I know the thread began with a request for a "simple" DIY GPSDO, and
this may not be quite as simple as some might like. However, PPS
discipline is generally the simplest and most universal scheme from
the standpoint of interfacing to whatever GPS engine one has
available. The PRS10 has a cle
On Fri, Dec 30, 2011 at 11:46 AM, Stanley wrote:
>
>
>>
>>> "What is the simplest design for a GPSDO that uses only the PPS signal
>>> from
>>> a modern GPS?"
>>
>>
>> Some sort of oscillator with a voltage control.
>> CPU with a timer/counter that can capture the PPS.
>> DAC.
>> Software.
>>
>
>
On Fri, Dec 30, 2011 at 10:16 AM, Hal Murray wrote:
>
>> "What is the simplest design for a GPSDO that uses only the PPS signal from
>> a modern GPS?"
>
> Some sort of oscillator with a voltage control.
> CPU with a timer/counter that can capture the PPS.
> DAC.
> Software.
As soon as you say "So
Don't need to stretch, use the two hardware interrupt pins...
Don
Chuck Forsberg WA7KGX N2469R
> I was thinking ... starting with a 5680a and a GPS with
> accurate 1pps but no 10 MHz ...
>
> Feed both 1pps signals to a 74ls123 to stretch the pulses to something
> longer.
> A 74ls74 is strobed by o
Mine was declared a woman's silk shirt for some reason.. Not sure why.
Sent From iPhone
On Dec 30, 2011, at 17:41, li...@lazygranch.com wrote:
> I got a feebay shipment from China today. Duty? No problem, it was declared a
> gift. ;-)
>
> ___
> time-
Did you test the LTC1655 INL? The data sheet says plus or minus 20
counts maximum.
I suspect Linear Technology designed those low DNL high INL parts for
just this sort of application where only monotonic behavior really
matters. Their equivalent current output DAC costs about twice as
much not i
I was thinking ... starting with a 5680a and a GPS with
accurate 1pps but no 10 MHz ...
Feed both 1pps signals to a 74ls123 to stretch the pulses to something
longer.
A 74ls74 is strobed by one of the one-shots, its D input being the other
one-shot.
Connect both one-shots and the 74 to an Ard
Then the best is probably to do your own survey. I am not sure that what is
being observed in an "undisclosed location" would have much weight with your
management.
You can rent a Dranetz for a couple of months and install it a week at a time
in carefully selected locations and get data that yo
I recently changed to an APC UPS (which was an upgrade in communications,
but a downgrade in efficiency) that which supports reading the voltage.
It's one of those AVR type that can boost or drop the voltage so it's
closer to spec. It seems to drop out below 95v, and above 135v (factory
eeprom set
It is one of those cost/benefit calculations. The cost of sorting the real
gifts from the commerce <$100 labeled as gift probably wouldn't pay for itself.
It is, of course illegal. The question is are we better off changing the
enforcement or the law. Not to mention the cost of the latter.
Ma
> Well, I design systems that we send out all over the world. I have various
> spec numbers that indicate some rather optimistic tolerance. For example, I
> have measured actual outlets in the US at 70VAC and 142VAC, which is well
> outside the published tolerances. I get a lot of flack from manag
I hope Customs is more worried about containers full of counterfeit and
pirated stuff, than a single electronc toy.
-John
=
> Was it really a gift ?? The U. S. Customs folks take a dim view on folks
> lying on a Customs Declaration.
> But, being realistic, it's so rampant that only
Was it really a gift ?? The U. S. Customs folks take a dim view on folks
lying on a Customs Declaration.
But, being realistic, it's so rampant that only by making a Federal Case
out of one will it ever stop. But, I am not holding my breath.
73 es HNY, Dick, W1KSZ
-Original Message-
>
Bert,
Would you have time to generate a brief report of your DAC testing?
I for one am very interested.
I could publish it on my web site if you want.
Didier KO4BB
Sent from my BlackBerry Wireless thingy while I do other things...
-Original Message-
From: ewkeh...@aol.com
Sender: time
I've never had to pay any duty for shipments from China, Japan, Europe, etc
-Dave
- Original Message -
From: li...@lazygranch.com
To: "Discussion of precise time and frequency measurement"
Sent: Friday, December 30, 2011 3:41:43 PM
Subject: [time-nuts] Speaking of shipments from Ch
I got a feebay shipment from China today. Duty? No problem, it was declared a
gift. ;-)
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and follow the instructions there.
I've been loging my TED5000 (voltage, current) for almost half a year
now. It does not provide frequency, but the log is down to the second.
I keep several periods in the archive for easy access (Daily, Hourly
Minute, Second) About 3.5gb of csv energy data per channel for my home.
Problem is that
It has occurred to me that using 3/4 of a quad 256-step digital pot (like
the AD5263, only 6$) set up as a Kelvin-Varley divider might be an alternative
to a DAC. Use 2 sections both voltage driven but set 2 values apart, such that
the "wiper" arms are just a fraction of the reference apart. Tha
No free lunch, of course, but I want to avoid dithering DACs. The 18bit DAC
(AD5680) is a 16bit+dithering, I think to use the AD5660 + AD5241 (already
available) the pot has a tempco of 30ppm/degree and a noise of
14nV/sqr(Hz). Maybe I have to find something better but to make the first
try is avai
From: time-nuts-boun...@febo.com [time-nuts-boun...@febo.com] On Behalf Of
shali...@gmail.com [shali...@gmail.com]
Sent: Friday, December 30, 2011 3:47 PM
To: Time-Nuts
Subject: Re: [time-nuts] line frequency website
The problem is that while the frequenc
Imagine a 3d map in which colour represents phase or frequency and Z
displacement of the sample point represents voltage.
Would make for a nice animation anyway.
On Dec 30, 2011, at 17:47, shali...@gmail.com wrote:
> The problem is that while the frequency is going to be pretty much the sam
Over the last two years along with two list members that may want to pipe
in, I have spend a large amount of time on D/A's and we went as far as
developing a test board using the LTC 2440 and testing numerous D/A's taking in
to consideration performance, solderability, cost, availability and
The problem is that while the frequency is going to be pretty much the same
anywhere on the same grid, the voltage is not. Knowing the voltage at some
point in your state (or another) is not all that useful. They may record it,
but I am not even sure it would be worth saving in a database.
Didi
> Yes, the DAC+reference is challenging and one way to go may be the
> coarse+fine approach to avoid large (18bit and beyond) DAC. My last GPSDO
> has an 18bit DAC but now I'm thinking to try the 8bit digital pot + 16bit
> DAC op-amp combined. The reference can't be overlooked anyway.
Be careful
On 12/30/2011 8:59 PM, Murray Greenman wrote:
> 2. The excellent 10kHz design by James G3RUH
> http://www.jrmiller.demon.co.uk/projects/ministd/frqstd.htm requires a 10kHz
> GPS source, and folk on this group asked where you can get a modern GPS
> module with 10kHz output. One suitable answer is
Yes, the DAC+reference is challenging and one way to go may be the
coarse+fine approach to avoid large (18bit and beyond) DAC. My last GPSDO
has an 18bit DAC but now I'm thinking to try the 8bit digital pot + 16bit
DAC op-amp combined. The reference can't be overlooked anyway.
On Fri, Dec 30, 2011
On 12/30/11 11:39 AM, Robert LaJeunesse wrote:
How about USB to an FT232 that talks SPI to a low-cost DAC or digital pot? Would
need a stable reference, though.
There's a bunch of eval boards from LTC, etc. which use this strategy.
Looks like a serial port to the computer, simple ASCII protoco
It very well could be USPS is acting as the agent for the package. Not
uncommon now days since so much is shipped from CN/HK/etc to the US.
On Fri, Dec 30, 2011 at 1:34 PM, Alberto di Bene wrote:
> On 12/30/2011 6:38 PM, Chris Albertson wrote:
>> Mine was sent by China Post. The Chinese post
On 12/30/2011 6:38 PM, Chris Albertson wrote:
> Mine was sent by China Post. The Chinese post office. Took 10 days
> to get to California. For me, this is typical for stuff I buy from
> Chinese eBay sellers. The Hong Kong Post is slightly faster. I've
> think it might just be a matter of luc
The DAC and it's voltage reference looks to be the weak link in the digital
control and the "simple" goal. The CPU I mentioned before on closer look
doesn't have a good DAC. The 20 bit TI DAC1220 looks better but not sure you
can find it in the same package as the CPU. The cheap Rb standards wit
Thanks to all of you for the feedback on this question. I ordered mine
mid-December on a free postage deal, so I'm guessing I should see them
within the next week hopefully.
Rob K
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Rob Kimb
Usually timing grade GPS receivers have better PPS outputs than navigation
GPS receivers and timing grade receivers support the so called position
hold mode that provides a valid PPS output even if only 1 bird is being
received.
Yes, it is better to implement the PPS synchronization in the digital
You can use the LEA5-T too that is a timing GPS receiver and supports the
position hold down-to-1-bird timing mode.
On Fri, Dec 30, 2011 at 8:59 PM, Murray Greenman wrote:
> Two thoughts re Simple GPSDOs:
>
> 1. For a conventional 1pps approach, see 'A Simple GPS Disciplined
> Reference" http://w
I believe those Rockwells have a 10 KHz output. Not a bad price.
73 es HNY, Dick, W1KSZ
-Original Message-
>From: b...@lysator.liu.se
>Sent: Dec 30, 2011 12:42 PM
>To: Discussion of precise time and frequency measurement
>Subject: Re: [time-nuts] Thunderbolt? (re simple gpsdo.)
>
>Hi Ch
May I suggest use of small controllers such as the Picaxe series? I find
them very useful around the "lab" for small tasks such as this. Easily
programmed, very reliable, and the software application can be as simple
or complex as needed, for example the suggested PID controller. No
soldering, no f
Two thoughts re Simple GPSDOs:
1. For a conventional 1pps approach, see 'A Simple GPS Disciplined
Reference" http://www.qsl.net/zl1bpu/MICRO/SIMPLE/SimpleGPS.htm, by yours
truly. It uses a high performance 10MHz OCXO and gently disciplines it.
Despite not having a Kalmann filter, the holdover
Heck- for a really good risetime, all you need is a mercury-wetted relay
:-)
Don
David
> What kind of performance would you expect in this application? Low
> jitter? 50 ohm output? TTL or better signal levels? Fast rise and
> fall times? Duty cycle correction?
>
> After reading your post I wa
IF the 1pps is accurate and stable, one could measure the time between
the GPS's 1pps and the 5680a 1pps and issue appropriate frequency
offset commands.
That's a big assumption or two, a Tbolt might still be cheaper.
There's always WWVB.
On 12/30/2011 11:39 AM, Robert LaJeunesse wrote:
How ab
"What is the simplest design for a GPSDO that uses only the PPS signal
from
a modern GPS?"
Some sort of oscillator with a voltage control.
CPU with a timer/counter that can capture the PPS.
DAC.
Software.
How about MSC1200 : http://www.ti.com/lit/ds/symlink/msc1200y3.pdf
Stanley
__
Hi Chris,
> I just finished reading about that one. It requires no longer
> available GPS reciever. Maybe I should r-phrase the question:
Most of us get (re)used stuff... Ebay #300437642776 has some Rockwell era
receivers. Many time-nuts find HP5065A rubidiums and 5370 counters
available and i
How about USB to an FT232 that talks SPI to a low-cost DAC or digital pot?
Would
need a stable reference, though. See http://www.sparkfun.com/news/386 and
http://www.chinwah-engineering.com/USB_SPI_Interface_Software.html for the
methodology. Could also use a parallel DAC via FT232 bit-banging,
On a related note is anyone aware of PC controlled (Ie. RS232 or maybe GPIB ?)
DAC's that would be suitable for this type of application ?
I've also contemplated simply using the DAC of a TBolt but it would seem to be
waste of a Tbolt. I'm thinking along the lines of something that might
ac
> "What is the simplest design for a GPSDO that uses only the PPS signal from
> a modern GPS?"
Some sort of oscillator with a voltage control.
CPU with a timer/counter that can capture the PPS.
DAC.
Software.
Drive the CPU from the osc so you can count cycles between PPS pulses. Use
the DAC t
There is no reason you can not do that.
It is tricky because the low comparison frequency limits the loop
bandwidth like any sampled data system and the analog requirements for
the low frequency design become an issue do to leakage and the
impedance levels needed. The long time constants involved
Yes, it can be done based on a PPS only timing. You must design a PI (maybe
PID) regulator: the EFC must stay steady when the phase difference between
the two PPSes is zero (integral action). Then you must move the EFC (when
there is a difference) proportionally with the difference itself and only
I currently use an HP5370B with a gpib interface to compare the 10 Mhz output
of each unit to another reference, and process the time interval data to
produce adev plots. My current reference is an fts 1050 and I'm confident it
is beating it's typical adev spec of 1e-12 at 100 seconds.
Regard
Mine was sent by China Post. The Chinese post office. Took 10 days
to get to California. For me, this is typical for stuff I buy from
Chinese eBay sellers. The Hong Kong Post is slightly faster. I've
think it might just be a matter of luck if your package gets on an
airplane or a boat.
On
On 12/30/11 9:13 AM, David VanHorn wrote:
I would love to see something like that which plotted voltage.
Send them a note.. Their little monitoring widgets record all of that
and send it back to the databases. I'll bet the data is available, you
just have to know how to ask for it.
__
On Thu, Dec 29, 2011 at 8:24 PM, Mark Spencer wrote:
> One of the designs using the 10 kHz output from a Jupiter gps engine and a
> simple PLL to discipline an ocxo might be good starting point if suitable gps
> engines are still available. There won't be much to tweak but the
> performance co
I would love to see something like that which plotted voltage.
From: time-nuts-boun...@febo.com [time-nuts-boun...@febo.com] On Behalf Of Jim
Lux [jim...@earthlink.net]
Sent: Thursday, December 29, 2011 5:16 PM
To: Discussion of precise time and frequenc
The spec is over the entire temp range, and it may not be linear to temp. It
could be more sensitive at some temps than others.. Especially if the temp is
digitally compensated inside the unit.
Sent From iPhone
On Dec 29, 2011, at 23:55, Chris Albertson wrote:
> On Thu, Dec 29, 2011 at 9:14 P
http://www.navsync.com/docs/mushroom_data_sheet.pdf
This device looks very similar, similar name also. Pure coincidence?
Regards
Chris Stake
> -Original Message-
> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
> Behalf Of Alberto di Bene
> Sent: 30 December 201
and an effect
http://www.youtube.com/watch?v=25fS7kS6PfQ
-pete
On Fri, Dec 30, 2011 at 7:46 AM, paul swed wrote:
> Interesting to watch the power freq shift.
> Thanks
> Paul
>
> On Fri, Dec 30, 2011 at 12:19 AM, Peter Gottlieb wrote:
>
>> Our battery-inverter systems follow frequency (or mor
What kind of performance would you expect in this application? Low
jitter? 50 ohm output? TTL or better signal levels? Fast rise and
fall times? Duty cycle correction?
After reading your post I was thinking about how to go about it and
ended up with an 8 transistor discrete design using a dif
Mine arrived in about 10 business days, in what looked like an
Amazon.com sourced shipment.
Peter
On 12/30/2011 5:30 AM, Rob Kimberley wrote:
I bought a couple of these on EBay recently. Would like to know from the
group what the typical shipping times have been so far from China.
Cheers
Ro
Interesting to watch the power freq shift.
Thanks
Paul
On Fri, Dec 30, 2011 at 12:19 AM, Peter Gottlieb wrote:
> Our battery-inverter systems follow frequency (or more usually the 4
> second AGC signal from the ISO) and give or take power at multi-megawatt
> levels to stabilize frequency changes
Very nice indeed with the opto isolation. I think Stans idea is reasonable.
Since you have no information its worth looking under the hood as they say.
See whats inside as a possible GPS engine. I suspect the optos are bolted
on and you may have access to at least cmos or ttl data signals to work
w
Yes the free shipping by post is about 4 to 5 weeks.
Regards
Paul
On Fri, Dec 30, 2011 at 10:24 AM, mike cook wrote:
> Mine was slow, but I expected it. 25/11-28/12.
>
> Le 30/12/2011 11:30, Rob Kimberley a écrit :
>
> I bought a couple of these on EBay recently. Would like to know from the
>>
Mine was slow, but I expected it. 25/11-28/12.
Le 30/12/2011 11:30, Rob Kimberley a écrit :
I bought a couple of these on EBay recently. Would like to know from the
group what the typical shipping times have been so far from China.
Cheers
Rob Kimberley
Do not forget that the thunderbolt was not designed to be the best GPSDO ever,
it was designed to meet a set of requirements that include a certain stability
in and out of holdover over a certain temperature range and it does that quite
well.
If you do not need holdover stability, you can come
My TDS210 has an extremely stable display, even at the max sweep speed.
Of course, the vertical amplifier has the noise you would expect from a broad
band amplifier, and if the signal is too low, that noise will contribute to
some jitter, but 200mV at 10MHz will show a very stable display on my
My second one is still in ether space .. but shipping from China can
vary a lot. I've had
small packages approx the same size and weight as the Rb's show up in
5 days, I've had identical packages from the
same shipper etc take 5 weeks.
-pete
On Fri, Dec 30, 2011 at 2:30 AM, Rob Kimberley
wrote:
Hello Al,
I hope you and yours have a Happy New Year.
I would start with the radome removal. Were those screws or pop rivets
on the edges ?
Hopefully our UK members can assist with documentation.
Stan, W1LE Cape Cod
On 12/30/2011 6:54 AM, Alberto di Bene wrote:
I received as a gift fr
I remember Navstar in Daventry, and have visited them a couple of times, but
I think they changed their name a few years back. There are a number of
references coming up on Google, relating to ex-employees.
These units were obviously supplied to Ericsson, so again it might be worth
trying that ro
I received as a gift from a friend what looks like a timing GPS
antenna integrated with the receiver, with optical links
for Rx and Tx (?).
This the label on the box :
http://dl.dropbox.com/u/15089947/NavSymm2.jpg
And these are the upper and lower sides of the unit :
http://dl.dropbox.com/u/150
Here's the phase vs time for two Thunderbolts.
--
Chuck Forsberg WA7KGX N2469R c...@omen.com www.omen.com
Developer of Industrial ZMODEM(Tm) for Embedded Applications
Omen Technology Inc "The High Reliability Software"
10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430
<>_
The analog computer is the standard good-old-PLL: if you have the 10KHz
from a Jupiter than your analog filter will be simple to build. If you have
only the PPS (or 100PPS from an Oncore) your analog filter will require
more attention (and large capacitors) but I think it is realizable. You
analog
How can you tell that your GPSDO consistently beats the TBolt?
On Fri, Dec 30, 2011 at 5:58 AM, Mark Spencer wrote:
> Yes that is correct. I have one of the units made by James Miller G3RUH.
> I had hoped to build some something along these lines on my own, but the
> Jupiter gps modules I acq
I bought a couple of these on EBay recently. Would like to know from the
group what the typical shipping times have been so far from China.
Cheers
Rob Kimberley
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