Archive for January, 2010

The UPS is beeping, the UPS is beeping!

Tuesday, January 26th, 2010

When the grid power does strange things around here, the UPS systems let you know. The NAS is connected to the Triplite via USB so it will know when it needs to shut down. The NAS will send an e-mail when it gets word from the UPS about going to battery power and whatnot.

The client computer on an APC UPS just beeps. It also beeps when grid voltage gets above 124v. Since the grid voltage goes over that threshold in afternoons this winter, the beeping can be annoying. The short term fix is to turn on a space heater. Even at the low, 800 watt, setting, the space heater will reduce the voltage to the UPS by 3 volts or so and stop the blasted beeping. The additional heat is, this winter, a nice side effect, too.

Then there’s the oven in the Kitchen. The gas valves don’t work if the grid voltage goes below about 108v. Since voltage drops like that were common this past summer, I had to put a Variac and meter on the line so the voltage could be adjusted to be closer to nominal to bake supper.

Low voltage was also a problem for the RV air conditioner parked in the driveway. For that, I used an autoformer manufactured for such problems. It provides a voltage sensing 8% or 16% voltage boost to prevent brownouts.

The source of these problems is probably a forty year old grid supply network. There are too many drops on the transformer and the drops are too long and their age may be taking a toll. The power company can only compensate so much so my UPS beeper gets exercise.

Dictionary of Algorithms and Data Structures

Thursday, January 21st, 2010

If you want to look up the definition of a software development term that you won’t be able to understand unless you already know the meaning, the NIST Dictionary of Algorithms and Data Structures might be a resource. Each definition seems to depend upon many other words in the dictionary and the links to those words can make for an interesting journey. I wonder if they get circular.

This is a dictionary of algorithms, algorithmic techniques, data structures, archetypal problems, and related definitions. Algorithms include common functions, such as Ackermann’s function. Problems include traveling salesman and Byzantine generals. Some entries have links to implementations and more information. Index pages list entries by area and by type. The two-level index has a total download 1/20 as big as this page.

If you don’t have a clue, the dictionary can be an interesting look at the terms and names and ideas that define software development and how they fit together. There are also links you can use to escape the dictionary into more complete treatments of the concepts, some with code.

My, how things change in communications

Friday, January 15th, 2010

K9EV talks about how communications infrastructure has been enhanced and hardened over the years in When Failure is Not an Option. Amateur Radio is no longer the option when failures in communications are remote.

There are stories about how Amateur Radio operators were first to hear the news of the Haiti earthquake but there is also the reality that one of the biggest disasters there is the failure of communications that even Amateur Radio could not fill. When all else failed, Amateur Radio wasn’t there, either. In the US, many cities or counties have extensive emergency preparedness plans that include communications capabilities. Amateur Radio no longer needs provide equipment or operating facilities as these local governments have specially prepared vans or trailers with equipment and supplies ready to go for emergency communications.

Then there’s the commercial communication infrastructure K9EV describes. Not only are cell phone towers being hardened for better security and capabilities to operate for up to a week in disaster scenarios plus redundancies to survive contingencies. That is supported by back-haul links to central exchanges and network redundancy that is also hardened. And the cell network is not the only ‘last mile’ link between consumers and the network as cable and other alternatives to the traditional battery operated hard wired telephone have become more reliable as well.

One big deal was in 1982 or thereabouts when the telephone company was required to allow connections of alien equipment to their POTS network. That had been a big problem for the autopatches hams used to facilitate connection between their radios and the commercial network. It was also an issue in the modem equipment used to connect computers for remote data access.

Behind the scenes was the telcos moving from traditional hard linked connections with embedded control signaling towards digital circuit systems with segregated controls systems. The old system was why ‘phreakers’ with ‘blue boxes’ could use tones to hack the system and get free long distance. The new system, the SS7 system, helped block this misuse and provided the opportunity for the telco to provide many new features.

Then there was the telecommunications act of 1996 that allowed ‘competitive’ local exchange carriers (CLEC) to access the switching facilities of the incumbent carriers (ILEC) that provided the wire link to the consumers. That paved the way to alternatives to the traditional telephone system and the integration of the SS7 backbone to the IP based I’net. That, in turn, made VOIP feasible.

The problem of cell phones in schools also demonstrates a part of this. School children are no longer amazed by simple crystal set radios and can-on-a-string intercoms. They have cell phones with cameras and music players and I’net access that their parents can used to keep track of them and that they can use to constantly communicate with their circle of friends using voice, text, or even video.

Obviously amateur radio will continue to stand in the gap providing emergency communication services wherever and whenever it is requested, … But we seem to have entered a phase where … our radio gear and communication know-how doesn’t add as much value as it did when our kind of wireless was the only wireless available.

I think we’re in need of some re-branding if we want to remain relevant.

The first commonly available public and popular wireless facility was citizens band radio (CB) that took off in the seventies. Since then, the Heathkit era faded as fabrication of electronic and electrical appliances became modular, integrated, and inexpensive and software took over many hardware functions. Many communications methods have become popular, useful, and reliable. Even the picture phone hypothesized as future tech in the 60′s has become reality with a miniature camera mounted at the top of a flat screen computer monitor that has enough picture quality to be embarrassing.

Since the rise of the CB era, the ‘Amateur Radio’ brand has needed a focus and direction that has not occurred. A unique and inexpensive way to chat over distance? gone. A resource for ‘when all else fails?’ handled. A build-it-yourself for cheap high grade equipment? can’t compete with COTS (commercial off the shelf). Leading edge communications technology development? you just try to build a GHz capable microchip that is software driven in your garage.

There is something left for a focus. That is people: operator training and public educations. Unfortunately, that aspect has also been diluted by government policy and tactical thinking.

The questions “who am I?” and “where, now?” are well overdue for the amateur radio community and the societies that allow them use of radio spectrum and other considerations.

Femtocells, VOIP, and cordless phones synthesis?

Thursday, January 7th, 2010

It has been a big change taking a lot of time. The landline telephone network started development just a bit over 100 years ago. Cable TV is less than half that and its expansion into networking is less than half of that. Cell phones have an age similar to cable networking of only a couple of decades.

It was a big deal when cordless phones could replace the old telephone sets in homes. Now that technology is up to DECT 6.0 standards with many features and, just as that standard is taking hold, another technology is encroaching on its territory.

Cordless household phones were only a small step towards wireless freedom. Those phones have only limited range and are still rather bulky. Cell phones, on the other hand, can be used nearly anywhere and are small, convenient, and packed with many features that make them much more than just a telephone. That is why the wired connections to houses business is shrinking.

Back towards the 1970′s you had to have specially certified equipment to connect to the telephone network and that network was the only readily available public method for communications. That gave Amateur Radio operators headaches as they built the interface between their hobby equipment and the telephone networks to extent the utility of their services in emergencies. It also raised costs on early data modems and other equipment that connected computing devices.

That monopoly was broken and now the back end networks are separated from front end consumer access points. Ironing out the standards to keep all of these parts functionally integrated has been a difficult process and is still suffering rough spots. What has happened is that there are now many ways to get into and out of the back end network and cost and pricing pressures are stimulating innovation.

VOIP is old hat now. The next step may be that of circumventing the front end cell network to be able to use common cell phones to connect more directly to less expensive I’net service points while still retaining the cell network access. This is where the femtocell idea comes in. (see Airvana Femtocell Technology)

Femtocells have the potential to transform communications by making the mobile device the tool of choice even in home settings.  However, vendors and operators face substantial technical challenges to realize the potential of femtocells.  For example, femtocells will increase the number of base stations by several orders of magnitude over the existing “macro” base station infrastructures.  This increase will demand new approaches to areas such as mobility and interference mitigation.  At such volumes, femtocell vendors will also need to follow an aggressive cost curve.  Femtocells will require new approaches to installation and configuration, because they will be installed by non-technical users.

Where the shift occurs is in the purchase of I’net services via an ISP and then using various service providers for such things as addressing such as telephone numbers and access methods. The interface out the the PSTN (public service telephone network) is the province of VOIP providers and they use either computer audio (e.g. Skype) or dedicated phone set to I’net devices (e.g. Vonage, Teleblend) or phone set to computer interfaces (typically USB) like Magicjack. These devices make it possible to use an existing I’net backbone like a regular telephone and that means that the costs for long distance and other such features are paid for in a customized way between your ISP and your VOIP provider.

Now it looks like Magicjack is going to provide a femtocell option (CES PSA) to build on their POTS to USB service interface. This means that you can ‘introduce’ your cell phone to the femtocell and then your cell phone calls will use that access point rather than a cell phone tower when you are in range of the femtocell. Since you don’t access the cell network, your cell phone provider should not charge you for the use of the phone when using the femtocell. What that means is that your cell phone acts like an old cordless phone around home except that is will still work when you are away from home, will be more compact, and may still have many features the cordless doesn’t have.

The portability aspects for travelers also have interesting implications. The Magicjack is intended to be portable so it can be used wherever there is a decent high speed I’net connection. If their femtocell works the same way, it means that you can reduce cell phone costs when traveling if you have access to a motel or RV park or other public access broadband service with your laptop.

Exactly when this will happen is a question. Magicjack has promised number porting and Linux capable software as being available ‘Real Soon Now’ and the wait has been extended. Someday. And someday, the femtocell, too. It is coming together and the pace, if looking back, is breathtaking. But seeing what is in the pipe can still be a frustration of anticipation.

pi calculator and FOSS hero

Thursday, January 7th, 2010

You may have heard (PhysOrg

A computer scientist in France has broken all previous records for calculating Pi, using only a personal computer. The previous record was approximately 2.6 trillion digits, but the new record, set by Fabrice Bellard, now stands at almost 2.7 trillion decimal places.

Which is impressive but there is more in the story. For one, “Bellard has been following the records for calculating Pi to the maximum number of decimal places since he received his first book about Pi at the age of 14.” Then there are other projects Bellard has done.

M Bellard is perhaps best known as the writer of the open source project FFmpeg and processor emulator QEMU. He said he has no immediate plans to calculate Pi to further digits in the future, but may do, depending on his motivation and the availability of larger and faster storage. He intends to release open-source versions of his software for Linux and Windows to enable anyone who is interested in furthering the calculation to beat him to it.

If you’ve been doing video transcoding, then you’ve appreciated Bellard’s work. QEMU is a system emulator that creates an artificial hardware environment to allow running systems within systems.

The mathematical ideas behind pi are fascinating in themselves but then there is the math behind arbitrary precision numbers and the infinite series calculations and algorithms used to calculate values such as pi out to a precision that would take an entire bleeding edge hard drive to store in decimal notation.

And then to think that the computers that can do this sort of calculation in weeks are readily available to anyone.