowest S/N (on Multipsk): + 4 dB in 75 bps mode (first decodings at +1.5 dB) and + 10 dB in 2400 bps (the signal to noise ratio must be, in general, very good, to be able to decode this mode, i.e "excellent" at 2400 bps and "good" at 75 bps).
Each frame contains a synchronization preamble phase where the sub-mode is defined, a data phase where the unknown data is transmitted (mixed with known data to follow the transmission characteristics) , an "End of Message" ("EOM") phase and a final flushing phase (to finish de-interleaving and de-convolution operations).
An adaptative equalization is required at this speed (2400 bauds).