marcus@osf.org (Mark Roman) (05/17/89)
I am trying to get some information on radio clocks, specifically the kind used to provide a reliable standard time for a LAN. I have been recommended to Precision Standard Time Inc. in Fremont, CA. They make a dandy clock called the Time Source, which is perfect for my needs. It's a radio receiver tuned to WWV in CO, which puts out serial data on an RS232 port. This data, as you might've guessed, is the decoded time according to the NBS. Now here's the rub: It seems that PSTI has disconnected their phones. Unfortunately, I don't know if they have simply moved, or if they are out of business. This, as you might imagine, makes it difficult for me to order equipment. Does anyone out there in netland have any information on PSTI or their distributors? If they have indeed gone belly up, does anyone have information on other vendors of similar products? Please forward this on to anyone with knowledge. Thanks in advance, mark roman
david@daisy.UUCP (David Schachter) (05/23/89)
PSTI went out of business a few weeks ago, a victim of poor management and lousy marketing. Radio clocks are available from Kinemetrics/True- time, Spectracom, and possibly from Heathkit. Most radio clocks are significantly more expensive or lower quality than the PSTI clock, un- fortunately. An alternative exists in the form of a dial-up modem service run by, if memory servers, the National Institute of Standards and Technology (formerly named the National Bureau of Standards, operators of WWV and WWVH.) I don't have the phone number or specifications handy; call the NIST in Boulder, CO, or in Washington, DC, for more information. -- David Schachter
jack@csccat.UUCP (Jack Hudler) (05/24/89)
In article <3086@daisy.UUCP> david@daisy.UUCP (David Schachter) writes: >An alternative exists in the form of a dial-up modem service run by, >if memory servers, the National Institute of Standards and Technology >(formerly named the National Bureau of Standards, operators of WWV and >WWVH.) I don't have the phone number or specifications handy; call the >NIST in Boulder, CO, or in Washington, DC, for more information. > > -- David Schachter And here it is. I found this in Sky & Telescope. If you are doing projects requiring your computer syncing with UTC, this is for you. The phone number is (303) 494-4774, they are to add a 900 number in the future. ---------------------------------------------------------------------------- DESCRIPTION OF THE AUTOMATED COMPUTER TELEPHONE SERVICE (ACTS) The following is transmitted (at 1200 baud) following completion of the telephone connection. ? = HELP National Bureau of Standards Telephone Time Service D L D MJD YR MO DA H M S ST S UT1 msADV OTM 47222 88-03-02 21:39:15 83 0 +.3 045.0 UTC(NBS) * 47222 88-03-02 21:39:16 83 0 +.3 045.0 UTC(NBS) * 47222 88-03-02 21:39:17 83 0 +.3 045.0 UTC(NBS) * 47222 88-03-02 21:39:18 83 0 +.3 045.0 UTC(NBS) * 47222 88-03-02 21:39:19 83 0 +.3 037.6 UTC(NBS) # 47222 88-03-02 21:39:20 83 0 +.3 037.6 UTC(NBS) # etc..etc...etc....... UTC = Universal Time Coordinated, the official world time referred to the zero meridian. _________________________________________________________________________ DST = Daylight savings time characters, valid for the continental U.S., are set as follows: 00 = We are on standard time (ST). 50 = We are on DST. 99 to 51 = Now on ST, go to DST when your local time is 2:00 am and the count is 51. The count is decremented daily at 00 (UTC). 49 to 01 = Now on DST, go to ST when your local time is 2:00 am and the count is 01. The count is decremented daily at 00 (UTC). The two DST characters provide up to 48 days advance notice of a change in time. The count remains at 00 or 50 at other times. _________________________________________________________________________ LS = Leap second flag is set to "1" to indicate that a leap second is to be added as 23:59:60 (UTC) on the last day of the current UTC month. The LS flag will be reset to "0" starting with 23:59:60 (UTC). The flag will remain on for the entire month before the second is added. Leap seconds are added as needed at the end of any month. Usually June and/or December are chosen. The leap second flag will be set to a "2" to indicate that a leap second is to be deleted at 23:59:58--00:00:00 on the last day of the current month. (This latter provision is included per international recommendation however it is not likely to be required in the near future.) __________________________________________________________________________ DUT1 = Approximate difference between earth rotation time (UT1) and UTC, in steps of 0.1 second. DUT1 = UT1 - UTC ___________________________________________________________________________ MJD = Modified Julian Date, often used to tag certain scientific data. ___________________________________________________________________________ The full time format is sent at 1200 baud, 8 bit, 1 stop, no parity. The HH:MM:SS msADV time format at 300 baud is also 8 bit, 1 stop, no parity. ___________________________________________________________________________ Maximum on line time will be 55 seconds. If all lines are busy at any time, the oldest call will be terminated if it has been on line more than 15 seconds, otherwise, the call that first reaches 15 seconds will be terminated. ___________________________________________________________________________ Current time is valid at the "on-time" marker (OTM), either "*" or "#". The nominal on-time marker (*) will be transmitted 45 ms early to account for the 8 ms required to send 1 character at 1200 baud, plus an additional 7 ms for delay from NBS to the user, and approximately 30 ms "scrambler" delay inherent in 1200 baud modems. If the caller echoes all characters, NBS will measure the round trip delay and advance the on-time marker so that the midpoint of the stop bit arrives at the user on time. The amount of msADV will reflect the actual required advance in milliseconds and the OTM will be a "#". The NBS system requires 4 consecutive delay measurements which are consistent before switching from "*" to "#". If the user has a 1200 baud modem with the same internal delay as that used by NBS, then the "#" OTM should arrive at the user within +-2 ms of the correct time. However, NBS has studied different brands of 1200 baud modems and found internal delays from 24 ms to 40 ms and offsets of the "#" OTM of +-10 ms. For many computer users, +-10 ms accuracy should be more than adequate since many computer internal clocks can only be set with granularity of 20 to 50 ms. In any case, the repeatability of the offset for the "#" OTM should be within +-2 ms, if the dial-up path is reciprocal and the user doesn't change the brand or model of modem used. This should be true even if the dial-up path on one day is a land-line of less than 40 ms (one way) and on the next day is a satellite link of 260 to 300 ms. In the rare event that the path is one way by satellite and the other way by land line with a round trip measurement in the range of 90 to 260 ms, the OTM will remain a "*" indicating 45 ms advance. For the user who wants the best possible accuracy at the OTM, NBS offers an alternate 300 baud service with only HH:MM:SS MSADV and OTM. To use the alternate service, simply call at 300 baud. Because of the simple FSK modulation scheme used at 300 baud, all modems tested had the same delay within about 1 ms. ___________________________________________________________________________ The full time format will be sent at 1200 baud, 8 bit, 1 stop, no parity. The HH:MM:SS MSADV time format at 300 baud will also be 8b, 1s, np. For user comments write: NBS-ACTS Time and Frequency Division Mail Stop 524 325 Broadway Boulder, CO 80303 Software for setting DOS compatable machines is available on a 360-kbyte diskette for $35.00 from: NBS Office of Standard Reference Materials B311-Chemistry Bldg, NBS, Gaithersburg, MD, 20899, (301) 975-6776 -------------------------------------------------------------------------- -- Classic Quotes from STNG: "Pen Pals" Picard: Her society is aware .. that there is intersteller life? Data: No Sir. Picard: Oooops..
cratz@icldata.UUCP (Tony Cratz) (05/26/89)
In article <2767@csccat.UUCP>, jack@csccat.UUCP (Jack Hudler) writes: > In article <3086@daisy.UUCP> david@daisy.UUCP (David Schachter) writes: > >An alternative exists in the form of a dial-up modem service run by, > >if memory servers, the National Institute of Standards and Technology > >(formerly named the National Bureau of Standards, operators of WWV and > >WWVH.) I don't have the phone number or specifications handy; call the > >NIST in Boulder, CO, or in Washington, DC, for more information. > > > > -- David Schachter There is a company out here in California that has a unit which has a RS-232 port and gets its information direct from WWV, (price ~$500.00). (more for a large computer room then a small office) There is also another company that will be making a PC board which will have the WWV RF interface. All you do is plug it into the PC and with the software be able to get the WWV information. Both system uses a SMALL di-pole (~2 ft in length). I'm not sure of what their names are but if you want I will find out from my friend the name and the phone numbers. Tony Cratz -- "Looks like plant food to me" Tony Cratz work phone: (408) 982-3585 UUCP: ames!versatc!icldata!cratz Snail: ICL Datachecker, 800 Central Expressway MS 33-36, Santa Clara, Ca 95052
hgp@lzaz.ATT.COM (H.PAGE) (05/26/89)
In article <2767@csccat.UUCP>, jack@csccat.UUCP (Jack Hudler) writes: > >An alternative exists in the form of a dial-up modem service run by, > >if memory servers, the National Institute of Standards and Technology > >(formerly named the National Bureau of Standards, operators of WWV and > >WWVH.) I don't have the phone number or specifications handy; call the > >NIST in Boulder, CO, or in Washington, DC, for more information. > > > I found this in Sky & Telescope. If you are doing projects requiring > your computer syncing with UTC, this is for you. The phone number is > (303) 494-4774, they are to add a 900 number in the future. > ---------------------------------------------------------------------------- . . . > > Software for setting DOS compatable machines is available on a > 360-kbyte diskette for $35.00 from: . . Send me a formatted 5 1/4 floppy and a self addressed, stamped return envelope, and I'll send you both the source (Turbo C?) and executable. Howard Howard G. Page 62 Stratford Rd. Tinton Falls, NJ 07724-3143 -- Howard G. Page AT&T LZ 1B-115K (201)576-2731 ..!att!lzaz!hgp
frank@ut-emx.UUCP (Frank Abernathy) (05/27/89)
> In article <2767@csccat.UUCP>, jack@csccat.UUCP (Jack Hudler) writes: > > >An alternative exists in the form of a dial-up modem service run by, > > >if memory servers, the National Institute of Standards and Technology > > >(formerly named the National Bureau of Standards, operators of WWV and > > >WWVH.) I don't have the phone number or specifications handy; call the > > >NIST in Boulder, CO, or in Washington, DC, for more information. > > > > > I found this in Sky & Telescope. If you are doing projects requiring > > your computer syncing with UTC, this is for you. The phone number is > > (303) 494-4774, they are to add a 900 number in the future. > > ---------------------------------------------------------------------------- WHY do people want to subsidize AT&T/Sprint/MCI and (insert your favorite long- distance company here)? Buy the Heath Clock, $249.95 plus $49.95 for the RS-232 interface, put it together, string a wire an get the correct time. You will always, if you have a halfway decent wire antenna, get GOOD time. The only inconvenience is setting the Year offset and DST changes. Heath 1-800-253-0570. No connection with Heath; we put their kit together and it works! Frank (512)-471-3216
henry@utzoo.uucp (Henry Spencer) (05/28/89)
In article <13437@ut-emx.UUCP> frank@ut-emx.UUCP (Frank Abernathy) writes: >WHY do people want to subsidize AT&T/Sprint/MCI and (insert your favorite long- >distance company here)? > >Buy the Heath Clock, $249.95 plus $49.95 for the RS-232 interface, put it >together, string a wire an get the correct time. Ever tried stringing a wire from inside the third floor of a university building? Without paying Physical Plant $$$$ to do it for you? Running one inside is useless -- too much old computer equipment that radiates fiercely and ruins reception. Not to mention that we're a long ways from WWV and reception isn't great to begin with. (The Heath clock's receiver is not a superb job, in fact several aspects of the design aren't great -- one would hope that for US$49.95, they could do real RS232 rather than a sloppy half-assed kludge, but no such luck...) We won't even mention considerations like lightning protection... -- Van Allen, adj: pertaining to | Henry Spencer at U of Toronto Zoology deadly hazards to spaceflight. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
root@grieg.CS.ColoState.Edu (the root) (05/30/89)
In article <1989May27.222428.4127@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes: >In article <13437@ut-emx.UUCP> frank@ut-emx.UUCP (Frank Abernathy) writes: >> string a wire an get the correct time. > >Not to mention that we're a long ways from >WWV and reception isn't great to begin with. >-- A lab on our foothills campus (in Ft. Collins, CO, home of WWV) had one of these units. The receiver front-end was being overloaded, so the dipole was turned 90 degrees and put in a cabinet! Randolph Bentson Computer Science Department Colorado State University Ft. Collins, CO 80523 303/491-7016 bentson@grieg.CS.ColoState.Edu
gordon@prls.UUCP (Gordon Vickers) (05/30/89)
In article <13437@ut-emx.UUCP> frank@ut-emx.UUCP (Frank Abernathy) writes: >WHY do people want to subsidize AT&T/Sprint/MCI and (insert your favorite long- >distance company here)? > >Buy the Heath Clock, $249.95 plus $49.95 for the RS-232 interface, put it >together, string a wire an get the correct time. > Over $300 just to get an accurate time ? I'll stick with the phone. Prehaps you check your clock more often than I do mine, or maybe you just need a better clock. When I consider how many calls I can make and how often I typically call, and compare this to the probable usefull lifetime of the Heath clock, then (at least for me), the phone is cheaper. Gordon Vickers 408/991-5370 (Sunnyvale,Ca); {mips|pyramid|philabs}!prls!gordon ------------------------------------------------------------------------------ Every extinction, whether animal, mineral, or vegetable, hastens our own demise.
dennis@gpu.utcs.utoronto.ca (Dennis Ferguson) (05/31/89)
In article <16468@bellcore.bellcore.com> karn@jupiter.bellcore.com (Phil R. Karn) writes: >Has anybody built a clock that uses CHU's encoded time signals? Not yet, really, but I've been working on and off on a CHU-synchonized NTP server for the past few months. Maybe a month more to get things tested to the point where I know whether it can be trusted or not. The nice thing about CHU, beyond the fact that if a serial time code is what you want you can get by with just a radio and a 300 bps modem, is that the data arriving at your computer's serial port is generated directly from the atomic clock itself, rather than being second hand via a radio clock. This allows you to process using some heavier duty algorithms than your average clock manufacturer is likely to be able to put together, and also gives you more intimate knowlege of how the receiver is doing so you can take approprate action (the Heathkit clock wouldn't be so bad if it would tell you it was running into difficulty early enough for you to stop believing it in time). The end of every data byte gives you a time sample (90 per minute in all) meaning you've got lots and lots of samples to feed to the filters. NTP eats errors and short term variations of known (observed, measured) statistical properties for breakfast. I like the idea of time-synchronizing random hosts (i.e. anything that has something to do besides time keeping) to a well behaved NTP server across a network rather than trying to deal with a radio clock directly. You can get some pretty amazing results with NTP, even across large chunks of Internet topology let alone across a single LAN, without much effort on the part of the host. The grot of dealing with a radio clock can probably be better handled by something which hasn't got much else to do besides watch the clock. For isolated hosts the telephone time service might be a better bet. Unless you live in Ft. Collins or Ottawa, or can afford a GOES clock, getting good, reliable time from a radio time source can take a lot of work. Dennis Ferguson
karn@jupiter (Phil R. Karn) (05/31/89)
>A lab on our foothills campus (in Ft. Collins, CO, home of WWV) had >one of these units. The receiver front-end was being overloaded, so >the dipole was turned 90 degrees and put in a cabinet! After some frustrating experiences with the GriefKit clock, I used to say that there's nothing wrong with it that couldn't be fixed by moving to Fort Collins, Colorado. I guess I was wrong. :-) Seriously, the biggest problem with the clock is how it behaves when propagation from WWV is poor. The clock accumulates a significant error (several seconds) when the signal is lost for even relatively short periods, and there's no way to set it manually. I don't understand why this should be so; my 10-year-old $25 National Semi wristwatch typically stays within 1 second/month with no WWV updates at all, and it's very easy to set manually. Has anybody built a clock that uses CHU's encoded time signals? CHU is generally much easier to receive in the northeastern US than WWV, but their time code format (300 bps FSK bursts, used as sound effects in the movie "The Empire Strikes Back") is of a different format. (CHU is on 3.330, 7.335 and 14.67 MHz. It uses AM with the lower sideband suppressed. Time is announced in voice every minute in both French and English.) Phil
dennis@gpu.utcs.utoronto.ca (Dennis Ferguson) (05/31/89)
In article <26174@ames.arc.nasa.gov> medin@cincsac.arc.nasa.gov (Milo S. Medin) writes: >Actually, our PSTI (now defunct) clock seems to be very happy to keep >a steady lock on WWV from here in northern California. It does have >an external antenna, but has no problems maintaining sync... You are right, I got carried away. If you are close enough and/or have a good antenna a radio clock can do very well. Even the PSTI clock is reputed to hang on longer than it should, however (I am assuming you know the clock maintains constant sync by having measured it against other clocks. Having the in-sync LED on the front of the thing on all the time may as likely be a symptom of a problem as it is an indication that no problem exists). Actually, "close enough" doesn't seem to be right either. I've had to invest in a fair amount of antenna wire to get CHU fairly noise free, I am told that 300 kilometers is actually a little too close and that the better signals are skipping over my head. I still think that if you want a source of time you can poll once in a while and get guaranteed reliable time, your HF radio clock may disappoint you from time to time unless you are in a location which is advantageous geographically, or the algorithms the clock uses to process the time are very good. In the latter case I think I'd rather have those algorithms running somewhere where I can see them and fix them when they do break. Dennis Ferguson
medin@nsipo.arc.nasa.gov (Milo S. Medin) (05/31/89)
Actually, our PSTI (now defunct) clock seems to be very happy to keep a steady lock on WWV from here in northern California. It does have an external antenna, but has no problems maintaining sync... Thanks, Milo
henry@utzoo.uucp (Henry Spencer) (05/31/89)
In article <1989May30.224116.2101@gpu.utcs.utoronto.ca> dennis@gpu.utcs.utoronto.ca (Dennis Ferguson) writes: >The nice thing about CHU, beyond the fact that if a serial time code is >what you want you can get by with just a radio and a 300 bps modem... Not just any 300-baud modem, unfortunately. Some folks up in Ottawa, including a friend of mine, did a CHU receiver at one point. They ended up custom-brewing a modem. The problem is that the 300-baud carrier is not continuous, and commercial 300-baud modems take too long to lock onto it -- you need something that will lock on almost instantly if you don't want to miss the start of the data. -- You *can* understand sendmail, | Henry Spencer at U of Toronto Zoology but it's not worth it. -Collyer| uunet!attcan!utzoo!henry henry@zoo.toronto.edu
ml@gandalf.UUCP (Marcus Leech) (06/05/89)
In article <16468@bellcore.bellcore.com>, karn@jupiter (Phil R. Karn) writes: > Has anybody built a clock that uses CHU's encoded time signals? CHU is > generally much easier to receive in the northeastern US than WWV, but Well, actually, yes. We use one I designed to keep our VAXen synched to CHU to within abt 0.03sec. The VAXen also synchronize other devices a couple of times a day. I published an article in the April, 1988 issue of "The Canadian Amateur" [hey, Phil, are you a C.A.R.F. member? :-)] about the modem I designed and the software. A regular 103-type modem won't work, because of some tight timing restrictions. My intention is to go commercial/semi-commercial with this thing. If I get enough encouraging noises from people, I probably will. If you build a modem based on my article, you can get the time-setting software from me for nothing. I live and work only a few km away from the CHU transmitter site, so the signal is pretty good :-) ;-). I've evaluated the signal in other parts of North America and concluded that a modem listening to the signal would be able to get a good "fix" at least several times per day, and usually several times per hour. The problem with WWV isn't so much propagation, it's that you need an entire minute of ungarbled digital timecode to encode the current time of day. The CHU format gives you nine bursts per minute, each encoding the entire T.O.D--that means that conditions can be pretty poor and still allow you to get one or two complete timecodes in a given minute. Your average PC would need to get a fix about four times a day to stay within 0.50sec of UTC. Our VAX (785) drifts only about 0.2 seconds per day when left unattended, depending on phase-of-the-moon. Many of the devices we periodically synchronize have drifts of up to 2 or three seconds per day. Why is a $5 Brand-X watch so much better than a $150 PC clock board? -- "Better Living through modern chemistry" PaperMail: 130 Colonnade Rd, Nepean,ON Marcus Leech E-mail: ml@gandalf.UUCP Gandalf Data Ltd PacketRadio: VE3MDL@VE3JF "The opinions expressed herein are solely my own" So there