Friday, July 31, 2009

900 MHz ATSC test, Cañada College, August 8, 1 PM

Well, since the entire goal of all of this experimenting is to set up an ATSC repeater output at 910-916 MHz, it's time to leave 70 cm behind and concentrate on the 900 MHz band. To that end, I'll be schlepping the gear up to the Cañada College location the Saturday after next. I'll be on the air for as long as I can starting at 1 PM on Saturday, August 8.

In order to receive this transmission, you'll need a 900 MHz antenna, a downconverter, and an ATSC receiver. You can get a suitable one from PC Electronics. Order the TVC-9S (use channel 2). Or you can build your own, if you're handy with that sort of thing. For an antenna, you're going to need to build a beam. In my experience with ATSC, having a directional antenna that you can use to reduce the impact of multipath is critical. It's going to be even more so at 900 MHz with all of the part 15 QRM.

The transmitter will be at 37.448773° North, 122.263856° West, and I'll be transmitting with about 150 watts of ERP. Look for me!

Monday, July 27, 2009

On progress

Western Digital is now shipping a 1 TB 2.5" hard disk.


A terabyte is now about the size of a deck of playing cards and can be powered by your laptop's USB port.

In about 1990, I participated in a Usenet (remember that?) "group buy" of 1 GB SCSI hard disks. That disk was a 5.25" "full height" form factor - that is, it fit in the same amount of space as two DVD-ROM drives stacked on top of each other.

It hasn't even been 20 years and now you can fit as much data as 1000 of those drives into about a tenth of the space, having paid about a fifth of the price for the privilege.

Free Joke

Here's a joke you can use on your friend. It requires you to be sort of good at improv, and your friend to be up on Hollywood gossip. It goes something like this:

You: "Man, what happened that all of the Celebrities are all dying at the same time? Karl Malden, Michael Jackson, Billy Mays... And the latest is some Hollywood actress just died after she stabbed herself with a knife!"

Him: "Really? Who was it?"

You: "I read about it this morning. I don't quite remember the name. Her first name started with an R.... Something like 'Reese.'"

Him: "Witherspoon?"

You: "No, no. With a knife."

Ba-dump bump. Thank you. I'll be here all week. Try the waitress and tip the veal.

Friday, July 24, 2009

The great myth of TV and customer service

You know, I'm rather surprised that I've never expressed this thought in my blog. I tried searching, and it hasn't turned up.

An awful lot of how TV works is rather easily explained once you know and understand the hidden truth of TV, at least as it is practiced in the United States today.

People watch TV and feel like they're the focus of the industry. That all that work and all that money spent goes into serving them and their entertainment needs. And that's true, so far as it goes.

But the fundamental, dirty secret truth is that despite that, you're not their customer.

You're the product being sold.

The advertisers are the customers, as far as the TV stations and networks are concerned. They make and transmit TV shows to attract eyeballs. Those eyeballs - our eyeballs - are sold to the advertisers. And that's what makes the world go 'round.

Don't get me wrong - TV stations want to keep you happy. The same way a shepherd wants to keep his flock happy. But they have no incentive to do anything at all that will cost them any money unless it brings more eyeballs, which indirectly brings them more money.

And that's not a bad thing. It's capitalism in action. It surely beats the alternatives on offer elsewhere - government funded broadcasting, where the only connection between the money and the programming is a bunch of government bureaucrats who either have an agenda of their own or - perhaps worse - are insufficiently incentivized to care.

Wednesday, July 22, 2009

Poker of late

So I haven't been playing a lot lately. Here's a good explanation for why not:

Out of the last 20 games I've played, I cashed 6 times, came in fourth 7 times, got 7th or 8th 5 times, one 9th and one 6th.

If just 3 of those 4ths were 3rds, I'd be profitable.

The 18 games before that, I cashed about half the time, got two fourths, 4 7ths, a 6th and 2 9ths - which is the way it normally is when I'm not getting skewered repeatedly. It's the pattern I would expect to see most of the time. The 4 7ths is a bit lumpier than I'd expect, but it is a very small sample size, after all.

To add to that, the last midnight tournament I lost in the first hour on the back of getting pocket kings vs. pocket aces, and the time before that I came in 7th when I needed to come in 5th to cash.

I hate this fucking game.

I wonder what they were really thinking

I don't think I quote or point to other blogs too often.

But I saw this one on EngrishFunny, and just had to share it:

engrish funny dont choking

Now, I can understand the "Toilet for ladies only" part, but what's up with the "Don't choking" warning?!

Friday, July 17, 2009

Walter Cronkite RIP

So help me out here. We lose Walter Cronkite, but we still have Larry King? Really?

YouTube fun!

Check this out. It's not the first time I've seen this sort of thing, but they've done a relatively good job. It's not quite Cookie Masterson material, but I have high hopes that they'll get better over time.

Thursday, July 16, 2009

Amateur Radio license exam prep - The Arithmetic

The amateur radio technician exam is mostly about memorizing rules and facts. As such, the best advice I can give is to go visit the AA9PW practice exam generator page and take the test repeatedly until you stop regularly failing it. It's actually not that hard to guess most of the answers. The ones you can't guess, you can just learn by repetition as you keep taking the practice tests.

There is, however, some math you should learn how to do rather than memorize, as it is easier. The laws of physics that embody the math you need to learn are embodied by 3 basic formulae. They are, E=IR, P=IE, and C=λω

Now, I can see some of your eyes have just glazed over. But bear with me. It's not that hard. Honest.

The first formula is E=IR, which is known as Ohm's Law. It's the relationship between the voltage drop across a load of a given resistance with a given amount of current flowing through it.

E, perversely enough, is the mathematical symbol for voltage. No, it's not V, 'cause that one was taken (Volume). It's E. You'll just have to remember that one. Voltage is electrical potential, more or less. People often compare voltage and current to water running through hoses. Voltage is analogous to the water pressure.

I, again, perversely enough, is the mathematical symbol for current. Electrical current is measured in Amperes, or Amps for short. Current, using the same water analogy, is how much water moves through the hose in a given time.

R is electrical resistance. Resistance is measured in units called Ohms, denoted by the greek letter Ω.

The basic formula is listed as E=I×R, but if you divide both sides of the equation by R, you get I=E÷R. Divide both sides by I and you get R=E÷I. If you think of those divisions as fractions, then you wind up with this little graphic symbol you can use to remember the relationship:

So that circle represents the relationship. If you remove from the circle the unknown you want to solve for, what's left tells you what the rest of the equation will look like. For example, if you remove the I, you're left with E over R, or E÷R. If you remove the E, you're left with I next to R, or I×R.

So, take question T4D04, for example:

What is the resistance of a circuit when a current of 3 amperes flows through a resistor connected to 90 volts?

A. 3 ohms
B. 30 ohms
C. 93 ohms
D. 270 ohms

They want to know R, and they've supplied you with I and E. R=E÷I. In this case, R=90÷3, or 30. The answer is B.

The next formula relates voltage and current to power. Power is P, and is measured in Watts. I and E are current and Voltage, just like before. P=IE. And like before, the circle chart can be used to figure out all of the relationships:

Let's use question T4E06 as an example:

How many amperes are flowing in a circuit when the applied voltage is 120 volts DC and the load is 1200 watts?

A. 20 amperes
B. 10 amperes
C. 120 amperes
D. 5 amperes

They want to know the current (Amperes), and they've given you the power and voltage. I=P÷E. Or, in this case, I=1200÷120: 10. The correct answer is B.

The last one looks a little funnier, but in truth it's actually easier. The formula is C=λω - the speed of light is equal to the frequency of a wave times its wavelength. Well, the speed of light is 300,000,000 meters per second, or 300 million meters per second. Wavelengths are in meters, at least for the purpose of this exam, and frequency is measured in Hertz (abbreviated as Hz). One Hz is one cycle per second. If we divide both sides of the equation by a million, you wind up with the formula 300 = frequency in Mhz × wavelength in meters. We can make a circle chart up for that one too:

In this case, we will never have the 'top' of the chart be an unknown, so we wind up with only two formulas, both of which look the same: You divide 300 by either the frequency in MHz or the wavelength in meters, and you get the other value.

Take question T1C05:

Which amateur band are you using when transmitting on 146.52 MHz?

A. 2 meter band
B. 20 meter band
C. 14 meter band
D. 6 meter band

300÷146.52 is approximately 2. The correct answer is A.

This formula can also be used to figure out antenna lengths. Take question T9A11:

What is the approximate length, in inches, of a quarter-wavelength vertical antenna for 146 MHz?

A. 112 inches
B. 50 inches
C. 19 inches
D. 12 inches

146 MHz is 2 meters. A quarter wavelength is half a meter. Half a meter is about half a yard, or a foot and a half or about 18 inches. The correct answer is C.

And that's it. So far as I know, that's all the math you need to know and understand to pass the technician exam. All the rest of it is just rote memorization of facts and rules.

Good luck!

Where's the beef?

Apple released a new version of iTunes today. One of it's "features" is to disable syncing between iTunes and the Palm Pre. As usual, there were immediate cries of "foul" from the haters over this perceived anti-trust violation.

Back when iTunes music was locked up with DRM, I would probably have agreed. But all of the music in the iTunes Music Store is now unencrypted AAC. There's no real tie-in between the store and the iPod, at least when it comes to music (we can continue to argue over the DRM encrusted movies and TV shows). But Apple doesn't really have anything like a monopoly in video content - certainly nothing like the market leadership they have in the music arena.

Put a bit more overtly, there's nothing at all preventing anyone from buying any track they want from the store and importing it into their Pre. Even if the Pre doesn't play AAC audio files (which I can't imagine it wouldn't be able to do), iTunes can happily convert them to MP3.

It says something about the Pre folks that they would rather try and make their device work with iTunes than design their own music management interface. Heck, their device manager could just read the iTunes music directory structure and suck the music out of it if they wanted to. But writing sync software is hard, gosh darn it, and emulating an iPod to leverage the hard work your competitor has done for nearly a decade, well, that's a lot easier. Or, at least, it was.

Sunday, July 12, 2009

There's a site for that

What amazes and sometimes amuses me about the Internet is the sheer variety. The secret ingredient on tonight's episode of Iron Chef America was Pineapple. I was intrigued by something Alton said made me curious, so I looked up the wikipedia article on pineapples, and since I had the computer in front of me, I wondered how one went about growing pineapples. Well, you ask a question, you you get an answer.

Back to D-ATV: 900 MHz amp

It's been a while, but I've decided to try and ready the ATSC transmitter for a possible placement as an additional output on K6BEN/R, at least to start with. I've talked with Ben (W2NYC) about it and he seems receptive.

I tested the DEMI 7730PAHS 70 watt 900 MHz amp. From what I can tell, I'm getting something like 35 watts out of the thing (the ATSC pilot is at about 33.7 dBm. If you measure the pilot, the signal's power level is about 11.8 dB up from that, so 45.5 dBm, which is about 35 watts), which actually is more than I expected, given the ~5 dB peak-to-average ratio of ATSC. That winds up, with the KP-20, being about 150 watts of ERP. That's still way low. By comparison, KFTL-CA transmits from the top of Mt. San Bruno with 15 kW of ERP. It barely cuts in and out here. My proposed signal is 20 dB down from that, and is double the frequency. That doesn't particularly bode well. The only TV station around here that will be doing ATSC with that little power is the proposed operation of KTVJ on Mt. Tamalpais on channel 4 at 300 watts of ERP. But channel 4 is 66-72 MHz - almost 4 octaves lower.

But really, there's nothing I can do but try. It will either work, or it won't.

Saturday, July 11, 2009

Military smoking ban

So I was walking by a newspaper and saw a headline suggesting that the military is considering a smoking ban.


"Alright, soldier! Here's your M-16, hand grenades and a parachute. You're going to Iraq to defuse IEDs. But we'd better not catch you smoking! That shit's dangerous!"

Thursday, July 9, 2009

Iran meets Florida

Let's take a moment to compare and contrast.

Many Americans fully believe that George W. Bush actually lost the 2000 presidential election, or won it by foul means rather than fair. Similar accusations, though perhaps on a wider scale, have been leveled at Mahmoud Ahmadinejad relating to the recently completed presidential election in Iran.

Let's take a look back at 2000:

At every stage of the proceedings there were demonstrations on both sides both large and small. At no point was there widespread outages of cell phone or text messaging service, nor were there riot police making mass arrests, nor was Al Gore held in "protective custody" until it all blew over. Perhaps most pointedly, nobody actually died protesting the election outcome (so far as I know).

All that stands in rather stark contrast to the ongoing situation in Iran. It's patently obvious to any observer, and it must be just as plainly obvious to anyone on either side in Iran that the current government lacks a basic level of legitimacy that even Bush had achieved in January of 2001. It doesn't even matter at this point if Ahmadinejad's election tally is as correct as he claims. A government of, by and for the people should not need mass arrests, tear gas and riot police to keep it in power. That's as true for Iran as it once was for Vietnam.

The Washington Post once editorialized: "[South Vietnamese] President Thieu says he'll quit if he doesn't get more than 50% of the vote. In a democracy, that's not called quitting." They were (and are) absolutely right, but the fact Thieu actually said that out loud says far more about the legitimacy of his government. But Thieu at least had the fig leaf of trying to resist a guerilla campaign staged and funded by the neighboring state (North Vietnam). Iran's borders are secure (indeed, Iran has been accused of attempting to destabilize its neighbor Iraq in recent months). The only possible threat to Ahmadinejad is his own people. You can't say such a thing when describing a democratically elected government and still be making any sense.

Wednesday, July 8, 2009

The Spanish Jerry Springer

Since I'm an RF enthusiast, I scan around the various TV channels checking on reception. I even check on the foreign language ones more or less just because I'm interested. In doing so, I ran across an interesting find.

Scarlet and I occasionally tune into the Jerry Springer show. It's a bit of a guilty pleasure. What I discovered on KTNC was what I believe is the Spanish Jerry Springer. The show is called José Luis Sin Censura (Sin Censura translates to Uncensored). The set looks like a virtual clone of Jerry's set. I tried to look it up on Wikipedia and IMDB, and I couldn't tell if it was a blatant rip-off or if it was authorized. But it looks funny as hell.

Sony makes good

I've lambasted Sony on numerous occasions. Well, to be fair, I'm not the only one. The last piece of Sony equipment I bought that didn't in some way disappoint me was a phone I bought back in 1993 or so. It's still out in the garage hooked up to the last POTS line in the house for emergencies. Well, Sony may have redeemed themselves. I'm still not 100% sure, though.

The product that did it is the HWS-BTA2W Bluetooth A2DP transmitter/receiver. I've put it out by the hot tub to use with the iPhone and XM streaming. The idea is that the XM app for the phone is not 100% perfect. It will sometimes have a hiccup that will keep it from working until you tap on it to retry. And if you play the music long enough, it will time out on inactivity. So because of that, it's sort of desirable to have the phone near the hot tub in a waterproof bag. Now that the phones support A2DP, bluetooth is the natural solution. I simply connected a 1/8" stereo to dual RCA audio cable between the line out port of the Bluetooth device and the two line-in ports of the amplifier for the speakers, and then paired it to my phone.

Alas, it's not total nirvana. For one thing, the hot tub is near the office. The office is where the Cell2tel is located. The Sony box is close by enough that the two will fight for the attention of my phone. So I have to tell the Cell2tel to "let go" of the phone by pushing the button on it before taking the phone outside. Once out there, I then need to turn the Sony box on. When I go back in, I need to reverse that procedure to get the Cell2tel working again. But that's not so bad. The other minor annoyance is that the WiFi signal doesn't quite reach the hot tub. The phone gets enough wifi signal to sign on, but actual data transfer doesn't work so well. So it's actually better to just turn off the WiFi and use 3G. But all those are just local considerations that affect my installation only. They're not condemnations of the device itself.

But there is one negative thing I can say about this product - it's overpriced. It's currently retailing for just shy of $80. I just bought a pair of LG A2DP headphones for just under $25 at Fry's. And those were battery operated and included headphones. This thing is a chip, two jacks, two buttons, a switch and two LEDs in a shiny plastic box with a wall wart and a short audio cable. It couldn't have cost them more than about $10 to build it. But It's a Sony! And they say that Apple gear is overhyped.

Tuesday, July 7, 2009

XM alarm clock

So I thought I'd share how I set up an XM alarm clock on the mac.

What you need to do, in the end, is somehow bring up their little plugin iframe content in a page. But in order to do that, you need to tickle the login page first. Fortunately, it's relatively easy to do with JQuery. What you do is make an AJAX call to the login page, and have the success function add an iframe to the page with the URL of the player.

You can download the html file here. You need to edit the HTML page to put in your credentials and the channel number that you want. If you save the resulting page somewhere on your machine and then double-click it in the finder, the resulting browser window should start playing the channel of your choice (assuming your machine has Internet connectivity).

To this point, this solution is platform independent, so long as your browser has the plugin support to play the audio stream. The next thing you need to do is somehow cause your machine to open the file at the time desired. I'm confident there's a way to do this on Windows, but I don't really care. So sorry.

On the mac, you use cron to schedule things. The thing you need to schedule is:

osascript -e 'open location "file:///path/to/html_file"'

And that's all there is to it.

Monday, July 6, 2009

The problem with DIY projects

This is why Heathkit failed.

If you've been following along, I built my own 30 watt per channel stereo audio amplifier, with a case. Twice, in fact.

While it did work out, you'd do well not to add up the cost:

The Velleman K4003 amp kit: $33.95.
24 VAC CT transformer: $13.95
Aluminum case: $21.00
Misc. parts: $10.00
Total: $78.90

Not including shipping and labor.

Cruising the Vista

It's been a while since the introduction of Windows Vista, and I've successfully managed to avoid it.

Until now.

My Dad, on my advice, bought a Dell about 3 years ago. The idea was that if he had trouble with it, he'd have someone to call. Well, this weekend while I was home helping him figure out why his backups weren't working to par, his installation of XP Home just died utterly. Every time you attempt to start, no matter which way, you got the Stop 0x000007B, which translates, more or less, to "I can't find your boot disk." Never mind that starting the recovery console and running chkdsk worked just fine.

Ok, so just reinstall XP. Well, that failed because when it got to the point where it had booted the installation software from the hard disk (after it copied that stuff from the CD), it couldn't find it.

So I said to myself, "Why am I killing myself with this crap? Mom switched to a mac years ago and hasn't had any trouble like this." So we went through the list of things he does with his machine. And it boils down to all the stuff that comes free with OS X, Office, Quicken and (eventually, but not right now) TurboTax - all of which are available on the mac.

But it sucks to spring him with a bill for a $600 machine (actually, since his monitor is starting to show symptoms, I'd probably have steered him to an iMac, so it'd be $1200), plus an additional $175 worth of software on a holiday weekend, so the compromise was to first go to Fry's and buy the cheapest copy of Vista we could find - Home Basic Upgrade.

The installation went well enough, but one problem sprang up immediately. We were legitimately allowed to use the upgrade version, since this was a machine that was running XP Home before, but because XP Home was not bootable, we needed to perform a clean install of Vista - something the license key did not allow. That resulted in spending an hour on the phone with Microsoft for them to engage in the workaround that makes the installation think it was upgraded.

Now, let's set aside for a moment the fact that they've wasted an hour in the life of a paying customer. That's not the sort of thing that you talk about in the sales brochures of most successful products. Sure, some products require maintenance, but this entire waste of time was of Microsoft's own invention. It serves no purpose that advances my Dad's computer's ability to do what it needs to do. No, this is just the 2009 manifestation with Bill Gates' personal vendetta against the perceived evils of software piracy. Bah.

But let's look at this another way. What does it cost Microsoft to staff the call center that needs to handle all of these issues? How much of the cost of a copy of Vista goes towards paying for the licensing bullshit that does me, the paying customer, no good at all - in fact, wasted (so far) an hour of my time? Since the vast majority of Windows Vista installations are done by OEMs, would just dispensing with the licensing bullshit really cost Microsoft that much?

Next on the hit parade is UAC - User Access Controls. The "Cancel or allow?" dialogs that sprinkle out of virtually every administrative task in which you engage. Now, to be fair, when you perform certain system updates and administrative changes in OS X, it pops up an authentication dialog, which is more or less the same thing. But in OS X, there are far fewer of them, and they're really built around security related things that really should be gated.

To quote Irving Berlin, it's spinach, and I say the hell with it.

Wednesday, July 1, 2009

Casing up the audio amp

The audio amp project turned out much better than I anticipated. There's just one hiccup to take care of before it's perfect.

First, a picture:

I had to cut a couple of square holes in the case to install a couple of the parts - namely the power switch and the power receptacle. So I just drilled a couple of holes in the middle of where the square holes needed to go and used a pair of files to enlarge them to the necessary size. It worked pretty well!

The right side is sort of the back panel and the left side is the front. The layout sort of winds up putting AC carrying wires rather close to the low voltage stuff, which is perhaps not the textbook way of doing it, but I don't intend to submit this thing for UL approval. The entire case is tied to ground, which ought to keep it safe enough once the cover is on and screwed in.

Note that each channel of the amp has the input grouped with the matching output. That way it's relatively easy to figure out left from right - in fact, there's no reason to label left and right, since the input is right next to the associated output. Of course, this might be a problem if your RCA cabling can't stretch far enough apart to hit both of them, but that's not a problem for my application.

You'll notice that leads from both sides of the AC in go over to the power switch. This is because the switch itself has a little neon light in it - it lights up when the unit is turned on. Bonus!

The one hiccup I mentioned above is that I put one of the big 2200 μF capacitors in backwards. When I applied power to the unit, it promptly started bubbling and smoking. The irony is that despite that, the amp works pretty well for brief periods. But I obviously can't leave it like that. I'm going to have to very carefully unbolt the heat sink, rotate the board up so I can get to the bottom, desolder and replace the blown cap and then put it back together - hopefully without wrecking the wiring job I did. Wish me luck!