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Space Forum / SETI / May 2004Request to SETI - Was: Thank You From SETI
"Seti Cruncher" skrev news:eausc.6932$J02.3841@edtnps84 > Today May 24th, I received a thank you letter from SETI@HOME that was > obviously sent out in mass to all users. > > It was nice after 4 years of crunching to get some acknowledgement and > thanks from SETI for our time and expense. We do it for the science but a > small thanks every now and then is always nice, > > Thank you SETI for acknowledging our effort. On óne point I have a REQUEST: ---------------------------------- (I'm sorry - My english is very bad) I don't understand Your DATA i file *work_unit.sah* 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) In the FUTURE people on Earth will understand, that it is important, we use a lot of small radio-telescopes, so that we can focus on many objects on the sky at the same time and for a long periode (more than a week, I think). Here in Denmark we can NOT see around the Center of our Galaxy, ... more stars, MORE (hypothetic) Life-2. ... but people in the tropics can do it for some hours of a day. By working together we, the Mankind, will be in able to watch the Center for a long time. Group 1 can watch frequency 1,42000 GHz. Group 2 can watch frequency 1,42001 GHz Group 3 can watch frequency 1,41999 GHz ... (and so on) Then - MAYBE - we will be in able to get a signal from E.T. ("Hello"-signal time-interval perhaps every 2 weeks) Input facts (?): Arecibo: 305m -> 73.062 m^2 Antenna signal-minimum: 1*10^-23 Watt / m^2 * 73.062 m^2 = 7,3*10^19 Watt Is this correct ? Little-Radio-reflector: 2m -> 3,14 m^2 7,3*10^19 Watt / 3,14 m^2 = 2,3*10^19 Watt/m^2 Such kind of antenna, You use, must be very expensive! A cheap one (around 200 US $) - how good is it ? (1*10^10 Watt ?) Can a little radio-telescope be inable to get contact with big-signals ? (like 1*10^10 Watt ?) If it can, I find it important, that You create a program we all can understand and use together to synchronization our positions. - For more informations, download and read file 0412 and it's links: Name: Kall, Mogens Date: 23. marts 2003 CET 14:45 Newsgroup: se.vetenskap.astronomi Subject: SETI: Open letter to Dr. David P. Anderson, Project Director - suggest (0371) 0412 news:q%hfa.1884$vn1.497898@news010.worldonline.dk (use http://www.google.dk/grphp ) - 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 Last-Informationfile: ( use http://www.google.dk/grphp ) 1662 news:sbX3c.108512$jf4.6509896@news000.worldonline.dk 2254 news:eAjsc.1939$Vf.82865@news000.worldonline.dk File-number: 2306 This file has been sent to alt.sci.seti se.vetenskap.astronomi SETI > I don't understand Your DATA i file *work_unit.sah* from work_unit.sah header subband_sample_rate=9765.62 nsamples=1048576 The data is BASE64 encoded, undo that and you have 256K of raw data or so, which means 2 bits per sample. 1 bit re, 1 bit img, judging by the samplerate. Much fun can be had guessing the bit order and such, even more fun finding out what S@H client thinks about Britney Spears. Do not try this without disabling the client from communicating with S@H. > > I don't understand Your DATA i file *work_unit.sah* > [quoted text clipped - 8 lines] > fun finding out what S@H client thinks about Britney Spears. Do not try > this without disabling the client from communicating with S@H. Thank you for your responce. I'm very bad in english (I'm danish), so it will take me some time to understand, what you have been written. I will be back :-) No! - I will try a little. I have an example: === start of quote === type=work unit task=seti version=262 name=26fe03aa.4223.10209.865918.142 end_header data_type=encoded data_class=0 splitter_version=0x0012 start_ra=26.460 start_dec= -0.78 end_ra=26.489 end_dec= -0.78 angle_range= 0.449 time_recorded= 2452697.36325 (Wed Feb 26 20:43:04 2003) subband_center=1418890991.21 subband_base=1418886718.75 subband_sample_rate=9765.62 fft_len=2048 ifft_len=8 subband_number=142 receiver=ao1420 nsamples=1048576 tape_version= 1.40 num_positions=23 coord0= 2452697.36319 26.459 -0.78 coord1= 2452697.36325 26.460 -0.78 coord2= 2452697.36331 26.461 -0.78 coord3= 2452697.36337 26.463 -0.78 coord4= 2452697.36343 26.464 -0.78 coord5= 2452697.36348 26.466 -0.78 coord6= 2452697.36354 26.467 -0.78 coord7= 2452697.36360 26.468 -0.78 coord8= 2452697.36366 26.470 -0.78 coord9= 2452697.36372 26.471 -0.78 coord10= 2452697.36377 26.473 -0.78 coord11= 2452697.36383 26.474 -0.78 coord12= 2452697.36389 26.475 -0.78 coord13= 2452697.36395 26.477 -0.78 coord14= 2452697.36400 26.478 -0.78 coord15= 2452697.36406 26.480 -0.78 coord16= 2452697.36412 26.481 -0.78 coord17= 2452697.36418 26.482 -0.78 coord18= 2452697.36424 26.484 -0.78 coord19= 2452697.36429 26.485 -0.78 coord20= 2452697.36435 26.487 -0.78 coord21= 2452697.36441 26.488 -0.78 coord22= 2452697.36447 26.489 -0.78 end_seti_header N5H!HDVXIS"$A"EOK ... === end of quote ==== As far as I understand ... "N5H!HDVXIS"$A"EOK" ... is the beginning of the DATA-string. no Hex Dec Bin ASCII 01 4E 078 01001110 N 02 35 053 00110101 5 03 48 072 01001000 H 04 21 033 00100001 ! 05 48 072 01001000 H 06 44 068 01000100 D 07 56 086 01010110 V 08 58 088 01011000 X 09 49 073 01001001 I 10 53 083 01010011 S 11 22 034 00100010 " 12 24 036 00100100 $ 13 41 065 01000001 A 14 22 034 00100010 " 15 45 069 01000101 E 16 4F 079 01001111 O 17 4B 075 01001011 K Can You explain it for me (in simple english) ? (do you need more DATA ?) - Another thing: Are you in able to crack the code, se ... 2233 news:Gb3sc.1684$Vf.53534@news000.worldonline.dk english version ... 2305 news:Z5vsc.2233$Vf.98365@news000.worldonline.dk (You can win around 140 US $, if You are the first one) With kind regards, Mogens Kall The servant of Michael File-number: 2337 [ sci.astro.seti added, as that is a more appropriate newsgroup for a posting with a science content. ] > Subject: Request to SETI - Was: Thank You From SETI You are addressing this to the wrong place, as there is no such organisation as SETI (SETI is a process done by many organisations) and Berkeley Space Sciences don't often read these newsgroups (they are more likely to read sci.astro.seti, but even then don't often contribute). > I don't understand Your DATA i file *work_unit.sah* You are not particularly supposed to, although they havn't taken any steps to obfuscate it. They don't want people doing their own analysis and either making a mistake in the analysis process and making false claims of a detection, or even making a real detection and getting to the press before them (the former being much more likely). However, the parameter part is fairly obvious and the uuencode type level of the encoding can easily be stripped. It is clear from the parameters that the data is a sequence of complex numbers containing only the sign bit for each of the real and imaginary parts; that part can easily be resolved by a few experiments to determine the sequence of the data and how it is interleaved. There is one other subtlety in that the splitting calculations roll the spectrum, but people have solved that one as well by trying test data. > 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. > 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). Note that there are still very few active stations and that is with a lower technical specification than you are assuming. > 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. > 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. 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. In fact, it works out that small antenna SETI is best for short duration signals, 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. > 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. 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. > 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. > ("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). > 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). > 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. 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. 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, which should be around US$100 to get well within an order of magnitude of the Arecibo figure, and the stability of the receiver, and most people seem to assume 10Hz in the short term. Being pessimistic on the noise, the threshold power will be about 400 times worse, so 1E-19 W in 10 Hz. You'll need to under illuminate the dish, to avoid looking at the hot ground, so maybe use 0.5 * pi. That gives about 6E-20 W/m^2 in 10 Hz. > Can a little radio-telescope be inable to get contact with big-signals ? > (like 1*10^10 Watt ?) If you are talking about effective isotropic power (EIRP) that is not big in a SETI context. Arecibo can do over 1E13 Watts. However, the answer is that you are many orders of magnitude below the 10 second integration detection threshold, even from the nearest star, at that level. If you go to a four metre dish, get the receiver stable to 1 Hz, and average over 200 seconds, you begin to achieve a few 10s of light year range (see the FAQ for details). > If it can, I find it important, that You create a program we all can > understand and use together to synchronization our positions. Who is you. Berkeley SSL are probably not even reading the thread, and they have no mandate to fund your research. There are a number of pieces of software, e.g. SETI-Fox, for processing amateur SETI inputs, available on the web. > The servant of Michael Drop this and your From line name, as they devalue your contribution. PS. You have a broken newsreader. You have posted this as a followup, but it doesn't have a References header. PPS. I hope all the arithmetic is right! > [ sci.astro.seti added, as that is a more appropriate newsgroup for a > posting with a science content. ] [quoted text clipped - 187 lines] > > PPS. I hope all the arithmetic is right! Thank you for your responce. I'm very bad in english (I'm danish), so it will take me a long time to understand, what you have been written. I will be back :-) - Another thing: Are you in able to crack the code, se ... 2233 news:Gb3sc.1684$Vf.53534@news000.worldonline.dk english version ... 2305 news:Z5vsc.2233$Vf.98365@news000.worldonline.dk (You can win around 140 US $, if You are the first one) With kind regards, Mogens Kall The servant of Michael File-number: 2338 [ ... ] > > I don't understand Your DATA i file *work_unit.sah* > [quoted text clipped - 3 lines] > false claims of a detection, or even making a real detection and > getting to the press before them (the former being much more likely). I understand :-) That's crazy! 2 brains can think MORE smart than just óne, and what about 6.000 millions ? > However, the parameter part is fairly obvious and the uuencode type level > of the encoding can easily be stripped. ... :-) > ... It is clear from the parameters > that the data is a sequence of complex numbers containing ... What do You exactly mean by this ? - Which kind of parameters ? Are You talk'ing about the fictiv Ra and Dec ? (example: 40 hr ... 28 deg ) > ... only the sign > bit for each of the real and imaginary parts; ... Does this means, that the amplitude (the level) still is there ? > ... that part can easily be > resolved by a few experiments to determine the sequence of the data and > how it is interleaved. Can You explain this for me ? I have a lille DATA-string here, downloaded from SETI, see ... 2337 news:Chatc.3706$Vf.140315@news000.worldonline.dk (use Courier New to read) === start of quote === ... coord22= 2452697.36447 26.489 -0.78 end_seti_header 530 65 72 0A 4E 35 48 21 48 44 56 58 49 53 22 24 41 er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end of quote ==== > ... There is one other subtlety in that the splitting > calculations roll the spectrum, ... Do You means by this, that SETI have encrypt the DATA ? > ... but people have solved that one as well > by trying test data. :-) I splitt up You message here. 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: 2341 [ ... ] > > 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) [quoted text clipped - 10 lines] > 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$mI2.81521@news000.worldonline.dk > Especially for small dishes, the range limits mean that there is unlikely > to be much benefit in aiming within the galactic plane. Any contact [quoted text clipped - 3 lines] > plane, but even straight out of the plane takes you to over 1000 years > round trip time. (My english is bad, well it dosn't matter) > > Group 1 can watch frequency 1,42000 GHz. > > Group 2 can watch frequency 1,42001 GHz [quoted text clipped - 4 lines] > On the other hand, there is no evidence that large enough numbers of > people are interested to be able to form multiple groups. Good :-) > > ("Hello"-signal time-interval perhaps every 2 weeks) > > Small dish SETI is only likely to produce comparable detection rates to > big dish SETI (approximately zero in 20 years). May I ask You for a request ? Please read file ... 0412 news:q%hfa.1884$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 [quoted text clipped - 7 lines] > 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 > [quoted text clipped - 7 lines] > 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 [quoted text clipped - 4 lines] > 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. [quoted text clipped - 7 lines] > 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 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). > [ ... ] > > > and therefore I have NO chance to compare with own downloads from the [quoted text clipped - 464 lines] > File-number: > 2342 > 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. Yes, indeed :-( > The Hz within 1.42 GHz refers to the bandwidth in which you are receiving. > Read SETI FAQ. I understand bandwidth (thank You). (+/- x Hz.) fx. 1,42 GHz +/- 5000 Hz. Correct ? > Every Hz of bandwidth contains kT (Bolzmann constant times system > temperature) Watt of noise power. ... By this You mean, that noise from 1,42 GHz -5000 Hz to +5000 Hz is greather that, noise from just -50 Hz to +50 Hz ... Correct ? ... And therefore at signal will drown in noise, then we are useing a big bandwidth. Correct ? > ... So to reduce noise SETI@home scans many, > many very narrow bandwidth portions of the spectrum around 1.42 GHz. ... By this scanning You mean, that the SETI-computer-program is in able to separate one frequence from another, and by this reduce the noise on this frequence ? > ... The > general assumption amount SETI activities is that interstellar radio > beacons will transmit in very narrow bandwidth exactly ... But the the signal is more difficult to find :-( > ... because wide band > transmissions are easily lost in the noise. ... Yes ... > ... 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), I have óne objection on this point: Are we looking for someone like us ? NO! - We just want contact. An "old" civilization with millions of years in space will send out really BIG "Hello"-signals, because they know, how difficult it is to find them. If Arecibo can do over 1E13 Watts in output, perhaps they can do more than 1E17 W. Is this technical possible ? (fx. more than 1000 parapol's mixed together) Can we "download" such kind of big signals by a little 2-4m parabol ? > and sender and receiver antenna have to point at each other, Yes, of course - that's our problem :-( > and the sender needs to transmit with TerraWatt (EIRP) power levels, TerraWatt ? Do You mean by this 1E12 W? > and they have to be tuned to the same frequency, Yes, of course - that's our problem :-( > 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. Yes, of course. > 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. ... Correct! - *Óne* will get the right position, at the right time, and at the right frequency :-) (look above, 1E17 W as output) > ... And since > it is a small dish, there is a good chance that the signal disappears in > the noise, ... Also when the output is more than 1E17W ? > ... so we still don't detect anything. ... Und das ist nich so gut :-( > ... You need 1 million big dishes to > detect that signal (larger dishes have a narrow beam, so you need more to > cover the sky). Arecibo 1E13W * 1E6 (as output) = 1E19W But ... if they send out the signal with 1E19W, what then ? Is this technical possible ? (fx. more than 100.000 parapol's mixed together) > Or, you need ONE big phased antenna (which can listen to as many > different > directions (beams) simultaneously as its phase-processing computers can > handle). But then You also get's the noise from all these directions! > ... The Allen radio telescope for example. So that is a revolutionary > new development. Do You have a web-side ? > 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. Yes, > 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. ... Correct :-( > ... 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. Correct :-( > If that is true, then your idea (of many small amateur dishes around the > world) might actually detect that signal.... You never know. Too bad :-( > Rob > > P.S. We really have no idea what kind of information any ETI would send > out. May I come with a suggest ? Are you in able to crack the code, se ... 2233 news:Gb3sc.1684$Vf.53534@news000.worldonline.dk english version ... 2305 news:Z5vsc.2233$Vf.98365@news000.worldonline.dk (You can win around 140 US $, if You are the first one) > 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). Did You understood my point in regard to this: 1. Time = 0 ............ (1. impulse) Time = 1 ............ (2. impulse) Time = Phi (22/7) (3. impulse) The final proof :-) Thank You for Your answer, Rob. 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: 2355 > fx. 1,42 GHz +/- 5000 Hz. Note that the input to S@H is 1.42GHz +/- 1.25 MHz and the data sent to the client has already been separated into multiple sub-channels. Even +/- 5000Hz is considered too wideband for an artificial signal confirmation and the S@H processing (because of the 1 bit quantisation) will ignore signals that wide. The bandwidth analysed is as low as about 0.07Hz. A 350MHz PII can reduce ~10kHz by 107 seconds to this frequency resolution in just over 1 second, so analyzing large numbers of narrow band channels is not difficult. Typical amateur SETI systems use sound cards and analyse to about 10Hz, which is limited more by receiver stability than processing power. > By this You mean, that noise from 1,42 GHz -5000 Hz to +5000 Hz is greather > that, noise from just -50 Hz to +50 Hz ... 100 times greater. > TerraWatt ? > Do You mean by this 1E12 W? Yes. > Arecibo 1E13W * 1E6 (as output) = 1E19W The 1E13 watts plus is effective isotropic power; it includes the antenna gain. The feed point power is only 1MW (1E6 W). But ... if they send out the signal with 1E19W, what then ? > But then You also get's the noise from all these directions! No. In any one beam direction, a phased array behaves the same as a big dish. The noise voltages sum non-coherently, so they form a gaussian statistical distribution with a mean of zero, and, more importantly, a standard deviation that scales as the square root of the number of elements. The signal sums coherently, as the number of elements. The voltage signal to noise ratio therefore scales as the square root of the number of elemnts and the power signal to ratio as the number of elements. That's exactly the same as a dish in a single direction. Each patch on the dish surface produces a contribution that is phased by different path length the rays through it take and is added up, passively, at the feedpoint. In other words, to calculate the gain of a dish, you actually have to treat it as though it was an array, with very small element. On the other hand, lots of individual dishes only get one unit of signal and one unit of noise, so they do have a poor signal to noise ratio. > Do You have a web-side ? http://www.google.com The SETI League, which I've already mentioned, has started assembling a network of small dishes that are precisely intended to detect small duration signals from any direction. <http://www.setileague.org/> > > fx. 1,42 GHz +/- 5000 Hz. > > Note that the input to S@H is 1.42GHz +/- 1.25 MHz ... I am VERY glad to hear this :-) > ... and the data sent to > the client has already been separated into multiple sub-channels. This information can help me to understand their DATA (thank You, David) I gave You an example, se ... 2337 news:Chatc.3706$Vf.140315@news000.worldonline.dk and ... 2341 news:naetc.3716$Vf.141833@news000.worldonline.dk Do You know how to read their ( S@H ) DATA Can You help me to understand the DATA ? > ... Even > +/- 5000Hz is considered too wideband for an artificial signal [quoted text clipped - 6 lines] > over 1 second, so analyzing large numbers of narrow band channels is > not difficult. ... Can such kind of frequency-separation be done possible on an incomming signal to a little parabol ? > ... Typical amateur SETI systems use sound cards and analyse > to about 10Hz, which is limited more by receiver stability than processing > power. This was maybe You answer (se above) > > By this You mean, that noise from 1,42 GHz -5000 Hz to +5000 Hz is > > greather that, noise from just -50 Hz to +50 Hz ... > > 100 times greater. Yes, of course. > > Arecibo 1E13W * 1E6 (as output) = 1E19W > > The 1E13 watts plus is effective isotropic power; it includes the antenna > gain. The feed point power is only 1MW (1E6 W). Okay. > But ... if they send out the signal with 1E19W, what then ? I think it's possible, maybe not 1E19W but still a big one, because ... If they have lived for a long time in space, they still want contact, just like we do :-) Nobody "phoned" them, and therefore they take steps to be the messenger :-) They build one interstellar radio beacons (in space). And what then ? A smart brain of them get's a idea ... Why don't we build one more ? And then they got 2 output ! Another brain says: Let's build a lot of interstellar radio beacons ! And then they got thousands of them. A smart brain then says: Let's connect them together, so that we can send a BIG Output, maybe them a young civilization will be in able to hear us !!! The young civilization is us, :-) > > But then You also get's the noise from all these directions! > > No. ... No ??? > ... In any one beam direction, a phased array behaves the same as > a big dish. The noise voltages sum non-coherently, so they form [quoted text clipped - 4 lines] > as the square root of the number of elemnts and the power signal > to ratio as the number of elements. This is very difficult for me to read and understand. I must read it again and again, untill I understand it :-( > That's exactly the same as a dish in a single direction. Each patch > on the dish surface produces a contribution that is phased by different [quoted text clipped - 6 lines] > signal and one unit of noise, so they do have a poor signal to noise > ratio. Yes. > > Do You have a web-side ? > [quoted text clipped - 3 lines] > a network of small dishes that are precisely intended to detect small > duration signals from any direction. <http://www.setileague.org/> I have reading a little from setileague.org, but I english is bad, so it takes me a long time to understand. Thank You for You help. Have a nice day :-) 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: 2363 In regard to my question ... 2342 news:qaetc.3717$Vf.142008@news000.worldonline.dk === start of quote === 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 ? ... :-) === end of quote ==== ... I have a little crazy thinking: Can You imagine we receives a message from someone in M31 ? The delay will be 2,2 mill. years, but they will be in able to tell us, what's going on in our Galaxy for 2,2 mill, years ago (total delay 4,4 mill. years). For instance: "You have a neighbour in Your area; look over there. The Postions is xxx. :-) 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: 2343 |
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