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February 18, 2010

Weird & Wireless: What is the coolest and most practical math equation?

Welcome again to the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International.

I know that many of you will look at the topic of the blog and give a big "ick" or some other guttural sound that I don't know how to spell. To you, I offer my sympathy. Of course, for the rest of you that choose to read on, you may be wondering what in the world this topic has to do with a wireless blog.

For you, I confess that my mind has been rejuvenated by what I will term cool math thoughts and the direct tie to wireless will need to be made clear in a future blog due to the length limitations placed upon me by the curators of the blog. For you, I request your patience.

Recently the eldest of my four sons went off to college. As a freshman at Arizona State, he has declared a major in math and psychology.

Continue reading "Weird & Wireless: What is the coolest and most practical math equation?" »

Posted by Alun Williams - Electronics Weekly.com on February 18, 2010 9:11 AM | | Comments (2) | TrackBacks (0)

February 11, 2010

Weird & Wireless: Microsoft versus Apple

Apple iPhone range small.jpgWelcome again to the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International.

Did the world's axial tilt just change?

As far as I know and after surveying the world's top scientists, there is no evidence of any kind of recent shift of the earth's axial tilt. Yet, I understand why people everywhere may be wondering about this.

From my own recent experience, something in the world has recently changed. Being a person in my mid 40s, my professional career has lived through the evolution of Microsoft Windows.

As such, from Windows 3.1.1 to Windows 95/97 to Windows NT to Windows ME to Windows 2000 to Windows XP and the curse of Windows Vista, I, like many, have become accustomed to learning how to kill locked up applications with task manager, the need for the daily reboot and the benefit of the cleaning reinstall to clean up my system.

Continue reading "Weird & Wireless: Microsoft versus Apple" »

Posted by Alun Williams - Electronics Weekly.com on February 11, 2010 11:39 AM | | Comments (0) | TrackBacks (0)

February 4, 2010

Weird & Wireless: Best way to connect iPods for car audio

iPod classic.jpgWelcome again to the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International.


What is the best way to connect an iPod into my car's audio system?

Okay, I admit it, I'm cheap.  I don't like overspending.  I always like to try to do things myself or get by piecing some lower-cost, good-enough solution together.   

So I don't drive a fancy new car with a dedicated connection for an iPod (or other portable music player).    

Most new cars today have a nice little port for connecting a music player.  Some even come with a fancy docking station built in.  Even with the cash for clunkers program, I couldn't justify to myself the need for a new vehicle.

Continue reading "Weird & Wireless: Best way to connect iPods for car audio" »

Posted by Alun Williams - Electronics Weekly.com on February 4, 2010 3:13 PM | | Comments (0) | TrackBacks (0)

January 28, 2010

Weird & Wireless: Why do we still have a land line phone?

Nokia N900 - Maemo 5.jpgWelcome again to the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International.

Why do we still have a traditional land line phone? In turns out that we don't need one.

Have you priced traditional landline telephone services lately?  I admit this is something that I haven't really paid much attention to until recently. 

I say recently, because like many out there, I've been spending time trying to figure out how to save a few dollars. 

In my household of six (counting my eldest in college), we have six cellular phones for six people. 

Continue reading "Weird & Wireless: Why do we still have a land line phone?" »

Posted by Alun Williams - Electronics Weekly.com on January 28, 2010 4:02 PM | | Comments (1) | TrackBacks (0)

January 22, 2010

Weird & Wireless: What happened to AT&T and Bell Labs?

att logo.gifWelcome again to the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International.

What happened to AT&T and the venerable Bell Laboratories?

I know some of you will look at this question and say - AT&T is still around, I keeping seeing ads for all sorts of AT&T stuff. Isn't it the largest cellular carrier?

Well, the answer is of course yes, but I'm actually talking about the original AT&T, the one that invented telephony. The company who, with its research arm Bell Laboratories invented the transistor, the laser, the Unix operating system, and color television, just to name a few.

Continue reading "Weird & Wireless: What happened to AT&T and Bell Labs?" »

Posted by Alun Williams - Electronics Weekly.com on January 22, 2010 1:13 PM | | Comments (0) | TrackBacks (0)

January 14, 2010

Weird & Wireless: Why do we still have freephone numbers?

Swiss bakelite phone.jpgWelcome again to the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International.

Why do we still have 800/888 numbers?

The toll free 800 number was born out of the long distance era. I call it the long distance era because that was where the "value" was in voice telecommunications.

We have since moved beyond this era, but a remnant, the 800 number still remains. Recently I discovered that many of the younger generation aren't familiar with the whole concept.

Continue reading "Weird & Wireless: Why do we still have freephone numbers?" »

Posted by Alun Williams - Electronics Weekly.com on January 14, 2010 11:25 AM | | Comments (1) | TrackBacks (0)

January 7, 2010

Weird & Wireless: Practical use of wireless power over 10 feet

capacitance plates small.jpgWelcome again to the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International.

So all of Tesla's work was cool, but how about a practical use of wireless power for say 10 to 20 feet?

Okay - well I acknowledge that, as cool as Tesla's work was, it probably isn't very practical in today's world for all of the obvious reasons.

Nonetheless, we can still learn a lot from this work as to how it relates to other wireless power solutions under development today. Unfortunately, while promising experimentally, wide availability of products has not yet been realised, but it is only a matter of time and I'm convinced that we will see easy to use, cost effective, personal area wireless power within the next few years.

But how will it work? Other than solutions like harvesting RF, the cornerstone for practical wireless power is related to some type of inductive coupling.

Continue reading "Weird & Wireless: Practical use of wireless power over 10 feet" »

Posted by Alun Williams - Electronics Weekly.com on January 7, 2010 11:46 AM | | Comments (0) | TrackBacks (0)

December 17, 2009

Weird & Wireless: How can wireless power transmission work?

weird and wireless fig 3 detail.jpgWelcome again to the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International.

In the last post I teased you by first stating that the traditional transverse electromagnetic wave method, i.e. how the sun works, doesn't scale very well for more moderate systems on the earth and second, telling you that Nikola Tesla had figured out a better way.

Unfortunately I didn't give you any details. However, before we get into too many details, we need to understand a few things about waves and the need to guide them.

Continue reading "Weird & Wireless: How can wireless power transmission work?" »

Posted by Alun Williams - Electronics Weekly.com on December 17, 2009 11:01 AM | | Comments (2) | TrackBacks (0)

December 10, 2009

Weird & Wireless: What about wireless power transmission?

Welcome again to the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International.

With everything going wireless, what about wireless power transmission too?

This is probably one of my favourite and most complicated topics to cover. As most of us know, the wireless transmission of electric power using traditional electromagnetic transverse waves is not practical.

Continue reading "Weird & Wireless: What about wireless power transmission?" »

Posted by Alun Williams - Electronics Weekly.com on December 10, 2009 10:41 AM | | Comments (0) | TrackBacks (0)

December 4, 2009

Weird & Wireless: How can light have temperature?

cc rainbow from plane.jpgWelcome again to the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International.

When I go to buy a light bulb, the packages seem to indicate light or colour temperature in something called Kelvin. What is this and how can light have temperature?

For me this is a really fun topic because it connects a label on the packaging of common consumer product, i.e. light bulbs, to some of the cool properties of thermal radiation, worked on by such physics legends as Max Planck and Albert Einstein.

In fact, these very properties helped disprove many of the commonly held notions surrounding classical physics, replacing them with the modern notion of Quantum mechanics.

Continue reading "Weird & Wireless: How can light have temperature?" »

Posted by Alun Williams - Electronics Weekly.com on December 4, 2009 3:29 PM | | Comments (0) | TrackBacks (0)

November 26, 2009

Weird & Wireless: CFL, LED, and the incandescent bulb

cc light bulb.jpgWelcome again to the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International.

I keep hearing about CFL and LED. What's the difference between these types of light technology and the classic incandescent bulb? Which is the best?

Of course, in today's world, we are all being encouraged to discard those ancient incandescent bulbs for the new compact fluorescent lamps (CFL) and light emitting diodes (LED), which for most of us seem really expensive to buy.

I admit that I never really liked the traditional tube fluorescent lights, probably because first, I always have trouble getting the bulbs in - it seems that I always have them out of alignment and second, I usually buy cheap lights that have ballasts that go bad. But I must admit, now that I've started using the screw in CFLs (like the one pictured), I've had quite a change of heart.

Continue reading "Weird & Wireless: CFL, LED, and the incandescent bulb" »

Posted by Alun Williams - Electronics Weekly.com on November 26, 2009 10:15 AM | | Comments (2) | TrackBacks (0)

November 19, 2009

Weird & Wireless: Differences between lumens, lux, candelas and watts

cc candle.jpgWelcome again to the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International.

When I go the store to buy light bulbs, I keep running into all of these different measurements. What is the difference between lumens, lux, candelas and watts and why should I care?

Different from the rest of the electromagnetic vocabulary, the most important thing to remember about the terminology around visible light is that it is a complete human construct related to our own perceptions.

In other words, the notion of visible light and associated colour only exist because we have eyes, i.e. antennas that tune into these frequencies of the electromagnetic spectrum. Now, once we accept this, the notion of all these units starts to make sense.

Continue reading "Weird & Wireless: Differences between lumens, lux, candelas and watts" »

Posted by Alun Williams - Electronics Weekly.com on November 19, 2009 10:33 AM | | Comments (1) | TrackBacks (0)

November 11, 2009

Weird & Wireless: "Line of Site" changing closer to the receiver

weird n wireless line of sight 101109.jpgWelcome again to the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International.

How does "Line of Site" change for a given distance as one gets closer to the transmitter and receiver?

In a previous post we discussed the notion of a Fresnel Radius which defines the "stay clear" area as the sort of official definition of "Line of Site." In this case one of the things that I pointed out was that this stay clear zone got bigger with respect to wavelength and distance. In doing so I showed a picture similar to the one below.
 
The Fresnel Radius R above at the midpoint between transmitter A and receiver B was √(Λ D) / 2, where Λ was the wavelength and D and R are all measured in meters. Since that time I have received a number of queries about how this radius changes as one gets closer to the transmitter A and receiver B.
 

Continue reading "Weird & Wireless: "Line of Site" changing closer to the receiver " »

Posted by Alun Williams - Electronics Weekly.com on November 11, 2009 10:25 AM | | Comments (0) | TrackBacks (0)

November 5, 2009

Weird & Wireless: Passive antennas and gain

cc antenna setup.jpgWelcome again to the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International.

Since most antennas are passive devices, how can they actually have gain?

Before I knew anything about the language of radios, this was always puzzling to me. I always thought I understood it for those fancy, powered antennas. It always seemed to make sense that some powered antenna would have an amplifier in it that would enhance the signal going out or in.

But the whole concept of a passive antenna was a mystery.

So, for those of you that are in the dark, but afraid to admit it, the only thing you really need to do is to think in the language of radios.

Continue reading "Weird & Wireless: Passive antennas and gain" »

Posted by Alun Williams - Electronics Weekly.com on November 5, 2009 10:45 AM | | Comments (0) | TrackBacks (0)

October 30, 2009

Weird & Wireless: What happens when an RF hits an obstacle?

Welcome again to the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International.

Let's get beyond line of sight. What's the definition of an obstacle and what happens when an RF hits one?

In previous blogs we discussed the concept of free space loss as it relates to spherical expansion from an isotropic transmitter, a.k.a. an inverse square law. We also covered the frequency dependency of propagation in free space as defined by the aperture of an isotropic receiver.

Most recently, we introduced a piece of wisdom from Augustin Fresnel which provides the basis for what is commonly referred to as "line of sight." Unfortunately all of these concepts present us with a set of rather big problems, because they are all based on "IDEAL" situations.

Continue reading "Weird & Wireless: What happens when an RF hits an obstacle?" »

Posted by Alun Williams - Electronics Weekly.com on October 30, 2009 10:25 AM | | Comments (1) | TrackBacks (0)

October 21, 2009

Weird & Wireless: RF "Line of Sight"

RF Line of Sight.jpgWelcome again to the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International

What does "Line of Sight" really mean in the RF world?

When discussing wireless solutions, invariably the first question asked is something like, "What kind of range will I get?" or "How far away can the radios be placed?"

Rather than give the proverbial "It depends" answer, I've noticed that those of us talking about wireless solutions tend to give the theoretical maximum distance followed by the phrase "line of sight."

Continue reading "Weird & Wireless: RF "Line of Sight"" »

Posted by Alun Williams - Electronics Weekly.com on October 21, 2009 8:10 AM | | Comments (0) | TrackBacks (0)

October 16, 2009

Weird & Wireless: Signals getting weaker in free space

Mars orbiter.jpgWelcome again to the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International

I get the inverse square law, but how does frequency factor into the mix when it comes to a signal getting weaker in free space?

In a previous blog we discussed the impact of the inverse square law on an isotropic transmitter. As such we came up with the observed power per unit area was related to the inverse-square of the distance from the transmitter, commensurate with the surface area of a sphere, or 1 / 4πr2, where r is the distance.

The problem here is that we are told that lower frequency (or longer wavelength) signals "go farther" in free space than higher frequency (or shorter wavelength) signals. This inverse square law says nothing about wavelength or frequency.

So what gives?

Continue reading "Weird & Wireless: Signals getting weaker in free space" »

Posted by Alun Williams - Electronics Weekly.com on October 16, 2009 11:35 AM | | Comments (1) | TrackBacks (0)

October 9, 2009

Weird & Wireless: Why don't wireless transmissions go on forever?

saturn.jpgWelcome again to the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International

If there's nothing in the way, why don't wireless transmissions appear to go on forever?

For those of you that are already experts in physics and engineering, you will most likely find this blog a bit elementary for you.

Nonetheless, I'm writing it because I routinely get asked questions similar to this one on a daily basis. Many see a bit of contradiction. For example, the stars in the sky are clearly very far away and millions of light-years and the visible and non-visible radiation still seems to make it all the way to us on earth, yet it seems that some radios die out quickly even when there aren't any obstacles in the path.

So the short answer is that all of these waves, unless they run into something and get absorbed or scattered will theoretically go on forever at the speed of light.

Continue reading "Weird & Wireless: Why don't wireless transmissions go on forever?" »

Posted by Alun Williams - Electronics Weekly.com on October 9, 2009 11:24 AM | | Comments (0) | TrackBacks (0)

September 30, 2009

Weird & Wireless: Adding solar power to your home

Roof Solar Panels.jpgWelcome again to the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International

See also: Weird & Wireless: Adding wind power to your home

What kind of impact can I get by adding solar power to my home?

Last week I set off to try to look at how I could self generate a good chunk of the electric power for my house. This is part 2 of a two part blog on green power. Why not solar?

As a reminder, my house sits on the top of a hill with a moderate line to the southern and western skies and uses on average about 24,000 kWh per year. At an average rate of 10.5 cents per kWh, electricity costs me over $2,500 per year. Like most, the usage goes way up during the summer months.
 

Continue reading "Weird & Wireless: Adding solar power to your home" »

Posted by Alun Williams - Electronics Weekly.com on September 30, 2009 10:16 AM | | Comments (0) | TrackBacks (0)

September 23, 2009

Weird & Wireless: Adding wind power to your home

Skystream.jpgWelcome again to the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International

What kind of impact can I get by adding wind power to my home?

Contrary to what I thought going into it, I've discovered that it's not yet all that easy or cost effective to be really green, at least when it comes to being electrically self-sufficient (at least in my neighborhood).

The past few weeks I set off to try to look at how I could self generate a good chunk of the electric power for my house. This is part one of a two part blog on green power.

Why not wind? My house sits on the top of a hill with, what I've thought was, typically a steady breeze. Now it turns out that my house uses on average about 24,000 kWh per year. At an average rate of 10.5 cents per kWh, electricity costs me over $2,500 per year.

Continue reading "Weird & Wireless: Adding wind power to your home" »

Posted by Alun Williams - Electronics Weekly.com on September 23, 2009 8:41 AM | | Comments (2) | TrackBacks (0)

September 9, 2009

Weird & Wireless: What's up with Antennas?

cc antenna.jpgWelcome again to the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International

What's up with Antennas? Some are short, some are long, some are round, some are straight - what gives?

For me there has always been something magical about antennas. Unfortunately, I never really did all that well in my antenna theory classes in school and now that I'm a bit wiser, I realize it would take hundreds of thousands of words to do antennas justice.

But, I'm not usually one to back away from a challenge, so let's see how far we get in a few hundred words.

First, remember that the job of an antenna is to convert electro-magnetic waves to an electric current matching the same pattern. This current is then amplified, filtered and decoded in the radio's receiver resulting in some communication - it might be music, it might be data, it might be voice.

Continue reading "Weird & Wireless: What's up with Antennas?" »

Posted by Alun Williams - Electronics Weekly.com on September 9, 2009 8:55 AM | | Comments (0) | TrackBacks (0)

September 3, 2009

Weird & Wireless: Why do mobile phones cause noise on my office speaker phone?

polycom speaker phone.jpg
I have a lot of conference calls in my office where a number of us are clustered around a speaker phone. It is one of those spider shaped Polycom devices and it used to be, that whenever we were on a call, someone's phone would cause a pulsing like noise on the phone.

It still happens today, but not as often and not as badly. You might think that we are getting fewer calls and fewer messages, but that's not it. So what gives?


Continue reading "Weird & Wireless: Why do mobile phones cause noise on my office speaker phone?" »

Posted by Alun Williams - Electronics Weekly.com on September 3, 2009 8:15 AM | | Comments (1) | TrackBacks (0)

August 27, 2009

Weird & Wireless: Does unplugging all your wall-warts really matter?

ganton street power switch small.jpgWelcome again to the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International

In the spirit of green, there has been a lot of talk lately about the need to unplug all those unused wall-warts (also known as those little black transformers that seem to be required for most every little electronic gadget).

Convention says these wall-warts consume some power when they are plugged in, even if there is no load.  Typical items are battery chargers, etc.  When we stretch our analysis a bit, we also recognize that there are many electronic gadgets that remain plugged in and consume power when they are turned off. Typical items here are your DVD player, television, etc. We like to think of these devices as "sleeping."

Continue reading "Weird & Wireless: Does unplugging all your wall-warts really matter?" »

Posted by Alun Williams - Electronics Weekly.com on August 27, 2009 5:02 PM | | Comments (6) | TrackBacks (0)

August 19, 2009

Weird & Wireless: How did we end up with a kilowatt-hour?

Welcome again to the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International

How did we ever end up with something called a kilowatt-hour? The kilowatt-hour has always been, at least for me, one of the more puzzling of all the units of energy.

I know, for many of us we are continually embroiled in the metric vs. imperial system debate, this is a debate that I understand - miles vs. kilometres for example, both seem reasonably arbitrary for me.

However, the kilowatt-hour is an abomination, created by someone who forgot what they learned in physics. Ever since we changed our first light bulb, we have been familiar with the almighty watt. We might not have completely understood the nuances of the watt, but it didn't take us long to figure out that light bulbs with more watts, are brighter and hotter. The bill payers in our house were noticeably irritated when we left the lights with big watt numbers turned on.

Continue reading "Weird & Wireless: How did we end up with a kilowatt-hour?" »

Posted by Alun Williams - Electronics Weekly.com on August 19, 2009 5:30 PM | | Comments (6) | TrackBacks (0)

August 13, 2009

Weird & Wireless: Why is the use of cell phones discouraged around petrol pumps?

cc no gas.jpgWelcome again to the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International

This is another one of those puzzlers for me. I've noticed recently that the number of posted signs prohibiting cell phone usage around gas pumps in the US has gone down. Often times they seem to disappear when the pumps are upgraded or replaced. So what's the deal? 

Well, let's look at what we know: Gasoline really only burns in its gaseous state, not in the liquid form. This is why you may have heard someone say that you could extinguish a cigarette in a bucket of gasoline. DON'T try this.

For a while the liquid gasoline will most definitely extinguish the cigarette and the path the cigarette has to take to get to the liquid will have it move through gasoline vapour mixed with oxygen - a deadly combination.

Continue reading "Weird & Wireless: Why is the use of cell phones discouraged around petrol pumps?" »

Posted by Alun Williams - Electronics Weekly.com on August 13, 2009 4:05 PM | | Comments (12) | TrackBacks (0)

August 6, 2009

Weird & Wireless: What is the difference between a human eye and an antenna?

cc eye.jpgWelcome again to the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International

As we grow up, until perhaps we enter our second physics class, we are never really taught that what we call visible light and other wireless things in the electromagnetic spectrum are really the same stuff.

Of course I very well realise that because the readers of this blog are naturally more intelligent than those non-blog readers, you all are well equipped with this knowledge.

Nonetheless, I think it is rather fun to consider that our eyes are perhaps the most advance antenna system ever created.

Continue reading "Weird & Wireless: What is the difference between a human eye and an antenna?" »

Posted by Alun Williams - Electronics Weekly.com on August 6, 2009 10:12 AM | | Comments (1) | TrackBacks (0)

July 30, 2009

Weird & Wireless: What's the deal with electronics and radios on airplanes?

Quantas aircraft.jpgWelcome again to the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International
I must admit I was somewhat reluctant to address this topic because there has already been a lot written and I fly a lot and I definitely don't want to offend anyone trying to keep me safe on an airplane.

Nonetheless, I was encouraged by one of my co-workers today as we pondered many of life's mysteries. So for those of you who fly, you know that that there are at least a couple of things that are puzzling about electronics usage (or maybe more).

First the flight safety speech says that during the flight, once it is declared safe, you are not allowed to use "televisions, radios, cell phones or any other electronics that operate in a transmit mode."

Continue reading "Weird & Wireless: What's the deal with electronics and radios on airplanes?" »

Posted by Alun Williams - Electronics Weekly.com on July 30, 2009 10:30 AM | | Comments (13) | TrackBacks (0)

July 24, 2009

Weird & Wireless: Can batteries be left out in the cold?

battery black.jpgWelcome again to the new series of posts on Electro-ramblings concerning the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International

Why are we told to store batteries in the refrigerator to preserve them even though battery life seems so poor when electronics are left out in the cold?

The thing I love about batteries is that they seem so utterly unpredictable and even nonsensical - as if to defy all logic - but once you understand their true nature, they make perfect sense. The first thing we must remember is that all batteries are little chemical power generators - as such, they are subject more to the rules of chemistry than they are electromagnetics.

One of the common laws of chemistry is that reactions generally speed up when they get warm and slow down when they get cold. Such is the life of a battery.

Continue reading "Weird & Wireless: Can batteries be left out in the cold?" »

Posted by Alun Williams - Electronics Weekly.com on July 24, 2009 10:31 AM | | Comments (2) | TrackBacks (0)

July 6, 2009

Weird & Wireless: GPS, and how do those satellites know where I am?

tom tom navigation.gifWelcome to a new series of posts on Electro-ramblings concerning the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International


As far as I can tell, my GPS unit doesn't have a transmitter, so how do those satellites know where I am?

When I was a freshman engineering student at the University of Southern California in 1982, I got to go on a tour of TRW's Space Division where I saw one of the first GPS satellites being assembled. We were told that this technology was going to revolutionise navigation. Yet I couldn't help but wonder how the satellites would know where I was.

Today that thought reminds me of a trip to the mall when my children were very young. We looked at the mall map and found the label saying, "You are here" and my son asked me how the mall people knew where we were.

So goes the world of GPS. GPS technology has evolved over the past 27 years and become much more accurate. Nonetheless, the basic principle remains the same and you don't have to be an RF expert or a math wizard to understand it. With GPS, most of the satellites know very little except the exact time.
 

Continue reading "Weird & Wireless: GPS, and how do those satellites know where I am?" »

Posted by Alun Williams - Electronics Weekly.com on July 6, 2009 8:43 AM | | Comments (5) | TrackBacks (1)

June 29, 2009

Weird & Wireless: Do microwave ovens cause cancer?

microwaves.jpgWelcome to a new series of posts on Electro-ramblings concerning the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International

Unfortunately, I'm not a cancer expert and I believe that there are things in this world that we may not think cause cancer that really do, and others which we believe cause cancer that really don't. I also am very will willing to admit that I've always loved microwave ovens because they seem to magically create something out of nothing - or rather initiate changes in the name of heat.

This love of microwaves has the tendency to cause me to give the microwave the benefit of the doubt when some accuse it of being a harmful device.  

Nonetheless, I've found that when questioned, most people actually believe that microwave ovens do nasty things, similar to X-rays or Gamma-rays, and provide dangerous effects.

Continue reading "Weird & Wireless: Do microwave ovens cause cancer?" »

Posted by Alun Williams - Electronics Weekly.com on June 29, 2009 8:08 AM | | Comments (2) | TrackBacks (0)

June 22, 2009

Weird & Wireless: Why can I use a 2.4-GHz phone and 802.11 network at the same time?

Nokia n97_new_main.jpgWelcome to a new series of posts on Electro-ramblings concerning the wonderful but sometimes weird world of wireless comms, written by Joel Young, CTO of Digi International

Why am I able to use my 2.4GHz phone and still have a 2.4GHz 802.11 network work at the same time?

Questions like this concerning RF interference go back to a classic misunderstanding about modern day, digital radios. Especially since many people go off and buy a 5.8 GHz cordless phone because they are afraid that their WiFi won't work very well.

Interestingly enough, these are the same people that may use a Bluetooth headset while working on their WiFi enabled laptop or better yet, may use their Nintendo DS at the same time as playing on the Wii. Unfortunately, in order to give the answer proper explanation, we need to look to how radios have evolved in the past say 40 years.

Yes it is true that all of these modern radios operate on the 2.4 GHz ISM band, spreading their transmissions across the spectrum from 2.4 to 2.5 GHz. The key lies in that all of these transmissions are (1) digital and (2) use different encoding and modulation schemes.
 

Continue reading "Weird & Wireless: Why can I use a 2.4-GHz phone and 802.11 network at the same time?" »

Posted by Alun Williams - Electronics Weekly.com on June 22, 2009 8:08 AM | | Comments (0) | TrackBacks (0)

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