Re: [time-nuts] 1PPS users?

Hi Scott, I do understand the reasons that these users want this quality of output.  It's who these users are, what fields, industries, etc, that I didn't quite understand. Bob - AE6RV.com GFS GPSDO list:

[time-nuts] Lady Heather for homebrew GPSDO

Heather can pretty much do that now. It has the ability to do screen dumps to a file (or series of files) on a scheduled basis. Heather doesn't do the "spit out an html file thing", but I know of several people that have scripts on their machine that take the screen dump images and serve

Re: [time-nuts] Lady Heather for homebrew GPSDO

Hi Jim, > --The EFC value is given as an integer percent -100 to 100, so there is not > enough resolution to really tell what the DAC is doing. Sounds like you're using :DIAG:ROSC:EFC:REL? which gives percent. Instead try :DIAG:ROSC:EFC:ABS? which gives absolute DAC value. > -- It does not have

[time-nuts] Lady Heather for homebrew GPSDO

The Z3801A does have a request for getting/setting the DAC value as a absolute (hex) number. Heather uses the percentage version of the message. Neither format tells you what you really want to know... the actual DAC voltage. There is nothing to prevent you from sending a DAC percentage

Re: [time-nuts] 1PPS users?

preilley_...@comcast.net said: > I would like to get better than the +-10 nS that the better receivers > provide. A GPSDO generally avoids the sawtooth offset. -- These are my opinions. I hate spam. ___ time-nuts mailing list --

Re: [time-nuts] 1PPS users?

Part of the reason 1PPS needs to be so clean is because you are continuously integrating phase noise of the LO (hopefully an OCXO). While 10 uS is pretty trivial off a gps receiver. Without gps, 10 us over 24 hrs with a plane jane AT-cut crystal subject environmental dynamics becomes ludicrous.

Re: [time-nuts] Performance of TDC7200

Hi Thanks for the info. The fpga baesed TDC is something I am interested in. However, I am a beginner of fpga programming. Maybe next year I will spend sometime study this project. VHDL is quite difficult for a C programmer :(. Regards Li Ang BI7LNQ ---Original--- From: "Attila

Re: [time-nuts] Lady Heather for homebrew GPSDO

On Sun, Dec 18, 2016 at 1:06 PM, Mark Sims wrote: > Binary or NMEA you need routines like send_msg_start, send item (like > integer, float, double), send_msg_end. For received messages you need > things like get_message, get_item_from_message, etc. The code to do that >

Re: [time-nuts] 1PPS users?

There was a discussion here a while ago about synchronizing radio telescopes that were separated by some miles. The 1PPS from GPS was suggested as a possibility. I am working on a project to do location by triangulation that uses the 1PPS signal. I would like to get better than the +-10 nS

Re: [time-nuts] 1PPS users?

For amateur use, PPS comparison requires less equipment and can be more accurate than trying to measure RF rates like 10 MHz. When comparing two PPS signals, phase slips are very infrequent so you can observe drift rate over minutes/hours/days with an oscilloscope or simple time interval

Re: [time-nuts] HP Z3801a piezo oscillator does work

Bob I think Mark was suggesting that. As I explained its a odd package. Regards Paul WB8TSL On Sun, Dec 18, 2016 at 7:13 PM, Bob Camp wrote: > Hi > > Can you pull the crystal? sure. > > Does your MV-89 have a 5 MHz crystal (the frequency doubled version) or a > 10 MHz crystal?

Re: [time-nuts] 1PPS users?

Hi Jim, Thanks Jim, So, what I'm seeing so far, assuming I'm interpreting it correctly, is big budget commercial and government applications, generally clustering around time-controlled multiplexing, as well as the niche that is the space industry.  Then there's the hobbyist, such as Eric who

Re: [time-nuts] Why is holdover LED on HP 58503A not lit, when GPS lock is unlit too?

drkir...@kirkbymicrowave.co.uk said: > I assume it wont start until it has tracked sufficient number of satellites. There is a chicken-egg problem with getting started. The satellites tell you where they are, but you need to know where they are and where you are in order to calculate the

Re: [time-nuts] 1PPS users?

Who uses 1PPS? In industry they are used to phase lock various oscillators. I would bet most of those oscillators are used in the telecommunications industry both for bit rate clocks and for carrier frequency synthesis. We also see a lot of 1 PPS used for NTP servers that in turn are used to

Re: [time-nuts] HP Z3801a piezo oscillator does work

Hi Can you pull the crystal? sure. Does your MV-89 have a 5 MHz crystal (the frequency doubled version) or a 10 MHz crystal? (sub harmonics viewed on a spectrum analyzer are a really good way to tell). Is the crystal the same size / pinout? Probably not. HP used an odd package. You might be

Re: [time-nuts] HP Z3801a piezo oscillator does work

Mark I tend to agree with you on Bob. But that said the 10811 crystal is a bit odd. Its actually a copper cylinder with a screw on top. I believe to insure correct even heat distribution. There are pix's of it on one of the sights. Maybe the crystal comes out of the copper. The 10811 used in the

Re: [time-nuts] 1PPS users?

Speaking as an owner of a well-behaved mechanical clock: Clock rate performance over time can be done based on time interval measurements anchored to a solid frequency standard. No 1pps needed per se. Bring a clock to time is simplified with a timescale-accurate 1pps source. > On 2016 Dec 18, at

Re: [time-nuts] 1PPS users?

Hi Roughly 99% of all GPSDO’s are only used for the PPS output. They go into cell sites and the reason they exist is to sync up the Gold Codes on CDMA. That’s also why you see a *lot* of PPS only Rb’s on the surplus market. The ones that don’t get used for cell towers, mostly go into other com

Re: [time-nuts] 1PPS users?

On 12/18/16 3:16 PM, Bob Stewart wrote: One thing I've never really understood is who actually uses the high-quality 1PPS output from a GPSDO. I have spent a lot of time, effort, and money on developing my GPSDO without a whole of thought to the user base. It was just a quest for the best

Re: [time-nuts] 1PPS users?

b...@evoria.net said: > So, if an NTP user can get his time fix directly from a noisy receiver, who > actually needs a time-accurate, low jitter 1PPS pulse? Most kernels have an option to capture a time stamp from a PPS signal at interrupt time. That is much more accurate than the timing you

Re: [time-nuts] Why is holdover LED on HP 58503A not lit, when GPS lock is unlit too?

It is looking much better now. I 1) Powered off 2) Left off for 30 s 3) Pulled antenna out. 4) Powered on 5) Connected antenna, making sure if was firmly screwed in. It then got GPS lock in a few minutes. It is running at reduced accuracy, with the survey only 9.7% complete, but it is looking

Re: [time-nuts] Why is holdover LED on HP 58503A not lit, when GPS lock is unlit too?

On 18 December 2016 at 18:19, Dan Rae wrote: > On 12/18/2016 9:34 AM, Dr. David Kirkby (Kirkby Microwave Ltd) wrote: > >> >> *12 -- ---MODE Survey: 0% >> complete >> >> > If it's still showing that after

[time-nuts] 1PPS users?

One thing I've never really understood is who actually uses the high-quality 1PPS output from a GPSDO.  I have spent a lot of time, effort, and money on developing my GPSDO without a whole of thought to the user base.  It was just a quest for the best result I could obtain with a particular

[time-nuts] HP Z3801a piezo oscillator does work

I have a wonky Morian MV-89... probably the well know output cap failure. I wonder if one could pull the crystal out of that and stick in the HP10811? Something tells me Bob would know ;-) ___ time-nuts mailing list -- time-nuts@febo.com To

[time-nuts] HP Z3801a piezo oscillator does work

OK the 10 MHz Piezo oscillator from a lucent RC/xtal pair does work and the 3801 is doing what it should. Some insights as mentioned. 3801 DAC being full scale is not an issue when a good signal within 2 HZ is used it will come out of limit. The DAC output was driving the piezo far to widely I

[time-nuts] Lady Heather for homebrew GPSDO

If you go digging in the Ladt Heather code, you will find references to a "luxor" device. This is a LED / power analyzer device that I built. It runs on a ATMEGA 2561 and uses the TSIP protocol. I've also implemented the same TSIP protocol code on a '328 with 32kB of program memory. It's

Re: [time-nuts] Why is holdover LED on HP 58503A not lit, when GPS lock is unlit too?

On 12/18/2016 9:34 AM, Dr. David Kirkby (Kirkby Microwave Ltd) wrote: *12 -- ---MODE Survey: 0% complete If it's still showing that after being on for five hours, maybe it needs to be explicitly told to

Re: [time-nuts] Why is holdover LED on HP 58503A not lit, when GPS lock is unlit too?

On 18 December 2016 at 14:31, Tim Shoppa wrote: > A common misconception, is that holdover is the opposite of GPS lock. > Sometimes we might even talk about the two as if we're in one or the other. > But really the power-on state, is that we're in neither holdover or GPS >

Re: [time-nuts] Why is holdover LED on HP 58503A not lit, when GPS lock is unlit too?

On 18 December 2016 at 17:34, Dr. David Kirkby (Kirkby Microwave Ltd) < drkir...@kirkbymicrowave.co.uk> wrote: > But perhaps things have improved, as its not attempting to track 6 > (PRN=15, 2, 21, 25, 26 and 28), whereas before it was attempting to track > just with a PRN of 32. I'm hoping its

Re: [time-nuts] Why is holdover LED on HP 58503A not lit, when GPS lock is unlit too?

A common misconception, is that holdover is the opposite of GPS lock. Sometimes we might even talk about the two as if we're in one or the other. But really the power-on state, is that we're in neither holdover or GPS lock. Holdover means the smartclock previously had GPS lock and had used it to

Re: [time-nuts] Why is holdover LED on HP 58503A not lit, when GPS lock is unlit too?

I believe the "Holdover" function only occurs when you you loose just the satellites Once locked disconnect the antenna for a minute and you will see the holdover LED light. IF the unit looses POWER it has no way of of powering the oscillator and its ovens ( to do a holdover) and has no

Re: [time-nuts] FPGA based TDC

Hi > On Dec 18, 2016, at 7:46 AM, Attila Kinali wrote: > > On Sat, 17 Dec 2016 10:48:35 -0500 > Bob Camp wrote: > >>> Sébastian told me that for the original TDC design (based on a Spartan3 >>> IIRC) >>> they didn't employ any method for increasing the

Re: [time-nuts] Lady Heather for homebrew GPSDO

Hi If your GPSDO is based on an quad core 1.8 GHz with 4 GB of RAM, you can implement a lot of things. Effectively your GPSDO has more horsepower than a lot of the computers people are using to monitor GPSDO’s. Given the economics of silicon, that’s still not a crazy expensive CPU to use.

Re: [time-nuts] FPGA based TDC

On Sat, 17 Dec 2016 10:48:35 -0500 Bob Camp wrote: > > Sébastian told me that for the original TDC design (based on a Spartan3 > > IIRC) > > they didn't employ any method for increasing the resolution by compensating > > for different bin sizes, as they got pretty close to the

[time-nuts] Why is holdover LED on HP 58503A not lit, when GPS lock is unlit too?

My 58503 GPS time/frequency reference had its power disconnected a few times yesterday as I moved things in the lab. At the modem the status of the LEDs are * Power green * GPS lock - not lit * Holdover - not lit * Alarm - not lit. That is what the manual says will happen when power is first

[time-nuts] Lady Heather for homebrew GPSDO

> NMEA is a fine interface, widely used, easy to play with. There's no need to > be pejorative. Not being perjorative... just commenting that it would be a lot easier to implement than TSIP... probably not as good, but a lot easier to code... the lazy bastards way... I'm a lazy bastard,