SETI has it wrong!

[CraigD]

Part of the SETI thing is that we are sending out signals not in english per say but in mathematics.

But we're not even that far yet! Not only are we not *sending* signals as a part of any current Seti project (unless you call the plaque on Voyager an attempt to communicate)…

To the best of my knowledge, there has been one, and only one powerful intentional radio message sent into space: the 1679-bit Arecibo message, in 1974. A t-shirt bearing its 2-d image was popular among astronomy fans, provokin jokes that aliens receiving it would conclude that it was a message from a pre-school child with an obsession with prime numbers. :D

[FrankM]

As far as ETI transmissions, the best we can do at the moment is to identify persistent clusters of signals (pulses) coming from a specific area in our galaxy.

 

Not only are we not *sending* signals as a part of any current Seti project (unless you call the plaque on Voyager an attempt to communicate), we're not even trying to "decode" or "demodulate" any signals yet, because we first have to find a "signal" that has a strength that would indicate it might potentially be artificial and carrying some sort of information.

 

I agree with Buffy, you need to find something before you can even consider what demodulation technique might be applicable to the signal.

 

SETI doesn't have the financial muscle of the traditional astronomy interests as they are still "grounded" in that they have to start out from the earth's surface. The optical and non-optical astronomers now have a variety of satellite sensors and it would be beneficial if SETI had a "broadband receiver" that could downlink its content to earth based receivers for analysis. There are obvious benefits from a space based antenna/receiver and it would improve the probability of detecting an ETI emission by several magnitudes, plus the antenna would be removed from some of the earth based interference.

 

Guest Editorial -- Protected Frequencies

 

After one finds a persistent emission then one can begin the spectral examination of the type of emission.

 

As for the Voyager message, I think those that designed the plaque made it too complicated, especially in how they attempted to identify hydrogen. All they had to do, and there was room, was inscribe a line 8.3097 inches long (21.106 cm). Even we would now recognize what that length meant, but we wouldn't have a century ago even if it was inscribed in solid rock.

[FrankM]

... Maybe Frank or another poster could instead use their intellect to propose how, using existing resources, the search for signals in general could be improved.

 

I don't know how the existing resources are being used, nor the concepts behind the signal analysis process. Could you provide me with some references where I can read just what SETI is doing in this area? The term BOINC identifies the distributed computing process that sends spectral snippets to someones computer and the analysis results back "home". The spectral analysis program is being executed within the BOINC process, what parameters are being examined?

 

The core of the search problem is not just how much spectrum is being examined, it is how the spectrum information is being processed. If you do not consider the methodology that might be used by an ETI to modulate their transmissions you will have no idea how much spectrum should be included in a particular "analysis algorithm". This has been discussed in previous posts on this thread.

 

FrankM 'I haven't been able to find within the SETI Home pages just what emission "modulation modes" they are examining, perhaps you can provide that info.'

 

Buffy 'Not only are we not *sending* signals as a part of any current Seti project (unless you call the plaque on Voyager an attempt to communicate), we're not even trying to "decode" or "demodulate" any signals yet, because we first have to find a "signal" that has a strength that would indicate it might potentially be artificial and carrying some sort of information. As I mentioned above, even for spread-spectrum signals, there would be "greater than background" signal strength (albeit on multiple frequencies) that would be detectable unless the sender was purposely trying to hide them by making them identical to "background".'

 

Buffy 'So I really don't need to know about AM or FM or spread-spectrum digital in order to find out if *something* is being sent that's not naturally occurring.'

 

If signal strength is the primary factor in SETI's spectral search algorithm I see an obvious problem.

 

Although SETI cannot focus on the demodulation process, they do have to consider how the modulation process will modify ETI transmissions. Our high power transmissions are gradually eliminating the carrier and putting all the power into the information pulses. We have to make the assumption that there will be few ETI emissions that are not using the most power efficient modulation techniques. There is a small time window when a society first discovers how to generate and receive EM signals before they gradually eliminate the processes we refer to as CW, AM, FM, and SSB type analog modulations, which are easier to identify as they require their signals to be above the background noise. We are about 100 years into that window and I doubt there will be any high power applications using such archaic modulation techniques 100 years from now, they will be some variants of spread spectrum (SS) or ultra-wideband (UWB).

 

The literature available on SS and UWB indicates that the only real limit on how much spectrum they could use for a transmission is our telecommunications laws and our technological limitations. The literature also states that SS and UWB signals do not have to be above the background noise, and doing this is not deliberately hiding them.

 

I still think that it would be easier to detect a sequence or set of signals if one uses the same "time duration" basis that was used to create the signals, as I would expect most ETI signals are open transmissions, commercial or govt, and will have a relationship to their "time base". The concept in Primitive.pdf identifies a "time base" that is superior to anything used on earth.

 

We typically limit our analysis of how somebody else will do something based upon how we do it. We assume the ETI signals are "time sequenced", that is each pulse has some time separation, ever so miniscule. I can envision an UWB transmission that would encode and transmit a complete block of "information" in a single transmission. Don't jump to the conclusion that elements of that concept haven't been used in the past or is not being used currently.

 

If the SETI people do not know how NSA searches for and identifies surreptious transmissions on this planet, then they are unprepared to search for ETI transmissions from other planets.

[CraigD]

If signal strength is the primary factor in SETI's spectral search algorithm I see an obvious problem.

…

We have to make the assumption that there will be few ETI emissions that are not using the most power efficient modulation techniques.

This is a problem if we assume that the ETI don’t want to be discovered, and are making no effort to transmit easy-to-detect signals, or, even worse, intentionally trying to eliminate or disguise incidental signals.

 

I believe that one of the fundamental assumptions of SETI is that any ETIs we have much hope of detecting want to be discovered.

[InfiniteNow]

I don't know how the existing resources are being used, nor the concepts behind the signal analysis process.

...

If the SETI people do not know how NSA searches for and identifies surreptious transmissions on this planet, then they are unprepared to search for ETI transmissions from other planets.

That's a mighty big If you've put out there Frank. Also, I'm guessing you meant "surreptitious?"

 

 

Per the first question:

 

SETI@home: An Experiment in Public-Resource Computing

Analyzing a work unit involves computing signal power as a function of frequency and time, then looking for several types of patterns in this power function: spikes (short bursts), Gaussians (narrow-bandwidth signals with a 20-second Gaussian envelope, corresponding to the telescope's beam movement across a point), pulsed signals (Gaussian signals pulsed with arbitrary period, phase, and duty cycle), and triplets (three equally-spaced spikes at the same frequency; a simple pulsed signal). Signals whose power and goodness-of-fit exceed thresholds are recorded in the output file.

 

Outer loops vary two parameters [KOR01]:

 

• Doppler drift rate. If the sender of a fixed-frequency signal is accelerated relative to the receiver (e.g. by planetary motion) then the received signal drifts in frequency. Such signals can best be detected by undoing the drift in the original data, then looking for constant-frequency signals. The drift rate is unknown; we check 31,555 different drift rates, covering the range of physically likely accelerations.
  
• Frequency resolution. We cover 15 frequency resolutions ranging from 0.075 to 1220.7 Hz. This increases sensitivity to modulated signals, whose frequency content is spread over a range.

 

Remember, though, that's just the SETI@Home project, not SETI in general.

 

/forums/images/smilies/banana_sign.gif

[FrankM]

I believe that one of the fundamental assumptions of SETI is that any ETIs we have much hope of detecting want to be discovered.

 

I think that is a given, as any society that industrializes would develop EM capability. If many centuries down the line a social system dictates no more EM radiation into space, their signals are already out there for others to detect, they can't call them back.

 

We have to consider that every ETI has gone through the same process we are doing right now. When an ETI identified artificial signals from a distant source they would consider contact by creating a "beacon" that transmitted a signal toward that distant source using a transmission protocol similar to that they identified. Isn't that what we would do?

 

I suspect ETI beacons are a progressive thing, when an ETI discovers they are not alone they reciprocate by creating a beacon(s) at their location directed at the ETI(s) they have identified. We are barely 100 years into our development of EM devices and we are looking for ETIs. The ETI are transmitting signals other than beacons and on diverse frequencies, but I suspect the beacon signal-modulation processes will be something very basic, something that will be recognized by a society with a somewhat primitive EM technology. They would put their beacon in a protected spectrum area. Once we find one ETI beacon I think it will be easier finding others.

 

... Also, I'm guessing you meant "surreptitious?"

Yep! Thanks for the SETI Resource Computer reference.

 

The SETI Resource Computer article provides considerable insight into what they assume an ETI signal will look like. It appears the signal analysis process is structured to detect a set of "assumed" modulation types that are typical of narrow-bandwidth radio, and they have to be above the "noise floor". The 2.5 MHz spectrum SETI@home is searching would not cover the spectrum of many of our current SS emissions, certainly not UWB, and It is not covering where the first logical offsets would be, see below.

 

From the SETI@home: An Experiment in Public-Resource Computing article - Like many other radio SETI projects, we centered our band at the Hydrogen line (1.42 GHz), within a frequency range where man-made transmissions are prohibited by an international treaty.

 

If we have found that this frequency should be protected, I don't understand why SETI thinks ETIs would not do the same. I understand some researchers think ETIs would provide a marker or beacon signal at very specific offsets from the 1.42 GHz value, plus or minus Pi and/or 2Pi Megacycles. Parallel with the information extraction that led to the concept in the Primitive.pdf article (2/16/07 post), included a result that was a difference value "1 Pi" above the ultimate "center" frequency, plus a frequency spread that translates to 0.224 Megacycles above and below the center of the offset frequency (using the universal time duration frequency scale). This frequency spread, plus-minus 224 kilocycles, is substantially wider than most narrow bandwidth radio modulation processes, which are typically under 10KHz wide.

 

From the SETI@home: An Experiment in Public-Resource Computing article - Work units are formed by dividing the 2.5 MHz signal into 256 frequency bands, each about 10 KHz wide.

 

SETI@home is looking closely at a spectrum area where man, and quite possibly ETIs, have excluded artificial transmissions.

 

If SETI doesn't care to look at the logical offset frequencies, those that do must use the "universal time duration" to define frequency, otherwise they will not be looking at the proper offset frequencies, see SETI-Offset.pdf (first post). The frequency scale in the SETI-Offset.pdf graph illustrates the difference between a frequency derived using the SI second duration versus that using the universal time duration. Most think the first higher offset would be at 1423.5472 MHz rather than 1425.4113 MHz.

 

If the SETI@Home receiver was centered on the 1423.5472 MHz frequency a 2.5 MHz bandwidth wouldn't cover the frequency at 1425.4113 MHz.

[FrankM]

The types of signals SETI is trying to detect is explained in the setiathome "cacm.php" article. I still do not understand why they are exclusively looking for narrow bandwidth signals when we are already converting many of our EM transmissions to various types of wideband processes. I ran across the following statement made on a SETI message board, allegedly attributed to David Anderson (Message 56798):

 

SETI researchers have known for many years that optimal communication resembles noise, and is therefore hard to detect.

 

SETI useless?

 

Even when there is no intention to hide the transmissions, a wideband mode of transmission is used because it is power efficient and allows information recovery even when it is received below the noise threshold floor.

 

It helps to know where to look to detect a wideband mode of modulation (spread spectrum (SS)), but there are well known techniques being used to detect SS, even those that are intended to be covert. Other techniques are probably known to NSA.

 

Although the backyard "private radio telescope" researcher does not have the signal gathering power of the SETI instruments, they can apply different signal analysis processes to what they are receiving, thus they may be the only hope that an ETI signal is recognized amongst the "noise".

[FrankM]

There are several factors that hinder our ability to detect ETI signals and beacons. Even if our antennas and receivers were considered adequate, there are some troubling philosophical factors.

 

SETI makes the assumption that other species that have developed the ability to transmit and receive electromagnetic (EM) emissions would be blasting all kinds of signals into space as we currently do. It is apparent that the open broadcast of high power carrier centered emissions is a phase we go through until we convert to more efficient information transmission techniques. We are observing these changing information transmission techniques in all spectrum areas.

 

It is my opinion SETI is making the wrong assumptions. (see message 56798 in the following URL)

 

SETI useless?

 

Radio SETI projects (like SETI@home) hope to find either a beacon (a signal intended to be heard by us) or a communication signal that is not optimal (like our current TV and radio stations) or a non-communication signal (like radar).

 

The above implies an ETI would be using the same primitive modulation techniques of a culture that just recently discovered how to use EM waves for communications.

---

SETI is making the assumption that an ETI is going to deliberately let other intelligent species know they are "out there".

 

I make the premise that an ETI would not make it easy for a primitive society, such as ours, to identify that they were not alone in the galaxy. An intelligent ET would know that the revelation there were other beings transmitting signals from a specific location in the galaxy could cause serious disruptions to those societies that have fractionalized governing processes and competing religious factions, a characteristic of a primitive society.

 

Although the ETIs would not be deliberately hiding their emissions, the information transmission method(s) would require a high degree of technical sophistication just to recognize that it was artificial. I would expect an ETI to make efficient use of the spectrum they allocate for beacons, which would preclude the use of CW, AM, FM or similar modulation types, plus they would be somewhat easily detected by a primitive society.

 

The "08p06.pdf" article illustrates a technical process to implement a "band-width efficient modulation scheme".

 

http://hcac.hawaii.edu/tcwct03/papers/s08p06.pdf

 

We should expect an ETI modulation scheme to satisfy "Shannon's Second Theorem" to a high degree. Implementation is only a matter of technical sophistication. To an ETI, an archaic EM modulation scheme might be the simultaneous transmission of all the bits of an octal code.

---

The ability to detect higher-order modulation processes would be facilitated if the sender and receiver are sharing the same clock.

 

We are using the SI second as our time unit. All ETIs would have found the mathematical basis for a common time unit.

[Jay-qu]

We are using the SI second as our time unit. All ETIs would have found the mathematical basis for a common time unit.

 

:) I thought we got passed this.. ;)

[joekgamer]

There are several factors that hinder our ability to detect ETI signals and beacons. Even if our antennas and receivers were considered adequate, there are some troubling philosophical factors.

 

SETI makes the assumption that other species that have developed the ability to transmit and receive electromagnetic (EM) emissions would be blasting all kinds of signals into space as we currently do. It is apparent that the open broadcast of high power carrier centered emissions is a phase we go through until we convert to more efficient information transmission techniques. We are observing these changing information transmission techniques in all spectrum areas.

 

It is my opinion SETI is making the wrong assumptions. (see message 56798 in the following URL)

 

SETI useless?

 

 

 

The above implies an ETI would be using the same primitive modulation techniques of a culture that just recently discovered how to use EM waves for communications.

---

SETI is making the assumption that an ETI is going to deliberately let other intelligent species know they are "out there".

 

I make the premise that an ETI would not make it easy for a primitive society, such as ours, to identify that they were not alone in the galaxy. An intelligent ET would know that the revelation there were other beings transmitting signals from a specific location in the galaxy could cause serious disruptions to those societies that have fractionalized governing processes and competing religious factions, a characteristic of a primitive society.

 

Although the ETIs would not be deliberately hiding their emissions, the information transmission method(s) would require a high degree of technical sophistication just to recognize that it was artificial. I would expect an ETI to make efficient use of the spectrum they allocate for beacons, which would preclude the use of CW, AM, FM or similar modulation types, plus they would be somewhat easily detected by a primitive society.

 

The "08p06.pdf" article illustrates a technical process to implement a "band-width efficient modulation scheme".

 

http://hcac.hawaii.edu/tcwct03/papers/s08p06.pdf

 

We should expect an ETI modulation scheme to satisfy "Shannon's Second Theorem" to a high degree. Implementation is only a matter of technical sophistication. To an ETI, an archaic EM modulation scheme might be the simultaneous transmission of all the bits of an octal code.

---

The ability to detect higher-order modulation processes would be facilitated if the sender and receiver are sharing the same clock.

 

We are using the SI second as our time unit. All ETIs would have found the mathematical basis for a common time unit.

So we should compile the frequencies (or at least certain ones, following patterns) and then analyze that data? Interesting...

[Catalyst]

SETI starts out with the premise that the species they tag as "extra-terrestrial intelligence" will be using the earth second for determining the numeric values used for frequency. The intelligent species are using a "universal time unit" which has a different duration than the second. The universal time unit has a duration of about 0.6255... that of the SI second.

 

SETI has its receivers set to listen to a certain range of the electromagnetic spectrum (in the hydrogen well), and because they start out with the wrong time base, they do not cover the most logical offsets from the center frequency.

 

If you add Pi or 2Pi to a smaller value it will result in a bigger change. SETI is not listening to the proper offset range, which is illustrated in the pdf article below.

 

http://vip.ocsnet.ne...SETI-Offset.pdf

 

The mathematical basis of the universal time unit would be known by all truly intelligent species.

 

I think I see what you're getting at here. That the closest extraterrestrial time unit that is their cultural equivalent of a second may be of a different length than our second, and therefore if they are sending out message at 'their' 1420 line, it won't be the same as 'our' 1420 line. For example, their second might equal 2 of our seconds (Or maybe not, but 2 is an easy number to work with). For them, they would see 1420 cycles a second, but since their second is twice as long, we would define it as 710 MHz. But that wouldn't matter. For them, they would realize that somewhere around 1840 cycles per alien second (AMHz) the universe is virtually clear. So they would broadcast at that frequency, and we would be listening at 1420 MHz, exactly half the value. If our second is half that of the aliens, then to figure out what channel they're on we simply have to divide their frequency in half. Even if the aliens never realized that there may be a discrepancy in how we measure time, it would not matter. The properties of hydrogen are the same regardless of who looks at them, so regardless of what time units are used, we would still be communicating on the same channel.*

 

What is this universal time unit, and it is equal to 0.6255...What? Seconds? Hours? Is it the fraction of the average velocity of an unladen swallow (European)? Oh wait, you said "... That of the SI second." So I looked up SI second. According to Wikipedia, it's first source http://www.bipm.org/...2-1/second.html (the bureau international des poids et mesures, as far as I can tell the originators of the International System of Units (SI) and a secondary source I found http://physics.nist....SP330/sp330.pdf (The national institute of standards and technology), the second is defined as "the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom" So I return again to my question, what is this universal time unit, and it is equal to 0.6255 of what?

 

The link you provided (http://vip.ocsnet.ne...SETI-Offset.pdf) seems to be broken. So I went to http://ocsnet.net/, which seems to be a mirror site to http://www.porterville.com/. As far as I can ascertain from that site, it's a wireless ISP in Tulare county, CA. So I went to the suggested site, http://vip.ocsnet.net/~ancient/, and read the abstraction of a paper titled "Methodology to Define Physical Constants Using Mathematical Constants", authored by one Frank H Makinson. So I looked up that paper and got to this (on the same vip.ocsnet server) http://vip.ocsnet.ne...20Postprint.pdf. The paper claims to "[have] been accepted for publication in an IEEE peer-reviewed publication" yet neglects to say which publication. The only contact method provided is an email to, once again, vip.ocsnet. No amount of searching for the paper turns up anything except for what I found on the ocsnet site. It seems as though the only time any one hears about this paper is when you link to it.

 

 

So I have a few questions to ask: Where has this paper been published? Is http://vip.ocsnet.net/~ancient/ a personal blog? Is the site supported by you personally? Are you Frank H. Makinson?

 

*I would like to note that I have left out other frequencies for the sake of simplicity, but the same argument applies.