iPod photo interference issue traced, explained | iLounge News

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iPod photo interference issue traced, explained

imageThird-party iPod developer Engineered Audio, maker of the RemoteRemote 2 RF remote control system, has provided to iLounge an excellent explanation of the radio frequency (RF) interference issue affecting certain iPod photo hardware. The company’s findings follow up on iLounge’s exclusive March 31, 2005 report, “Yes, the new iPod photo -is- different,” in which we detailed an interference issue that prevents current RF-based remote controls from fully working with “first-generation” (pre-February 2005) 40/60GB iPod photos. As a result of the interference, the RF remotes work at only one-sixth to one-twelveth of their performance ranges with all other iPods.

“The current crop of RF remote controls for the iPod operate at or near 433.92 Mhz,” explains Engineered Audio. “The reasons for this frequency choice are not particularly relevant, except to say that this particular frequency is usable (or certifiable) in the US and in Europe. Further, most of the receivers for these remote control systems are simple super-heterodyne or super-regenerative. And without very careful filtering at the antenna, both types may suffer a degradation in performance when there is a nearby noise source.

“In this case the iPod photo is generating an undesirable RF noise source at 432.00 Mhz (see plot 1). Some might consider the difference between the two frequencies to be enough to not cause interference, however, this is simply not the case. Most of these simple receivers have a fairly wide bandwidth with relatively high gain, and so are easily swamped by an interferer that is within a few megahertz of desired signal. What’s inside the iPod that is generating this signal we can only guess at (perhaps an harmonic of the primary clock for the processor…) At any rate, it would appear that Apple has since modified the iPod photo to either reduce or eliminate this particular signal.” A spectrum analysis photo (“Plot 1”) and additional details are available by clicking on Read More below. We thank Engineered Audio for explaining the interference, and all iPod RF remote manufacturers for being forthright with consumers about the incompatibility.

The RF interference issue is believed to affect only “first-generation” 40 and 60GB iPod photos, which included packed-in accessories such as an A/V cable and iPod photo Dock in their boxes, and not “second-generation” 30 and 60GB iPod photos that ship without those items. iLounge has previously requested comment from Apple regarding audio interference affecting certain iPod photos and fourth-generation iPods, but still has not been updated on the status of units shipped to Apple in 2004 for testing.

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Comments

1

A few additional things to keep in mind ... 1) This does not appear to be related to any (real or perceived) audio issues.  2) By the FCC rules (Part 15), these types of remotes are secondary services, and thus must accept any interference in the course of normal operation.  The interference could have just as easily come from a DVD player, or a cell tower, or a video game.  It’s just a bit of bad luck that the stars aligned like they did ...

Posted by EngAudio on May 4, 2005 at 12:57 PM (PDT)

2

Thanks for the info, EA!

I hope there will be some remotes that have the filtering—or a different frequency—to work around this.

(And I think some of the recently-reviewed remotes don’t suffer from this as much as others. AirClick was pretty “bad” and another one was better… name escapes me but I don’t think it was RemoteRemote 2.)

Posted by Nagromme on May 4, 2005 at 2:21 PM (PDT)

3

Perhaps they should design it to work at 315MHz?

Posted by Eriamjh on May 6, 2005 at 4:23 AM (PDT)

4

Well I just (Sept 05) recieved my new Photo 60 (black box unit) that was not supposed to be affected and much to my dismay the range is about 3 feet tops.
So it would seem that the problem is not limited to early releases of the Photo 60.
If anyone has a mod for the remote that corrects the issue please let me know.
Brad

Posted by Brad on September 24, 2005 at 2:18 PM (PDT)

5

Me too. I have a first generation iPod photo and a Griffin AirClick the reliable range is about 2 feet. Completely worthless.

There was no warning in the packaging for the AirClick. Even more worthless when considering my next iPod is probably going to be 5G or later. The remote control is basically useless to me.

Posted by Kurt Hammond on March 5, 2006 at 10:19 AM (PDT)

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