archiv~1: Re: SETI Arecibo message to m13

Re: SETI Arecibo message to m13

Alfred A. Aburto Jr. ( (no email) )
Tue, 10 Nov 1998 17:42:04 -0800

There is no way to read in a text file into an email
message. The only option is attachments unfortunately!
I've suggested to NETSCAPE and QUALCOMM to allow
reading text files directly into an email message but
no dice. They want us to use attachments ---

On UNIX for example with the 'pine' email program one
can read text files directly into the body of an email
message. This is nice since one can compose an email
off line then send it off --- no wasted time doing
everything online.

Anyway I thought NETSCAPE would put the text attachment
inline, but I guess it doesn't work with all mail
programs ... sorry about that ...

> David Woolley wrote:
>
> [ Why have you sent an empty message with a text attachment? ]
> > 1's and 0's. Each bit had a duration of 0.1 seconds. It is
> > not clear what the bandwidth of the signal was unfortunately,
>
> That would depend on whether the pulses were shaped for optimimum
> bandwith or just keyed on and off with (relatively) fast rise and
> fall times. I'd have to check the text book, but the first ought
> to put nearly everything into about +- 7.5Hz and the latter
> would generate a signal with significant power to several 10s
> of Hz and a theoretically infinite bandwidth.
>
> > but an FFT of 0.1 seconds indicates a binwidth of 10Hz. It
>
> That could be the worst possible bin width for this signal in search
> mode, as the sidebands wouldn't show up at all if you were in phase with
> the modulation (FFTs and DFTs in general do have some artefacts due to
> their finite nature). It would be the optimimum width for recovering
> the modulation, but you couldn't use any integration, and you would have
> to synchronise the start of the FFT with the start of the bits.
>
> > The 2.8 minute message was only transmitted once. Averaging
> > longer than 2.8 minutes would be counter productive as it
> > would degrade the SNR.
>
> Just for clarification, we are talking here from a hindsight point of
> view as far as the receiver is concerned. 2.8 m is rather a short
> integration time for a general search.

Perhaps. Myself, I'd go with the FFT time span and avoid averaging
altogether. Well, I'd overlap the FFT's maybe 50% at most.

Al