IC's for WWVB Reception at 60kHz

[Skysoldier]

I have googled all day, and can't find a chip level solution. Am designing a solar tracking controller system for Solar PV Arrays. I found references to obviously discontinued parts from Timec and Atmel. I am an old fart Engineer, so any help you young guy's can give me with internet search would be greatly appreciated. GPS is too complicated, I only need time of day to the minute. I need to do it cheap, as most of the budget is in the 900MHz RF modules for networking the whole array.

"IF YOU WANT IT BAD, YOU"LL GET IT BAD"

 

[IRstuff]

If you're already networking, why not simply broadcast TOD over the network? They make small microcontroller systems that have TCP/IP capability.

Whatever's on the other end, if it's got access to the Internet, you can get time synchronization to better than 5 seconds.

TTFN

 

[Skysoldier]

Thanks IRstuff. First, the wireless network is just between all the arrays, not on the internet. I will be sending
clock data to all PV arrays (clients) from a main server array. The server array needs the time data.

 

[VEBill]

"...need time of day to the minute..."

For solar tracking, to the nearest hour (a peak error of 30 minutes) will keep you within 7.5 degrees. Isn't a peak error of 7.5 degree still about 99% of perfection?

 

[Comcokid]

I don't think WWB is the only way to automatically get time. I have no direct experience with it, but you can get time from GPS signals as well. A quick web search found this.

http://www.franklinclock.com/gps.htm

There are probably time outputs available on the serial links of many GPS receivers.

 

[VEBill]

Hmmm...

One might be able to combine a cheap sun sensor (two photocells with a vertical shade in between), some absolute position feedback information, and a basic free-running real-time clock chip.

The idea is that when the sun is shining brightly, the controller could easily find the exact angle of the sun using the sensor. Then knowing the date, it could update the real time clock against the exact time (with a sun-time to local time algorithm). If you have enough time to create the SW, you could even take it to the next level and predict the long term clock drift against ambient temperature.

Personally, I'd just use the cheap sun sensor (period) and move the array about twice an hour. If the sun isn't shining enough to find it, then who cares?

Maybe the sun sensor could even be fixed to simply find solar noon once in a while. As mentioned earlier, you don't really need time to the nearest minute to be close enough.

Note - it's probably not too difficult to consume a significant portion of your solar generated power with your control system. You'll be wanting to keep a very close eye on the overall average electric power consumption of the entire control and motion system. Turn it off at night.

 

[IRstuff]

How cheap?
Duration of autonomous RTC operation, e.g., how often will the system get maintained?

TTFN

 

[nbucska]

I think discrete design would be simple

<nbucska@pcperipherals DOT com> subj: eng-tips
read FAQ240-1032

 

[Skysoldier]

Appreciate all you guy's trying to help. But none of you answered the question! I don't need two-bit advice I already know. I just want to know if anyone knows who still makes the receiver chips.

 

[analogkid2digitalman]

I know

Wheels within wheels / In a spiral array
A pattern so grand / And complex
Time after time / We lose sight of the way
Our causes can't see / Their effects.

 

[VolkerR]

Hi Skysoldier:
Try the U4223B.

If you google for a chip, also try "DCF77" as a searchstring, since that is the European version WWVB. It just operates on a different frequency, but also VLF.
DCF77 is very popular in Europe, and you can find hobby-kits and receiver modules at various vendors, e.g. Conrad Elektronik.
The receiver chips are often suitable for both WWVB and DCF77.

 

[VEBill]

"...don't need two-bit advice I already know..."

Someone (ahem) once posted some good advice: "IF YOU WANT IT BAD, YOU'LL GET IT BAD" This advice seems to apply to the concept of using the 60 kHz time signal and building something starting with a chip when there might be better solutions.

I still don't understand why you think you need to track the sun 'to the nearest minute' in the first place. Have you checked the cosine of 7.5 degrees yet ? Anyway - carry on...

Oh - be prepared for outages of that 60 kHz signal. Depending on your location, the signal can disappear for days at a time (propagation?, interference?, maintenance or repairs at WWVB?).

 

[Skysoldier]

To VE1BLL: Never said I needed the time for tracking. Outages are not a problem with WWVB. Just need to know that the time is periodically updated and maintained for data logging/utility record keeping without a trip to a remote location. Sorry about the two-bit advice comment.
If you have a better idea, I would love to hear it.
(You aren't by a any chance a Marine?)
To VolkerR: Thanks, that is all I wanted to know.
Cheers!

 

[VEBill]

Sorry. I misinterpreted your posting: "...designing a solar tracking controller system..." and "...only need time of day to the minute." I lept to the wrong assumption.

How much solar power (peak and average) are you generating?

What is the power budget for your control and motion system?

The RTC chip in my PC is accurate (without update) to a minute for weeks and weeks and weeks. You could use a laptop to control the whole system and simply have the laptop dial-out to a time server. The laptop could put itself into standby mode most of the time to conserve power.