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WWV Receiver/decoder? aka Atomic Clock Chip — Parallax Forums

WWV Receiver/decoder? aka Atomic Clock Chip

HarborHarbor Posts: 73
edited 2006-12-25 19:44 in BASIC Stamp
I've been postponing writing the code to have the Linux boxes here send a time hack to a BS2P/PINK combination I'm putting on the local network. It's one of those jobs best done by a chip and a week's pain to do in Ruby code or the like. Since I have the professional programmer's lazy gene, my subconscious has been looking for a way out. I may have thought of one.

Those "atomic clocks" that update regularly from WWV have gotten down to about fifteen dollars now. Surely someone is selling a standard chip that combines an 80khz receiver with a decoder for the time signal. (Or one of the other WWV freqs.) Anyone heard of one?

Incidentally, this may be ripe for introduction as a Parallax product, guys. "Add Atomic Time to your Stamp project!" for... I don't know, forty bucks? It would certainly be cheaper than using a GPS receiver just to get time hacks, and it would be worth forty or fifty to a lot of us to avoid the programming hassle of keeping a Stamp on the local·LAN synced with the big boxes. But that's figuring it as a little daughter board, like the appmods.·The cost·might be as little as five bucks if some company has reduced the whole thing to a single chip and a few external parts like an antenna.

Any ideas?

Comments

  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2006-06-25 04:53
    This is basically a short wave receiver tuned to a specific frequency.

    Here is an interesting more than you want to know info on the signal format as well as a telephone number (page 50) you can call to "listen" to the WWV information if you don't
    have a shortwave receiver.

    http://tf.nist.gov/general/pdf/1383.pdf

    here is another article that might be of interest...

    http://www.buzzard.me.uk/jonathan/radioclock.html

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    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.

    Post Edited (Beau Schwabe (Parallax)) : 6/25/2006 4:56:56 AM GMT
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2006-06-25 11:02
    The "atomic clocks" tune WWVB, which is a longwave transmitter.

    If you want a receiver IC, then you'll have to hack a working unit.· I think that it was TEMIC used to make these, but not available from Mouser, DigiKey, etc.

    It's PWM (longs, shorts, = 1s, 0s).

    WWV/WWVH transmit 1-bps (that's pretty darned slow) time and date information, but I haven't seen how to isolate (from the aural transmission) and demodulate the data.
    I once tried faking it·this, trying to make a super Hi-Q filter to trigger a clock update based on the 1kHz tone at the top of the hour, but sometimes a voiced frequency (allophone, fricative, or whatever) would sneak through it.· I thought to make my clock updatable only if the time was between xx:59:30 and xx:00:30, but never got round to it.

    [noparse][[/noparse] I may have told this story before, but I think I probably left out a comma. ]

    Post Edited (PJ Allen) : 6/25/2006 11:45:08 AM GMT
  • JonathanJonathan Posts: 1,023
    edited 2006-06-25 14:22
    Parallax used to sell such a unit, buy I beleive the company making them discontinued the product. I have one, and I use it to drive my Atomic Nixie Clock:

    http://madlabs.info/atomic_nixie_clock.shtml

    Since you can't get the WWVB unit anymore, what I did was set up a local re-broadcast of the time using a 433mHz RF unit. Now all of my projects needing a time base can use a cheap RF receiver to get the time. I currently have 4 projects that use the system.

    I think the easiest way to get atomic time these days is to use a GPS. Motorola untis are very cheap on ebay these days.

    Jonathan

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    www.madlabs.info - Home of the Hydrogen Fuel Cell Robot
  • HarborHarbor Posts: 73
    edited 2006-06-27 01:28
    Haven't checked eBay yet, but I looked into using a Garmin eTrex and it is straightforward for sure. Even if you don't know how to write a parser, Parallax provides sample code for the NMEA sentences used in GPS. Sucking UTC out of that will be dead simple.

    Thanks for the tip, guys, though an $85 GPS to tell me the absolute speed of my gatepost seems... like overkill. Especially since the cable costs another 20 to 35 unless I want to try cobbling one together that is weather-proof. And I would regret not spending the extra $35 about fifteen minutes into an effort like that.

    Incidentally, I need the power part of the tandem cable to provide an external, rechargeable arrangement with solar cells. The GPS operates on 2.5V to 3.0V but the cable is a 12V adapter and apparently includes internal regulation to take it down to 3.0V.

    It is a crying shame to stack enough solar cells to reach a 12V level just to have the regulator disperse the extra energy in heat. I'd rather set up solar cells to provide the five volts I need for the included stamp and regulate that down one step further to below three volts for the GPS unit.

    Has anyone tried hacking that cable?
  • steve_bsteve_b Posts: 1,563
    edited 2006-06-27 12:56
    tried hacking the GPS cable?

    Although the cable has a db9 on the end (unless you got the USB version...) be aware that your gps only uses 3 wires (also, regardless of the 4 pins on the back of the GPS.
    I think the GPS has a power contact in there for cigarette lighter adapters...but for the most part it's RS232 Tx/Rx and ground.

    All I did was solder a couple of wires to the pads I wanted. You don't leave the heat so long that you melt the plastic around....and if you're concerned that you opened up the hole around the contact with the solder heat, then dab a little silicone on there for extra protection.

    Google will help you find the actual pinouts....go to Garmin and download their manual...pretty sure it states right in there!

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    ·

    Steve

    "Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
  • JonathanJonathan Posts: 1,023
    edited 2006-06-27 14:28
    Harbor,

    An $85 Garmin does seem a waste. Look for a Motorolla Oncore I or II on Ebay. I got one with an antenna for about $35. It has no LCD or anything, just a GPS unit. Also, there are several new GPS chips out there in the $20 range I think. I haven't used any of them, so I can't provide details.

    Another option is to hack a regular clock with a WWVB receiver. Most of them have a 1PPS output that you can easily use to synch a RTC. You will in that case have to set the time manually, but it will keep in synch with WWVB once set.

    Jonathan

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    www.madlabs.info - Home of the Hydrogen Fuel Cell Robot
  • JonathanJonathan Posts: 1,023
    edited 2006-06-27 14:34
    Another thought, since you are running a PINK unit, if the system is full time connected to the internet, you might be able to synch the time throught the 'net. I seem to remeber seeing some bit of software that keeps a PC's local time synched through the 'net. Not sure how it is done, perhaps there is a "time server" out there.

    Jonathan

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    www.madlabs.info - Home of the Hydrogen Fuel Cell Robot
  • TimCTimC Posts: 77
    edited 2006-06-27 19:13
    The PINK is a very powerful unit and could go out via NTP and get the time from places like pool.ntp.org but Parallax would have to add NTP as a feature since the PINK firmware can not be updated by the user. hint hint.

    A long way around this would be to visit your PINK web site and the PINK could steal the time from the visiting PC using javascript. Look for posts I made last winter which should show the java script you need.


    A direct answer to your question might be something like this:

    www.atomictimeclock.com/radsynreceiver.htm

    I am afraid it's $$ and maybe not the way you want to go.

    The GPS route may be the best answer cost wise. Don't forget the GPS antenna needs to have a good view of the sky. The LF devices can sit in the basement but may need a day to get the sync signal.
    Regards
    Tim
  • HarborHarbor Posts: 73
    edited 2006-06-27 20:33
    steve_b said...
    tried hacking the GPS cable?

    Although the cable has a db9 on the end (unless you got the USB version...) be aware that your gps only uses 3 wires (also, regardless of the 4 pins on the back of the GPS.
    I think the GPS has a power contact in there for cigarette lighter adapters...but for the most part it's RS232 Tx/Rx and ground.
    Garmin does provide a wiring diagram. I already checked that. The data part is no problem, and I just don't care to try putting together a weatherproof version for mounting down at our front gate. The tricky part is a Garmin statement to the effect that the unit requires "externally regulated power" on that power input pin. (Which is the fourth one as you correctly guessed.) Presumably, and it would be this way if I were the designer, the regulation of 12V down to 3V takes place in the bulky "cigarette lighter" connector or whatever car manufacturers call the 12V outlet in this politically correct age.

    I plan to buy a tandem cable from Garmin or a second source that provides a data lead on one side and a second lead that goes to the 12V source. This is a molded unit that with a little care eliminates concern about foul weather problems. But a 12V connector is great for cars with a hunking lead acid battery under the hood, and problematic for me. What I'm hoping is that I can cut the 12V connector off the end and solder the power lead directly into my rechargeable power unit (not designed yet). With strain relief and weatherproof grommeting of course.

    What I'm trying to figure out -- before cutting into things -- is whether I can simply supply 3V on the correct lead of that cable with its connector removed, or if the regulation actually takes place closer to the GPS unit itself. (Or inside the unit, despite that statement about external regulation. Though this seems very unlikely.)

    Obviously, since I'm going to be relying on solar cells, I'd much prefer providing 3V since that is what's needed internal to the GPS. Upping the ante to 12V, just to have it regulated back down, is one of those inelegant design solutions. Not to mention being more expensive.
  • HarborHarbor Posts: 73
    edited 2006-06-27 20:51
    Jonathan said...

    An $85 Garmin does seem a waste. Look for a Motorolla Oncore I or II on Ebay. I got one with an antenna for about $35. It has no LCD or anything, just a GPS unit. Also, there are several new GPS chips out there in the $20 range I think. I haven't used any of them, so I can't provide details.

    Nothing on eBay today below a couple of hundred, although I can get a portable GPS free with a Porsche Boxster that's going for $26K...
    Is the "Oncore" an out-of-production unit? Didn't find any reference to it at all in an admittedly quick search. The extra fifty bucks for a Garmin unit certified waterproof to the IPX7·standard is not really excessive. I'd pay $85 in a heartbeat for "Precision Time Unit, good to one meter immersion for 30 minutes". It's just the irony of strapping a waterproof "Navigation Unit" onto a gatepost. Once you've logged the first thousand position reports to know your gate post's location to the nearest meter... well, what's it all about after that, Alfie?
    Saving work of course. Or at least making it more enjoyable work.·Any way I do this is going to be work. Either I have to write code for the Linux boxes to forward UDP messages to the PINK, or I have to hack an "Atomic Clock" to get the pps output and write code to sync a DS1302 to that, or... Well, I go this way and get to mess around with a GPS for the first time since the bygone days when they took up entire racks. So I might as well take the path of greatest entertainment value to go with the work.

    Besides, my wife has been bugging me to put our gate post on the Internet so it's about time I guess...
  • HarborHarbor Posts: 73
    edited 2006-06-27 21:03
    TimC said...
    The PINK is a very powerful unit and could go out via NTP and get the time from places like pool.ntp.org but Parallax would have to add NTP as a feature since the PINK firmware can not be updated by the user. hint hint.

    A long way around this would be to visit your PINK web site and the PINK could steal the time from the visiting PC using javascript. Look for posts I made last winter which should show the java script you need.
    Now that last one is an interesting thought, since Parallax have not risen to their feet and cheered at the idea of updating the Pink's microcode. It might actually be the least amount of work to put a blind field on our web page that invokes a display-nothing retrieval from the PINK, which causes your Javascript to execute and pass the current Apache server time to the PINK in one of the variables. And of course our servers all use NTP to keep their clocks synchronized. I wouldn't want to suck time out of the PC for random visitors to our web page. Likely to get time results all over the map, not to mention needing code to work out the time zone problems. But by putting the invocation in our own server, I suppose I can change your Javascript to use an SSI time call from the server itself instead of the end client.

    Of course, my wife really does want that web-enabled gate... Have to think about this one. Thanks, Tim.
  • HarborHarbor Posts: 73
    edited 2006-06-27 21:10
    Incidentally, if I go with this GPS method, which seems likely now, I plan to use Jonathan's approach. The unit will be down by the old mill stream, so to speak. Where it has a clear view of the sky for the GPS antennas, and also to be out from under the tree canopy so the solar cells to power the GPS and all my Stamp stuff will be insolated for as many hours as possible.

    So I'm using a Parallax 433 MHz transceiver pair to ship time hacks off to the main building. (Somehow I think I'll skip the position reports after the testing phase is complete.) Once I've done that, it means precision time will available to any unit on the property with just a cheap 433 MHz receiver. Not constantly, since the drift of a DS1302 doesn't justify using up the solar power like that. Probably one hack an hour at most. Maybe only four a day.

    Thanks, Jon.
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2006-07-02 19:06
    www.galleon.us.com

    They don't have online ordering, from the looks of things maybe they only do volume (??).· There's an EM2S, antenna for it, and an MCMRS232 decoder module -- price = $x.xx
  • HarborHarbor Posts: 73
    edited 2006-07-03 04:46
    They look like a supplier with all the possible combinations, including WWVB and GPS with PC and Linux software and all that stuff. Except prices. As you say, that looks like they only want to deal with distributors. In lieu of a price, they show a "Contact Galleon".

    Incidentally, yesterday I received a Garmin eTrex I ordered from Amazon for $84 including delivery. I added a two-headed cable that plugs into the GPS and has a 12V connector on one lead and a serial port adapter on the other. Plugging it into the same serial cable I use to program Stamps, Google Earth spotted the Gps immediately. Although I would recommend it for use with a clear view of the sky, it actually did quite well getting a fix from inside my home office, apparently using the two windows on the North and West side to pick up sat transmissions.

    I'll post on the progress of this project when I have interfaced the GPS to a spare BS2. Time hacking a BS2P/DS1302 is not trivial when the BS2P unit is doing other real time work. So I plan to use a dedicated BS2 collocated with the GPS somewhere with good reception. That BS2 will update it's own DS1302 regularly. Then I'll use a 433 mHz transceiver pair to let the BS2P ask for the current time at its leisure and use that to update the DS1302 that is keeping my network time.

    Or maybe I'll buy a sundial...
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2006-07-03 14:40
    OK -- They sent me some pricing info and it's about $50 for the receiver, $50 for the 232module, and $50 for the antenna (as "samples", <100.)
  • BamseBamse Posts: 561
    edited 2006-07-03 16:24
    What about the CME8000-BUS ???

    Would that work for you, $27 @ Digikey in stead of $150 @ Galleon...

    http://rocky.digikey.com/WebLib/C-MAX/Web Data/CME8000-BUS.pdf
    http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?Ref=110485&Row=195187&Site=US

    I might be ordering one myself... wink.gif

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Living on the planet Earth might be expensive but it includes a free trip around the sun every year...

    Experience level:
    [noparse][[/noparse] ] Let's connect the motor to pin 1, it's a 6V motor so it should be fine.
    [noparse][[/noparse] ] OK, I got my resistors hooked up with the LEDs.
    [noparse][[/noparse]X] I got the Motor hooked up with the H-bridge and the 555 is supplying the PWM.
    [noparse][[/noparse] ] Now, if I can only program the BOE-BOT to interface with he Flux Capacitor.
    [noparse][[/noparse] ] I dream in SX28 assembler...

    /Bamse
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2006-07-03 16:33
    · Bingo!

    · Heckuva find.
  • BamseBamse Posts: 561
    edited 2006-07-03 16:36
    PJ,
    If you do decide to try it out please keep me informed...
    I'll let you do the dirtywork, figuring out how to read the time etc...
    Then I'll order one when I know it works with a BS2... wink.gif

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Living on the planet Earth might be expensive but it includes a free trip around the sun every year...

    Experience level:
    [noparse][[/noparse] ] Let's connect the motor to pin 1, it's a 6V motor so it should be fine.
    [noparse][[/noparse] ] OK, I got my resistors hooked up with the LEDs.
    [noparse][[/noparse]X] I got the Motor hooked up with the H-bridge and the 555 is supplying the PWM.
    [noparse][[/noparse] ] Now, if I can only program the BOE-BOT to interface with he Flux Capacitor.
    [noparse][[/noparse] ] I dream in SX28 assembler...

    /Bamse
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2006-07-03 16:42
    Looking closer at the DOCs -- it's not EXACTLY plug'n'play, but we may see.
  • HarborHarbor Posts: 73
    edited 2006-07-04 02:35
    Bamse said...
    What about the CME8000-BUS ???
    Well spotted, Bamse. That's exactly what I was hoping for, but I couldn't find it on Digikey. Thank you.·I just ordered one. As PJ says, it's not exactly plug n'play, but under all those specs is a pretty simple protocol I think. Especially in a direct interface of one master/ one slave. I'll post a report and the code after I've worked it out.

    Of course, I already have that Garmin GPS unit... So many chips, so little time.
  • BamseBamse Posts: 561
    edited 2006-07-05 14:10
    Guess the search link for Digikey didn't work...
    If you want to order it from Digikey, just do a part search for CME8000-BUS-LP...

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Living on the planet Earth might be expensive but it includes a free trip around the sun every year...

    Experience level:
    [noparse][[/noparse] ] Let's connect the motor to pin 1, it's a 6V motor so it should be fine.
    [noparse][[/noparse] ] OK, I got my resistors hooked up with the LEDs.
    [noparse][[/noparse]X] I got the Motor hooked up with the H-bridge and the 555 is supplying the PWM.
    [noparse][[/noparse] ] Now, if I can only program the BOE-BOT to interface with he Flux Capacitor.
    [noparse][[/noparse] ] I dream in SX28 assembler...

    /Bamse
  • eightbitseightbits Posts: 2
    edited 2006-12-25 01:12
    Has anyone had any luck in using the C-MAX 8000 chip?
  • sam_sam_samsam_sam_sam Posts: 2,286
    edited 2006-12-25 14:59
    Hi, EveryOne

    Guess the search link for Digikey didn't work...

    Just to let everyone know that i have tried to use search link for Digikey works sometime and sometime it dose not work
    is Because Digikey·says that they are up grading there system and at tiimes it may not work

    I thought i would let you guys knows

    Sam·· smile.gif






    ······················································· hop.gif·· These· guys are having to muck funjumpin.gif
  • JonathanJonathan Posts: 1,023
    edited 2006-12-25 19:44
    Just a quick update...

    My WWVB reciever failed, so I used a Motorola Oncore to replace it. It is MUCH better than the WWVB unit, it can aquire a signal anytime, and quickly. The one PITA is that you have to manually calculate DST, as the GPS has no DST flag, whereas WWVB does. If you go that route, let me know, I'd be happy to pass on the DST routine.

    Jonathan

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    www.madlabs.info - Home of the Hydrogen Fuel Cell Robot
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