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Another project post! Huzzah! The post will provide some detail on how I installed my Yaesu FT-1900 into my truck. Unfortunately, I only thought about cataloging the install after I had completed, so you only get finished project pictures instead of the fun, chaos-filled everything-ripped-apart pictures.

I finally got my Ham license back in January, which I discussed in this post. Now that I’m out of school and have some real free time, I’ve been using my amateur radio equipment on a regular basis. I’ve been volunteering a lot, having joined the Maricopa County Emergency Communication Group, and have been helping out with event communications. As the heat has finally begun to recede, the number of outdoor events has begun to skyrocket; the MCECG has been supporting 4 or 5 events a weekend since mid-October. A number of these events happen out in the dessert or mountains, requiring 4×4 access which a lot of hams don’t have.

Well, I just happened to have an extremely fun 4×4 truck. And I just happen to have a 2m mobile ham radio. Sounds like the perfect combination. My job grants me every other Friday off, so I decided to take one of those days and install the radio.

It took me the better part of the day, but it was totally worth it. I have a clean, awesome looking radio install in my truck that works beautifully. This first post will discuss the project planning. Subsequent posts will discuss details and implementation.

Yaesue FT-1900 secured in place

Yep, that's my awesome truck. What's that, a second antenna?!

Stage 1: Planning

I cannot stress this enough. When doing any project, especially one with something as complex as a vehicle, there is no substitute for a good plan. There are a lot of things to think about when installing a radio in a vehicle. Where is the antenna going to go? Where will I get power? Where will I run the cables? Where will I mount the radio? Pervasive throughout all of these questions is safety. That’s a good spot, but is it safe? Is it close to any moving parts? How hot does that get? What about when the vehicle is moving?

For most amateur radio equipment, you will want to pull your 12 V lines for power straight off of the battery. This provides a couple of  benefits:

1. A clean (less-noisy) power source. You don’t want your alternator or spark plugs throwing EMI down the supply line into your radio. Best case you’ll get static in your TX and RX, worse case you could damage some of your more sensitive equipment. By tapping straight off of the battery and going directly to the radio, you are utilizing the battery as a very large, very stable capacitor; this will act as a filter to limit all that EMI coming from the rest of the vehicle’s components.
2. Ensures a safe current path. Most amateur mobile radios are often capable of putting out anywhere from 25 W to 100 W. That requires a fair bit of current. By pulling straight from the battery, you can ensure that you are using the correct gauge of wire for your current draw. The last thing you want is to key up your radio and have your wires melt; this is a very dangerous fire hazard.

For planning this project, I broke it down into 3 primary phases: antenna, power and radio. I will discuss the planning for each phase of this project in this post, watch for subsequent posts to describe implementation and details.

Antenna Planning

This first thing I started this project with was the antenna. Where was I going to mount it? What kind of antenna? How was I going to route the antenna feed line into the cab and to the radio? As with any project, I started with research. For any vehicle, the optimal location for any antenna is the dead center of the roof. This yields the largest possible height for any antenna while providing a large ground plane. After that, the other possible locations for my truck are hood/fender mounts, door mounts, mirror mounts, glass mounts, bed mounts and tailgate mounts. Talk about your choices.

I started with a few restrictions to help narrow down my search. First, I use my truck a lot. Not just for commuting but I love going camping, hiking, off-roading, mudding, trail blazing and all kinds of other fun things you can do with a 4×4 with big tires. Whatever antenna mount I end up with has to be sturdy and not get in the way with any activity I do. The second restriction is tied along with the first. I use the truck a lot, which means I’m constantly throwing stuff in and out of the bed. People, gear, trash, furniture, groceries, you name it. I don’t want any antenna getting in the way of that.

This limited me to antenna mounts on the cab and forward.  Of course, I would want the best performance, so the first thing I considered was the roof mount. The most popular roof mounts utilize a NMO connector with requires a 3/4 inch hole. Hmm, that’s kind of a large whole to drill in the roof of my truck. Then I would need  to route the antenna feed line down the ceiling of my truck, behind the seat and to the radio. Not exactly the cleanest looking install. I also would need to consider weatherproofing; don’t want water coming in the roof. There is also height to consider. My truck already sports oversize tires and a lift, adding a tall antenna to that will pretty much guarantee I’ll have problems parking, not to mention hitting trees and bushes.

That leaves fender and mirror mounts. I ruled mirror and door mounts out right away. I didn’t want an antenna whipping around every time someone opened or closed a door.  I started looking a fender mounts, handling a feeling a number of them before decided on the K412 SNMO mount from Diamond Antenna. This first thing I noticed about this thing was the weight. No aluminum here, this puppy is made from solid black anodized steel.

K412SNMO mount on the hood of my truck.

This mount uses the NMO connector many roof antennas use, allowing a wide variety of antennas to choose from. It is adjustable in three dimensions, allowing the user to achieve a nice, vertically aligned antenna on any surface. Normally I’m against adjustable mounts, as I’ve seen them fail and slip time and time again. But this mount has teeth for each joint, preventing slip even when not tight. The user has to undo the bolts and physically separate the parts to adjust them.

The next step was to look for an antenna. I didn’t want to add too much to the overall height of my truck, so I was looking for antennas under a meter. I also wanted a dual band 2m/70cm antenna. My FT-1900 is only a 2m radio, but I am planning on replacing it soon with a FT-8800, which will do both bands with cross-band repeat and I didn’t want to buy a new antenna. I ended up purchasing the SBB5NMO 146/446MHz Dual Band antenna made by Comet. Not only does it meet my requirements, but also posts a VSWR less than 1.5 and an impressive gain in both bands. It can also handle the power my FT-1900 and future FT-8800 are capable of putting out. Plus its black anodized finish matched the mount and the overall motif of my truck .

Power Planning

The next thing to plan was the route my power cables would take from my battery in the engine compartment to the radio inside the cab. My initial thought was to find other cables making this transition through the firewall and piggyback on to them. After a hour of poking around with a flashlight and disassembling my console and dashboard, I decided this wasn’t going to happen. All of the wire harnesses running through the firewall were tightly bundled and sealed against heat and moisture. Definitely not something I wanted to screw with. I started looking at other ways to get wire into the cab. After coming up with nothing I began searching around on-line and made a discovery. A large number of components in vehicles have to be screwed in from underneath, particularly mounts for seats. As such, there a numerous holes underneath my truck that allowed manufacture assembly access that are then sealed with rubber plugs. A quick trip under my truck provided me with a number of possible entry points into my cab. I could route the lines down out of the engine, along the vehicle frame and into the cab from under neath. Excellent.

The other important thing to consider in the power planning was wire. You need to use the right gauge for the current draw. My owner’s manual for my FT-1900 indicates that my radio draws approximately 13 A at 12V DC when transmitting at max power. Thus, I had to make sure to use 12 AWG wire rated for automotive use. I also need 15A fuses and fuse holders to protect the radio from my truck and my truck from my radio in case anything goes wrong with either. Thankfully, Yaesu provides the fuse holders with the purchase of the radio.

Radio Planning

Where the put the radio. It needs to be easily accessible when station and moving, yet not distracting. When not in use it needs to be out of sight. I wanted a clean looking install without wires dangling about and I didn’t want to see the antenna feed line or power line at all. Unlike some of the newer, more advanced models, my FT-1900 does not have detachable head capability. This allows you to install the bulk of the radio out of sight while mounting the slim control face plate someplace convenient. After 30 minutes of fidgeting and gather second opinions, I decided the only place the radio really fit and met all my requirements was in the center console. And even then just barely.

Coming next post: Installing and photos!

Electricity. Just about every single person in the country is dependent on it and the vast majority of them have no idea how it works. You want a fun experiment? Go up to someone and ask them what happens when you flip a light switch. It is 20 times worse than listening to the Internet being described as a series of interconnected tubes.

The recent disaster in Japan has set of a whirlwind of nuclear energy slandering around the world. I recently heard that Germany plans to shutdown all of its nuclear generation by 2020 (or somewhere around there). Given the country’s reliance on heavy industry, I find that pretty amazing. But wait, what does heavy industry have to do with this?

Electricity is a rather unique form of energy. Unlike the more common energy storage methods most people are familiar with, such as chemical (batteries, gasoline, food) and mechanical (springs, pendulums and weights), electrical energy is not easily stored. In fact, it must be consumed almost instantly after generation. This means that your utility company that you cut a cheque to (or online bill pay) is constantly playing a very delicate balancing game, trying to generate just enough energy to meet demand. Missing the mark high or low results in services outages, which we all see as blackouts.

This means that utility companies hate you and love commercial and industrial customers. Your demand varies throughout the day. You wake up, lights on and off, coffee maker, stove, then you go to work and your AC shuts off. When you get home, your AC kicks back on, lights on and off, TV and computers, you get the idea. Your use varies over the day by quite a bit. And what’s worse, there’s a million more people doing the same thing, so the swings in demand are huge. But industries, utilities love these guys. Sure they eat up a lot of energy, running big three phase motors, smelters and robot assembly. But they do it the same way, all day long, all night long, their consumption never changes. And that’s great because of the difficulty of starting a starting and stopping an electrical generator.

A utility company uses two kinds of generators. The first are the big, high output systems. These systems takes a long time to start up and shutdown, but are the biggest producers in terms of megawatts. The second kind of systems are smaller, faster response systems. These produce much less output but are much, much faster to start and stop and quicker to change their generation output.

What the utility company would like to do is setup their big generation stations and run them at a set generation output and have everyone be happy. Unfortunately, the demand doesn’t work like that. They have to run their smaller stations and adjust the output as the demand changes throughout the day. This is an expensive and delicate procedure and the utility company hates doing it. Not only because of the cost but because it is actually very hard to do and if they screw up even once then an entire city of customers wants to know why they don’t have power.

But that’s only the first half of the story. In a follow up post I’ll talk a little about generation methods and where nuclear and renewable energy fit into this balancing game.

I have, from time to time, become frustrated with user interfaces. I’m sure you have all had similar experiences. Ever try to use a iPod without any instructions or previous experience? How about switching between GUIs on different OS? Or even using the credit card machines in the grocery store? Sometime YES is on the left, sometimes right, sometimes top, sometimes bottom. It is absolutely ridiculous how maddeningly unintuitive some interfaces are. But when user interfaces come up in discussion it is often related to computers and other digital devices.

This leads me to my story. In the number of months that have gone by, I have picked up my Masters and a nice, professional job. Turns out, most professional jobs require professional clothing. Naturally, my younger sisters got super excited to go out shopping for clothes, dragging me in tow. While it wasn’t the most joyful experience, I was very appreciative for their help.

My user interface story starts when I get back to Phoenix, unpack and beginning the task of washing and ironing my new clothes. Being a direction oriented guy, I read the care labels.  Just about every tag reads:

Machine wash cold with like colors. Tumble dry low. Warm iron if needed.

Ok, fairly straight forward, I made a point of getting wrinkle resistant clothes, I like the bit about ironing. (Not that I don’t know how to iron, I just think there are better uses of my time.) Next step, examine washer and dryer for recommended settings. Washer, no problem. I got a cold wash, cold rinse setting and I’m not color blind. Next step, check dryer… ummm….

Options on the left of the dryer.

Ok, so start I got, that makes sense, 100% clear on the start. Next dial, temperature, excellent, looking for low here. Ummm… low? I am presented with, from left to right, Regular, Medium and Fluff. What the hell? What’s the difference between Regular and Medium? Thoughtfully, there is a subtext on Fluff that explains that no heat is used. But Regular and Medium? Well, let attempt to puzzle out the difference.

Here in North America, we do things left to right. In my car and most other gauges I’ve used, low something ( speed, pressure, fuel level) is on the left and high something is on the right. Well, here we have no heat on the right, so maybe this is backwards and Regular is actually more than Medium. But in clothing Regular and Medium are often used as the same thing, I know cause that’s the size I buy.

Either way, none of this pondering helps me because I still only have Fluff, Medium and Regular and no Low as specifically requested by the manufacturer of my clothing. Ok, don’t panic, let’s look at the other dial.

You have got to be kidding me.

What the hell does any of this crap mean? Timed dry, gotcha that makes sense. Cottons ok, I understand. Easy Care? What? None of my clothes are labeled easy care. And what the hell is this? More Dry, Optimum Dry, Less Dry? Optimum Dry, what the shit is that? Are you trying to tell me there are different types of dry? Like something can be too dry? What the hell is the difference?

I started with wanting “Tumble Dry Low” and my options are Medium or Regular heat with More, Optimum or Less Dry. This is ridiculous. What genus thought this up? This is a dryer in an apartment. I don’t know any tailors or dryer cleaners and part of me wonders if even they would know what this meant. I mean, judging by the layout I would say that one drys for longer, but how? Is it just timed? Is there a moisture sensor for some kind of feedback?

Just so you are not sitting there in suspense, I ended up getting an answer from a nice lady working at Avery Dennison who recommended Medium Heat, Easy Care Optimum Dry and to immediately remove the items when the cycle finished. That happened to work out great, but how is a user suppose to go from “Tumble Dry Low” to that just looking at the machine?

DISCLAIMER: Yes, I have been doing my own laundry for just over 13 years, after an ill fated attempt at demanding clean clothes from my mother. And yes, with a little work I could have puzzled it out or used the Internet. The point is, most user interfaces, and this one in particular, suck. Next time you have to use an interface, think about it. How would you see this if you had never used it before? If someone had never shown you? What if you were not familiar with the vocabulary? Brings a little insight to the rants and raves of your family during tech support calls doesn’t it?

Well after a nearly a year of talking about it, I finally have my Amateur Radio License  (Technician Class), joining the ranks of “ham” radio operators. Not from a lack of trying you see, but rather a lack of opportunity. The exams are not offered very often in Northern Arizona, the next examination session is at the end of April.

The Amateur Radio License is available in three classes, Technician, General and Extra. Each class grants more privileges in terms of transmit power and frequency, with Technician being the most limited and Extra the most privileged. Anyone with a basic knowledge of EE concepts should be able to pass the Technician (V=IR), however the General and Extra require a large amount of brute memorization of FCC guidelines. With the amount of time I’ve been putting into my thesis, I didn’t have the chance to study all that much, so I only obtained my Technician. However, a friend of mine (who needs a real domain name ) was a bit more dedicated and was able to pass all three exams and qualify for his Extra license in one sitting. Quite the impressive feat. Congrats again bud.

I have my 2 meter radio all set up and ready to go, just waiting for my assigned call signed from the FCC to appear in the database.  Then I can start transmitting!

P.S. As a side note, the ham community is mostly retired people and they love talking to and helping out younger hams like me, especially with an EE degree. If you have any interest in radio at all, look them up, they have tons of knowledge and experience and are more than willing to pass it on.

I run in to way too many people who talk politics and taxes and have no idea how it works.  I found this lovely piece by an econ prof and thought I would share it in attempts to educate those that are numerically challenged.

Suppose that every day, ten men go out for beer and the bill for all ten comes to $100. If they paid their bill the way we pay our taxes, it would go something like this:

The first four men (the poorest) would pay nothing.

The fifth would pay $1.

The sixth would pay $3.

The seventh would pay $7.

The eighth would pay $12.

The ninth would pay $18.

The tenth man (the richest) would pay $59.

So, that’s what they decided to do.

The ten men drank in the bar every day and seemed quite happy with the arrangement, until one day the owner threw them a curve. “Since you are all such good customers,” he said, “I’m going to reduce the cost of your daily beer by $20. Drinks for the ten of you now cost just $80.”

The group still wanted to pay their bill the way we pay our taxes.

So the first four men were unaffected. They would still drink for free. But what about the other six men — the paying customers? How could they divide the $20 windfall so that everyone would get his “fair share?”

They realized that $20 divided by six is $3.33. But if they subtracted that from everybody’s share, then the fifth man and the sixth man would each end up being paid to drink his beer. So the bar owner suggested that it would be fair to reduce each man’s bill by roughly the same amount and he proceeded to work out the amounts each should pay.

And so the fifth man, like the first four, now paid nothing (100% savings).

The sixth now paid $2 instead of $3 (33% savings).

The seventh now pay $ 5 instead of $7 (28% savings).

The eighth now paid $9 instead of $12 (25% savings).

The ninth now paid $14 instead of $18 ( 22% savings).

The tenth now paid $49 instead of $59 (16% savings).

Each of the six was better off than before.

And the first four continued to drink for free.

But once outside the restaurant, the men began to compare their savings.

“I only got a dollar out of the $20,” declared the sixth man, then pointing to the tenth man he said, “But he got  $10!’”

“Yeah, that’s right,” exclaimed the fifth man. “I only saved a dollar, too. “It’s unfair that he got ten times more than I did.”

“That’s true!” shouted the seventh man. “Why should he get $10 back when I got only two? The wealthy get all the breaks!”

“Wait a minute,” yelled the first four men in unison. “We didn’t get anything  at all. This system exploits the poor!”

The nine men then surrounded the tenth and beat him up.

The next night the tenth man didn’t show up for drinks, so the nine sat down and had beers without him. But when it came time to pay the bill, they discovered something important. They didn’t have enough money between all of them for even half of  the bill.

And that, boys and girls, journalists and college professors, is how our tax system works. The people who pay the highest taxes get the most benefit from a tax reduction. Tax them too much, attack them for being wealthy, and they just may not show up anymore. In fact, they might start drinking overseas where the atmosphere is somewhat friendlier.

David R. Kamerschen, Ph.D. Professor of Economics University of Georgia

Over the past 5 years the FCC has been talking about licensing the unused television broadcast channels for a kind of ‘Super-Wifi’ (we’ll get to this term in a minute).  As usual when in comes to the FCC and government actions, I’m skeptical. There’s a lot of buzz floating around the Internet about how awesome this is going to be and yadda yadda yadda, but most of the news is long on hope and short of fact. Let’s see if I can clear that up a bit hmm?

The original TV broadcast band was split into three frequency blocks: Very High Frequency low band (VHF-band I), Very High Frequency high band (VHF-band III) and Ultra High Frequency band (UHF).  VHF band I spans 54 to 88 MHz and is allocated to channels 2 to 6, VHF band III spans 174 to 216 MHz and is allocated to channels 7 to 13 and the UHF band spans 470 to 698 MHz and is allocated to channels 14 to 51. It actually use to go all the way up to 890 MHz and channel 83, but large chunks where reallocated for cell phone use and the infamous 700 MHz spectrum block that was recently auctioned off.  Oh, and don’t forget that channel 37 is reserved for radio astronomy use in the United States, Canada, Bermuda and the Bahamas.  Oh, and that channels 14 to 20 have been reallocated in certain areas.  Sounds kind of complicated doesn’t it? Just wait, it gets better.

The FCC’s plan is to allow manufactures to utilized unused TV channels for a new brand of wireless Internet. The problem is that different areas have unused TV channels. Before any of these new devices can operate, they have to query an FCC database with their location to see what channels they are allowed to use in that area. Sound clunky yet? Even better, because these channels have been in use by broadcasters for wireless mics and the like (think NFL games and Broadway shows) for years, there is a special caveat for them. They can tell the FCC when they need the channels for their own use and the FCC will update the database to prevent your device from using those channels.  This could seriously effect quality of service and I’ll tell you why.

The throughput of your wireless signal (11 Mbps, 54 Mbps, etc) is directly related to the amount of channel bandwidth you have available and the technology you use. The industry loves 2.4 GHz because they get nice fat channel bandwidth, around 22 MHz, to push their data through. The TV band is current split into 6 MHz channels, which isn’t really that great for a nice robust data connection. I would imagine the plan would be to combine TV channels into ‘Super-Wifi’ channels. But let’s say it is a Sunday afternoon and you are trying to use your new ‘Super-Wifi’ device. Ah, but the 49ers are playing at home and the FCC has just told all devices in the area you can’t use a selection of channels. Bam! Your awesome data connection drops to a crawl because you only have a few TV channels for your data to use.

Which brings me to this term ‘Super-Wifi’. I personally feel it’s a bit of a misnomer. For sure you won’t be getting  higher data rates than the original Wifi, you don’t have the bandwidth for it. You will get much longer distance, thanks to the propagation effects  of the lower frequency carriers. But you have to deal with this FCC database and worst of all, the QoS will very from place to place. How do you explain that to your consumer? Right now, if someone buys a wireless router and setups up there home, they get pretty much the same quality and some else across the country doing the same thing (unless they are all jammed into a college residence hall). But with this new ‘Super-Wifi’, quality will have a direct impact on location.

I have no doubt that the EE’s around the world can make awesome device that will work great and overcome all the problems I have mentioned. But what do we actually need this additional bandwidth for?  Can you actually say that you are legitimately using all the bandwidth in your 802.11n router? That you need to have greater than LTE download rates away from your home? (Downloading episodes of SeqQuest DSV doesn’t count.) Honestly this sounds like a case of the cart pulling the horse.

This project is something I’ve always wanted to do for a really long time but never really had the proper impetus to actually work on it (well, except for the occasional Bud Light Mr. Loud-Cellphone-Talker-Guy). However, now that I’ve reached a stage in my education where I understand all of the technical aspects of the project, I find myself running out of excuses not to.

I’m going to break this project into multiple posts. This first one will be a lot of theory and background, basically explaining what we are trying to achieve and why. The second will be about schematic design, the third about PCB layout and construction and the fourth about construction, testing and results.

NOTE: I’m providing these posts for educational/interest purposes only. Actually manufacturing, owning or operating a cell phone jammer in the United State of America violates the Communications Act of 1934 and the Homeland Security Act of 2002. You will not go to white-collar resort prison! You will go to federal… ah you know the rest.

Background

Before we can stop something from working, we need to know how it works first (Unless you are a fan of the smash-it-to-pieces approach). The cell phone system, as far as the wireless side goes, is composed of two major players. The first and hopefully most obvious is your cell phone, called the mobile station. The second is the cell phone tower, often referred to as the “tower”, the “cell”, “local node” and called the base station. In normal operation the tower broadcasts a standard message consisting of a large amount of information, such as routing info, codes, time, location, etc. The most important information contained in this broadcast is the “If-there-is-any-cell-phones-out-there-please-let-me-know” packet. Presumably your phone hears this message and sends a message back, telling the tower your number and that you are in the area and can receive calls.  The processes happens a lot. Like a lot a lot. At least every 5 seconds, sometimes more than that depending on the local, phone and service provider.

When you get an incoming call or text or whatever fancy data phones can do now, the tower sends your phone a ring indicator (RI). This is the tower saying “Hey, recently you told me you were in my area and I have something for you”. At which point your phone responds back and the two negotiate the data transfer. When you place a call, a similar thing happens. Your phone says “Mr. Tower, I have something for you”. When Mr. Tower answers back, the two negotiate the transfer. What we want to do is screw up this process, so that the phone and the tower cannot successfully transfer data back and forth. Sounds pretty easy eh? Unfortunately the guys and gals that design this system expected noise and interference (which is what our jammer will be), so they made the system pretty robust.

Cell Phone Frequencies

Screwing up this transfer means we need to prevent the tower and phone from communicating on any of their allotted frequencies. And there are a lot of frequencies. What’s worse, in the United States we have multiple carriers that use different protocols on different frequencies, which just increases the number of bands we have to jam. It wouldn’t do to have us turn on our jammer only to have everyone with a Verizon phone jammed and everyone on AT&T still working. Remember when I mentioned the mobile and base stations earlier? (Read up two paragraphs.) This gets important because the frequencies used depend on the direction the data is being sent. Communication from the mobile to base station is referred to as the uplink, while communication from the base to the mobile station is referred to as the downlink. The uplink and the downlink use different chunks of frequency to allow the mobile and base to send data simultaneously, known as a full-duplex communications link.

We can narrow down our target frequencies using a little knowlegde and some system design. We don’t have to jam all the uplinks and downlinks on all the frequency bands. Jamming either the uplink or the downlink will effectively jam the cell phone, as it the system will not work without both link. The idea behind your jammer is to overpower the signal in either the uplink or the downlink. This effectively prevents the phone or the tower from “hearing” the other. We overpower the signal by sending out radio energy that is stronger (more powerful) than the energy in the uplink or the downlink. This effectively makes the receiver “hear” our jammer instead of the cell phone or the tower. Since we are really sending nothing, that’s what the phone gets, nothing. Now, which link to jam? This question comes down to distance. Imagine this…

You’re sitting outside on the patio of a nice cafe, enjoying the morning air, watching people walk by on their morning commute. Suddenly, the beautiful tranquility of your morning respite is disrupted by a loud-talking asshole jawing into his phone about some deal or merger or what loot he got from WoW last night. You calmly reach down into your purse (that’s right, this is an example from a women’s point of view, you got a problem with that? No offense to men with purses, just not my thing…) and switch on your cell-phone jammer and the aforementioned asshole’s call gets dropped. He glares at the “No Service” indicator on his phone, gets up and leaves to find service somewhere else. You smile, turn off your jammer and go back to enjoying your morning.

Now that you see the intended use, let me point out a few situational facts. More often than not, you (and your jammer) are going to be significantly closer to a transmitting cell phone then a transmitting tower. Recall from high-school physics that the magnitude of electromagnetic signals (light, radio, infrared) radiating from a point decrease exponentially with distance. Thus, in the case above, the downlink signal is going to be significantly (like super <<) less then the uplink signal, due to the fact that you are much closer to the mobile unit than the base unit. This will make the downlink much easier to jam, as we do not have to put as much energy out to overpower the tower’s transmissions. The benifit to us is two-fold. First, by only jamming the downlink frequencies we have cut the range of frequencies that our jammer needs to operate on by half. Secondly, we don’t use as much energy jamming, which means we can use a smaller battery or we can get more run-time for a given battery.

Target Frequencies: United States of America

Luckily, or unluckily depending on how you feel, we here in the USA do things a bit differently that the rest of the world. We need to worry about GSM and CDMA networks if we want our jammer to work on all phones. This means we need to block the GSM-850, CDMA-850, GSM-1900, CDMA-1900, WCDMA-1900 and WCDMA-2100 bands. If we want to have our jammer work world wide, we would also need to block the GSM-900 and GSM-1800 bands as well. Sorry Europeans, but my design will only work in the good ol’ US of A. (If you think I’m actually gonna travel with one of these you’re nuts!) At this point you may be thinking that that’s a lot of frequency bands to cover, and you’d be right, except that because GSM and CDMA use orthoginal technologies (mostly), they can use the same frequency ranges and not interfere with each other. If you take a look at this lovely colored chart, you can see that instead of having to worry about 6 different frequency ranges, we actually only have to worry about 3!

• 869 – 894 MHz
• 1930 – 1990 MHz
• 2110 – 2170 MHz

That’s it! All we have to do is screw up transmissions in three frequency ranges! Haha! This is gonna be easy right? Umm.. right?

Stay tuned for the next installment, where we talk about how we are going to accomplish this “easy” goal!

I just returned from North Carolina and Duke University, where I trained up a number of ecologists on the new radios and software that we pushed to them. As such, I have some observations to make about The South.

1. When you ask for iced tea, you get sweet tea, which is pretty much like drinking sugar through a straw.
2. Grease. Every single food item has two primary components. One is grease, the other is butter. While delicious, you will definitely feel it 30 min after eating.
3. People are courteous. And I don’t mean polite, I mean genuinely courteous. Everyone says “Good Morning” to people they pass in the morning, everyone says “Hello” when you pass them in the afternoon. They all watch where they walk, yielding when appropriate and holding doors for each other and thanking those that do so. Very nice change of pace from the West Coast.
4. Every woman raised in the South calls everyone “Sweetie”, “Sugar”, or “Honey” regardless of their age, gender, race or any other determining factor.
5. 87% humidity + 98 degrees F + overgrown deciduous forest = holy crap. You know those older cartoons where characters wipe their foreheads and then fling what at the time seems to be a copious and ridiculous amount of water from their hand? That shit ain’t made up, that really happens.
6. Spiders get huge. Like so huge that you are torn between being utterly fascinated and wanting to run the hell away.
7. 

   Sorry about the focus, silly phone. But that thing is a little bigger than my fist.

   Unless you want to hear a very fun, albeit long, diatribe don’t mention the Civil War. Also, under no circumstances should you ever, ever mention the name William Tecumseh Sherman.

8. Country music isn’t as prevalent as you think it would be. Granted, it’s NC and not Tennessee. The fact that I was in a university district also may have had something to do with that.
9. You may not think that you have an vocal accent, but to everyone else you do.
10. No one gets Canada jokes.
11. What the hell is with all the traffic circles?

Just recently Apple launched their new iPhone 4, their next generation of smart phone technology. I recall reading something like 1 million units sold in the first 3 days or so. Now that’s a dedicated fan base. It’s really too bad that Apple’s engineers are not as good as their PR department.

Within days of the launch, users report that their calls get dropped and their data connections slowed to a crawl if you held the phone in such a manner that the bottom left corner of the phone is covered. Now, if you are right handed (and a fairly decent portion of the world is) then this is the way you would hold the phone. As a matter of fact, this is the way all Apple’s commercials and PR shots hold the phone as well, gripped in your left hand, with the meat of your thumb on the bottom left of the phone.  Well, it seems given the amounts of fancy hardware the managed to cram into the newest Apple offering, it seems they ran out of room for the antenna. These days most phone designers put the antenna at the bottom of the phone, this is to meet FCC regulations on the amount of RF energy the brain and surrounding tissue absorbs. That’s when the Apple engineers decided to get clever. They decided to use the metal band that runs around the phone as an antenna.  The metal band has a few plastic spacers in it to separate the antenna from the rest of the case. You can see them in the photo I blatenetly stole from Apple’s website.

Check out the lines at the bottom separating the antenna from the case.

When your big meaty thumb or hand or other conductive parts touch both the antenna and the case, your antenna’s performance drops like a rock. Some more tech savvy users are reporting anywhere from 3 to 5 dB loss in signal gain. For those of you who don’t recall your logarithmic scale, that’s a reduction of signal from 50 to 70%.  When the average received cell phone signal is in the -95 dBm range (316 pico-Watts), you can’t afford to lose 50% because someone is holding the phone.

Now some people (cough, this guy, cough) would like to point the finger at the FCC, saying that the test you have to pass to get your device certified for public use only takes into account the head and the device, not the hand.  Then he decides to drop this little gem:

So, naturally, the design evolved to meet requirements – and efficient transmission and reception while being held by a human hand are simply not design requirements!

What the hell do you think the Apple engineers were designing? A clock radio? I could see why hand issues wouldn’t be a problem here. But for a phone? How can you justify not taking the user’s hand into account? I don’t care that the FCC doesn’t require it. This is what happens when you get clever. You get all excited about how smart you think you were instead of actually being smart. What makes this technical snafu even better is Apple (and Steve Jobs) response to the problem:  “You’re holding it wrong.” “Buy a case.” Gee, thanks.  I know you’ve been king of the mobile device market with your fancy iMusicPlayer and iSuperPhone, but guess what, your shit is still broken.

I guess the real reason I started writing was to convey the following: Engineering is more that getting something to work. You have to anticipate environment, users, worst cases. You have to think about the why you are doing something, not just the what and how. And most importantly, what are the ramifications, both good and bad, of doing x?

Oh, and those clever engineers? Looks like three of these antenna engineering positions just opened at Apple. Ouch.

Updated to WordPress 3.0 and bringing website back on line, more later.