kuze...@gmail.com said:
this is a no-name cheapo SIRF module
1) I need a computer with a serial port. The curent GPS module I'm using is
INTERNALLY RS232 -- USB converter, and recognized by my windows 7 computer
as: Prolific USB-to-Serial Comm Port (COM3) ... the latency and jitter is
I will jump in a bit. I, and many have been right where you are. You are
correct...USB is a no go for accurate time. Same on windows. So you need a
Linux box with serial port. Anything from a Beaglebone, pandabox...or pc will
work. You certainly need a gps with a pulse per second output
Just one further question.
When the pps input triggers, so my linux box knows a second has just
ticked; is the time of that second the one the NMEA sentence has just
sent, or will send next?
Or to put it another way, when I receive an NMEA sentence is this the
current time (as was when the
The time when the names sentence was sent is the time in the sentence.. The pps
signals every second..they are independent. Tat is the very nature of the
problem with the nmea sentence..latency associated with the message itself.
Sent from my iPad
On Aug 19, 2012, at 6:11 AM, Ken Duffill
Ken:
From what I've read, most GPS modules which output PPS, the NMEA
sentence has the timestamp of the next, upcoming pulse. Regardless of
how the NMEA or other time data is, the PPS itself is only a guarantee
this is the boundary for a second and NTP documentation typically
recommends a second
Hello The Net,
For your consideration:
The INTEL model DN2800mt ITX mother board uses a ATOM CPU and
draws about 11 watts of AC power when configured as:
(I have not measured DC power yet.)
30 GB OCZ Nocti mSATA solid state drive,
WIN7 pro, 64 bit, USB keyboard and mouse
APEX MI-0008 case.
In my experience (which is admittedly less than that of many others here) the
time reported is that of the PPS pulse that just happened, and the
documentation usually bears that out. There's a real-time clock running inside
the receiver that is synchronized to the PPS. At the top of the second,
Greetings nuts,
All this recent NTP discussion has me thinking about a dedicated NTP
server again. The usual solution is to use commodity hardware of some
persuasion (PC, mini-itx or even ARM) running ntpd, but I'm thinking we
can do better. The only reason a full ntpd is needed is for its
This sounds like a newer version of the board I use. The thing to check
is if the CPU heat sink has a fan or not. Having no fan indicates that the
CPU is not using much power. It also removes a common failure point.
To reduce power even more. On an NTP server you can unplug the keyboard,
Why not just use a raspberry pi? Uses a whole 2w at idle. Ntp might bump that
to 2.01.
On Aug 19, 2012, at 13:06, Chris Albertson albertson.ch...@gmail.com wrote:
This sounds like a newer version of the board I use. The thing to check
is if the CPU heat sink has a fan or not.
On Sat, Aug 18, 2012 at 10:23 PM, li...@lazygranch.com wrote:
If you are using a desktop, I'd suggest putting in a serial card. The
Netmos chip based cards work on windows and linux, though your should do an
internet search on the particular card before you buy.
I have the prolific based
Hi
Onboard ethernet on the pi model B is hooked into the CPU via the USB port.
That may not be best for accurate time.
Bob
On Aug 19, 2012, at 1:16 PM, bownes bow...@gmail.com wrote:
Why not just use a raspberry pi? Uses a whole 2w at idle. Ntp might bump that
to 2.01.
On
On Sun, Aug 19, 2012 at 10:16 AM, bownes bow...@gmail.com wrote:
Why not just use a raspberry pi? Uses a whole 2w at idle. Ntp might bump
that to 2.01.
You certainly could run ntpd on that box. But I wonder how the PPS is
supported in hardware? What is the standard deviation of interrupt
On Sun, Aug 19, 2012 at 8:21 AM, Michael Tharp g...@partiallystapled.comwrote:
Thoughts? Has it been done before, preferably with open source? I'd love
to make it myself but I have to finish the GPSDO first :-)
NTP is not as easy as you think. Just doing the cryptography to handle
I have a soekris box but got hung up on the compact free bsd install. Wish I
had more time to get a handle on that. I am certain the thing would be hard to
beat power wise and it is all in one nice tidy box.
Doc
Sent from my iPhone
On Aug 19, 2012, at 12:38 PM, Chris Albertson
Hi Bill --
Your lucky day may be at hand -- I've been struggling to get my herd of
Soekris 4501s running again and thought the process of updating from BSD
4 to 9 would be simple. Well, several months later I have a working
CF image and am just getting the four 4501s Soekris's (Soekri?)
This is probably something that very, very few other people are going to
encounter, but thought I would note it here for posterity.
I'm using the Soekris 4501 with high-resolution Elan CPU for nanosecond
timestamps as documented at http://www.febo.com/pages/soekris. When
using a PPS-only
On 08/19/2012 01:38 PM, Chris Albertson wrote:
NTP is not as easy as you think. Just doing the cryptography to handle
authentication is more then I would want to write. When a free open source
ntpd exists it will be really hard to get people to help work on
re-inventing it. But your idea to
If your design gets off the ground, I'd surely try to replicate it from
your part list or buy a kit from you or whatever. Sounds great.
On 8/19/2012 2:19 PM, Michael Tharp wrote:
On 08/19/2012 01:38 PM, Chris Albertson wrote:
NTP is not as easy as you think. Just doing the cryptography to
It's important to remember that on a computer, the wattage shown has no
relationship to the wattage pulled from the socket. The numbers shown
are maximum values. You have to measure the power draw and you have to
measure it in volt-amps, not watts because that's how residential power
is
Hi Ed;
I may not have had enough coffee yet, but if Volt X Amps = Watts why would
there be a difference?
Best Wishes;
Thomas Knox
Date: Sun, 19 Aug 2012 12:35:51 -0600
From: ed_pal...@sasktel.net
To: time-nuts@febo.com
Subject: Re: [time-nuts] Modern motherboard with RS232 port
It's
Sarah,
If you want to filter in ebay, you can use a- for a subject that you don't
want to see. It is the same syntax as you can use in a browser.
Regards,
Willy
-Oorspronkelijk bericht-
Van: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] Namens
oh wow, thanks. I'll try that.
Also, I figured out that typing in trimble thunderbolt instead of
thunderbolt gps gives me zero hits for phone... but fewer hits for the
GPSDO too :(
On 8/19/2012 3:21 PM, Willy Willemse wrote:
Sarah,
If you want to filter in ebay, you can use a- for a subject
Ed:
you're sorta right, but only on a really basic level of electrical
engineering.
Induction and capacitance and random transformer magnetic flux nonsense
that makes AC currents act in unexpected ways. The difference between
volt-amp versus RMS watt versus peak watts, etc, etc. can be off by
Power factor.
-Original Message-
From: Tom Knox act...@hotmail.com
Sender: time-nuts-boun...@febo.com
Date: Sun, 19 Aug 2012 13:19:20
To: Time-Nutstime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Modern
There is no difference for a resistive load. For a reactive load, you have
to take in account the phase angle between the current and the voltage. If I
remember correctly, power = Volts X Amps X cosine of the phase angle. Some
refer to the phase angle as the power factor.
John WA4WDL
If you live near a Fry's, get a basic Kill-A-Watt. About $20. Often less on
sale. You don't need the fancy version that computes cost versus time of day,
etc.
-Original Message-
From: Ed Palmer ed_pal...@sasktel.net
Sender: time-nuts-boun...@febo.com
Date: Sun, 19 Aug 2012 12:35:51
To:
Phase angle/power factor
Don
Tom Knox
Hi Ed;
I may not have had enough coffee yet, but if Volt X Amps = Watts why
would there be a difference?
Best Wishes;
Thomas Knox
Date: Sun, 19 Aug 2012 12:35:51 -0600
From: ed_pal...@sasktel.net
To: time-nuts@febo.com
Subject: Re: [time-nuts]
On 08/19/2012 03:38 PM, Christopher Brown wrote:
Though I am a little surprised about residential power being
measured/billed in VA not KW/h in North America. Pretty sure the US is
in North America, even Alaska in slightly more North America. Never
seen a VA/h meter in the US.
Was guessing it
Is it just me, or has this thread gone off topic a tad ??
73, Dick, W1KSZ
-Original Message-
From: Michael Tharp g...@partiallystapled.com
Sent: Aug 19, 2012 12:42 PM
To: time-nuts@febo.com
Subject: Re: [time-nuts] Modern motherboard with RS232 port
On 08/19/2012 03:38 PM, Christopher
No it is not.
VA * PF = W for VA = volt amps, PF = power factor, W = watts (or true power)
PF = the cos of the phase angle between the current and the voltage
(assuming both are sine waves)
+
Peak Volts * 0.707 = RMS volts, again for sine waves only.
+
- Original
Cosine of the phase angle is the power factor, a number between 0 and 1
But only for sine waves.
- Original Message -
From: jmfranke jmfra...@cox.net
To: Time-Nuts time-nuts@febo.com
Sent: Sunday, August 19, 2012 3:36 PM
Subject: Re: [time-nuts] Modern motherboard with RS232 port
I stand corrected, shows what I get for listening to a UPS vendors
documentation.
On 8/19/12 11:52 AM, Tom Miller wrote:
No it is not.
VA * PF = W for VA = volt amps, PF = power factor, W = watts (or true power)
PF = the cos of the phase angle between the current and the voltage
ed_pal...@sasktel.net said:
You have to measure the power draw and you have to measure it in volt-amps,
not watts because that's how residential power is measured (at least in
North America).
Are you sure about that? I've never seen that claim before.
Here is PGE's blurb that covers
In message 503141b7.6070...@partiallystapled.com, Michael Tharp writes:
On 08/19/2012 03:38 PM, Christopher Brown wrote:
VA is used all over the place in electrical systems calculations and
equipment specs but have never seen billing on it.
Billing VA is usually a kWh price and a KVAR
On Sun, Aug 19, 2012 at 12:19 PM, Tom Knox act...@hotmail.com wrote:
Hi Ed;
I may not have had enough coffee yet, but if Volt X Amps = Watts why would
there be a difference?
That relationship holds for DC but with AC the phase relationship between
voltage and current depends of the complex
On Sun, Aug 19, 2012 at 1:16 PM, Chris Albertson
albertson.ch...@gmail.comwrote:
If the load is reactive the phase will not be exactly 90 degrees.
The above is not what I meant. I meant voltage and current might not be
in phase and might even be 90 out of phase. Then you can see that each
Hi;
Thanks for the responses. I did not mean to steer the thread off course. I
understand all the theroy, I just didn't understand that VA automatically
included PFC or crest factor where watts did not.
I would have assumed the opposite since watts is based on RMS.
Thanks;
Thomas Knox
From:
On Sat, Aug 18, 2012 at 9:20 AM, David J Taylor
david-tay...@blueyonder.co.uk wrote:
From: Chris Albertson
Sent: Saturday, August 18, 2012 4:55 PM
[]
Power is a bigger issue. It really does cost a bit to keep some
machines owered up 24x7 and NTP needs to run all the time. It takes
NTP
I was afraid that this topic would turn into a swamp and I didn't help
things by getting it backwards. Yes, the residential meter measures
WattHours, not VoltAmpHours. My apologies for adding confusion to an
already confusing topic.
While new PCs may have power factor corrected power
On 19 August 2012 21:36, Tom Knox act...@hotmail.com wrote:
I would have assumed the opposite since watts is based on RMS.
Thanks;
Thomas Knox
Power measured in Watts RMS is a useless unit. Sure you can
mathematically calculate the RMS value of power, but it does not have
any physical
Another option is a low end laptop.
I use a Dell D400 laptop, with a 1.8GHz Pentium M and it draws about 20W from
A/C with the display blanked, which is the way an NTP server will be most of
the time.
The power brick rating assumes running the laptop AND charging the battery at
the same time.
On Aug 19, 2012, at 12:15 PM, John Ackermann N8UR j...@febo.com wrote:
This is probably something that very, very few other people are going to
encounter, but thought I would note it here for posterity.
Thanks! You've already helped one person. I ran up against that problem when
testing one
Hi
The pi doesn't have a conventional serial port. It does have a TTL serial on
the 28 pin connector. There are also IRQ pins on the same connector. Since they
go directly to the CPU chip, hardware latency should be pretty good. It should
interface directly to a TTL output gps receiver like a
On Sun, Aug 19, 2012 at 5:21 PM, Bob Camp li...@rtty.us wrote:
Hi
The pi doesn't have a conventional serial port. It does have a TTL serial
on the 28 pin connector. There are also IRQ pins on the same connector.
Since they go directly to the CPU chip, hardware latency should be pretty
good.
Hi
There has been a lot of work done on FreeBSD kernel timing and ntp. That and
the work PHK has done on some of the drivers makes it a tough thing to beat.
Since the pi is ARM hardware, a lot of the 386 specific work isn't going to
apply to it. Still that's less of an issue than the USB to
Hi,
I am looking for opinions on the RFT Gm II- XO and RFT Gm II- RB combination
compared to TBolt or HP 3815A. I can get the Lucent pair at a very
reasonable price. Are manuals easily obtained for them?
Thanks
Jerry
K1JOS
___
time-nuts mailing
Hi
Compared to the other two, there is a lot less support for the RFTG parts. Lady
Heather is a *very* good reason to use a TBolt.
Bob
On Aug 19, 2012, at 9:06 PM, Jerry jster...@att.net wrote:
Hi,
I am looking for opinions on the RFT Gm II- XO and RFT Gm II- RB combination
compared to
It comes w ntp out of the box if you run fedora.
On Aug 19, 2012, at 20:21, Bob Camp li...@rtty.us wrote:
Hi
The pi doesn't have a conventional serial port. It does have a TTL serial on
the 28 pin connector. There are also IRQ pins on the same connector. Since
they go directly to the
Hi
But you still need:
1) Porting of the kernel timing stuff to the ARM6 architecture. Once it's
ported, you need it debugged and fine tuned.
2) The low level drivers in NTP ported to the ARM6 i/o setup. They also need
some work to reduce latency.
3) The timing work on the USB to Ethernet
On Sun, Aug 19, 2012 at 6:49 PM, bownes bow...@gmail.com wrote:
It comes w ntp out of the box if you run fedora.
You can run NTP without a Pulse Per Second (PPS) driver. It will work just
fine. Most NTP installations don't use PPS. But if you want to connect a
GPS receiver and use it for
Residential power is traditionally measured in watts, not V-A. Commercial
power is typically measured in V-A, with an additional fee for power factor
problems.
-Chuck Harris
Ed Palmer wrote:
It's important to remember that on a computer, the wattage shown has no
relationship
to the wattage
The long and the short of it is that when AC encounters a reactive
load, it results in a current that is not in phase with the voltage.
Power is equal to volts x amps only when the current and voltage are
in phase which can only happen if the load is purely resistive.
If you hang a perfect
Agreed. Just pointing out there isn't a big porting effort to get ntpd itself
up and running.
On Aug 19, 2012, at 22:24, Chris Albertson albertson.ch...@gmail.com wrote:
On Sun, Aug 19, 2012 at 6:49 PM, bownes bow...@gmail.com wrote:
It comes w ntp out of the box if you run fedora.
Boy do I agree with Bobs comment.
But I have several of the lucent RBs and at least most of mine are quite
old. Hey $20 you can't really argue. Or as they say you get what you pay
for.
So reasonable is a curious question. Or a caution.
By the way I am not at all complaining actually.
Regards
Paul.
Hi Paul;
Has anyone played with these Lucent units much to see if LH could be tweaked to
work?
Thanks;
Thomas Knox
Date: Sun, 19 Aug 2012 22:44:38 -0400
From: paulsw...@gmail.com
To: time-nuts@febo.com
Subject: Re: [time-nuts] Lucent GPS and RB pair
Boy do I agree with Bobs comment.
It's a pain to capture on any scope, but really easy to see with an
LED across the output. it's not bright, but definitely easy to see on
my tbolt.
-Bob
On Mon, Jul 23, 2012 at 10:11 AM, Stephen Farthing squir...@gmail.com wrote:
Hi Guys,
I have a couple of Trimble T Lassen 2 boards I bought
On 8/19/12 7:26 PM, Chuck Harris wrote:
Residential power is traditionally measured in watts, not V-A. Commercial
power is typically measured in V-A, with an additional fee for power factor
problems.
residential meters measure watts (active power) not VA...
What you want is the
On Sun, Aug 19, 2012 at 9:27 PM, Robert Darlington rdarling...@gmail.comwrote:
It's a pain to capture on any scope, but really easy to see with an
LED across the output. it's not bright, but definitely easy to see on
my tbolt.
That is true. One must have very good eyes to see a one
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