ARLA/CLUSTER: O IMPRESSIONANTE modo JT9 consegue descodificar sinais a -40dB.

[João Gonçalves Costa]

Boas Renato,

Tu até sabes em relação a quê, quanto tu próprio seguidamente fazes a pergunta que contem a resposta.

Talvez não saibas é que filosoficamente chama-se a isso dialética erística, hihihihi.


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De: cluster-bounces  radio-amador.net [mailto:cluster-bounces  radio-amador.net] Em nome de Renato Encarnação
Enviada: quinta-feira, 22 de Novembro de 2012 09:03
Para: Resumo Noticioso ARLA/CLUSTER
Assunto: Re: ARLA/CLUSTER: O IMPRESSIONANTE modo JT9 consegue descodificar sinais a -40dB.

Boas João

Esse novo modo descodifica sinais de -40dB em relação a que?

-40dBm certamente não será, pois isso é um sinalão.

Não estarão a referir-se à relação sinal-ruido??

Adiante lá.

73, Renato
2012/11/21 João Costa > CT1FBF <ct1fbf  gmail.com>
New Mode for MF and LF

If you are on 160 meters, or perhaps on 472 or 137 kHz, you may be
interested in a new mode called JT9, designed especially for making
QSOs on these bands. JT9 uses the structured messages introduced in
2003 for the JT65 mode, now widely used for EME and for QRP operations
at HF.

JT9 can operate at signal levels as low as -27 dB (in a 2500 Hz
reference bandwidth), with one-minute timed transmissions. It also
offers slower transmissions of 2, 5, 10 and 30 minutes duration, and
the slowest mode can decode signals as weak as -40 dB. With one-minute
transmissions, submode JT9-1 has a total bandwidth of 15.6 Hz -- less
than one-tenth the bandwidth of a JT65A signal. The other submodes are
narrower still: a JT9-30 signal occupies about 0.4 Hz total bandwidth.

JT9 is implemented in an experimental version of WSJT called WSJT-X.
Some further details can be found at
 http://www.physics.princeton.edu/pulsar/K1JT/WSJT-X_Quick_Start_Guide.pdf ,
 and an early version of WSJT-X can be downloaded from
 http://physics.princeton.edu/pulsar/K1JT/WSJTX_01r2695.exe .

If you want to try JT9, I suggest using dial frequency 1838, which is
also used for JT65A, PSK31, and MFSK. In default configuration WSJT-X
allows transmission and reception 1 to 2 kHz above the dial frequency.

Please note: WSJT-X is in an early development stage. Your feedback
(direct email to me is best) will be much appreciated. And feel free
to email me for a sked!

-- 73, Joe, K1JT


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