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Wake On Demand in Snow Leopard

Putting your Mac to sleep saves power, but it also disrupts using your Mac as a file server, among other purposes. Wake on Demand in Snow Leopard works in conjunction with an Apple base station to continue announcing Bonjour services that the sleeping computer offers.

While the requirements for this feature are complex, eligible users can toggle this feature in the Energy Saver preference pane. It's labeled Wake on Network Access for computers that can be roused either via Wi-Fi or Ethernet; Wake on Ethernet Network Access or Wake on AirPort Network Access for wired- or wireless-only machines, respectively. Uncheck the box to disable this feature.

Submitted by
Doug McLean

 

 

Other articles in the series Trippin' Tunes

 

 

Taking an iTrip: Three FM Transmitters

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I've put 110,000 miles on my car in the last four years, and that doesn't count the untold miles I've driven in company vehicles. In other words, I spend time on the road. A lot of time.

The disk-based MP3 player was a godsend for me, freeing me from dependence on dubious radio stations in the middle of nowhere, letting me carry my music without packing stacks of tapes or CDs. First a Nomad Jukebox, then an Archos Jukebox (both of which I reviewed for TidBITS), and finally an iPod have made driving a lot more enjoyable for me. Unfortunately, listening in a car isn't terribly convenient - very few car stereos have an input jack for direct connection, and cassette players (the second-best choice, using a cassette adapter) are increasingly rare in new cars.

<http://db.tidbits.com/article/06261>
<http://db.tidbits.com/article/06521>

Fortunately, there's another option: miniature FM transmitters. These devices broadcast music over an FM signal on a frequency you select. To listen to your music, plug the transmitter into the headphone jack on the player, tune your car's FM radio to the desired frequency, and your music emanates from your car speakers as though it were being played by a normal radio station. An FM transmitter is also useful for playing someone a song from your iPod through a stereo that lacks the appropriate input jack. Note that these transmitters are apparently illegal in some areas of Europe - the link below gives a sense of how confusing the situation is.

<http://www.neurosaudio.com/community/forum/ topic.asp?TOPIC_ID=255>

I've tried two FM transmitters originally designed for general use, Arkon Resources' SoundFeeder 100 and the iRock 300W, and been disappointed with aspects of both of them. Then at the 2002 Macworld Expo in New York, Griffin Technology - long known for well-engineered specialty peripherals like the PowerMate - started talking about the iTrip, a new FM transmitter designed especially for the iPod that promised to deal with the problems I had with the other two. Now that the iTrip is finally out, how does it compare?

<http://www.arkon.com/SF100.htm>
<https://www.myirock.com/players/300W%20- %20FM%20Transmitter.htm>
<http://www.griffintechnology.com/products/itrip />

Baseline Conditions -- I've found that the performance of these units can vary considerably depending on where and how they're used. I live in Kansas City, a moderately sized city in the midwestern United States. Kansas City has a number of radio stations, and about two-thirds of my listening time has been driving in the city and the surrounding area; the other third has been spent on longer road trips. My car is a 1998 Pontiac Sunfire, which has the radio aerial mounted on a back corner. I also spend a fair amount of time driving the full-size GM pickup trucks my company uses; they have the aerial mounted just in front of the windshield on the passenger side and generally seem to have better reception. All of these vehicles have the standard GM CD/FM stereo unit, so it's possible that a different stereo would perform better.

Because I frequently switch among different company vehicles and must often leave on a few minutes' notice, the smaller and less cumbersome the FM transmitter, the better.

Finally, while I love music, I'm not a technical audiophile; I can't promise accurate descriptions of frequency response, for example, and the most I'll be able to tell you about how good something sounds is whether I liked listening to it. Cars aren't exactly high fidelity listening environments anyway.

The SoundFeeder 100 -- I tried the $30 SoundFeeder first, and while it's better than nothing, it's far from my favorite. It draws power from a 12V cigarette lighter socket, eliminating the need for batteries, and it can be tuned to any frequency. It also includes a built-in power supply for other devices, which was useless to me as it wouldn't power any of the MP3 players I've used.

These good points are outweighed by the SoundFeeder's problems. First, and most annoying, its mechanical tuner tends to drift, forcing me to fiddle with it frequently to keep it on the same frequency. Second, the broadcast signal often seemed weak, though that may be a side-effect of the tuner issue. Third, it is physically cumbersome. With a box for the tuner, a lighter socket plug/power adapter that's almost as large, and cables for the headphone jack and secondary power support, it's a bother to carry and tends to tangle.

There are better choices, and I gave up using mine shortly after I acquired an iRock.

The iRock -- The $30 iRock, also sold under the Link-It! name, was a substantial improvement over the SoundFeeder. It avoids the problem of tuner drift by restricting itself to four fixed frequencies: 88.1, 88.3, 88.5, and 88.7. The iRock is powerful enough that it can sometimes override stations on the same frequency - 88.1 is the home of a local radio station, but it's where I usually found the best reception from the iRock. It's also a cleaner design than the SoundFeeder, with just a rounded pod for the transmitter/batteries and a short cable to plug into the headphone jack. When used with an iPod, it's both possible and convenient to pick up the iPod and just let the iRock dangle, though I wouldn't advise this for any significant amount of time.

The iRock is not without disadvantages. By far the most annoying is the power switch, a large press-on, press-off button that requires very little pressure to operate. It's far too easy to drain the batteries accidentally by bumping the switch, and the switch was often triggered in my laptop case.

The four fixed frequencies can leave you stuck if your area has multiple stations in the 88.x band. Kansas City has stations on 88.1 and 88.5, and the signal on 88.5 is strong enough to cause interference on 88.3 and 88.7 as well.

Finally, while the pod-on-short-cable design is a major improvement over the SoundFeeder's tangle, it is still inconvenient and vulnerable to damage. I had to replace my first iRock because the wires apparently frayed and then broke close to the headphone plug, presumably because I was spending too much time carrying it around hanging from the iPod, with the cable bearing the weight of the iRock plus 2 AAA batteries.

Speaking of batteries, I strongly suggest getting a set of AAA NiMH rechargeables if you get an iRock. Although I've had a single set of two batteries last several hours on the road, the power switch issue will likely put you through a lot of battery changes.

The iRock is not a bad FM transmitter, and I was fairly satisfied with mine for many months, but I still found myself wanting something better.

Enter the iTrip -- The $35 iTrip was the first FM transmitter designed to work specifically with the first and second generations of Apple's iPod, and it shows in the industrial design. It's a small cylinder that clips to the top of the iPod, adding almost nothing to the iPod's size and weight. A plug goes into the headphone jack, while a small ring around the plug fits into the remote control contacts that circle the headphone jack on the iPod; this ring draws power from those contacts to power the iTrip. A solid plastic second plug fits into the iPod's FireWire port to hold the iTrip in place. To select a broadcast frequency, the iPod itself controls the iTrip via software, eliminating the need for a power switch or tuning control.

This design is far more convenient than the competition. Instead of juggling boxes and wires, you carry a single unit that still fits into your shirt pocket. Picking the iPod up to switch playlists or browse music is easy, with no cables to interfere... unless you plug in a charger. To accommodate a charger, you can rotate the iTrip 90 degrees, putting the plastic FireWire port plug in front and leaving room for a cable. See the picture linked below for a comparison of the iTrip in both positions with the iRock. The rightmost picture shows an edge-on view of the plastic plug that goes into the FireWire socket on the iPod.

<http://www.tidbits.com/resources/681/ iTripComparisons.jpg>

Unfortunately, I have had a lot of trouble getting the power ring to seat solidly without the assistance of the FireWire port plug, and for now I'm not even trying to charge the iPod while I'm using the iTrip.

Tying the design so closely to the iPod has another liability: Apple changed the remote control socket in the just-released third generation of iPods, and the iTrip won't work with them. Hopefully Griffin will be able to redesign the iTrip's case to work with the new units; that's all that should be necessary.

iPod Controller -- When I heard that the iTrip would use the iPod as a controller, I was both admiring and dubious. I wanted to see the clean design this promised, but I was worried it would require an invasive software patch that would break the next time Apple revised the iPod firmware. Griffin's solution turns out to be both more elegant and more Rube Goldbergian than I had anticipated. They include a set of 102 five-second MP3 files: one for each FM frequency plus a couple to toggle the iTrip's status LED. To tune the iTrip to a specific frequency, you play the appropriate MP3 file, which sends a set of modulated pulses that the iTrip interprets as a tuning command. The iTrip also uses output sensing to control the power. When it hears output from the iPod, it switches on (which takes about 3 seconds), and 30 seconds of silence causes it to switch off.

As ingenious as this method of tuning is, it has some disadvantages. First, it's slightly finicky; you have to start the tuning track playing, wait until the iTrip flashes its LED to show the command was accepted, and then quickly pause the iPod before it can play the next code. If the iTrip is asleep, it doesn't wake up fast enough to catch the full tuning command; the LED flashes, but the station is not set correctly.

Second, it clutters up your iPod with those five-second files. Griffin gives them a unique artist and album, so you're unlikely to find them in casual browsing, but they're still there in the global song list. This fact leads to the third irritation - if you like to shuffle through all the songs on your iPod, accessing one of the tuning files could accidentally change your frequency. You can work around this by creating a Smart Playlist that excludes the artist or album tag for the iTrip files, but that's still a bit less convenient.

Fourth and finally, changing the frequency interrupts whatever is currently playing, requiring you to back out of wherever you are, drill down to the tuning tracks, then navigate back to where you were. Griffin seems to assume most people will set the frequency once, as the documentation mentions that it's all right to throw away all of the frequency files beyond the one(s) you need. Unfortunately, I often need to change frequencies when driving around town, to say nothing of long road trips.

Despite these disadvantages, I still find the iTrip's tuning approach a big improvement over the SoundFeeder's drifting mechanical tuner or the iRock's fixed frequencies.

iTrip Performance -- So how well does the iTrip work? Ideally, I'd like to see better performance. It prefers a clear frequency, and when it gets one, it sounds very good, at least as good as a clear FM station. Unfortunately, finding a frequency that clear can be deucedly difficult. In twenty hours of driving around the greater Kansas City area, I could not find a single frequency that remained clear throughout the region, though I could always find at least one usable frequency wherever I went. I often experienced some mild static or fading as I moved around the city, as if driving on the fringes of a radio station's reception area. Sometimes the static lasted for a only few seconds, other times it caused me to switch frequencies. I also occasionally hear a high-pitched whine that appears to be radio interference, since it changes with location and occurs even when the iPod is paused, but it vanished when I went 30 miles outside of the city. If you turn the volume up loud enough on the iPod (past about 80 percent), you can start getting static on the peaks in the music. The iRock has from the same problem, though not as badly.

However, I can't grade the iTrip too harshly based on these performance problems, because all the FM transmitters I've tried have suffered from similar troubles. FCC regulations limit the power of this type of device, and that fact likely accounts for the similarity of the performance issues for all three of these FM transmitters. Nonetheless, the SoundFeeder was the worst; its mechanical tuner was difficult to lock solidly on a frequency, and the way it drifts made it difficult to tell whether the poor performance was tuner drift or radio interference.

The iRock performs well in areas where there's no strong signal in the 88.x frequency range. Unfortunately, these areas aren't as common as the iRock's designers seem to think. The iRock seemed to handle competing signals somewhat better than the iTrip, and when I compared them side-by-side on the same frequencies the iRock seemed to have a slightly stronger signal, though not so much that I'd give it a clear advantage. The iTrip's much broader range of usable frequencies gives it the overall win.

One last issue is battery drain. Since the iTrip draws power from the iPod, how does that affect the iPod's battery life? It's hard to estimate, since the iPod's battery gauge is imprecise. Griffin says using the iTrip shouldn't affect battery drain any more than using normal headphones, but when I compared the iTrip against the iRock in normal use, the iPod's battery level appeared to drop somewhat faster when using the iTrip. Still, that's a more-than-adequate trade-off for not having to mess around with lots of batteries and chargers or tangled power cables.

Take the iTrip -- Is the iTrip perfect? No. I wish the signal was stronger so reception could be clear and consistent across the city. I wish Griffin could have come up with a less cluttered approach to tuning, though I'm not sure what would work better.

Would I recommend the iTrip to others? Yes. If nothing else, the massive improvement in convenience over the other FM transmitters is worth it. The wide-ranging digital tuning - even given the Rube Goldbergian approach - is also welcome.

And although the performance of FM transmitters in general leaves something to be desired, I don't think there's a good alternative for people who have a car stereo without an input jack or cassette player. Trying to use headphones in a car is inconvenient, dangerous, and illegal in some places. And even if I were willing to spend the money to have an input jack installed in my car, I'm still out of luck when using a company vehicle. I'll stick with an FM transmitter, even with the hassles, and the iTrip is by far the best of the lot if you have an older iPod that works with it. I just hope Griffin can come up with a version that works with the third-generation iPods.

PayBITS: If Travis's comparison helped you decide which FM
transmitter to buy, say thanks with a few bucks via PayBITS!
<https://www.paypal.com/xclick/ business=tbutler%40mac.com>
Read more about PayBITS: <http://www.tidbits.com/paybits/>

 

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