Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-15 Thread David
On Fri, 10 Feb 2012 18:19:53 -0800, Hal Murray wrote: >> Flip-flops hardened against metastability are available. > >Do you have a part number in mind? Here is another one with 125pS of specified metastability if you can spare 27mA at 5 volts: http://www.onsemi.com/pub/Collateral/MC10EL31-D.PDF

Re: [time-nuts] GPS lock of the FE5680. Current experiment andquestion

2012-02-13 Thread paul swed
- > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On > Behalf Of paul swed > Sent: Saturday, February 11, 2012 1:04 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] GPS lock of the FE5680. Current experiment > andquestion

Re: [time-nuts] GPS lock of the FE5680. Current experiment andquestion

2012-02-13 Thread Bob Camp
requency measurement Subject: Re: [time-nuts] GPS lock of the FE5680. Current experiment andquestion Looks like analog devices makes a pretty nice sample and hold chip. A bit pricey. But can't really work at 10 MC so that would complicate things On Sat, Feb 11, 2012 at 10:54 AM, paul swe

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-12 Thread Bob Camp
Hi The sawtooth correction needs an accurately calibrated time offset measurement to work against. That's not a requirement for a simple loop. Not impossible to do, but it adds another constraint. Bob On Feb 12, 2012, at 3:05 PM, Chris Albertson wrote: > On Sat, Feb 11, 2012 at 4:45 AM, Bo

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-12 Thread Chris Albertson
On Sat, Feb 11, 2012 at 4:45 AM, Bob Camp wrote: > Hi > > Another way to build an analog phase detector... > > Next layer on the onion is how to get the sawtooth correction out of the GPS > and into your loop. > Assuming you have a uP in the loop the sawtooth is easy the GPS sends the value out

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-11 Thread David
There are no temperature coefficient effects or calibration drift with the current sources and ramp circuits in this case. Between 1 PPS measurements, there is more than enough time to gate a sample waveform from the convenient 10 MHz source to the time to voltage converter to calibrate it. One i

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-11 Thread GandalfG8
How about using the 10KHz output from one of the Jupiter receivers as per James Miller's simple GPSDO? There's TU60s available on Ebay from China right now at reasonable prices. regards Nigel GM8PZR In a message dated 11/02/2012 18:04:22 GMT Standard Time, paulsw...@gmail.com writes:

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-11 Thread paul swed
Looks like analog devices makes a pretty nice sample and hold chip. A bit pricey. But can't really work at 10 MC so that would complicate things On Sat, Feb 11, 2012 at 10:54 AM, paul swed wrote: > Getting very interesting. > Bob had mentioned just sample the 10 MC sine wave. What I used to do o

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-11 Thread paul swed
Getting very interesting. Bob had mentioned just sample the 10 MC sine wave. What I used to do on homebrew Loran C. Thats easier to do because today its nothing to buffer that 10 MC signal to drive a fast sample and hold. This eliminates the ramp circuitry and constant current sources used in the

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-11 Thread Azelio Boriani
This is the simplest part if a microprocessor can be used: by the serial port you get the sawtooth correction in nS to be applied to the sampled data. The sampled data must be converted to nS or the sawtooth correction must be converted in a suitable sampled data correction. It is possible even to

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-11 Thread Bob Camp
Hi Another way to build an analog phase detector... Next layer on the onion is how to get the sawtooth correction out of the GPS and into your loop. Bob On Feb 11, 2012, at 12:05 AM, Chris Albertson wrote: > All these different suggestions build down to one thing, the precision > with whic

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-10 Thread Chris Albertson
All these different suggestions build down to one thing, the precision with which you measure the phase when you sample it each second. The single flip flop will tell you which half cycle. a simple two bit counter made with two '74 FFs tells you which half cycle and with direction. The "best" may

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-10 Thread David
On Fri, 10 Feb 2012 18:19:53 -0800, Hal Murray wrote: >> Flip-flops hardened against metastability are available. > >Do you have a part number in mind? Some logic families are better than others. In general you want faster ones with shorter setup and hold times. On Semiconductor has an interes

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-10 Thread Robert LaJeunesse
You don't. That's why the HC4046 has 3 phase comparators. Different strokes for different folks... From: Hal Murray To: Discussion of precise time and frequency measurement Sent: Fri, February 10, 2012 9:35:01 PM Subject: Re: [time-nuts] GPS l

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-10 Thread Hal Murray
paulsw...@gmail.com said: > Hang on here. If the signal was 10 MHz for ref and RB its easy as suggested > here XOR gates and such. Assume I have 2 signals that are (very) close to 10 MHz and I get to read their XOR. How do I know which one is faster? -- These are my opinions, not necessaril

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-10 Thread Hal Murray
paulsw...@gmail.com said: > Why 24 bits because it was pretty easy using 74hc596 8 bit counters with > latch and tristate outputs. Unfortunately the schematics are on paper at the > moment scribbles. But the cntrs are stacked on top each other as a unit and > soldered together. Only a few pins are

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-10 Thread Bob Camp
ver a sub-range and add a small micro for >> noise filtering and averaging and one can achieve measurements result in the >> 10s >> of femtoseconds. >> >> ________ >> From: David >> To: Discussion of precise time and frequency measurement &

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-10 Thread Bob Camp
Hi If your GPS puts out 1 pps, you get one sample per second out of your phase detector. If it's digital you get a one or a zero. Dead time between edges is 50 ns. You throw away a lot of the accuracy of GPS by doing it this way. With an analog detector you would know how early or late you are.

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-10 Thread Hal Murray
> Flip-flops hardened against metastability are available. Do you have a part number in mind? The only data sheet that I remember for a part that looked interesting was actually 2 FFs inside one package. For something like that, you save the prop time of the output driver and the input receive

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-10 Thread David
On Fri, 10 Feb 2012 19:54:11 -0600, David wrote: >Flip-flops hardened against metastability are available. > >I would try a track and hold before a sample and hold but I wonder how >accurate it would be having to rely on the oscillator waveform. Fast >sample gates are non-trivial. I believe bet

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-10 Thread paul swed
Good question and the reason for the large counter. If locked its a hard number and a number above or below that number is how far its off and in what direction. Yup 24 bits was a bit crazy but it wasn't anything to do. That said a single 8 bit counter would have been fine given the stability the R

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-10 Thread David
On Fri, 10 Feb 2012 17:28:53 -0800, Chris Albertson wrote: >On Fri, Feb 10, 2012 at 5:10 PM, David wrote: > >> All you need for this is the flip-flop.  Clock the flip-flop with the >> 1 PPS signal and capture whether the oscillator is leading or lagging. > >I can see how this can detect lock. I

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-10 Thread David
ging and one can achieve measurements result in the >10s >of femtoseconds. > > >From: David >To: Discussion of precise time and frequency measurement >Sent: Fri, February 10, 2012 8:10:56 PM >Subject: Re: [time-nuts] GPS lock of the FE5680. Cu

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-10 Thread Chris Albertson
On Fri, Feb 10, 2012 at 5:10 PM, David wrote: > All you need for this is the flip-flop.  Clock the flip-flop with the > 1 PPS signal and capture whether the oscillator is leading or lagging. I can see how this can detect lock. If the FF is the same each second you are good. But if it changes h

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-10 Thread Robert LaJeunesse
averaging and one can achieve measurements result in the 10s of femtoseconds. From: David To: Discussion of precise time and frequency measurement Sent: Fri, February 10, 2012 8:10:56 PM Subject: Re: [time-nuts] GPS lock of the FE5680. Current experiment and

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-10 Thread David
On Fri, 10 Feb 2012 16:35:26 -0800, Chris Albertson wrote: >On Fri, Feb 10, 2012 at 3:52 PM, Bob Camp wrote: >> Hi >> >> I think you will need some sort of analog detector to get what you are >> looking for. > >I don't think it needs to be analog. For example you can xor the two >10MHz signal

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-10 Thread Chris Albertson
On Fri, Feb 10, 2012 at 4:48 PM, paul swed wrote: > Hang on here. If the signal was 10 MHz for ref and RB its easy as suggested > here XOR gates and such. > > But the GPS is a 1 second interval and the RB is 10 Mhz. So the GPS 1 > second is the reference. Thats much harder then dealing with 100 Hz

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-10 Thread paul swed
Hang on here. If the signal was 10 MHz for ref and RB its easy as suggested here XOR gates and such. But the GPS is a 1 second interval and the RB is 10 Mhz. So the GPS 1 second is the reference. Thats much harder then dealing with 100 Hz or up. So the answer I have seen which seems to fit is Bobs

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-10 Thread Chris Albertson
On Fri, Feb 10, 2012 at 3:52 PM, Bob Camp wrote: > Hi > > I think you will need some sort of analog detector to get what you are > looking for. I don't think it needs to be analog. For example you can xor the two 10MHz signals and then sample the digital xor output then deduce its duty cycle b

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-10 Thread paul swed
Good comments so I am on target in thinking. Why 24 bits because it was pretty easy using 74hc596 8 bit counters with latch and tristate outputs. Unfortunately the schematics are on paper at the moment scribbles. But the cntrs are stacked on top each other as a unit and soldered together. Only a fe

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-10 Thread Bob Camp
Hi I think you will need some sort of analog detector to get what you are looking for. Bob On Feb 10, 2012, at 6:34 PM, Chris Albertson wrote: > On Fri, Feb 10, 2012 at 2:53 PM, paul swed wrote: >> Just for fun have built up a simple multi-chip project to try my hand at >> locking the FE56

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-10 Thread Chris Albertson
On Fri, Feb 10, 2012 at 2:53 PM, paul swed wrote: > Just for fun have built up a simple multi-chip project to try my hand at > locking the FE5680 using the external efc connection mod. mentioned in > time-nuts. Typical counter micro rs 232 port stuff. > > Essentially the system is 2 X 24 bit count

Re: [time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-10 Thread Bob Camp
Hi Without seeing the schematic it's a little hard to be sure this is all correct... If it is all based on 10 MHz, then yes you are doing it all modulo 100 ns. To get 1 part in 1x10^13 you would need 100,000 seconds. If that drives the LSB of a 16 bit counter for the DAC you would take a very

[time-nuts] GPS lock of the FE5680. Current experiment and question

2012-02-10 Thread paul swed
Just for fun have built up a simple multi-chip project to try my hand at locking the FE5680 using the external efc connection mod. mentioned in time-nuts. Typical counter micro rs 232 port stuff. Essentially the system is 2 X 24 bit counters that toggle back and fourth every interval selectable fr

Re: [time-nuts] GPS lock

2010-05-11 Thread Brooke Clarke
Hi Joe: My RAIM failure message has come back today. I'm starting to log which sats are being used just after the message shows up to see if I can tell which sat is causing it. So far it might be SV# 11 or 20. Have Fun, Brooke Clarke http://www.PRC68.com Joseph Gray wrote: Did anyone else

Re: [time-nuts] GPS lock

2010-05-11 Thread Brian Kirby
I would doubt it. Even though the frequencies are the same, each satellite and WAAS satellite has a separate PRN code and your receiver has to lock up on it. The elder Motorola Oncore VP gps receiver thats in the Z3801A will ignore all WAAS signals. Joseph Gray wrote: Did anyone else loose G

[time-nuts] GPS lock

2010-05-11 Thread Joseph Gray
Did anyone else loose GPS lock from about 0600-1200 UTC on the 11th? My Z3801A went into holdover for the entire period, despite several satellites being visible. I wonder if this has anything to do with that malfunctioning WAAS bird that is supposed to be spewing RF everywhere? Joe Gray KA5ZEC _