Re: [time-nuts] Cheap jitter measurements

Am 10.04.2018 um 01:03 schrieb Gary E. Miller: Yo Hal! On Mon, 09 Apr 2018 13:53:21 -0700 Hal Murray wrote: The API for the kernel clock can be read to a ns. I don't see ntpd having much use for finer grain than that. I should look at the source to see what the

Re: [time-nuts] Cheap jitter measurements

Yo Hal! On Mon, 09 Apr 2018 13:53:21 -0700 Hal Murray wrote: > The API for the kernel clock can be read to a ns. I don't see ntpd > having much use for finer grain than that. I should look at the > source to see what the internal details look like. Yeah, but the

Re: [time-nuts] Cheap jitter measurements

Hi > On Apr 9, 2018, at 4:53 PM, Hal Murray wrote: > > > kb...@n1k.org said: >> Somewhere in the NTP algorithm, there is a “zero error” estimate. GPS >> modules have the same thing buried in them. A GPS module (like NTP as >> described above) can only *express* a PPS

Re: [time-nuts] Looking for IEEE-488 codes and formats for Datum 9700AT Programmable Time System

Hi Yes, there is what appears to be a socketed ROM on the board. Next step seems to be to dump the ROM and see what’s inside. Bob > On Apr 9, 2018, at 3:55 PM, Forrest Christian (List Account) > wrote: > > Just curious, is there by chance a removable eprom or other

Re: [time-nuts] ADEV dead time w/ HP 53131A & TimeLab

Hi David, On 04/09/2018 03:29 AM, David Burnett wrote: > Hi time-nuts, > > I'm doing oscillator-related research for my PhD and found this list > recently. It's been a great resource in trying to refine my freq > measurement setup and in starting to understand what's really going on > inside my

Re: [time-nuts] Cheap jitter measurements

kb...@n1k.org said: > Somewhere in the NTP algorithm, there is a “zero error” estimate. GPS > modules have the same thing buried in them. A GPS module (like NTP as > described above) can only *express* a PPS modulo some clock rate. GPS > modules get around this with a firmware hack. They

Re: [time-nuts] Looking for IEEE-488 codes and formats for Datum 9700AT Programmable Time System

Just curious, is there by chance a removable eprom or other programmable device on these boards? Assuming a fairly verbose scpi like command interface, I've occasionally had luck reverse engineering a command set by looking through an eprom dump for a list of commands? Also, does this by chance

Re: [time-nuts] Cheap jitter measurements

Hi > On Apr 9, 2018, at 2:19 PM, Achim Gratz wrote: > > Bob kb8tq writes: >>> Similarly, the box should be able to give me a pulse at a known time. >> >> how do you set up NTP to do that? > > Not at all, that must be done in the kernel if you want any accuracy at > all.

Re: [time-nuts] Looking for IEEE-488 codes and formats for Datum 9700AT Programmable Time System

I have two of these with 488 interfaces. Would appreciate any 488 info you get. br...@otelco.net -Original Message- From: Bob kb8tq Sent: Saturday, April 07, 2018 10:27 PM To: lee...@aol.com ; Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Looking for

Re: [time-nuts] Cheap jitter measurements

Bob kb8tq writes: >> Similarly, the box should be able to give me a pulse at a known time. > > how do you set up NTP to do that? Not at all, that must be done in the kernel if you want any accuracy at all. But you could modify an existing device driver (for the LPT port) to use GPIO instead to

Re: [time-nuts] Weird Stuff WareHouse shutting down

On 4/9/18 5:20 AM, Dave Daniel wrote: Responding to Jim's post ( I can't find his original post), a significant advantage to owning "vintage" instruments is that, in general, they may be repaired more easily than later model instruments. This fact was my guiding principle when setting up my

Re: [time-nuts] Weird Stuff WareHouse shutting down

Hi > On Apr 9, 2018, at 9:30 AM, jimlux wrote: > > On 4/8/18 8:20 PM, Glenn Little WB4UIV wrote: >> The USB stuff has no front end and stability and calibration is highly >> questionable.. > I'm thinking here of the $1K sort of device - traceable cal, quite stable, >

Re: [time-nuts] ADEV dead time w/ HP 53131A & TimeLab

Dave, > My research concerns oscillator drift on time scales of ~1ms to ~10s, so > I'm guessing the 53131A with its 5-130ms of dead time isn't suitable for > what I'm trying to measure. True. Try a fancy TIA (time interval analyzer) or MDA (modulation domain analyzer) instead. Or consider a

Re: [time-nuts] Weird Stuff WareHouse shutting down

On 4/8/18 8:20 PM, Glenn Little WB4UIV wrote: The USB stuff has no front end and stability and calibration is highly questionable.. I'm thinking here of the $1K sort of device - traceable cal, quite stable, etc. Not the $20 RTL-SDR How can you discriminate between mixes within the USB

Re: [time-nuts] Cheap jitter measurements

Hi > On Apr 9, 2018, at 2:53 AM, Trevor N. wrote: > > Bob kb8tq wrote: >> Hi >> >> Without the ability to put out a “known good” time pulse there is no quick >> way to >> check NTP. GPS modules suffer a similar issue. They put out a pulse and a >> “correction” (sawtooth

Re: [time-nuts] Weird Stuff WareHouse shutting down

Responding to Jim's post ( I can't find his original post), a significant advantage to owning "vintage" instruments is that, in general, they may be repaired more easily than later model instruments. This fact was my guiding principle when setting up my lab, and that was based on Jim Williams'

Re: [time-nuts] Cheap jitter measurements

There is a program for the RPi which handles the PPS input for NTP and can produce an output on a GPIO pin here: https://vanheusden.com/time/rpi_gpio_ntp/ but it's user-mode so of limited use. Perhaps the OP could adapt it? Cheers, David -- SatSignal Software - Quality software written to

[time-nuts] Cheap jitter measurements

Bob kb8tq wrote: >Hi > >Without the ability to put out a “known good” time pulse there is no quick way >to >check NTP. GPS modules suffer a similar issue. They put out a pulse and a >“correction” (sawtooth error) to tell you what they just told you. Doing the >same >sort of thing with NTP may

Re: [time-nuts] Weird Stuff WareHouse shutting down

drkir...@kirkbymicrowave.co.uk said: > I think people learn more with old test equipment. I know someone who has a > 1 GHz LeCroy scope, as well as a high end Agilent, but can't seem to > measure the simplest of signals, that I could easily measure with a 50 year > old scope. With modern