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
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
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
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
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
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
___
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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?
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
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 /
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 =
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
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
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,
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.
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
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
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
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
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
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
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:
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
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
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
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
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
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.
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
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
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
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
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
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,
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...
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
Looks like my counter is reciprocal.
Thanks for the info.
Fred Bray
W6WAW
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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.
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
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
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,
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
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
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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
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
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
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
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
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
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
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