[time-nuts] Re: Why Jan 6th?
> Why is it 0UTC Jan 6, 1980
Short answer: GPS time is based on week numbers. The week number
increments at midnight between Saturday and Sunday. Thus for the
timescale to start at 0 seconds, in the year 1980, you have to pick
January 6th (Sunday) not January 1st (Tuesday) as the starting day.
See also:
https://en.wikipedia.org/wiki/Epoch_(computing)
https://gssc.esa.int/navipedia/index.php/Time_References_in_GNSS
Long answer: GPS time is kept as two continuous counters. One is a
binary wrapping count of weeks and the other is a count of seconds
within the week, which starts at 0 and resets at 604800 (7 * 24 * 60 *
60). Timing in GPS is based on this {week, seconds} tuple.
The week number increments at midnight between Saturday and Sunday. In
the US, Sunday is considered the first day of the week and civil
calendars show weeks going from Sunday to Saturday so a GPS week starts
at 0h Sunday and ends 24h Saturday. Note this is GPS midnight and not
UTC midnight. The two were equal in 1980 but now close yet unequal due
to leap seconds in UTC.
To create what we call "time of day" from this tuple some sort of
starting point must be defined. That's because fundamentally time is
relative and the SI unit of time is interval. So the time "now" must be
represented as as interval, such as now minus then, where "then" is some
agreed upon origin point (aka epoch). There are many different timing
systems and for practical or historical reasons each one gets to borrow
or define its epoch. Some examples:
01-Jan-1601 Windows NT
17-Nov-1858 VMS
01-Jan-1900 NTP
01-Jan-1958 Loran-C
01-Jan-1970 UNIX
01-Jan-1980 DOS
06-Jan-1980 GPS
22-Aug-1999 Galileo
01-Jan-2006 BeiDou
These choices are an interesting mix of history, convenience, round
numbers, and math. The main difference is that astronomical or computer
epochs tend to count seconds or days and thus have no week alignment
requirement. By contrast all three GNSS systems mentioned above are
based on week numbers. So if you want the timescale to start at {0,0}
the starting day needs to be a Sunday. Type cal 1 1980; cal 8 1999; cal
1 2006 to verify for the above 3 GNSS systems.
You'll recognize many of these numbers. The VMS epoch is MJD 0, which is
JD 240.5 and the Loran-C epoch is the de facto beginning of atomic
time. UNIX and DOS chose round decade numbers; NTP chose a round century
number; Windows NT chose a four century number (recall 4-100-400 leap
year rule). Many more examples are found in the wikipedia page I linked
above.
/tvb
On 3/22/2022 5:15 PM, Lux, Jim wrote:
I've been hunting around for the origin of GPS zero - Why is it 0UTC
Jan 6, 1980? Is it a subtle joke about "Twelfth Night"? Does it have
some useful properties that "end of year" does not?
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time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an
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[time-nuts] Re: CF cards and the Trimble NetRS
Quick question. I am looking at the netrs and do not believe it can act as a NTP server. I do see the ntp client settings. Am I missing something? Thanks Paul WB8TSL On Tue, Mar 22, 2022 at 3:09 PM paul swed wrote: > Did get the "convert to rinex" working. I actually seemed to have a bad > exe. I found a newer one on the actual trimble site not unavco and that > installed and operated correctly. I can see why a rinex file is useful. Its > readable. > Regards > Paul > WB8TSL > > On Mon, Mar 21, 2022 at 6:25 PM paul swed wrote: > >> Well Bob >> There you go changing the game just a bit. I saw the NTP settings and was >> thinking for some reason it might want to access a NTP server. I can see I >> have it backwards. Just may add a IP. I would have gotten there given time. >> But I will take a short cut any day. >> The Net RS is reasonably low power at 12V @ .35A or 4.5W. Its not >> apparent in the unit that the power coming in hits an inverter. I think >> its a linear regulator. Nothing looked like a choke for conversion. >> Did stick the antenna out of the window for a clearer view of the sky and >> picked up 8-10 db. The house blocks to the north. >> Regards >> Paul >> WB8TSL >> >> On Mon, Mar 21, 2022 at 5:50 PM Bob kb8tq wrote: >> >>> Hi >>> >>> More NetRS trivia: >>> >>> One of the features of the NetRS is that it will act as an NTP server. >>> It’s not the most modern device so I very much would not want to >>> serve a ton of clients off of one. It also has been a *long* time since >>> the OS was patched. If you are looking for “modern” features or >>> security patches, maybe not the best thing to use. It certainly isn’t >>> going to compete with the Leo Bodnar NTP in terms of size or >>> power consumption. You won’t get a steady stream of updates and >>> patches like you would on something cool from Meinberg. >>> >>> That said, for a “shop for a while” sub $150 sort of price, they would >>> be a reasonable deal. Not many packaged NTP products on eBay >>> that you “just plug in” and that run multi-band GPS. You would get >>> the frequency monitoring and RTK base station stuff “for free”. >>> >>> Can you / could you / might you upgrade the OS? Since there really >>> isn’t much info on what the hardware looks like, that could be >>> exciting. The cards are “locked down” (though not encrypted) as >>> received so even poking around to try this or that isn’t trivial. How >>> much was done (if anything) to keep the OS “out of the way” of the >>> GPS code …. who knows …. >>> >>> Fun !! >>> >>> Bob >>> >>> >>> >>> > On Mar 21, 2022, at 1:01 PM, John Ackermann N8UR wrote: >>> > >>> > You can stream data out of the receiver via either TCP or serial port >>> without storing to disk, so that's probably the best bet to save CF wear >>> and tear. I'm not sure if it's more difficult to turn the >>> > >>> > But for now I'm doing as you suggest -- I have one "T00" format >>> session logging to disk in 24 hour files, with the "autodelete" function >>> turned on to delete oldest files first when the disk gets nearly full. >>> > >>> > However, I've been collecting data now for almost 4 months, and have >>> used 68.5 MB, with 770 MB still available, so I won't need to delete >>> anything for quite a long while. >>> > >>> > John >>> > >>> > >>> > On 3/21/22 11:22, Skip Withrow wrote: >>> >> Hello Time-Nuts, >>> >> Seems like there has been a lot of interest in the NetRS lately >>> >> because of their availability at reasonable prices (sometimes). >>> >> They use a Compact Flash card to store the operating system and logged >>> >> data files. I'm not very knowledgeable about Linux, but I would guess >>> >> that there is no wear leveling implemented in this receiver. >>> >> So, when considering how best to use the data logging area it would >>> >> seem that instead of collecting some data, downloading it, deleting >>> >> file(s), and repeating the best strategy would be to collect data and >>> >> let the data logging area fill up before deleting (the files could be >>> >> read anytime). >>> >> This would minimize the number of writes to any one area of the CF >>> >> card I believe (except perhaps the directory structure). >>> >> However, even if you were deleting data often, you still may not be >>> >> able to get to the life of the CF card. The good news is that even if >>> >> a card does go bad you can reconstruct a new one from the image of >>> >> version 1.3-2 of the software that is floating around. I have tried >>> >> it and it works. >>> >> If there is better insight into the operation of this receiver, or >>> >> best practices strategy I'm all ears. >>> >> Regards, >>> >> Skip Withrow >>> >> ___ >>> >> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe >>> send an email to time-nuts-le...@lists.febo.com >>> >> To unsubscribe, go to and follow the instructions there. >>> > ___ >>> > time-nuts mailing
[time-nuts] Re: Why Jan 6th?
On 3/22/22 5:43 PM, Bill Beam wrote: You gotta start the clock some time. 0UTC Jan 6, 1980 is when the GPS clock was started. Do a search on "0UTC Jan 6, 1980" and you will get lots of answers. regards Bill NL7F Oh lots of "GPS zero = 6 Jan 1980 at 0 UTC" answers, but none that had Hal's explanation - it was the first Sunday in 1980. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Why Jan 6th?
You gotta start the clock some time. 0UTC Jan 6, 1980 is when the GPS clock was started. Do a search on "0UTC Jan 6, 1980" and you will get lots of answers. regards Bill NL7F On Tue, 22 Mar 2022 17:15:10 -0700, Lux, Jim wrote: >I've been hunting around for the origin of GPS zero - Why is it 0UTC Jan >6, 1980?- - Is it a subtle joke about "Twelfth Night"? Does it have some >useful properties that "end of year" does not? >___ >time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an >email to time-nuts-le...@lists.febo.com >To unsubscribe, go to and follow the instructions there. Bill Beam NL7F ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Why Jan 6th?
On 3/22/22 5:30 PM, Hal Murray wrote: j...@luxfamily.com said: I've been hunting around for the origin of GPS zero - Why is it 0UTC Jan 6, 1980? Is it a subtle joke about "Twelfth Night"? Does it have some useful properties that "end of year" does not? GPS weeks start on Sunday. That was the first Sunday in 1980. OK, that's too easy.. I was going for some connection to Twelfth Night. When trickery, deception, and all around tomfoolery occur. Or overconsumption of wassail. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Why Jan 6th?
j...@luxfamily.com said: > I've been hunting around for the origin of GPS zero - Why is it 0UTC Jan 6, > 1980? Is it a subtle joke about "Twelfth Night"? Does it have some useful > properties that "end of year" does not? GPS weeks start on Sunday. That was the first Sunday in 1980. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Why Jan 6th?
I've been hunting around for the origin of GPS zero - Why is it 0UTC Jan 6, 1980? Is it a subtle joke about "Twelfth Night"? Does it have some useful properties that "end of year" does not? ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Tuning a GPSDO loop for optimal disturbance handling
Eric, Do the observed DAC steps correspond in polarity to the observed frequency changes, or just the reverse? That's a key determination to make in placing blame, for it tells you whether the DAC steps are causative to the frequency changes, or rather the PLL's reaction to problems in, say, the VCO itself. Dana On Tue, Mar 22, 2022 at 2:10 PM Erik Kaashoek wrote: > Hi Bob, > By your advice I went for a 6.5 digit DVM and after logging and plotting > the DAC output its clear there are some stability issues in the DAC > output. The voltage is wandering around at about the level of frequency > wandering observed. > A different supply topology for the DAC and VCXO will have to be > created.. The DAC resolution is 50 uV (2.048 V / 40 steps) but the > random variations are about 4 times p-p larger. > Once this is done I hope longer term logging of frequency and voltage > will make sense. > Or is it better to have a low pass filter between the DAC and the VCXO > Vtune input so the loop is fast enough to remove the remaining drift? > If so, what should the time constant of the filter be compared to the > intersect of the ADEV of the GPS and the VCXO (100 s)? > Having a big time constant (10s?) will be a pain in the initial tuning > and will require active components. > Does owning a 6.5 digit DVM qualify one as a volt-nut? Or should first > some voltage references be added? > Erik. > > On 5-3-2022 20:50, Bob kb8tq wrote: > > Hi > > > > One suggestion on the frequency plot: > > > > TimeLab as you have it set does a “per pixel” process on its charts. You > have > > a limited screen resolution and a ton of data. You have to do something. > There > > is no way to display it all. > > > > It’s a good idea to zoom in to some of the “problem regions” and see > > what is really going on. This reduces the number of data points that > > map to one pixel and potentially changes what you see a bit. The closer > you > > get to one data point per pixel, the closer you are to “reality” without > any > > processing potentially getting in the way. > > > > On the DVM, eBay (with some time spent shopping) will sell you a working > > 6 1/2 digit device for < $100 if you are patient. If you need it now, > it’s still > > likely to be below $200. Yes it will be a big clunky box that takes up > bench > > space. It will be HPIB and not serial i/o. The display might be a bit > fun in > > bright lighting. > > > > While you are shopping, I would get set up for phase noise as well. Often > > it can spot issues that are tough to find with a second to second data > stream. > > The setup does not have to be very fancy or terribly expensive. > > > > Bob > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send > an email to time-nuts-le...@lists.febo.com > To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Tuning a GPSDO loop for optimal disturbance handling
A few weeks ago I was working on a prototype containing a MAX5443 single supply 3V 16-bit DAC in a circuit very similar to the one in its datasheet, using another MAX voltage ref. and a buffer and as far as I remember the output was pretty stable. Mete On Tue, 22 Mar 2022 at 20:10, Bob kb8tq wrote: > Hi > > > On Mar 22, 2022, at 12:14 PM, Erik Kaashoek wrote: > > > > Hi Bob, > > By your advice I went for a 6.5 digit DVM and after logging and plotting > the DAC output its clear there are some stability issues in the DAC output. > The voltage is wandering around at about the level of frequency wandering > observed. > > That’s a very typical result as you dig into the DAC ( = the DAC isn’t > perfect ). > > > A different supply topology for the DAC and VCXO will have to be > created.. The DAC resolution is 50 uV (2.048 V / 40 steps) but the > random variations are about 4 times p-p larger. > > Once this is done I hope longer term logging of frequency and voltage > will make sense. > > Or is it better to have a low pass filter between the DAC and the VCXO > Vtune input so the loop is fast enough to remove the remaining drift? > > You can go to a stable ADC and let it “servo” the DAC. That’s going to add > cost and > (likely) some noise from the ADC. The most common outcome is to find > another DAC > and possibly a better reference. > > > If so, what should the time constant of the filter be compared to the > intersect of the ADEV of the GPS and the VCXO (100 s)? > > Having a big time constant (10s?) will be a pain in the initial tuning > and will require active components. > > Does owning a 6.5 digit DVM qualify one as a volt-nut? Or should first > some voltage references be added? > > Erik. > > There’s *always* a way to spend more money on bench gear :) :) :). In > terms of this > project, what you have sounds like it’s doing the job just fine. > > Bob > > > > > On 5-3-2022 20:50, Bob kb8tq wrote: > >> Hi > >> > >> One suggestion on the frequency plot: > >> > >> TimeLab as you have it set does a “per pixel” process on its charts. > You have > >> a limited screen resolution and a ton of data. You have to do > something. There > >> is no way to display it all. > >> > >> It’s a good idea to zoom in to some of the “problem regions” and see > >> what is really going on. This reduces the number of data points that > >> map to one pixel and potentially changes what you see a bit. The closer > you > >> get to one data point per pixel, the closer you are to “reality” > without any > >> processing potentially getting in the way. > >> > >> On the DVM, eBay (with some time spent shopping) will sell you a working > >> 6 1/2 digit device for < $100 if you are patient. If you need it now, > it’s still > >> likely to be below $200. Yes it will be a big clunky box that takes up > bench > >> space. It will be HPIB and not serial i/o. The display might be a bit > fun in > >> bright lighting. > >> > >> While you are shopping, I would get set up for phase noise as well. > Often > >> it can spot issues that are tough to find with a second to second data > stream. > >> The setup does not have to be very fancy or terribly expensive. > >> > >> Bob > >> > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send > an email to time-nuts-le...@lists.febo.com > To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: CF cards and the Trimble NetRS
Did get the "convert to rinex" working. I actually seemed to have a bad exe. I found a newer one on the actual trimble site not unavco and that installed and operated correctly. I can see why a rinex file is useful. Its readable. Regards Paul WB8TSL On Mon, Mar 21, 2022 at 6:25 PM paul swed wrote: > Well Bob > There you go changing the game just a bit. I saw the NTP settings and was > thinking for some reason it might want to access a NTP server. I can see I > have it backwards. Just may add a IP. I would have gotten there given time. > But I will take a short cut any day. > The Net RS is reasonably low power at 12V @ .35A or 4.5W. Its not apparent > in the unit that the power coming in hits an inverter. I think its a linear > regulator. Nothing looked like a choke for conversion. > Did stick the antenna out of the window for a clearer view of the sky and > picked up 8-10 db. The house blocks to the north. > Regards > Paul > WB8TSL > > On Mon, Mar 21, 2022 at 5:50 PM Bob kb8tq wrote: > >> Hi >> >> More NetRS trivia: >> >> One of the features of the NetRS is that it will act as an NTP server. >> It’s not the most modern device so I very much would not want to >> serve a ton of clients off of one. It also has been a *long* time since >> the OS was patched. If you are looking for “modern” features or >> security patches, maybe not the best thing to use. It certainly isn’t >> going to compete with the Leo Bodnar NTP in terms of size or >> power consumption. You won’t get a steady stream of updates and >> patches like you would on something cool from Meinberg. >> >> That said, for a “shop for a while” sub $150 sort of price, they would >> be a reasonable deal. Not many packaged NTP products on eBay >> that you “just plug in” and that run multi-band GPS. You would get >> the frequency monitoring and RTK base station stuff “for free”. >> >> Can you / could you / might you upgrade the OS? Since there really >> isn’t much info on what the hardware looks like, that could be >> exciting. The cards are “locked down” (though not encrypted) as >> received so even poking around to try this or that isn’t trivial. How >> much was done (if anything) to keep the OS “out of the way” of the >> GPS code …. who knows …. >> >> Fun !! >> >> Bob >> >> >> >> > On Mar 21, 2022, at 1:01 PM, John Ackermann N8UR wrote: >> > >> > You can stream data out of the receiver via either TCP or serial port >> without storing to disk, so that's probably the best bet to save CF wear >> and tear. I'm not sure if it's more difficult to turn the >> > >> > But for now I'm doing as you suggest -- I have one "T00" format session >> logging to disk in 24 hour files, with the "autodelete" function turned on >> to delete oldest files first when the disk gets nearly full. >> > >> > However, I've been collecting data now for almost 4 months, and have >> used 68.5 MB, with 770 MB still available, so I won't need to delete >> anything for quite a long while. >> > >> > John >> > >> > >> > On 3/21/22 11:22, Skip Withrow wrote: >> >> Hello Time-Nuts, >> >> Seems like there has been a lot of interest in the NetRS lately >> >> because of their availability at reasonable prices (sometimes). >> >> They use a Compact Flash card to store the operating system and logged >> >> data files. I'm not very knowledgeable about Linux, but I would guess >> >> that there is no wear leveling implemented in this receiver. >> >> So, when considering how best to use the data logging area it would >> >> seem that instead of collecting some data, downloading it, deleting >> >> file(s), and repeating the best strategy would be to collect data and >> >> let the data logging area fill up before deleting (the files could be >> >> read anytime). >> >> This would minimize the number of writes to any one area of the CF >> >> card I believe (except perhaps the directory structure). >> >> However, even if you were deleting data often, you still may not be >> >> able to get to the life of the CF card. The good news is that even if >> >> a card does go bad you can reconstruct a new one from the image of >> >> version 1.3-2 of the software that is floating around. I have tried >> >> it and it works. >> >> If there is better insight into the operation of this receiver, or >> >> best practices strategy I'm all ears. >> >> Regards, >> >> Skip Withrow >> >> ___ >> >> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe >> send an email to time-nuts-le...@lists.febo.com >> >> To unsubscribe, go to and follow the instructions there. >> > ___ >> > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe >> send an email to time-nuts-le...@lists.febo.com >> > To unsubscribe, go to and follow the instructions there. >> ___ >> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe >> send an email to
[time-nuts] Re: Tuning a GPSDO loop for optimal disturbance handling
Hi > On Mar 22, 2022, at 12:14 PM, Erik Kaashoek wrote: > > Hi Bob, > By your advice I went for a 6.5 digit DVM and after logging and plotting the > DAC output its clear there are some stability issues in the DAC output. The > voltage is wandering around at about the level of frequency wandering > observed. That’s a very typical result as you dig into the DAC ( = the DAC isn’t perfect ). > A different supply topology for the DAC and VCXO will have to be created.. > The DAC resolution is 50 uV (2.048 V / 40 steps) but the random > variations are about 4 times p-p larger. > Once this is done I hope longer term logging of frequency and voltage will > make sense. > Or is it better to have a low pass filter between the DAC and the VCXO Vtune > input so the loop is fast enough to remove the remaining drift? You can go to a stable ADC and let it “servo” the DAC. That’s going to add cost and (likely) some noise from the ADC. The most common outcome is to find another DAC and possibly a better reference. > If so, what should the time constant of the filter be compared to the > intersect of the ADEV of the GPS and the VCXO (100 s)? > Having a big time constant (10s?) will be a pain in the initial tuning and > will require active components. > Does owning a 6.5 digit DVM qualify one as a volt-nut? Or should first some > voltage references be added? > Erik. There’s *always* a way to spend more money on bench gear :) :) :). In terms of this project, what you have sounds like it’s doing the job just fine. Bob > > On 5-3-2022 20:50, Bob kb8tq wrote: >> Hi >> >> One suggestion on the frequency plot: >> >> TimeLab as you have it set does a “per pixel” process on its charts. You have >> a limited screen resolution and a ton of data. You have to do something. >> There >> is no way to display it all. >> >> It’s a good idea to zoom in to some of the “problem regions” and see >> what is really going on. This reduces the number of data points that >> map to one pixel and potentially changes what you see a bit. The closer you >> get to one data point per pixel, the closer you are to “reality” without any >> processing potentially getting in the way. >> >> On the DVM, eBay (with some time spent shopping) will sell you a working >> 6 1/2 digit device for < $100 if you are patient. If you need it now, it’s >> still >> likely to be below $200. Yes it will be a big clunky box that takes up bench >> space. It will be HPIB and not serial i/o. The display might be a bit fun in >> bright lighting. >> >> While you are shopping, I would get set up for phase noise as well. Often >> it can spot issues that are tough to find with a second to second data >> stream. >> The setup does not have to be very fancy or terribly expensive. >> >> Bob >> > ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Tuning a GPSDO loop for optimal disturbance handling
Hi Bob, By your advice I went for a 6.5 digit DVM and after logging and plotting the DAC output its clear there are some stability issues in the DAC output. The voltage is wandering around at about the level of frequency wandering observed. A different supply topology for the DAC and VCXO will have to be created.. The DAC resolution is 50 uV (2.048 V / 40 steps) but the random variations are about 4 times p-p larger. Once this is done I hope longer term logging of frequency and voltage will make sense. Or is it better to have a low pass filter between the DAC and the VCXO Vtune input so the loop is fast enough to remove the remaining drift? If so, what should the time constant of the filter be compared to the intersect of the ADEV of the GPS and the VCXO (100 s)? Having a big time constant (10s?) will be a pain in the initial tuning and will require active components. Does owning a 6.5 digit DVM qualify one as a volt-nut? Or should first some voltage references be added? Erik. On 5-3-2022 20:50, Bob kb8tq wrote: Hi One suggestion on the frequency plot: TimeLab as you have it set does a “per pixel” process on its charts. You have a limited screen resolution and a ton of data. You have to do something. There is no way to display it all. It’s a good idea to zoom in to some of the “problem regions” and see what is really going on. This reduces the number of data points that map to one pixel and potentially changes what you see a bit. The closer you get to one data point per pixel, the closer you are to “reality” without any processing potentially getting in the way. On the DVM, eBay (with some time spent shopping) will sell you a working 6 1/2 digit device for < $100 if you are patient. If you need it now, it’s still likely to be below $200. Yes it will be a big clunky box that takes up bench space. It will be HPIB and not serial i/o. The display might be a bit fun in bright lighting. While you are shopping, I would get set up for phase noise as well. Often it can spot issues that are tough to find with a second to second data stream. The setup does not have to be very fancy or terribly expensive. Bob ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
