[R-390] WWV Frequency Standard

[Perry Sandeen]

Gentlemen,

Wrote: Using WWV to ascertain the generator accuracy percentage is VERY problematic.  The propagation effects alone rule out using this a frequency standard.

You need to use a "true" frequency standard.  Not using a "true" frequency standard will ALWAYS result in differences using on-air frequency transmissions.

Wrote: It is - the path length is important for absolute time, then there's the variance of the reflection height. 

That gives a variable path length as well as a Doppler shift with the motion.  WWVB is better.

Uh, if all that is true, please don’t tell the USAF and Hewlett Packard or they might become confused.  (At least in the past.)

Using the well known formula of a kebelsa sausage divided by the length of the ballast tube (or something like that) they use the 1ms (which is five cycles of  1kHz) tick for frequency calibration by feeding that one tick per second tick to the input of an external scope trigger and the source to be checked or calibrated to the vertical amp.  Then on watches which direction and the rate at which the wave appears to move. Using a watch or clock one can then accurately calculate the difference.  One can also reverse the input configuration and watch the “tick” move.

Watching the “tick” move was how we kept the receiver site HP 105 at Karamursel Air Station in Turkey, 40 years ago, calibrated even though we had a muti-thousand mile path from Boulder Colorado.

HP also recommends this as one method for the HP 5335A frequency counter(among others)time base calibration.   They also list a frequency offset table for rates from 1E6 to 1E10.

The beauty of this technique is anyone at home having a scope with external trigger capabilities can calibrate their “house standard” oscillator to extremely fine tolerances at a very low cost and effort. 

Regards,

Perrier