Re: ARLA/CLUSTER: Novo software ROS - é possível recuperar sinais a -35dB SNR!
Jorge Capelo
ct2jvh gmail.com
Quarta-Feira, 24 de Fevereiro de 2010 - 18:17:00 WET
Caro Colega João Gonçalves
Já vi o manual sim e este site também.
http://www.southgatearc.org/news/february2010/ros_proving_popular.htm. Até
agora só oiço Olivia nas frequencias que lá indicam. 2.2Khz é um bocado e
não é propriamente um 'narrow band mode'. Mas fiquei curioso só isso. Vou
experimentar um pouco de 'escuta'.
Cordiais 73s
JC.
CT2JVH
Lx.
2010/2/24 João Gonçalves Costa <joao.a.costa ctt.pt>
> Boa Tarde Jorge Capela, CT2JVH.
>
> Efectivamente existe ainda muito a clarificar sVHobre este novo software e
> respectivo modem.
>
> Já tentas-te ler a apresentação e fazer o download do manual:
> http://rosmodem.wordpress.com ..?
>
> Segundo as ultimas declarações do seu autor, o novo software ROS, trabalha
> numa espécie de "técnica áudio de Spread Spectrum..???", para assim não
> violar a regulamentação FCC sobre a matéria em HF. O que criou,
> imediatamente, uma série de duvidas; ler mais em:
> http://forums.qrz.com/showthread.php?p=1869017
>
> Sendo que a técnica de spread spectrum consiste originalmente em codificar
> e modificar o sinal de informação executando o seu espalhamento num espectro
> de radiofrequências, fica-se sem saber muito bem o que é neste caso é uma
> "técnica áudio de Spread Spectrum" .
>
> Assim e na minha opinião e salvo futuros desenvolvimentos, o ROS pertence à
> grande família dos FSKs, neste caso, usando até 144 tons, não me parecendo
> uma nova e revolucionária técnica antes uma evolução.
>
> João Costa, CT1FBF
> ________________________________
>
> De: cluster-bounces radio-amador.net [mailto:
> cluster-bounces radio-amador.net] Em nome de Jorge Capelo
> Enviada: quarta-feira, 24 de Fevereiro de 2010 10:41
> Para: Resumo Noticioso Electrónico ARLA
> Assunto: Re: ARLA/CLUSTER: Novo software ROS - é possível recuperar sinais
> a -35dB SNR!
>
>
> Caro colega João Gonçalves Costa
> c/c Flávio PY2ZX
>
> Não sendo eu entendido em modos digitais, tenho curiosidade e queria
> perguntar-lhe se o ROS usa o protocolo de algum dos modos digitais já
> existentes (entendo que é da família dos FSKs), apenas tendo a capacidade de
> lidar com estas espantosamente baixas relações sinal-ruído ou é um novo
> modo em si mesmo (o modo 'ROS'...). Isto é, se a comunicação só é possível
> entre correspondentes usando o programa ROS, ou será possível por exemplo
> entre o HRD e ROS, por ex.? Cordialmente, obrigado.
> 73.
> Jorge Capelo
> CT2JVH
> Lisboa
>
>
>
> 2010/2/22 João Gonçalves Costa <joao.a.costa ctt.pt>
>
>
> ROS
> Enviado por: "PY2ZX" py2zx.ham gmail.com py2zx
> Dom, 21 de Fev de 2010 3:40 pm
>
>
> Olá pessoal,
>
> Informações na zsvhf e debate no qrz.com sobre o novo software ROS
> que
> trabalha em Spread Spectrum. Segundo o manual é possível recuperar
> um
> sinal a -35 dB SNR!
>
> Flávio PY2ZX
>
> ====================================
> Date: Sun, 21 Feb 2010 12:45:46 +0200
> From: "Derek" <derek fotogravett.com>
> Subject: Re: [ZSVHF] New Digital mode
>
> ROS is a digital communications software based on Spread Spectrum
> techniques. It is designed to fully optimize the power available and
> make contacts in the toughest conditions, for HF, EME or Meteor
> Scatter.
> The software has two Symbol Rates: 16 and 1 baud (the latter aimed
> at
> weak signals until -35 dbs of S/N) and can automatically synchronize
> any
> Symbol Rate. ROS also automatically reply to the operators that
> include
> an email in any of your messages, reporting on the parameters of the
> received signal.
>
> The decoding is done in real time, even in the case of 1 baud, and
> automatically synchronizes in frequency within a range of + -200 Hz.
> So,
> ROS simplifies the work of the operators.
>
> Hardware & Software Requirements
>
> . a SSB transceiver connected to an antenna
> . a computer with WindowsT.
> . 700 MHz or faster CPU and 32 MB of available RAM
> . Monitor with at least 1024 x 768 resolution
> . a 16 bit sound card
> . a serial port radio interface (to use PTT).
>
> Download manuals and software here.
>
> http://rosmodem.wordpress.com/
>
> 73's ZS5Y
> ===================================
>
> Recorded at University of Twente (Netherlands) Web SDR:
> http://websdr.ewi.utwente.nl:8901/
>
> 2205z ROS: PA3FWM, one hour ago has place the first offcial QSO with
> ROS, and it was received at this SDR. Thank you
> 2205z PA3FWM: Ah, I had seen your repeated advertisements for your
> experiment, so it's nice to know that it worked out!
> 2206z ROS: It was a historical moment. It was on 7065 LSB
>
> The First QSO
> 18 February 2010, at 20:56 UTC took place the First Official QSO
> with
> ROS from Vitoria (Spain) to University of Twente (Netherlands)
> covering
> a distance of 1265 Km. on 7.065 Mhz. The first Ham Radio Operator to
> get
> it was EA2LE.
>
> The First Automatic Reply
> ROS notification: EATEST has received your Radio Message
> ********** Please don't reply to this email ********************
> EATEST has received your Radio Message sent at: 21:03 UTC
> Received Message: 'CQ CQ CQ de EA2LE EA2LE EA2LE pse k My email is:
> <ea2le ure.es> <ea2le ure.es> <ea2le ure.es>'
> Operator Info:
> Callsign: EATEST
> Name: Jose Alberto Nieto Ros
> E-mail: nietoros hotmail.com
> QTH: La Aljorra-Cartagena SPAIN
> Locator: IM97lq
> Station: web SDR
> ROS Version: 1.6.1 beta
> Signal Info:
> Symbol Rate: 16 bauds
> Frame Acquisition: 20/20
> Final Acquisition: 15/16
> Frequency Shift: -39,1 Hz
> Symbol Errors detected by Viterbi: 2/50
> Metric: 0 dB
> Vumeter Level: -8 dB
> CPU Usage: 20 %
>
> Download the ROS beta Software and give it a try, sounds cool.
> http://rosmodem.wordpress.com/
> Requires WinRaR or similar Rar unzipper.
> =====
>
> I have pretty good evidence: For starters, if you use the supplied
> WAV
> file on the website (labeled as a test sample of -35 dB S/N), you
> get
> -35dB S/N. This noise has fairly high peaks and some good troughs.
>
> I've been playing with Audacity and playing recording of the mode
> and
> noise at the same time, and I've gotten at least -31dB with fairly
> reliable copy. I used the white noise generator in Audacity, and
> read
> the "Metric" scale in ROS. Audacity's "white noise" is a worse-case
> scenario - absolutely NO nulls or peaks. I would say -31dB in this
> scenario is pretty darn good, considering real-life noise will wax
> and
> wain over time.
>
> -31dB is beyond WSPR mode, and ROS is real-time, whereas WSPR
> requires
> ~2 minutes to decode before you can read it.
>
> KE7HQY
> --------------
> Up on the wide open spaces of VHF it may not be a problem but there
> just
> isn't enough space for digimodes that wide on HF. Fine when it's
> just a
> couple of experimenters using it, but the more who use it where are
> they
> all going to go?
> Julian, G4ILO
> --------------
> That's true if, and only if, the baud (a.k.a. signaling) rate equals
> the
> bit rate. According to Shannon-Hartley, the maximum error-free bit
> rate
> that can be sent on a noisy channel with a bandwidth of 2.2K Hz and
> a
> signal-to-noise ratio of -35dB is 1 bps.
>
> Shannon-Hartley formula...
>
> S/N = 10^(dB/10)
> S/N = 10^(-35/10) ~= 0.000316
> C = 2200 * (log(1 + 0.000316) / log(2)) ~= 1 bps
>
> N3RQ
> =================
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