Allowed range of the 60Hz mains frequency

What would you do about the phase modulation? The system was highly modified, some time back.

I got it straight from my sister who was working at the station at the time. I fully believe that the NE outage caused such a drag on the whole national system that generators all over the country were slowed down.

Bill

Still not buying it, even if she is your sister. The grids don't work that way. That's the whole point of having more than one grid. They're independent (with only a few "small" ties between them).

I've seen people babble about how being on your wrist acts to moderate the crystal temperature, but it can't be all that large an effect. I had a watch with a built in thermometer and it worked to measure air temperature just fine.

It would not be hard to construct a circuit to sync only to the reference portion of the signal if you can adequately receive the signal. So a PLL would be needed.

The clock in my minivan keeps time better than my wristwatch yet the van sits outside in the winter cold and the summer sun. I reset the clock only twice a year for CDT and CST and I usually update only the hour. I am amazed by this.

I've wondered about this myself. The typical time keeping crystal is optimized at typical room temp and slows both for hot and cold temps. Don't you think they've used a temperature compensation circuit? I've seen clock chips that do that automatically by digital techniques.

It wouldn't if the sensor was on the back side, where the crystal is.

That would be a TCXO.

I could recover over seven V, P-P in Central Florida before NIST installed the new WWVB antennas, raised the EIRP with the new transmitters and changed the modulation from AM to PM. After the change, none of my 'Atomic Clocks' keep proper time. Go to the NIST website were they describe the changes, and the problems. That is why cal labs moved from WWVB to GPSDO frequency standards.

I am building my own GPSDO 10 MHZ standard, and I have a one input, 32 output distribution amplifier waiting to connect it to my test equipment.

Automotive clocks, particularly those in instrument clusters or radios, use the embedded micro to compensate for temperature. Moderns ones may steal the time off the air, or linked devices, too.

Which GPS module did you choose? I'd like to embed one in my new sin-gen/VNA design. The ones with 10MHz output seem to be about 4x the price of the cheapies that have only 1PPS.

Clifford Heath.

It is a used one from a Cellular base station.

'SYMMETRICOM UCCM GPS 10MHz Frequency/Time Receiver OCXO' like this, but I paid a lot less for it:

SYMMETRICOM-065-03861-02-GPS-10MHz-Frequency-Time-Receiver-ASSEMBLY-

I also have a couple Meinberg that are on IBM PC cards for windows computers but the computer has to be powered up at all times.

From the listing:

Antenna Characteristics

Frequency range Antenna: Receive frequency: 1575.42 MHz

Converter: Local oscillator to converter frequency:: 10 MHz First IF frequency: 35,4 MHz Physical dimensions Dimensions of the GPS Antenna - see datasheet. Antenna connector type-N connector Bandwith 9 MHz Power supply 12V ... 18V, @ 100mA (provided via antenna cable) Form Factor ABS plastic case for outdoor installation (IP66)

Warranty Three-Year Warranty RoHS-Status of the product This product is fully RoHS compliant WEEE status of the product This product is handled as a B2B category product. In order to secure a WEEE compliant waste disposal it has to be returned to the manufacturer. Any transportation expenses for returning this product (at its end of life) have to be incurred by the end user, whereas Meinberg will bear the costs for the waste disposal itself.

I'm familiar with the WWVB format, before and after. They didn't *replace* AM with PM, they added PM. I don't recall the details of why it causes a problem with the clocks, but the problem in reality is that the clocks weren't designed the way NIST recommended in the first pace.

Yes, that is the definition of a TCXO.

The recommendation was to detect the AM only modulation. They CHANGED the recommendation after the new system was installed.

So they connect the crystal to the removable back cover of the watch??? Yeah, right...

Ask the Chinese. That's how my "atomic" watch works. Basically it's a crystal oscillator with the time adjusted daily by WWVB. Works like a champ. What kills me is that in the past I tried to get WWVB at my location had a communications quality receiver and long wire antenna and got NOTHING! And here is this freakin' wristwatch and it picks up WWVB with some antenna the size of what? Can't be bigger than the watch. And it does it pretty regularly too. Sometimes it misses a day if you lay it in the wrong place at night (it updates at night) but it easily keeps accuracy to a fraction of a second which is plenty for a watch. Just amazing. IF the Chinese ever learn to speak good English they will take over the world.

And by the way all that technology and I think I paid about $30 each for two of them at the local discount store.

Back in the old days you could use Broadcast color burst frequencies to set standards as they were traceable to NIST UTC. But those days are long gone. So my "super clock" now just sort of drifts. Internet time has pretty big delays.

Yawn. It is not on the faceplate, is it?