U.S. Spec for mechanical and quartz, why?

Ever wonder why the MIL-W 46374F/G specifies both quartz and mechanical movement timepieces? Is there specific needs for both or what?? I don't exactly know, that is why I ask. EMP protection perhaps?
You would think that like the MOD, quartz is the way to go for reliability and accuracy, but mechanical can go longer than a battery change period.

[Gert]

EMP could certainly be behind that thinking. Weapons that specifically emit ?clean? electromagnetic pulses are being researched. They could wipe out all computerized transactions and paralyze transportation systems with no nasty fallout. But today, the most likely EMP sources are nuclear bombs. In which case accurate timekeeping may be the least of one?s worries? It might be better to keep an old car without electronic transmission wrapped in grease paper in your shed. :lol:

Quartz watches do emit electronic noise themselves. Perhaps a mech watch might also be desirable around fancy electronic equipment?

Gert

[Crusader]

Quartz watches do emit electronic noise themselves. Perhaps a mech watch might also be desirable around fancy electronic equipment?

Gert

Hello Gert,

Ithink you have got a good point there. The thing about electronic fileds and mil watches is not only the watches' susceptibility, but also their active electromagnetic signature.

Best regards,

Crusader

[IanW]

Hello

Ithink you have got a good point there. The thing about electronic fileds and mil watches is not only the watches' susceptibility, but also their active electromagnetic signature.
Crusader

Interesting thought as 32.768 KHz crystals (in the electronic sense rather than the watch sense) are advertised by the component suppliers as being watch and timer crystals since they can easily be divided down to 1 Hz by an electronic circuit. Therefore electronic watches must contain a 32.768 KHz oscillator. - Now I wonder how far away that could be detected ?

Sadly the lowest frequency of all my receivers only goes down to 100 KHz so I can't prove this little theory.

Regards

Ian

[mindbender]

I might be able to ask a few friends.

[hkperfection]

great

[xpatUSA]

Hello

Ithink you have got a good point there. The thing about electronic fileds and mil watches is not only the watches' susceptibility, but also their active electromagnetic signature.
Crusader

Interesting thought as 32.768 KHz crystals (in the electronic sense rather than the watch sense) are advertised by the component suppliers as being watch and timer crystals since they can easily be divided down to 1 Hz by an electronic circuit. Therefore electronic watches must contain a 32.768 KHz oscillator. - Now I wonder how far away that could be detected ?

Sadly the lowest frequency of all my receivers only goes down to 100 KHz so I can't prove this little theory.

Regards

Ian

A digital watch works on square wave pulses. Square waves theoretically contain all the odd (IIRC) harmonics of the fundamental but with the power decreasing for each higher harmonic. So theoretically there will be one emission at 32.768 kHz, another at 98.304 kHz, another at 163.384 kHz, etc, etc.

As to power, I would say that a watches effective radiated power would be undetectable in just about any environment. Consider the power source: a tiny 1.5V battery running for two years - what is the current drain? Let's say 5 uA - giving a power consumption of 7.5 microwatts which is the absolute maximum possible radiated power and is more likely to be a few nanowatts or less.

By the way, don't take a Blackberry to war with you. Mine will interfere with just about anything that's a few feet away. A guitar amp set to 11 for example.