By John E. Blyler
The huge RF radio observatory at Arecibo, Puerto Rico has all of the key ingredients for a high-tech adventure movie. First, its location is remote, as it’s buried deep within the rainforest of a Caribbean island. Second, the sheer size of the radio telescope renders it sublime. It measures 305 m (1001 ft.) in diameter and more than 500 m from the jungle floor to the top of the moveable radio feed platform (see Figure 1). Unlike other astronomic R&D facilities in the United States, the observatory at Arecibo also is more than just a radio telescope. It also is a complete R&D facility. Its mission – in part – is to search for the stuff of science fiction stories ranging from extraterrestrials and gravity waves to asteroids that could devastate the Earth.

We will return to the cool sci-fi aspects of Arecibo later. For now, let’s explore the technology that makes all of this possible—starting with an overview of the RF telescope and the critical electronics. Radio astronomy studies celestial objects using radio transmissions. Often traveling great distances, these radio waves are reflected from the objects of study. The returning signal is analyzed and developed into amazing images. Although this may seem like a straightforward task, the returning signal is typically so weak as to be almost indiscernible from the cosmic noise.

Thus, the successful detection of the returning signal requires the very best that modern electronics has to offer. Indeed, the noise generated by even the most modern low-noise amplifier (LNA) and other sources are orders of magnitude greater than the signals being examined. Dana Whitlow, research technician at Arecibo, estimates that the return signals may be over 40 dB below the overall system noise level—a factor of 10,000 lower!

Critical Sensitivity To Noise
Simply put, everything that can be done is done to maximize the sensitivity of the receivers. The front-end electronics are cytogenetically cooled in 99.99% pure Helium to between 10 and 15 Kelvin. These temperatures can only be achieved in a vacuum. As a result, all of the specially designed electronic systems must be evacuated before the cooling can begin.

The front-end electronic systems consist of amplifiers, filters, and mixers. The amplifiers are specifically designed to minimize noise. Toward that end, Ganesan Rajagopalan, a senior receiver engineer and head of the Electronics Deptartment at the observatory, has been improving the sensitivity of the receivers by slowly replacing the existing gallium-arsenide (GaAs) monolithic microwave integrated circuits (MMICs) with indium-phosphide (InP). MMICs are devices that operate at microwave frequencies between 300 MHz and 300 GHz.

InP-based amplifiers have lower noise and higher gain than their GaAs counterparts. Yet these circuits also must be customized for the lowest noise possible. The Cornell University-based team at Arecibo collaborated with the experts at CalTech’s JPL team to make these customized application-specific integrated circuits (ASICs) tailored to a cryogenic environment. The CalTech design also has been implemented at the Allen Telescope Array (ATA) in California. ATA is a “large number of small dishes” (LNSD) array that’s designed to be highly effective for simultaneous surveys of conventional radio-astronomy projects and Search for Extraterrestrial Intelligence (SETI) observations at centimeter wavelengths.

With such innovative LNA devices, it’s no wonder that the Arecibo Observatory is considered state of the art in receiver technology. In terms of the available bandwidth per receiver, however, the facility is playing catch-up. The receivers used at Arecibo are 2 GHz wide, ranging from 2 to 4 GHz and another from 4 to 8 GHz. The goal is to widen the current 2-GHz signals, which are being received using Ultra Wideband (UWB) technology. Here too, the R&D team is working with other scientists and engineers around the globe to develop a UWB feed that will operate from 1 to 10 GHz. Such a feed would reduce the number of existing receivers from 8 down to 1, which would further reduce the collective number of noise generators in the system.

A Noisy Planet
Reducing the noise sensitivity of the receiving electronics is critical to analyzing the radio signals returning from deep space. But another challenge exists closer to home— namely, the effective “noise” created by wireless devices ranging from cell phones to data devices. The RF telescope operates to 10 GHz and includes receivers in the S-, C-, and X-bands. Wi-Fi technology occupies a relatively small bandwidth centered around 2.4 GHz—right in the middle of the lower S-band space. Another source of radio interference comes from a much more powerful source—namely, the various airports on the island. These sources are mission critical and cannot be turned off at select times during the day.

To help reduce the opportunities for radio noise interference, the Arecibo team actively works with the Puerto Rico Spectrum users’ group. In cases involving mission-critical systems like airport radar, the team has coordinated the on-off time of the radar. The airport radar goes blank for a short period of time when it points in the direction of the Arecibo observatory. Unfortunately, this well-intentioned gesture has proven to be of limited value. The radar signal has more power located in the back lobes of the radar signature than in the front lobes.

Sci-Fi Becomes Reality
As fascinating as the engineering work at Arecibo is, does it really have any practical value? Can it turn science fiction into science fact? Some would suggest that the jungle-hidden facility will play an important role in saving humanity from near-earth objects (NEOs) like asteroids, which may be on a collision course with earth. The RF Observatory has the capability to pinpoint the orbit of NEOs as far away as Jupiter or Saturn and then calculate whether that object poses a threat to humanity. Such knowledge could be used to evacuate populations and move important property to a safe location. This is just one reason why the U.S. Congress is interested in keeping the Arecibo radar telescope working.

“We are also doing a lot of work on pulsars,” explains Rajagopalan. “Pulsar timing is very important in the detection of gravitational wave radiation.” Described as a fluctuation in the curvature of spacetime, which propagates as a wave, gravitational waves were predicted by Albert Einstein’s theory of general relativity. Sources of gravitational waves include binary star systems (e.g., white dwarfs, neutron stars, or black holes).

Pulsar astronomers believe that they can detect gravitational waves. Telescopes at Arecibo, PR and the mainland US, Europe, and Australia are all part of an array that’s being used to carefully time pulsars. All of these facilities make very long, simultaneous observations of the same deep-space source using long baselined interferometry (LBI). Precise synchronization timing among the global facilities is achieved using a hydrogen maser atomic clock. Thus, the research being done here is not just astronomy. It’s planetary radar science and ionospheric as well.

Signal Processing
What happens to the signal returning from the reflection off of nearby planets or from signals originating from a deep-space pulsar? The signal comes into the feed in a concentrated form after reflection from the big reflector (see Figure 3). An ortho-mode transducer (OMT) —some more than 3-ft. long—splits the signal into two separate channels. Noise-injection couplers are connected to one channel. These couplers inject a weak but carefully calibrated noise source into the main signal.

Figure 3: Antenna feed and electronics on platform suspended 500 ft above the main reflector dish floor.

The injected noise signal is switched on and off at a rapid rate that’s called a “winking” rate calibration, says Dana Whitlow, a senior receiver engineer. “By a measurement of the levels later in the system with the cal on and the cal off, we can determine the system noise temperature. Also, this calibration allows us to track unique time-dependent changes and gain of the amplifiers.”

The signal then travels through isolators, which flatten out the frequency response. Effectively, they remove reflections from the amplifiers back into the earlier part of the signal path. Finally, the signal is amplified in the LNAs mentioned earlier.

All of these electronics are contained with a dewar, which is used to cool the amplifiers down to 15 Kelvin. Cables connect the dewar to the next signal-conditioning module, which contains a pulse amplifier module to provide additional amplification. Computer-selectable filters are used to exclude unwanted frequency bands, limiting the bandwidth from radio-interference sources like Wi-Fi and airport radar.

What happens if the ionospheric, planetary, or deep-space phenomena that a researcher is trying to study occur at the same frequency as the radio-interference sources—perhaps centered at 2.4 GHz (same as Wi-Fi)? To study these signals, researchers would have to go to one of the other RF telescope facilities on the mainland United States. For example, the Robert C. Byrd Green Bank Telescope in West Virginia operates in a radio quiet zone.

Aside from rejecting unwanted interference signals, filters also help to prevent the interference from compressing the gain of the subsequent signal chain. If it’s strong enough, an interfering signal could drive an amplifier into saturation. This forces the gain to go down, says Whitlow. “If there’s anything that radio astronomers hate, it’s unexpected gain changes in their signal path. It’s difficult, if not impossible, to deal with from a perspective of obtaining calibrated data of their signal or source they are looking at.” After more filtering and amplification, just to increase the signal strength, the signal is then downconverted to a lower, intermediate frequency.

One might wonder if all of these filters don’t attenuate the signal even further—especially because they are passive filters, which contain no power source to help boost the signal strength. While it’s true that passive filters attenuate the signal slightly, these attenuations can be corrected by the numerous amplifiers. Active filters would have their own problems, such as the introduction of extra noise and distortion.

Finally, the conditioned signal is sent down from the receiver platform to the control-room area some 500 m below using analog optical fiber cable. Fiber-optic cable is used because it has a much broader frequency response. Plus, it doesn’t pick up electrical noise due to the imperfect shielding of coaxial cable. Fiber cables are typically much less lossy than coaxial—especially at the higher frequency ends.

Perhaps the most compelling reason for fiber over coaxial cable is that the former doesn’t conduct lightning down to the control room, explains Whitlow. “I haven’t been down here to see this firsthand, but I’ve been told by many people that in the early days of the observatory, when lightning struck the platform, there would be sparks jumping around things inside the control room.”

Coming in Part II: We’ll delve into the technology used in the control room and laboratory, where the data is digitized and analysis is performed. Of particular interest to chip and embedded designers will be the evolution taking place from ASIC- to FPGA-based systems.

By John Blyler

Albert Einstein once said that imagination is more important than knowledge. So where do you go to find great imagination?

I caught up with Lou Anders, the editorial director of Prometheus Books’ science fiction and fantasy imprint Pyr, at the recent OryCon convention in Portland, Ore. Here's what he had to say.

SLD: What effect does science fiction have on technology?

Anders: There is a wonderful website called “Technovelgy.com” – where science meets fiction – on which they list every sci-fi idea that has become reality. The last time I went to the site, they had something like 1,400 entries listing both the device and the expression of the device. A great many of the devices are there because someone read about them in a sci-fi story.

SLD: How about that other way around, i.e., what effect does technology have on Sci-Fi?

Anders: William Bison and Bruce Sterling created the cyberpunk movement in science fiction. Gibson first wrote about cyberspace on a manual typewriter. Later, he talked about getting his first computer, sent to him by a company that wanted his endorsement. He took apart to the computer and was absolutely depressed to find a disk inside. He said, “Well, this is just a record player.” He had expected to see some kind of crystalline thing with red lasers shooting out it. Instead, he found a record player. He said he never would have written cyberspace in “Neuromancer” if he had known that it was implemented on little more than a record player.

SLD: Record player? You mean the computer's hard drive or perhaps an early floppy disk. Both systems do look like record players. But that brings up an important difference between science fiction and technology innovation. Most technology improvement, as brought forth by engineers, is accomplished by incremental changes. That's because most designs are constrained by cost and time-to-market pressures to use existing technology.

Anders: Have you seen Microsoft's Project Natal demonstrations? It's the Nintendo Wii minus any kind of physical controller. A camera sits on top of the Xbox monitor and just tracks what you're doing. I saw the demo that they showed their game developer partners event. Microsoft was showing their partners what was coming so the partners could start thinking about what games to put on it. Here's one example: A kid walks into the living room. On the screen is a monk who sees him walk in. The monk spontaneously says, “ I see you have returned for another lesson.” Then the kids and the monk battle each other. The kid has no hardware on him at all, not controller or anything. But his image suddenly appears on the screen and his motioned are copied real-time into the game. It blew my mind.

SLD: I knew that Intel and others have been developing commercial grade facial recognition systems, but this application is amazing. It is far more interesting than the digital signature application that I've written about. Variations on that theme include headbands that respond to thoughts in the brain, as well as recent developments in chips implants.

Anders: I wouldn't mind wearing a chip, as soon as I was sure they couldn't spam it. Nothing frustrates me more than having my computer's browser stop working when you can't make a connection. I'd hate to not be able to access my own brain.

We have an author named David Louis Edelman who wrote a trilogy called ‘The Jump 225 Trilogy.' The third and final book in the series comes out in February. It's a world where, at some point, there was a robot revolution that caused a backlash against technology. Now the society is rebuilding. The way that the people deal with their fears of external technology is to restrict all tech to internal systems. Everybody has nanite threads throughout their bodies and software companies compete for the rights to build the software that runs on it. In this society, you have small four- or five-person companies who compete to write this software. One program is called Poker Face 3.5, which you run during a business meeting so you don't give anything away during negotiations. All of these software programs are loaded into your body. Whenever a new program comes out, it's ranked based upon popularity and performance.

But remember; this author wrote this book in 2000. Again, the model is not huge corporations, but smaller five-person teams writing quick software that is dumped into a data sea and then ranted instantly. It mirrors what have become the applications on an iPhone. The crux of the story, though, is the creation of a program called “multi-real,” which allows instantaneous parallel processing of anything you might want to do. So the nanites in a person's body that run multi-real can do anything. It's a real game changer for that society.

SLD: Even in this example, science fiction touches upon reality. Embedded multicore systems are everyone, although not yet in our bodies. But few of these multicore devices are true parallel processors. Max Domeika, a multicore software expert at Intel, said the software challenges in true multicore processing are significant. Here, too, we find that technology moves by increments. Although multicore processors are now readily, software technology is lagging. Most programs are still using non-parallel languages on multicore like C/C++. We must use legacy system for economic and other reasons. That is the inertia. There are “game changing” technologies, like superconductors, nanotech, and other. But they take a while to be realized. Still, the direction we select may be greatly influenced by our imagination – not the engineers, but the writers of Sci-Fi.

Anders: Maybe, but maybe not. Remember the quote by John Schaar: ‘The future is not a result of choices among alternative paths offered by the present, but a place that is created—created first in the mind and will, created next in activity. The future is not some place we are going to, but one we are creating. The paths are not to be found, but made, and the activity of making them, changes both the maker and the destination.”

SLD: The theme of our conversation seems to be one of man's merging with his creations, resulting in the connectivity of everyone at some bizarre level – hardware being the commodity, software being the dynamic variable. How about other areas of technology, like biomedical?

Anders: We have only scraped the surface of genetic engineering. I remember reading somewhere that there is a 60-year cycle from the invention of the technology and the revolutionizing of the world by that technology. We build the first computers and they are giant things that take up whole suites of business building. Now, 60 years later, they have become miniaturized and everyone has one on their watch. Genetic engineering is not yet 50 years old. At some point in the near future we'll have a genetic revolution that will be equivalent to the computer revolution. Right now we're at the stage where transistors are so cheap that you can buy a birthday card that players music and then throw it away! That will happen with genetic engineering.

SLD: Freeman Dyson delivered a lecture on this very topic. “Freeman Dyson Talks About Biotech vs. Nanotech.”

Anders: Some say this genetic revolution is still 50 to 60 years away. But that is still the 21st century. For the last 40,000 years we have just used plows to till the earth and hit each other with sticks. Then suddenly, in the last couple of hundred years, we are ramping up asymmetrically. So if I don't see a genetic revolution in my lifetime my children and grandchildren will. That's still an astronomical leap. I firmly believe that we will not end this century as one human race. We've already cracked the genome. Within the next 50 years we will be able to tinker with our own genomes to the point where people will start splicing themselves into whatever they want to be. We will be a multiplicity.

Michio Kaku, famous physicist and technology evangelist, recently said that 90% of what you see on Star Trek will be real by the end of this century.

SLD: Which 90%?

Anders: It's interesting what he puts downs as possible and not possible. He's one of those who thinks that artificial intelligence – a form of genetic engineering – is a lot further out in time. He thinks that thought processes in the brain at an order of magnitude deeper than people think they are. On the other hand, he thinks the teleporter technology and faster than light travel is right around the corner.

SLD: Right around the corner – direct conversion of mass to energy and vice versa? That doesn't seem possible. It may be scientifically possible, but to bring it to reality is a daunting task for the engineer. As an engineer, you must move forward cautiously.

Anders: Science fiction, like science, has to be extremely conservative. Sci-Fi is the art of taking the improbable (not the impossible) and making it seem convincing. Fantasy is taking the impossible and making it seem credible. One of my favorite quotes of all came from Paramount Studios. DC Comics wanted to create a Star Trek-Superman crossover. They asked Paramount if Superman can go to the Enterprise? The people at Paramount said “no,” since Superman isn't real, which meant by extension that Star Trek was real because it uses technology.

SLD: Science fiction seems to help shape the future of our technology. What does the future hold for sci-Fi?

Anders: It's an odd time for Sci-Fi. It's being outsold by fantasy and fantasy is being outsold by urban fantasy. That's any book you see with a girl's back with a tattoo on either her shoulder or right above her buttock. It actually represents a confluence of the sci-fi genre with romance readers.

I think the sci-fi category is migrating out of adult and back into Young Readers (YR). Perhaps this is where is should have been, since the golden age of science fiction is 12. At the same time, Sci-Fi is migrating to the mainstream literature, with writers like Cormac McCarthy, Michael Chibon, and everyone else.

I met someone recently who told me they are a huge fan of sci-fi . They went on to describe the physics of faster-than-light travel and warfare in space. His descriptions sounded a lot like the mass effect games from Bioware. Turns out I was right and he had never read any science fiction. All of his admiration and knowledge came from playing games. This is a little bit of what sci-fi is up against. Its audience is teenage boys who are getting their sci-fi fix from the video games or TV.

SLD: Seems like a bit of an incomplete fix.

Anders: I'm surprised at the sophistication of some of those games. What seems to be happening is that people are getting tired of just blowing the same stuff over and over again in these games. They are looking for more sophisticated narratives. I think long term we will see video games looking to actual writers to bring in the complexity.

It's the same thing that is happening in Hollywood. The Matrix films – are they progressively better films or worse? Setting aside the narrative, you can see that the technology in the films is improving by leaps and bounds. But what happens when you can do anything with special effect, when they are ubiquitous? Then narrative becomes important again. You need special effects married to a good story. I think that is starting to happen in gaming. Just look at Walter John Williams who wrote the dialog for Spore. I think we will see more parallels between video games and science fiction.