© 2005 Door & Access Systems
Publish Date: Summer 2005
Author: Tom Wadsworth
Page 64


To the Editor:

I just finished reading your article entitled “The Battleship and the Lighthouse.” I found it very interesting, but you left out the fact that all the companies involved except Johnson Controls are changing frequencies to 315 MHz.

Your article seems to say that the problem has been solved. If so, why did the manufacturers change their frequencies?

Everyone in our industry knows about cross-talk problems in multiple installations. In a 3-car garage, you might have three GDOs and three car key fob door locks, all using 315 MHz. That's six receivers in the same garage!

Why didn't these manufacturers go to another frequency like 320 MHz or maybe go higher, like 433.92, as Europe did? The manufacturers are making us feel like the government did this terrible thing when, in fact, all the manufacturers knew this day would come.

I would love to hear your comments on this. Is the game between the government and the manufacturers of GDOs over? Not in this lifetime!

Larry Smith
Hobbit Distributing



Thanks for your letter. You ask some good questions. Some responses:

1. When we finished the Battleship story in late February, Genie and LiftMaster had not announced any plans to utilize the 315 MHz frequency. We reported what we knew at the time.

2. Our article certainly implies that serious problems have been averted. But the article doesn’t say the problem is solved. Our article says, “We still have a long way to go,” and it questions “if indeed we’ve seen the end” of the problem.

3. I suspect that the manufacturers chose 315 MHz because of the large number of wireless devices that use that frequency (e.g., car-door remotes, tire pressure sensors, other GDOs, etc.). One would hope that the government will not use a frequency that is used by millions of various common devices.

4. I understand that cross-talk was once a GDO issue but is no longer prevalent. Three DASMA-member GDO engineers tell me the problem has been very rare for the last 5-10 years.

5. Concerning using the 433.92 MHz frequency … The HomeLink Web site says their compatibility ranges from 288 up to 418 MHz. Thus, anything above 418 MHz would not be a practical GDO frequency in the United States.

The Editor

Letters to the Editor may be faxed to Tom Wadsworth, editor, at 815-285-2543 or sent to daseditor@dasma.com. Letters may be edited for length and content.