Hi Mogens,

Your enthusiasm is intoxicating, but I think you misunderstood David's reply
especially regarding some of the technical aspects of unphased small-dish
receivers.

The Hz within 1.42 GHz refers to the bandwidth in which you are receiving.
Read SETI FAQ.
Every Hz of bandwidth contains kT (Bolzmann constant times system
temperature) Watt of noise power. So to reduce noise SETI@home scans many,
many very narrow bandwidth portions of the spectrum around 1.42 GHz. The
general assumption amount SETI activities is that interstellar radio beacons
will transmit in very narrow bandwidth exactly because wide band
transmissions are easily lost in the noise. Light-year distances, and the
inverse-square law does horrible things with even the strongest signals.

To detect any signal in microwave range over such distances,
you need big antenna's (Arecibo-size),
  and sender and receiver antenna have to point at each other,
  and the sender needs to transmit with TerraWatt (EIRP) power levels,
  and they have to be tuned to the same frequency,
  and they should have matching bandwidth.
If one of these things is not there (for example, small receiver antenna, or
listening to wide bandwidth), then the signal is not detected at all.

So, if there are thousands of small dishes which are all pointing at
different parts of the sky (as you suggest), and there is one ET signal out
there, then only one small dish points at the transmitted signal. And since
it is a small dish, there is a good chance that the signal disappears in the
noise, so we still don't detect anything. You need 1 million big dishes to
detect that signal (larger dishes have a narrow beam, so you need more to
cover the sky).
Or, you need ONE big  phased antenna (which can listen to as many different
directions (beams) simultaneously as its phase-processing computers can
handle). The Allen radio telescope for example. So that is a revolutionary
new development.

Maybe now you see that even though microwave organized SETI has been done
for a decade or so, we still barely scratch the surface. There is so much to
explore still.

To get back to your plan, Arecibo is only listening to one spot in the sky
at one time, and thus it might miss some really loud signal from somewhere
else. So, an immensely strong and short (maybe switched on for a few seconds
only once/week or so) is easily missed by even all the seti searches so far.
If that is true, then your idea (of many small amateur dishes around the
world) might actually detect that signal.... You never know.

Rob

P.S. We really have no idea what kind of information any ETI would send out.
If it's some sequence of numbers or so, pulse-spaced, whatever, we dont
know. We should not anticipate.
But we DO know that is we find a signal (continuous or slowly pulsed) with
bandwidth smaller than 100Hz or so, then it comes from a artificial source
(ETI), since mother nature does not produce such signals. So narrowband is
good for two reasons (less noise, and receiver knows that it is ETI-made).


"Jesus loves you" <John15.13@Heaven> wrote in message
news:qaetc.3717$Vf.142008@news000.worldonline.dk...

"David Woolley" skrev
news:T1085607350@djwhome.demon.co.uk

[ ... ]

and therefore I have NO chance to compare with own downloads from the
Univers (I have NOT make them yet, but I wish to do it)

S@H 1 work units are only suitable for antennas with the same beam width
as Arecibo, although BOINC provides additional parameters to remove
that restriction.  A lot of the frequency resolution will be wasted as
well, as the frequency stability of amateur equipment is one to two
orders of magnitude worse than that for which S@H is optimised; that

will

mean that an awful lot of time will be wasted processing 128K FFTs on
data that might only support 4K FFTs, unless you completely fake the
time scales of the data, in which case you will end up wasting
time processing chirp rates that are unreasonably large, will not be
using the full beamwidth in drift scan mode and will require a much
larger receiver bandwidth.

My thought was this:

Start up looking at a known X-source, and then compare with DATA from
Arecibo and by this find out how good my own system is :-)

Can we get anything important at all ?

In the FUTURE people on Earth will understand, that it is important,

we

use

The SETI League has been doing this for the best part of a decade
(http://www.setileague.org).  ...

I'm GLAD to hear this :-)

... Note that there are still very few active
stations and that is with a lower technical specification than you
are assuming.

I understand. Well - but it's still better that nothing :-)

a lot of small radio-telescopes, so that we can focus on many objects

on

the

Focussing on many objects at the same can also be done using relatively
compact phased arrays, e.g. the Allen telescope.

Sorry - I misunderstand You now!

Do You mean by this, that You do NOT use a parabol but a parabel.

Then the noise-signal will be greather, but - of course - *if* the

ET-signal

is a BIG one, we will get it :-)

What I was talking about, is this:

1. group is watching Galaxic Longitude 0� and Latitude 0� (the Center)
2. group is watching Gal. Lon 1� and Lat 0�
3. group is watching Gal. Lon 359� and Lat 0�
4. group is watching the center of M31
... (and so on) ...

(apropos low noise-signal)

sky at the same time and for a long periode (more than a week, I

think).

That requires steerable antennas.  Most people doing amateur SETI can
only afford, or only live with the neighbours, by using fixed antennas.

Yes, of course, but ...

If You are looking for a long time at the same position, You do not have

to

use more than a parabol on a wheel :-)

Very simple, just a wheel.
(equatorial suspension)

You know ... like a astronomical telescope.

A little step-motor can turn the wheel round, 1 rotation each day.

And then You can watch Your position for a long time :-)

Expensive ?

No, I don't think so. Not if we build a lot of them.

Because you have to do non-coherent averaging of the signal
above about 10 seconds, with a stable receiver and more like above 0.1s,
with an amateur system, and taking into account the relative sizes of

the

antennas, you will need to observe for over a day to match 13 seconds
of Arecibo time.  That means that the first order chirp (second order
Doppler) corrections in the client will be totally inadequate.

I think, I understand You, but ... I think You MISUNDERSTOOD me.

I don't believe, we can expect a signal from Life-2 out there ESPECIALLY

for

us, because the Universe is to big.

Therefore we MUST what untill it is our direction on their

Radio-lighthouse.

(2 weeks maybe)

see ...
0412 news:q%hfa.1884$vn1.497898@news010.worldonline.dk
(use http://www.google.dk/grphp )

In fact, it works out that small antenna SETI is best for short duration
signals, ...

Precisely!

I expect a "download" like this:

(Update 3 from file 0412)
0464 news:Rgzga.948$mI2.172585@news000.worldonline.dk

=== start of quote ===

Update 3:

1 bit/day    =   5104 days = 13,97 years
1 bit/week = 35728 days = 97,82 years

This will take too long time!

Bit-compression:
-----------------

Suggest

bit 1 =   + 001 minute (0h01m00s)
bit 2 =   + 002 minute (0h02m00s)
bit 3 =   + 004 minute (0h04m00s)
bit 4 =   + 008 minute (0h08m00s)
bit 5 =   + 016 minute (0h16m00s)
bit 6 =   + 032 minute (0h32m00s)
bit 7 =   + 064 minute (1h04m00s)
bit 8 =   + 128 minute (2h08m00s)

The result wil then be:
1 byte/day =      638 days =   1,75 years
1 byte/week = 4466 days = 13,97 years

2 years !!! - That's fine - very good !!!

-

By this we will get (which also will help to understand the code):

Input "The Song of the Bride", (5104 bits)

(an time-example):

y=year
d=day
h=hour
m=minute
s=second

START:
Time=0000y000d00h00m00s000 - 0001 inpulse - 0
Time=0000y000d00h00m10s000 - 0002 inpulse - 1
Time=0000y000d00h00m31s416 - 0003 inpulse - Phi (22/7)

Byte            001 (out of 638 bytes)
10000000 =                1 (out of 256 possible, 0-255)
Time=0000y001d00h01m00s000 - 0004 inpulse - 0
Time=0000y001d00h01m10s000 - 0005 inpulse - 1
Time=0000y001d00h01m31s416 - 0006 inpulse - Phi (22/7)

Byte             002
01000000 =                2
Time=0000y002d00h02m00s000 - 0000 inpulse - 0
Time=0000y002d00h02m10s000 - 0000 inpulse - 1
Time=0000y002d00h02m31s416 - 0000 inpulse - Phi (22/7)

Byte            003
11000000 =                3
Time=0000y003d00h03m00s000 - 0000 inpulse - 0
Time=0000y003d00h03m10s000 - 0000 inpulse - 1
Time=0000y003d00h03m31s416 - 0000 inpulse - Phi (22/7)

Byte            004
00100000 =                4
Time=0000y004d00h04m00s000 - 0000 inpulse - 0
Time=0000y004d00h04m10s000 - 0000 inpulse - 1
Time=0000y004d00h04m31s416 - 0000 inpulse - Phi (22/7)

Byte            005
10100000 =                5
Time=0000y005d00h05m00s000 - 0000 inpulse - 0
Time=0000y005d00h05m10s000 - 0000 inpulse - 1
Time=0000y005d00h05m31s416 - 0000 inpulse - Phi (22/7)

Byte            006
01100000 =                6
Time=0000y006d00h06m00s000 - 0000 inpulse - 0
Time=0000y006d00h06m10s000 - 0000 inpulse - 1
Time=0000y006d00h06m31s416 - 0000 inpulse - Phi (22/7)

Byte            007
11100000 =                7
Time=0000y007d00h07m00s000 - 0000 inpulse - 0
Time=0000y007d00h07m10s000 - 0000 inpulse - 1
Time=0000y007d00h07m31s416 - 0000 inpulse - Phi (22/7)

Byte            008
00000000 =                0
Time=0000y008d00h00m00s000 - 0000 inpulse - 0
Time=0000y008d00h00m10s000 - 0000 inpulse - 1
Time=0000y008d00h00m31s416 - 0000 inpulse - Phi (22/7)

(on this position they will be enable to understand the byte-syntax)

=== end of quote ====


Hope You can understand, what I'm talking about, David :-)

It's just a suggest.

If it works, why should Life-2 NOT use it ?

... as long duration signals will stay around to be found by the
much more sensitive large antennas.  The real advantage of small

antennas

is that a small number of them can, together, simultaneously cover the
whole sky, alowing the detection of short duration signals.

May I misunderstood You :-(

Here in Denmark we can NOT see around the Center of our Galaxy, ...

Note that there is a European Radio Astronomy Society (ERAC).

:-)

            more stars, MORE (hypothetic) Life-2.

Using large dishes is the way to get more stars.  The range scales with
diameter and volume with the cube, meaning n times diameter allows you
to search n^3 stars.

You misunderstood me (I think)

I was talking about the "Network"

se ...

(Update 1 and 2 from file 0412)
0452 news:xdega.483$mI2.81521@news000.worldonline.dk

Especially for small dishes, the range limits mean that there is

unlikely

to be much benefit in aiming within the galactic plane.  Any contact
which is far enough out for spherical symmettry to have broken down will
have a very long round trip time.  Most of the benefit that is

associated

with the galactic centre would apply to any direction in the galactic
plane, but even straight out of the plane takes you to over 1000 years
round trip time.

(My english is bad, well it dosn't matter)

Group 1 can watch frequency 1,42000 GHz.
Group 2 can watch frequency 1,42001 GHz

In practice, some people will have receivers that have much wider pass
bands.

On the other hand, there is no evidence that large enough numbers of
people are interested to be able to form multiple groups.

Good :-)

("Hello"-signal time-interval perhaps every 2 weeks)

Small dish SETI is only likely to produce comparable detection rates to
big dish SETI (approximately zero in 20 years).

May I ask You for a request ?

Please read file ...

0412 news:q%hfa.1884$vn1.497898@news010.worldonline.dk

... and then You will understand, why I think 2 week i enougth

(maybe I got it wrong, but ...)

Arecibo:
305m -> 73.062 m^2

The effective diameter is rather less (about 100m for the line feed on
the carriage house and up to 200m for the Gregorian).

Okay.

Antenna signal-minimum:
1*10^-23 Watt / m^2    *    73.062 m^2   =    7,3*10^19 Watt

Depends on detection thresholds and integration time.  Your estimate
is rather pessimistic.  See below.

Little-Radio-reflector:
2m -> 3,14 m^2

Typical amateur SETI is 3 or 4m, ex C-Band TVRO (in the USA).  ERAC

claims

to be able to source dishes in Europe.

:-)

7,3*10^19 Watt    /    3,14 m^2    =    2,3*10^19 Watt/m^2

This is a rather round about way of doing things.  The threshold power,
as described in the FAQ, is kT per Hertz, where the bandwidth for

Arecibo

is about 100 times better than a typical amateur system, and the system
noise
is likely to be less as well.  The SERENDIP system has an overall T of
about 45K.  About 12K of this is extrasterrestial, so irreducible.

You can't use this as the actual threshold, but must multiply it by a
factor to produce an acceptable false positive rate.

Okay (I was just trying to find out, how good it could work).

... That's 8 for Phoenix and 22
for S@H; S@H is larger because of the large number of different

parameters

it tries.

k is 1.38066...E-23 J/K.

So the noise is about 3E-23 W in 0.05Hz.  Using an 8 times threshold
(basically assumes signal is source chirp compensated) it's about

2.4E-22.

Oh - NOW I understand a little about, what You are talking about.

IF the signal is there for 8 times.

So my "plan", see ...

(Update 3 from file 0412)
0464 news:Rgzga.948$mI2.172585@news000.worldonline.dk

... will NOT work in pratice ?

Multiplying by the capture area and using a SERENDIP type 100m radius,
gives about 3E-26 W/m^2 in 0.05Hz.

Such kind of antenna, You use, must be very expensive!

A cheap one (around 200 US $) - how good is it ?
(1*10^10 Watt ?)

The antenna won't make much difference, once you have a big enough
area (1m is probably too small for 1.4GHz as it's only five wavelengths
across).  What matters is the low noise amplifier, ...

Yes, of course :-)

... which should be around
US$100 ...

GLAD to hear this :-)

... to get well within an order of magnitude of the Arecibo figure,
and the stability of the receiver, and most people seem to assume 10Hz
in the short term. ...

Are You talking about a message inside the 1,42 GHz. ?
(fx music of Mozart, or news)

I *expect* no such kind of message.

I will only look after 3 pulse at 1,42 GHx, the "Hello"-signal:

1.
Time = 0 ............ (1. impulse)
Time = 1 ............ (2. impulse)
Time = Phi (22/7) (3. impulse)

Therefore my antenna maybe don't have to be a very good one.
(some in regrad to my computer-program)

I *expect*, that Life-2 will send me a clear message, easy to find :-)

(just "Hello", Here I am, I'm alive, 22/7 can only intelligent life find
out)

Can such kind of signal be received by a simple antenna ?

... Being pessimistic on the noise, the threshold power
will be about 400 times worse, so 1E-19 W in 10 Hz.

You'll need to under illuminate the dish, to avoid looking at the hot
ground, so maybe use 0.5 * pi.   That gives about 6E-20 W/m^2 in 10 Hz.

How much will that give in W/m^2 in 1,42 GHz ?

Can a little radio-telescope be inable to get contact with big-signals

?

(like 1*10^10 Watt ?)

If you are talking about effective isotropic power (EIRP) that is not
big in a SETI context.  Arecibo can do over 1E13 Watts.

I did a mistake!

I should have wrote:

Can a little radio-telescope be inable to get contact with big-signals ?
(like 1*10^-10 Watt ?)
(like 1E-10 W ?)

But I'm glad for this mistake, because now I know that Life-2 can be in

able

to send out for more that 1E13 Watt :-)

A globe in a sun-system like ours (in worst care) have an signal-input at
...

1E13 / (1 AE^2 * Pi) = 1,4E-10 W/m^2

... No, a parabol at only 1 meter is not enougth :-(

...  However, the
answer is that you are many orders of magnitude below the 10 second
integration detection threshold, even from the nearest star, at that
level.  If you go to a four metre dish, ...

Yes, I know, right now :-)

... get the receiver stable to
1 Hz, and average over 200 seconds, you begin to achieve a few 10s of
light year range (see the FAQ for details).

I still don't understand all this talking about Hertz inside the 1,42 GHz.

Do I need to take matter of this in my case ?

If it can, I find it important, that You create a program we all can
understand and use together to synchronization our positions.

Who is you.  Berkeley SSL are probably not even reading the thread, and
they have no mandate to fund your research.  ...

But *You* did it, and thank You for it :-)

... There are a number of
pieces of software, e.g. SETI-Fox, for processing amateur SETI inputs,
available on the web.

Can You give me a web-side ?

[ ... ]

PPS.  I hope all the arithmetic is right!

I hope so :-)

-

Another thing:

There was maybe a "Hello"-signal in 1973 - as far as I know (Discovery
Channal). I came from a position near the Galaxy Center. Do You know the
exactly position ? ... :-)

Thank You very much for Your help.


With kind regards,
Mogens Kall
The servant of Michael

Win (vind) 1000 Danish Kr. (around 140 US $), jump ...
2233 news:Gb3sc.1684$Vf.53534@news000.worldonline.dk

File-number:
2342