标签: satellite

One of the principles of broadcast engineering is that when something fails you shouldn't focus on fixing it. Your first action is to get things back on-air! Also, you can't panic. Too many times I have seen talented technicians melt under the pressure of knowing that the systems they are working deliver TV to millions of people. Anyone prone to moments of headless-chicken hysteria or paralysis through fear is simply not fit to work in this type of environment. At the beginning of my career I worked 12-hour shifts running the satellite earth station master control room of a major European communications company. Engineers worked solo on an eight-day week with two day shifts, 24 hours off, two night shifts, and then three and a half days off. Frankly this was a great shift pattern, and I did loads of overtime during my off days. On the day of this particular incident I was in the middle of a long run of overtime. I was pretty beat, but loving the extra cash! I handed things over to the day-shift engineer and went home to grab some sleep. At 1 p.m. my jangling phone jolted me out of a dream. "The Middle East has gone down," shouted the day shift engineer. Now wide awake, I asked "What service?" His reply cut through me like a knife: "All of them, and the MCR manager is on holiday. Can you come in?" I threw some clothes on and literally ran halfway across central London to the office. He was right, almost every Middle-East service was offline. We had a number of large telcos in the Middle East and some call centres in South Asia that used us either as backup links or for premium rural customers. The day shift engineer was one of those guys who didn't do well under pressure, so I seized command and started digging in. After a few hours of getting nowhere, I sent the day guy home because he was really just getting in the way. One of the senior managers had turned up because his phone was ringing off the hook. He was fielding calls from irate customers. I stripped half the entire satellite earth station, bypasssing or reworking just about everything. This is very challenging when you can't actually see the other end of what you are transmitting to and have very little indication if what you are doing is even working. I had to call people on sat-phones in Iraq who I knew would have spectrum analysers and ask them to help me. I had to call the satellite owners and ask for their help, but it took me hours. By 2 a.m. I had switched over half the systems. Quite frankly, I don't know or I forget what combination actually worked, but the system was back and customers were somewhat happy again. The manager taking the calls went out to get me a kebab while I came down from my caffeine and adrenaline buzz. When he came back, he said, "Hey, isn't it your shift now?" Yes, at 8 p.m. the previous evening I was on shift, so I now had to do my shift until the next engineer came in at 8 a.m.! On two hours of sleep I was now finishing the final five hours of my very long day. Needless to say, that was a long night. It wasn't the last time I did several days without sleep, but thankfully I never had another failure that big. This article was submitted by Bob Hannent as part of Frankenstein's Fix, a design contest hosted by EE Times (US).  

Back in the early 2000s, I first subscribed to the Knology cable company for my Telephone, TV, and Internet services. I no longer recall what service I used before, but I do remember how radically different and super-duper I found Knology to be by comparison. All went well until about six years ago when we moved into a new house and discovered that the only TV service we could receive was via satellite from DIRECTV. One upside was that this was the first time we'd had a DVR (which I found to be amazing). One downside was that we had to get our telephone and Internet services via ATT. I have to say that the DIRECTV channel line-up and picture quality was superb. However, in addition to the fact that we kept on losing reception in the middle of a storm (which is, arguably, the time when you need it most), the combined ATT / DIRECTV bill made my eyes water, and it kept on inching up year-by-year (the little scamps). The end result was that, about three years ago, when the folks from Knology finally noticed that our subdivision existed and decided to offer service there, we decided to switch back. Arrggghh! I generally try to find something nice to say about everything, but I'm struggling here. OK, to be fair, all of the folks who work for Knology with whom I have come into contact (in the service center, for example, and also the technicians who have visited our home) have been great (having said this, we still get only a very "blocky" digital picture in the master bedroom). Also, the "look-and-feel" usage model of the Knology TV controller doesn't come close to that of DIRECTV in any respect. For example, when we were watching a movie on DIRECTV, my wife ( Gina The Gorgeous ) used to enjoy the ability to find out which actors were in the film, and to then look up information on those actors (it kept her busy for hours :-) With Knology, by comparison, you are lucky to be able to work out what film you are watching in the first place. Or, to take another example, if you were "fast-forwarding" on DIRECTV until you hit a scene of interest and pressed the "Play" button, the system would automatically rewind a little to compensate for your response time (or lack thereof). Furthermore, the amount of time the system rewound was a function of how fast you'd been going in the first place. Now that was smart. Suffice it to say that no similar capability is available on Knology. Over time, and I say this with love, I've come to believe that Knology's user interface has been thrown together by a bunch of people who (a) don't like each other and don't talk to each other and (b) have never actually created (or used) a user interface before in their lives. It's the little things that tell you the designers simply don't have a clue. Let's assume that you are using the TV guide, for example, and you click the 'Up' button repeatedly (often in frustration at the slow response). Now let's assume that you see a channel of interest scrolling by and you press the "Down" button... what do you expect would happen at this juncture? I think any reasonable person would expect the control algorithm to say "Ah, the user has reversed direction, so let's immediately stop going 'Up'." (Actually, if you were scrolling quickly, it might be nice to automatically go one or two channels back 'Down', but let's not get carried away.) What actually happens is that the controller has stored all of your 'Up' clicks on a stack somewhere and it doggedly keeps on going 'Up' until they run out, at which point it starts executing your 'Down' clicks. Hopefully you didn't click the 'Down' button too many times, or you will sit there with a little tear rolling down your cheek as the channel of interest scrolls by in the other direction. Give me strength! I'm sorry. I see that I've started to rant and rave. It's been a long day. The point is that I just received a really chatty and friendly letter from the folks at a company called WOW! ( www.wowway.com ) who – I am informed – are now my "New Internet, Cable, and Phone provider, formally known as Knology." I won't go into the nitty-gritty details here, but the overall impression given by this letter is that they are jolly nice people whose main source of satisfaction is going to be to make me happy. Well, I certainly can't argue with that as a philosophy. Generally speaking, I think the world would be a much better place if more people made my happiness their goal in life. The letter was signed: Colleen Abdoulah Hugger, Mother, Keeper of the Culture CEO and Chairwoman of the Board WOW! Internet, Cable and Phone I know it's silly, but how can you not trust a CEO who bills herself as "Hugger, Mother, Keeper of the Culture." Quite apart from anything else, this letter was presented in such a happy and flamboyant style (unlike the dross one usually receives from big companies) that I find myself all enthused with great hopes for the future. So, am I easily pleased, or easily fooled?

Quite a long time ago that we used to call the early 2000s, I first subscribed to the Knology cable company for my Telephone, TV, and Internet services. I no longer recall what service I used before, but I do remember how radically different and super-duper I found Knology to be by comparison. All went well until about six years ago when we moved into a new house and discovered that the only TV service we could receive was via satellite from DIRECTV. One upside was that this was the first time we'd had a DVR (which I found to be amazing). One downside was that we had to get our telephone and Internet services via ATT. I have to say that the DIRECTV channel line-up and picture quality was superb. However, in addition to the fact that we kept on losing reception in the middle of a storm (which is, arguably, the time when you need it most), the combined ATT / DIRECTV bill made my eyes water, and it kept on inching up year-by-year (the little scamps). The end result was that, about three years ago, when the folks from Knology finally noticed that our subdivision existed and decided to offer service there, we decided to switch back. Arrggghh! I generally try to find something nice to say about everything, but I'm struggling here. OK, to be fair, all of the folks who work for Knology with whom I have come into contact (in the service center, for example, and also the technicians who have visited our home) have been great (having said this, we still get only a very "blocky" digital picture in the master bedroom). Also, the "look-and-feel" usage model of the Knology TV controller doesn't come close to that of DIRECTV in any respect. For example, when we were watching a movie on DIRECTV, my wife ( Gina The Gorgeous ) used to enjoy the ability to find out which actors were in the film, and to then look up information on those actors (it kept her busy for hours :-) With Knology, by comparison, you are lucky to be able to work out what film you are watching in the first place. Or, to take another example, if you were "fast-forwarding" on DIRECTV until you hit a scene of interest and pressed the "Play" button, the system would automatically rewind a little to compensate for your response time (or lack thereof). Furthermore, the amount of time the system rewound was a function of how fast you'd been going in the first place. Now that was smart. Suffice it to say that no similar capability is available on Knology. Over time, and I say this with love, I've come to believe that Knology's user interface has been thrown together by a bunch of people who (a) don't like each other and don't talk to each other and (b) have never actually created (or used) a user interface before in their lives. It's the little things that tell you the designers simply don't have a clue. Let's assume that you are using the TV guide, for example, and you click the 'Up' button repeatedly (often in frustration at the slow response). Now let's assume that you see a channel of interest scrolling by and you press the "Down" button... what do you expect would happen at this juncture? I think any reasonable person would expect the control algorithm to say "Ah, the user has reversed direction, so let's immediately stop going 'Up'." (Actually, if you were scrolling quickly, it might be nice to automatically go one or two channels back 'Down', but let's not get carried away.) What actually happens is that the controller has stored all of your 'Up' clicks on a stack somewhere and it doggedly keeps on going 'Up' until they run out, at which point it starts executing your 'Down' clicks. Hopefully you didn't click the 'Down' button too many times, or you will sit there with a little tear rolling down your cheek as the channel of interest scrolls by in the other direction. Give me strength! I'm sorry. I see that I've started to rant and rave. It's been a long day. The point is that I just received a really chatty and friendly letter from the folks at a company called WOW! ( www.wowway.com ) who – I am informed – are now my "New Internet, Cable, and Phone provider, formally known as Knology." I won't go into the nitty-gritty details here, but the overall impression given by this letter is that they are jolly nice people whose main source of satisfaction is going to be to make me happy. Well, I certainly can't argue with that as a philosophy. Generally speaking, I think the world would be a much better place if more people made my happiness their goal in life. The letter was signed: Colleen Abdoulah Hugger, Mother, Keeper of the Culture CEO and Chairwoman of the Board WOW! Internet, Cable and Phone I know it's silly, but how can you not trust a CEO who bills herself as "Hugger, Mother, Keeper of the Culture." Quite apart from anything else, this letter was presented in such a happy and flamboyant style (unlike the dross one usually receives from big companies) that I find myself all enthused with great hopes for the future. So, am I easily pleased, or easily fooled?  

This is going to be a different kind of article for me. As I was planning it, I considered several possible topics. I couldn't decide which one to cover, so I decided to cover them all. You may find some of them incomplete—I'm giving you my thoughts as I'm having them. I welcome your thoughts and comments.   Vector/Matrix class redux Whenever I set out to (re)create a vector/matrix math package, I always wrestle with the decision: should I include separate functions for the special case where the vectors are dimensioned 3, and the matrices, 3×3? Clearly, classes that can handle general, n-dimensional vectors and m × n matrices can also handle the case m = n = 3. On the other hand, it's certain that if we know in advance the dimensions of the objects, the code will be a little faster and more compact.   While it's important to be able to deal with general forms of the mathematical entities called vectors and matrices, there's a good argument for the specialized functions as well.   We live, after all, in a three-dimensional universe (unless your field is String Theory). Most of the computations I do—space mechanics, rocket and aircraft dynamics, robotics, dynamic simulations—involve the motions of real, physical bodies in this three-dimensional space. It's the discipline called dynamics, whose math is defined by Newton's laws of motion.   The mathematical entities called vectors and matrices weren't exactly invented specifically to deal with physics problems, but they might as well have been. The simplifications that result from their use in physical problems is so profound, it's hard to over-emphasize the point.   That being the case, I'm always tempted to define special computer functions to process 3-d vectors and matrices. Usually I succumb to the temptation. When I was developing the C++ classes called Vector and Matrix , I wrestled with the same decision. For the sake of brevity, I chose to omit the special 3-d case. For the column, I was focused more on showing you the principles rather than defining a production-quality library of functions.   However, the argument for the special case is even stronger than usual, when defining C++ classes. That's because my general-case solutions required dynamic memory allocation . Any time we declare a new object of a certain class, whether it be a named variable or an anonymous temporary, the compiler is going to have to invoke the memory manager. That's a given. But in my general-purpose functions, I also had to dynamically allocate the storage for the object's member data, because we don't know the size of the data until the constructor is invoked. So with every declaration of one of the general-purpose objects, we get a double dose of memory allocation .   If you declare all named objects statically, you can move most of the memory allocations to the initialization phase of the programs. We might do this, for example, when writing flight software for a satellite or missile.   But if you make use of those lovely overloaded operators, you can't avoid the creation of temporary objects, and the overhead to construct and destruct them.   Finally, there's the issue of the vector cross product, which only works for 3-vectors. In our n-vector class, I had to include tests to make sure that both vectors were, in fact, dimensioned 3. That's not a problem in the special case. (Optional for extra credit: some of us gurus in the know, know that the cross product isn't really limited to 3-vectors. There's a 4-d cross product as well. If you're "one of us," drop me a line. Say the magic word, "quaternion," and I'll send you the Secret Decoder Ring Tone.)   If we know in advance that all the vectors will be dimensioned 3, and matrices, 3×3, the double dose of dynamic allocation goes away.   The situation with respect to matrices is even nicer. If you followed the creation of the Matrix class, you'll recall that we struggled with the issue of allocating matrices with arbitrary dimensions. Because C/C++ doesn't support conformant arrays, we can't just declare the array data in the form:   double x ;   Instead, we had to resort to defining a single-dimensioned array and generating our own code to index into it. This isn't a problem for the 3×3 case. We simply declare the array:   double x ;   and let the compiler use its own indexing, presumably optimized out the gazoo.   Recently, I had occasion to do a lot of computations in the 3-d universe. So I succumbed to the temptation and wrote a new C++ class called ThreeVec . As the name implies, the class is specialized to the case of 3-d vectors. I'm going to show it to you, but in a rather unconventional way. Instead of walking you through all the design decisions yet again one more time, I'm simply going to post the files on Embedded.com. I think you'll find that the differences between the n-vector and 3-vector cases are straightforward enough so that you won't need me leading you by the hand. Please let me know if you need more help.   Do something ... For the same project, I also need a class for 3×3 matrices. I'll tell you about it soon, but first I have a confession to make. I have a character flaw (No! Really?).   I'm basically an optimizing sort of fellow. Before I do anything, I tend to look at the options, weigh them carefully, and choose the one that's, in some sense, optimal. I'm the guy who tries to guess which lane I should be in at a traffic light. There's no malice involved, no jamming my way in front of someone else. But given a choice, I'll choose the option that's most likely to get me where I'm going sooner with fewer hassles.   This tendency to optimize can be both a blessing and a curse. A blessing in that the code I generate is usually pretty good. A curse because it takes me longer to produce it. Because I'm looking for the best solution, I can never keep up with the software wizard who simply codes the first thought that comes to him.   In another lifetime, I built and raced midget cars. My kids also raced, and I was their chief mechanic. Naturally, optimizing the route to the front is a good habit for a driver, and I was pretty good at it. But optimization is also good when deciding how best to tune or modify the car. When it came time to make a modification, I'd find myself spending considerable time trying to optimize the design. The design optimization process goes something like this:   while(1){ if(option(a) option(b)) return a; if(option(b) option(a)) return b; }   The problem, of course, is that there's no predicate for equality. If I can't find a clear reason to choose one option over the other, I'm paralyzed into inaction, stuck in an infinite loop.   This sometimes happened when I was planning a new modification. I'd sit in the garage, holding the parts I could use, and literally weighing my options. I'd look at the parts in one hand, and see advantages in using them, but also disadvantages. I'd look at the other and see a different sets of pros and cons. I could find no clear winner.   Fortunately, my decision-making system had a priority interrupt. Not hearing any work being done, my wife would open the door behind me. She'd shout, "Do something, even if it's wrong!!!" and slam the door again. This interrupt was usually enough to jog me out of the loop.    

The sun can be the cause of more than just a nasty sunburn in the world of technology.  Harmful solar radiation can, in certain instances, cause satellites to experience glitches, lose communications with earth, and even damage incredibly expensive components.  One such instance, a major coronal mass ejection (CME) triggered by sun spot "930" in late 2006, forced numerous satellites to power down or go into "safe mode" in order to avoid damage.  In the past these CMEs have knocked out satellites and tripped terrestrial power grids.  These storms can arrive in moments with little warning, and in the future it is quite possible that an even larger storm could cause irreversible damage to communications systems the world over.   In addition, for Low Earth Orbit satellites at or around 6,000 km orbit face increasing difficulties with the South Atlantic Anomoly (SAA), an ever growing spot between Brazil and Southern Africa where the earth's Van Allen belt of electro-magnetism is weakening.  Since it's discovery in the 1950's its borders have grown steadily in the North, Northwest, Northeast, and East.   When satellites within this orbital range pass through the SAA it is necessary for them to shut down as they recieve abnormally high proton bombardment exceeding 10 million electron volts.  As the region continues to expand, with several scientists believing this may be the beginning of a full polarity shift, it will become increasingly important for telecommunications, aerospace, and satellite designers to seek long term solutions to avoid very costly and irreversible damages.   One theory, stumbled onto by an international team of scientists in 2008 is to bathe the skies in radio waves.   The scientists indicated that magnetospheric electrons can be discharged into the atmosphere by using ground-based radio transmitters.   In the future, during periods of intense solar activity there could be a system in place to bathe the sky in radio waves, allowing the safe passage of satellites.   While this is still largely untested, it represents an exciting possibility for the future of this industry.  In the near future, the sun, man's greatest ally, may pose a very real problem for our telecommunications and aerospace industries.  If we are aware and prepared, hopefully this issue can be overcome in order to save millions of dollars in potential damages.