RE: [multipsk] Re: Difference between ais and gmdss ?


Nov 11, 2012

 


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#15481 Nov 11, 2012

Hi all



I tried to understand the differnce between this 2 modes . I leave near Toulon on med seanand i can hear both vhf and hf ...but on gmdss frequency i havnt hear anything and in ais vhf freq same .

Question does multipsk can decode ais sig ? And on what freq hear gmdss ? Does the sound is same like rtty ? Navtex ?



Thank for infos



73 eric



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#15484 Nov 11, 2012

Hello Eric,



I'm on the AIS decoding (among other things). I will propose a test version

before the end of the year.



AIS frequencies: 161.9275 and 162.025 MHz. There is a lot of traffic (in

Rouen harbor for example). It is similar to Packet 9600 bauds GMSK (sounds

as noise).

>And on what freq hear gmdss ?

Click on the "QRG" button. In HF, yes it sounds as AMTOR or ASCII.



Baud rate : 100 in MF/HF and 1200 in VHF. A character is composed of 10

bits, which allows to easily detect an error as the minimum number of bits

is 7 (the bits 8, 9 and 10 are parity bits).



Modulation : FSK two tones ("mark" and "space", "mark" high) with a shift

between tones of 170 Hz in MF/HF and 800 Hz in VHF (1300/2100 Hz)



73

Patrick



-----Message d'origine-----

De.: multipsk@yahoogroups.com [mailto:multipsk@yahoogroups.com] De la part

de eric

Envoy..: dimanche 11 novembre 2012 21:40

..: multipsk@yahoogroups.com

Objet.: [multipsk] Difference between ais and gmdss ?



Hi all



I tried to understand the differnce between this 2 modes . I leave near

Toulon on med seanand i can hear both vhf and hf ...but on gmdss frequency i

havnt hear anything and in ais vhf freq same .

Question does multipsk can decode ais sig ? And on what freq hear gmdss ?

Does the sound is same like rtty ? Navtex ?



Thank for infos



73 eric







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Yahoo! Groups Links



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#15492 Nov 12, 2012

Thank patrick for the quick answer..ok for ais ..does we will can use output speaker or 9600 to take signal?

For gmdss i tried in vhf , no signal same in hf i try again on 8414 to test this mode.

Thank fer infos.



73 eric



Envoy. de mon iPad



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#15494 Nov 12, 2012

It can be confusing.Infact.GMDSS (Global Maritime Distress and Safety System) is not a system itself, it refers to a number of different maritime safety broadcast systems, which includes AIS (HF and VHF) and Navtex etc.en.wikipedia.org/wiki/Global_Maritime_Distress_Safety_System.

.On 12 November 2012 12:04, f1smv.eric f1smv.eric@...> wrote:.Thank patrick for the quick answer..ok for ais ..does we will can use output speaker or 9600 to take signal? For gmdss i tried in vhf , no signal same in hf i try again on 8414 to test this mode.Thank fer infos.

73 eric

Envoy. de mon iPad



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#15510 Nov 12, 2012

Ah ok thank derek for url and more infos

73 eric



Envoy. de mon iPad



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#15511 Nov 12, 2012

Hello Eric,



If really you don't success in decoding HF GMDSS, I will put a GMDSS WAV recording on the site so as you see how it sounds and how to decode it.



73

Patrick



-----Message d'origine-----

De : multipsk@yahoogroups.com [mailto:multipsk@yahoogroups.com] De la part de f1smv.eric

Envoy. : lundi 12 novembre 2012 19:23

. : multipsk@yahoogroups.com

Objet : [multipsk] Re: Difference between ais and gmdss ?





Ah ok thank derek for url and more infos

73 eric



Envoy. de mon iPad



---------------



Yahoo! Groups Links



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#15512 Nov 12, 2012

Eric,



For AIS, you will have the possibility either to decode the base band or to demodulate (FM) the I/Q signal (from a Fun Dongle or any low cost dongle) and decode it through the SdR Multipsk feature.



73

Patrick



-----Message d'origine-----

De : multipsk@yahoogroups.com [mailto:multipsk@yahoogroups.com] De la part de f1smv.eric

Envoy. : lundi 12 novembre 2012 13:04

. : multipsk@yahoogroups.com

Objet : [multipsk] Re: Difference between ais and gmdss ?



Thank patrick for the quick answer..ok for ais ..does we will can use output speaker or 9600 to take signal?

For gmdss i tried in vhf , no signal same in hf i try again on 8414 to test this mode.

Thank fer infos.



73 eric



Envoy. de mon iPad



---------------



Yahoo! Groups Links



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#15515 Nov 12, 2012

Hi the group



Thank Patrick its a good idea. I taked yesterday for the first time msgs on vhf in gmdss on canal 70 -4 msgs- in the afternoon , without any interest...hi , i checked msi number on site seems unknow..stealth boat ? Hi



73 eric







Envoy. de mon iPad



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#15518 Nov 13, 2012

Hello Eric,



Here is a GMDSS WAV file (GMDSS_dsc_27.WAV). Click on the waterfall at about 790 Hz. The decoding will give you a position. Try to extract information about the ship pushing "Auto ITU".



Note: you can read the file directly from the Configuration screen by selecting this file in the "Decoding:..." panel and ticking "Sound file" ("Carte son").



73

Patrick



-----Message d'origine-----

De : multipsk@yahoogroups.com [mailto:multipsk@yahoogroups.com] De la part de f1smv.eric

Envoy. : mardi 13 novembre 2012 07:44

. : multipsk@yahoogroups.com

Objet : [multipsk] Re: Difference between ais and gmdss ?



Hi the group



Thank Patrick its a good idea. I taked yesterday for the first time msgs on vhf in gmdss on canal 70 -4 msgs- in the afternoon , without any interest...hi , i checked msi number on site seems unknow..stealth boat ? Hi



73 eric







Envoy. de mon iPad



---------------



Yahoo! Groups Links







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#15526 Nov 14, 2012

Hello Patrick

sorry but i dont understand where is the file you sended me , on the yahoo group i searched but nothing ...

73 Eric



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#15528 Nov 15, 2012

Hello Eric ,  It was attached to my message. However, I just add it to the Files section of the Multipsk Yahoo group. See GMDSS .WAV sound file for test (on 790 Hz)  73Patrick  De : multipsk@yahoogroups.com [mailto:multipsk@yahoogroups.com] De la part de Eric CohenEnvoy. : jeudi 15 novembre 2012 06:58. : multipsk@yahoogroups.comObjet : [multipsk] Re: Difference between ais and gmdss ?


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