[time-nuts] Clock Correction Algorithm

2011-11-24 Thread Miguel Gonçalves
Hi! I am building a clock that fetches its time from a local NTP server (GPS synched machine). I am using a timer based on a 16 bit interrupt on an Arduino (ATmega328 clocked at 16 MHz). I am implementing an algorithm to steer the this clock (nothing as complicated as the NTP algorithms) and

[time-nuts] SDR GPS

2011-11-24 Thread Poul-Henning Kamp
Has any of you played with this: http://www.sparkfun.com/products/8238 -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by

Re: [time-nuts] SDR GPS

2011-11-24 Thread Attila Kinali
On Thu, 24 Nov 2011 11:19:37 + Poul-Henning Kamp p...@phk.freebsd.dk wrote: Has any of you played with this: http://www.sparkfun.com/products/8238 I had a look at this (and a few other GPS SDR solutions) back a year or two ago and decided that they are either way too expensive or

Re: [time-nuts] Clock Correction Algorithm

2011-11-24 Thread Attila Kinali
On Thu, 24 Nov 2011 10:14:17 + Miguel Gonçalves m...@miguelgoncalves.com wrote: The clock is set by sending an NTP packet and setting the clock with the replied timestamp plus half of the round trip time. In a local LAN this seems a good solution. I am not after micro-second accuracy as

[time-nuts] DGPS@home

2011-11-24 Thread ehydra
Hi all! I wonder what would be reasonable location accuracy if two cheap same type GPS modules will be several meters apart? I understand that it involves statistical numbers. Any idea? Say for a small robot. Thanks! - Henry -- ehydra.dyndns.info

Re: [time-nuts] SDR GPS

2011-11-24 Thread ehydra
Pricey, but allows to fly on high-attitude/speed. The region where money ist not so important ;-) - Henry Poul-Henning Kamp schrieb: Has any of you played with this: http://www.sparkfun.com/products/8238 -- ehydra.dyndns.info ___

Re: [time-nuts] Low noise power supplies for time nuts circuitry

2011-11-24 Thread Attila Kinali
On Wed, 23 Nov 2011 04:50:49 -0800 Chuck Forsberg WA7KGX N2469R c...@omen.com wrote: How well would a pair of cascaded 3 terminal regulators do - say a 7815 feeding a 7812. 78xx Regulators are quite noisy. You can use them to filter the noise of a cheap DC/DC converter, but i wouldnt use them

Re: [time-nuts] Clock Correction Algorithm

2011-11-24 Thread Miguel Gonçalves
On 24/11/2011, at 11:42, Attila Kinali att...@kinali.ch wrote: On Thu, 24 Nov 2011 10:14:17 + Miguel Gonçalves m...@miguelgoncalves.com wrote: The clock is set by sending an NTP packet and setting the clock with the replied timestamp plus half of the round trip time. In a local LAN this

Re: [time-nuts] Clock Correction Algorithm

2011-11-24 Thread Javier Herrero
El 24/11/2011 13:56, Miguel Gonçalves escribió: Right! That is what I am doing. The problem is the drift between adjustments. Arduino's clock is slow 25 ms every minute and if temperature changes it will surely be different. That is more than 400ppm error, that sounds quite high. Is the

Re: [time-nuts] DGPS@home

2011-11-24 Thread Azelio Boriani
Usually GPS receivers have DOP figures you can use to estimate the position precision. Maybe worth using timing receivers for position to increase the position accuracy. On Thu, Nov 24, 2011 at 1:01 PM, ehydra ehy...@arcor.de wrote: Hi all! I wonder what would be reasonable location accuracy

Re: [time-nuts] Clock Correction Algorithm

2011-11-24 Thread Attila Kinali
On Thu, 24 Nov 2011 12:56:31 + Miguel Gonçalves m...@miguelgoncalves.com wrote: Right! That is what I am doing. The problem is the drift between adjustments. Arduino's clock is slow 25 ms every minute and if temperature changes it will surely be different. The proposed algorithm

Re: [time-nuts] Clock Correction Algorithm

2011-11-24 Thread Miguel Gonçalves
Hi Javier! Thanks for your help. On 24/11/2011, at 13:16, Javier Herrero jherr...@hvsistemas.es wrote: El 24/11/2011 13:56, Miguel Gonçalves escribió: Right! That is what I am doing. The problem is the drift between adjustments. Arduino's clock is slow 25 ms every minute and if

Re: [time-nuts] Clock Correction Algorithm

2011-11-24 Thread Miguel Gonçalves
Hi!! On 24/11/2011, at 13:48, Attila Kinali att...@kinali.ch wrote: On Thu, 24 Nov 2011 12:56:31 + Miguel Gonçalves m...@miguelgoncalves.com wrote: Right! That is what I am doing. The problem is the drift between adjustments. Arduino's clock is slow 25 ms every minute and if

[time-nuts] Clocking a PIC16F628A from a Rubidium Standard

2011-11-24 Thread Stephen Farthing
Greetings all, I have an Efratom 101 frequency standard with a 10 MHz TTL otput. I want to use this to clock a PIC 16F628A so I can make a frequency counter with a resolution of 1 Hz. I am going to use the design by EI9GQ here http://homepage.eircom.net/~ei9gq/counter.html . What I need to know

Re: [time-nuts] Clock Correction Algorithm

2011-11-24 Thread Attila Kinali
On Thu, 24 Nov 2011 14:21:37 + Miguel Gonçalves m...@miguelgoncalves.com wrote: I am using an Arduino Uno that presumably is running at 16 MHz. I am using a 16 bit timer with a 256 pre-scaler: 1600 / 256 = 62500 Hz 1 / 62500 = 16 us 65536 - 62500 = 3036 I am setting the

Re: [time-nuts] SDR GPS

2011-11-24 Thread Jim Lux
On 11/24/11 3:38 AM, Attila Kinali wrote: On Thu, 24 Nov 2011 11:19:37 + Poul-Henning Kampp...@phk.freebsd.dk wrote: Has any of you played with this: http://www.sparkfun.com/products/8238 I had a look at this (and a few other GPS SDR solutions) back a year or two ago and

Re: [time-nuts] Low noise power supplies for time nuts circuitry

2011-11-24 Thread shalimr9
From a noise and long term stability standpoint, it would not be better than the last device in the chain, and the 78xx series is not great. But you would gain additional ripple and line variation rejection, so if that's what you need to do, it may help. Didier KO4BB Sent from my BlackBerry

Re: [time-nuts] Clocking a PIC16F628A from a Rubidium Standard

2011-11-24 Thread Attila Kinali
On Thu, 24 Nov 2011 14:41:24 + Stephen Farthing squir...@gmail.com wrote: I have an Efratom 101 frequency standard with a 10 MHz TTL otput. I want to use this to clock a PIC 16F628A so I can make a frequency counter with a resolution of 1 Hz. I am going to use the design by EI9GQ here

Re: [time-nuts] Low noise power supplies for time nuts circuitry

2011-11-24 Thread Joe Gwinn
At 2:28 PM + 11/24/11, time-nuts-requ...@febo.com wrote: Message: 3 Date: Thu, 24 Nov 2011 13:22:38 +0100 From: Attila Kinali att...@kinali.ch To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Low noise power supplies for time nuts

Re: [time-nuts] Clock Correction Algorithm

2011-11-24 Thread Javier Herrero
El 24/11/2011 15:21, Miguel Gonçalves escribió: I am using an Arduino Uno that presumably is running at 16 MHz. I am using a 16 bit timer with a 256 pre-scaler: 1600 / 256 = 62500 Hz 1 / 62500 = 16 us 65536 - 62500 = 3036 I am setting the counter to 3036 and let it overflow after

Re: [time-nuts] Clock Correction Algorithm

2011-11-24 Thread Bob Camp
Hi How about simply adding 1 ms every other second? You could then fine tune it by picking a small number of seconds to not add a ms to. Bob On Nov 24, 2011, at 7:16 AM, Javier Herrero jherr...@hvsistemas.es wrote: El 24/11/2011 13:56, Miguel Gonçalves escribió: Right! That is what I

Re: [time-nuts] SDR GPS

2011-11-24 Thread Bob Paddock
On Thu, Nov 24, 2011 at 6:19 AM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: Has any of you played with this:        http://www.sparkfun.com/products/8238 Anyone look at the the one from Parallax that Radio Shack is selling for less than $50?

Re: [time-nuts] Symmetricom TimeSource 2700

2011-11-24 Thread Charles P. Steinmetz
I wrote: pretty much every BTMon window contains a TOD display. I did a little investigating, and it turns out that the TOD displayed in the BTMon windows is the local system time, NOT time received from the TS2700. Apparently, the TS2700 does not send TOD on the Craft output. Best

Re: [time-nuts] Clock Correction Algorithm

2011-11-24 Thread Miguel Gonçalves
Hi Atilla! On 24/11/2011, at 14:42, Attila Kinali att...@kinali.ch wrote: On Thu, 24 Nov 2011 14:21:37 + Miguel Gonçalves m...@miguelgoncalves.com wrote: I am using an Arduino Uno that presumably is running at 16 MHz. I am using a 16 bit timer with a 256 pre-scaler: 1600 /

Re: [time-nuts] Clock Correction Algorithm

2011-11-24 Thread Miguel Gonçalves
Hi Javier! On 24/11/2011, at 15:15, Javier Herrero jherr...@hvsistemas.es wrote: El 24/11/2011 15:21, Miguel Gonçalves escribió: I am using an Arduino Uno that presumably is running at 16 MHz. I am using a 16 bit timer with a 256 pre-scaler: 1600 / 256 = 62500 Hz 1 / 62500 =

Re: [time-nuts] Clock Correction Algorithm

2011-11-24 Thread Miguel Gonçalves
Hi! On 24/11/2011, at 15:16, Bob Camp li...@rtty.us wrote: Hi How about simply adding 1 ms every other second? You could then fine tune it by picking a small number of seconds to not add a ms to. An idea but I am searching for a more global and elegant solution. In fact, after reading

Re: [time-nuts] Clocking a PIC16F628A from a Rubidium Standard

2011-11-24 Thread Robert Darlington
I've done this but don't remember the detail on the wiring. The data sheet made it clear though. One thing I did notice is that the oscillator seemed to power the chip! If I were doing it again I'd probably use some kind of powered buffer on the oscillator input so that when I power down the

Re: [time-nuts] SDR GPS

2011-11-24 Thread Robert Darlington
If you want altitude and speed, I recommend the Lassen IQ. ~$25 USD receiver. Good to 18000 meters (59k feet) and 500m/s (1118 MPH). You can exceed any ONE of these specs, but not both. Not really useful for timenuttery though but used often in high altitude balloons. -Bob On Thu, Nov 24,

Re: [time-nuts] Symmetricom TimeSource 2700

2011-11-24 Thread Frederick Bray
Thanks for that information. I had assumed that it was obtained from the cell towers -- after all, my cellphone does show local time. I was hoping that there would be a TOD output. Still the device is very nice and useful as a frequency standard. On 11/24/2011 8:25 AM, Charles P.

Re: [time-nuts] SDR GPS

2011-11-24 Thread Collins, Graham
Perhaps not in the same league or with the same gee-whiz appeal as a SDR GPS receiver but how about your own DIY GPS receiver: http://dangerousprototypes.com/2011/11/24/homemade-gps-receiver/ and the authors web page: http://www.holmea.demon.co.uk/GPS/Main.htm cheers, Graham ve3gtc

Re: [time-nuts] Symmetricom TimeSource 2700

2011-11-24 Thread Charles P. Steinmetz
Frederick wrote: Thanks for that information. I had assumed that it was obtained from the cell towers I was hoping that there would be a TOD output. Still the device is very nice and useful as a frequency standard. Symmetricom sold the TS2700 as a Stratum 1 source, so it is likely that

[time-nuts] Differences / Jitter Between Frequency Standard Sources

2011-11-24 Thread Frederick Bray
I have what would probably be considered to be a newbie question, so please excuse my likely ignorance. I have a HP 5385A frequency counter, which I am using with an external standard. If I try to compare one 10 MHz standard against another, using one as the external standard and the other

Re: [time-nuts] Differences / Jitter Between Frequency Standard Sources

2011-11-24 Thread Robin Kimberley
Any frequency counter will have an given accuracy +/- the LSD (least significant digit), so alternating between 10.000 and 9.999 looks perfectly normal to me. Rob Kimberley -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of

Re: [time-nuts] Symmetricom TimeSource 2700

2011-11-24 Thread Kevin Rosenberg
On Nov 24, 2011, at 9:25 AM, Charles P. Steinmetz wrote: I did a little investigating, and it turns out that the TOD displayed in the BTMon windows is the local system time, NOT time received from the TS2700. Apparently, the TS2700 does not send TOD on the Craft output. Hi Charles, When I

Re: [time-nuts] Low noise power supplies for time nuts circuitry

2011-11-24 Thread Kevin Rosenberg
78xx Regulators are quite noisy. You can use them to filter the noise of a cheap DC/DC converter, but i wouldnt use them feed high precision electronics. There are a lot better designs these days. Hi Attila, Would you mind recommending some low-noise regulators? Perhaps for both low and high

Re: [time-nuts] Low noise power supplies for time nuts circuitry

2011-11-24 Thread Kevin Rosenberg
On Nov 23, 2011, at 5:50 AM, Chuck Forsberg WA7KGX N2469R wrote: How sensitive are each of a Thunderbolt's 3 supplies to noise? This doesn't break down the sensitivities to noise, but Tom shows a range of TBolt output noise for different 3 voltage power supplies:

Re: [time-nuts] Clock Correction Algorithm

2011-11-24 Thread Kevin Rosenberg
On Nov 24, 2011, at 9:35 AM, Miguel Gonçalves wrote: The software way is probably the best idea as it would account for small differences in different oscillators. I have 3 Arduino boards and will make 3 time displays. For precision timing with a microcontroller, I've been using the 10 MHz

Re: [time-nuts] Differences / Jitter Between Frequency Standard Sources

2011-11-24 Thread Randy D. Hunt
On 11/24/2011 10:01 AM, Robin Kimberley wrote: Any frequency counter will have an given accuracy +/- the LSD (least significant digit), so alternating between 10.000 and 9.999 looks perfectly normal to me. Rob Kimberley -Original Message- From: time-nuts-boun...@febo.com

Re: [time-nuts] Differences / Jitter Between Frequency Standard Sources

2011-11-24 Thread David Bobbett
Just as an aside, you /can /get rid of the 'dithering digit' problem if you use a counter which employs a reciprocal counting technique. I use a Thandar Thirlby TF830 locked to a 10MHz reference derived from a Tbolt, but I'm sure there must be others. David Bobbett, G4IRQ On 24/11/2011

Re: [time-nuts] Clocking a PIC16F628A from a Rubidium Standard

2011-11-24 Thread Kevin Rosenberg
On Nov 24, 2011, at 7:50 AM, Attila Kinali wrote: Have a look at the PIC 16F628 data sheet, it will tell you the requirements for the clock input and there should be circuit for external clock signal listed. If it's not in the datasheet, it should be in an appnote. Usually, chips accept

Re: [time-nuts] Low noise power supplies for time nuts circuitry

2011-11-24 Thread lists
When you design a regulator, lots of gain is not a criteria in the error amp. (Who needs microvolt accuracy?) High gain generally means two gain stages, which in turn makes it difficult to compensate when driving reactive loads. Thus most op amps are generally a bad idea for an error amp in a

Re: [time-nuts] Clocking a PIC16F628A from a Rubidium Standard

2011-11-24 Thread Hal Murray
One thing I did notice is that the oscillator seemed to power the chip! If I were doing it again I'd probably use some kind of powered buffer on the oscillator input so that when I power down the circuit it actually stops. That's a reasonably common problem. Occasionally it's a feature.

Re: [time-nuts] Symmetricom TimeSource 2700

2011-11-24 Thread Charles P. Steinmetz
Kevin wrote: reading more about the TL1 messages from the Craft output, there are messages for date and time: date: This parameter is the current date in the 8-digit form -mm-dd, where is year, mm is month (01­12), and dd is day (01­31). time: This parameter is the current time in

Re: [time-nuts] Differences / Jitter Between Frequency Standard Sources

2011-11-24 Thread Azelio Boriani
Or modern counters where internally every type of measurement is reduced to a time interval measurement like the HP53132 (150pS resolution). On Thu, Nov 24, 2011 at 8:04 PM, David Bobbett d.bobb...@tiscali.co.ukwrote: Just as an aside, you /can /get rid of the 'dithering digit' problem if you

Re: [time-nuts] Differences / Jitter Between Frequency Standard Sources

2011-11-24 Thread Frederick Bray
Thanks to all who replied. I thought that it was a counter artifact, but I didn't know why. Any suggestions for a reasonably priced good frequency counter that uses the reciprocal method? I saw there were a couple TF830's on ebay, but they were outside the U.S. The HP 5340A looks like it

Re: [time-nuts] Clocking a PIC16F628A from a Rubidium Standard

2011-11-24 Thread Hal Murray
I have an Efratom 101 frequency standard with a 10 MHz TTL otput. I want to use this to clock a PIC 16F628A so I can make a frequency counter with a resolution of 1 Hz. I am going to use the design by EI9GQ here http:// homepage.eircom.net/~ei9gq/counter.html . What I need to know is how i

Re: [time-nuts] Low noise power supplies for time nuts circuitry

2011-11-24 Thread Azelio Boriani
The -12V in the TBolt is not used for the serial port. the HIN232 of the TBolt goes from the +5V only, it generates the + and - by the usual switched capacitor technique common to other RS232 interfaces (ADM232, MAX3221 and so on). The -12V powers the LT1014 quad precision opamp that I presume

Re: [time-nuts] Differences / Jitter Between Frequency Standard Sources

2011-11-24 Thread cfo
On Thu, 24 Nov 2011 12:54:12 -0800, Frederick Bray wrote: Thanks to all who replied. I thought that it was a counter artifact, but I didn't know why. Any suggestions for a reasonably priced good frequency counter that uses the reciprocal method? I saw there were a couple TF830's on ebay,

Re: [time-nuts] Low noise power supplies for time nuts circuitry - 40μV Adjustable Voltage Regulator Board

2011-11-24 Thread Tim
Hi All , I find it interesting that this subject came up just as I was looking into cleaning up some of my supplies that power my RB's. Anyway I just bought two of these to play with http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItemitem=130605436528 and they're based on this device...

Re: [time-nuts] Symmetricom TimeSource 2700

2011-11-24 Thread Charles P. Steinmetz
I wrote: The Craft output feeds a PC Com port -- I'd think that reading the Com port with a terminal emulator should verify whether the date and time events are sent regularly, or only with Alarms or Events. I just did this, and the TS2700 has been silent for 30 minutes (it has not had an

Re: [time-nuts] Differences / Jitter Between Frequency Standard Sources

2011-11-24 Thread Frederick Bray
Looks like my counter is reciprocal. Thanks for the info. Fred Bray W6WAW ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.

Re: [time-nuts] Symmetricom TimeSource 2700

2011-11-24 Thread Kevin Rosenberg
On Nov 24, 2011, at 2:43 PM, Charles P. Steinmetz wrote: I just did this, and the TS2700 has been silent for 30 minutes (it has not had an Alarm or Event since its last power cycle, about 6 months ago, according to its log). I did not want to disturb it by creating an Alarm or Event.

Re: [time-nuts] Differences / Jitter Between Frequency Standard Sources

2011-11-24 Thread Tom Van Baak
I have a HP 5385A frequency counter, which I am using with an external standard. If I try to compare one 10 MHz standard against another, using one as the external standard and the other as the device being measured, the readout fluctuates between 10.000 and 9.999. This happens when

[time-nuts] Clocking a PIC16F628A from a Rubidium Standard

2011-11-24 Thread Kit Scally
Stephen, As well as limiting the input voltage swing into the PIC with a ~2k2 resistor, add an additional 4k7 or 10k resistor (AOT) across the PIC's Vcc rail to ground. This swamps the rectified DC produced by the input drive signal when the PIC DC supply is removed. I've used /tvb's PIC

Re: [time-nuts] Low noise power supplies for time nuts circuitry

2011-11-24 Thread Bob Camp
Hi The Linear LT1764 is reasonably quiet / high current / low dropout. Don't count on getting all three at once. Bob On Nov 24, 2011, at 12:45 PM, Kevin Rosenberg ke...@rosenberg.net wrote: 78xx Regulators are quite noisy. You can use them to filter the noise of a cheap DC/DC converter,

Re: [time-nuts] Low noise power supplies for time nuts circuitry - 40μV Adjustable Voltage Regulator Board

2011-11-24 Thread gary
The LTC datasheet crows about low current in dropout. Yeah, it's worth crowing about since not all chip use what is called a sat catcher circuit. High current in dropout with PNP pass devices can be a problem. I've seen Micrel regulators that are horrible in dropout. The sat catcher is yet

Re: [time-nuts] Low noise power supplies for time nuts circuitry

2011-11-24 Thread Kevin Rosenberg
On Nov 24, 2011, at 4:46 PM, Bob Camp wrote: The Linear LT1764 is reasonably quiet / high current / low dropout. Don't count on getting all three at once. Thanks, Bob! Kevin ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to

Re: [time-nuts] Symmetricom TimeSource 2700

2011-11-24 Thread Charles P. Steinmetz
Kevin wrote: I use the Craft connector for monitoring with BTMon rather than the RS-232 port. It appears the Craft output, while spontaneously emitting alarm/events, does respond to queries from BTMon on the Craft input. Everything I reported previously involved the Craft port feeding a PC

[time-nuts] Using Thyme for Stuffed Mushrooms

2011-11-24 Thread Bill Hawkins
Stuffed mushrooms are a fine holiday treat. Begin with a box of baby Portabella (Crimini) mushrooms. You know, the ones that start out as spores in a soil of horse manure and hay in a dark, moist limestone cave. The young mushrooms dream of becoming large, but one day the cave is filled with

Re: [time-nuts] DGPS@home

2011-11-24 Thread ehydra
I read that for position accuracy ionospheric effects are the main source for typical single frequency receivers. So looking for DOP would be not helpful because the ionospheric way is for two 'relative' on the same position located teceivers vs. satellites position almost the same and that

Re: [time-nuts] DGPS@home

2011-11-24 Thread Chris Albertson
I think the accuracy could be quite good if you took advantage of the times the robot was motionless. During those times it could build up many seconds of averaging and then while moving either use dead reckoning or inertial navigation. On Thu, Nov 24, 2011 at 4:01 AM, ehydra ehy...@arcor.de

Re: [time-nuts] Using Thyme for Stuffed Mushrooms

2011-11-24 Thread Eric Garner
Happy thanksgiving bill - eric Sent from my Banana Jr.(tm) mobile device On Nov 24, 2011, at 8:55 PM, Bill Hawkins b...@iaxs.net wrote: Stuffed mushrooms are a fine holiday treat. Begin with a box of baby Portabella (Crimini) mushrooms. You know, the ones that start out as spores in a soil

Re: [time-nuts] Low noise power supplies for time nuts circuitry

2011-11-24 Thread Attila Kinali
On Thu, 24 Nov 2011 11:45:05 -0700 Kevin Rosenberg ke...@rosenberg.net wrote: 78xx Regulators are quite noisy. You can use them to filter the noise of a cheap DC/DC converter, but i wouldnt use them feed high precision electronics. There are a lot better designs these days. Would you

Re: [time-nuts] Clock Correction Algorithm

2011-11-24 Thread Attila Kinali
On Thu, 24 Nov 2011 16:32:04 + Miguel Gonçalves m...@miguelgoncalves.com wrote: Hi Atilla! On 24/11/2011, at 14:42, Attila Kinali att...@kinali.ch wrote: I'm not quite sure i understood you correctly, and i dont know anything about the arduino and the avr32. But usually, you set a