American Time and Signal Company Wall Clocks UHF Frequency

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JASII

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I was at a community college yesterday. They had a wall clock on a stand near a desk where you check in. I happened to look at the back and saw what looked like a wifi antenna. But, then I saw the labels and UHF frequency. It would appear as if they have a UHF transmitter located high up in one of the buildings and it sends a time sync to the clocks throughout the campus. I had no idea they did that.







Clock 1.jpg
 

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mmckenna

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There's a number of those systems on the 70MHz band, also.

With NTP being available almost everywhere, they are sort of falling out of favor.
 

Dude111

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Wow those look interesting........ I wonder what the range is?? (I reckon its better on 70Mhz)
 

mmckenna

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Wow those look interesting........ I wonder what the range is?? (I reckon its better on 70Mhz)
Depends on the system design.

70MHz can travel pretty far with good antennas and power, but won't penetrate buildings as well as UHF. Usually the systems are designed to cover a campus or small area, so the design is adjusted accordingly. Power level and transmit antennas are chosen to cover the area.

I was chasing down some interference to one of our radio systems a few weeks ago and finally tracked it down to a community college. Turned out to be their sprinkler control system. But, working with their facilities director, we were looking at several different systems. They had a UHF based master clock system still running for the campus. One antenna on a facilities shop was used to cover the whole campus.

Better ways to do this stuff now. It's easy to pull NTP over the data network, even WiFi. One option is to pull time off the cellular systems. Build it in to the clock and you only need a master system for bells, etc.
 
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