Re: [time-nuts] More Z3801/Tbolt comparisons
> -Original Message- > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On > Behalf Of Stan, W1LE > Sent: Friday, September 04, 2009 10:27 AM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] More Z3801/Tbolt comparisons > > If I see the rack mounting ears on a piece of test equipment I assume > that it was rack mounted > and acoustically sheltered from the user. I assess my bid to include a > new fan, usually 30-50$. > > Yes, rack mounted test equipment was usually from a fixed location, and > has no "road rash". > > Stan, W1LE > I don't know about that. I've got a fair amount of "gear with ears" that looks beat up. Here at JPL, when you get something from the loan pool it may or may not have ears, and may or may not have been slid across the bench or floor a few times. At least you know that it probably works. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] More Z3801/Tbolt comparisons
If I see the rack mounting ears on a piece of test equipment I assume that it was rack mounted and acoustically sheltered from the user. I assess my bid to include a new fan, usually 30-50$. Yes, rack mounted test equipment was usually from a fixed location, and has no "road rash". Stan, W1LE Roy Phillips wrote: Nigel I must say that much of what you have stated is right, I have a 53131A counter and the basic time-base is a joke, but agreed, we mostly use a common external reference with our instruments. There are some exceptions, as I am finding with a very recently purchased HP 8657A Sig. Gen. that has the option 001 oven oscillator. This is a 1998 production (made in the US), the TCXO would seem to be a very stable device with coarse and fine adjustment - after running for 48 hours its holding 10 Mhz to ^10. In fact it would seem to be somewhat better than the TCXO in my Marconi 2024 Sig. Gen. - - hence my singing the praises of HP. The large number of Racal 199# on the UK market in recent times are I would suggest, ex UK military issue and as portable instruments have probably had a rough life, and have frequently been stored for ten years in somewhat poor environments. I would suggest that buying equipment that has come from a commercial origin, and has been part of a rack test set-up, have been better cared for and sometimes have had very little use. What do you others think about this theory ? Roy - Original Message - From: To: Sent: Friday, September 04, 2009 12:36 PM Subject: Re: [time-nuts] More Z3801/Tbolt comparisons In a message dated 04/09/2009 11:18:07 GMT Daylight Time, phill...@btinternet.com writes: Racal 19## Counters are something else - - I got rid of mine some years back, not only the ongoing problems with the key-pad, but I don't think they put much cost into the oven osc. Perhaps you should consider moving on to an HP or other quality counter, "you deserve it" -- Even the best counters can sometimes suffer from poor internal oscillators. The basic onboard oscillator in the HP53132A for example has no practical use whatsoever, other than to demonstrate that the counter is functional, but I suspect most, if not all, list members will generally be operating counters with external references anyway Whilst I wouldn't even consider swapping my 53132A for a 199x I must be a glutton for punishment as I've just bought another 1991 after also selling my previous one some time ago. Aside from the reported key pad problems, which haven't affected me so far, and the lesser resolution, it's a good solid workhorse and, something not to be sneezed at, this one in very good condition cost me at least 80% less than I'd expect to pay for a similar condition 53132A:-) Earlier 19xx counters also strike me as being underrated these days. Although it's lacking in resolution for most of my current needs I've still got a 1905 I bought new in the late 70s/early 80s and that has served me very well as a general purpose counter. I'd suggest that too as an excellent workhorse and more than adequate for such things as transmitter or receiver adjustment etc and, at the give-away prices the 1904 and 1905 often seem to fetch on Ebay, they can be quite a bargain. regards Nigel GM8PZR ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] More Z3801/Tbolt comparisons
In a message dated 04/09/2009 16:32:09 GMT Daylight Time, phill...@btinternet.com writes: I must say that much of what you have stated is right, I have a 53131A counter and the basic time-base is a joke, but agreed, we mostly use a common external reference with our instruments. There are some exceptions, as I am finding with a very recently purchased HP 8657A Sig. Gen. that has the option 001 oven oscillator. This is a 1998 production (made in the US), the TCXO would seem to be a very stable device with coarse and fine adjustment - after running for 48 hours its holding 10 Mhz to ^10. In fact it would seem to be somewhat better than the TCXO in my Marconi 2024 Sig. Gen. - - hence my singing the praises of HP. - Hi Roy I suspect the 8657A option 001 is likely to be a 10811B, which also appears in quite a lot of other HP kit and is also the better of the options for the 53131A and 53132A. They are certainly very nice oscillators. -- The large number of Racal 199# on the UK market in recent times are I would suggest, ex UK military issue and as portable instruments have probably had a rough life, and have frequently been stored for ten years in somewhat poor environments. I would suggest that buying equipment that has come from a commercial origin, and has been part of a rack test set-up, have been better cared for and sometimes have had very little use. What do you others think about this theory ? You're quite right that the majority of 199x counters available in recent times are ex-mil but that doesn't always mean a hard life, although I agree there can be an element of risk involved when buying them. My first 1991, bought a few years ago, was ex-mil but had never been issued and was still new in its original box, having been taken out just once since original calibration to check it was still "serviceable". The one just bought is also ex-mil, this one has been used but looks to have been very well treated. It carries a label indicating the warranty ran out in 2001, so I assume it was manufactured in 2000, with last calibration expiring in April 2009. Although it's fitted with the manual pouch for portable use it doesn't show any signs that it's actually been used portable, the case and front and rear panels are unmarked, so I suspect it may have just seen bench use. There's no obvious problems with the front panel switches either, which is another good sign, although, of course, that could change tomorrow:-) It's very likely that there's a lot more of all sorts of test gear, on Ebay at least, that's ex-mil rather than ex-commercial so it's really quite difficult to avoid unless prepared to always buy from dealers who are able to guarantee previous ownership, and also prepared to pay their much higher prices. regards Nigel GM8PZR ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] More Z3801/Tbolt comparisons
Nigel I must say that much of what you have stated is right, I have a 53131A counter and the basic time-base is a joke, but agreed, we mostly use a common external reference with our instruments. There are some exceptions, as I am finding with a very recently purchased HP 8657A Sig. Gen. that has the option 001 oven oscillator. This is a 1998 production (made in the US), the TCXO would seem to be a very stable device with coarse and fine adjustment - after running for 48 hours its holding 10 Mhz to ^10. In fact it would seem to be somewhat better than the TCXO in my Marconi 2024 Sig. Gen. - - hence my singing the praises of HP. The large number of Racal 199# on the UK market in recent times are I would suggest, ex UK military issue and as portable instruments have probably had a rough life, and have frequently been stored for ten years in somewhat poor environments. I would suggest that buying equipment that has come from a commercial origin, and has been part of a rack test set-up, have been better cared for and sometimes have had very little use. What do you others think about this theory ? Roy - Original Message - From: To: Sent: Friday, September 04, 2009 12:36 PM Subject: Re: [time-nuts] More Z3801/Tbolt comparisons In a message dated 04/09/2009 11:18:07 GMT Daylight Time, phill...@btinternet.com writes: Racal 19## Counters are something else - - I got rid of mine some years back, not only the ongoing problems with the key-pad, but I don't think they put much cost into the oven osc. Perhaps you should consider moving on to an HP or other quality counter, "you deserve it" -- Even the best counters can sometimes suffer from poor internal oscillators. The basic onboard oscillator in the HP53132A for example has no practical use whatsoever, other than to demonstrate that the counter is functional, but I suspect most, if not all, list members will generally be operating counters with external references anyway Whilst I wouldn't even consider swapping my 53132A for a 199x I must be a glutton for punishment as I've just bought another 1991 after also selling my previous one some time ago. Aside from the reported key pad problems, which haven't affected me so far, and the lesser resolution, it's a good solid workhorse and, something not to be sneezed at, this one in very good condition cost me at least 80% less than I'd expect to pay for a similar condition 53132A:-) Earlier 19xx counters also strike me as being underrated these days. Although it's lacking in resolution for most of my current needs I've still got a 1905 I bought new in the late 70s/early 80s and that has served me very well as a general purpose counter. I'd suggest that too as an excellent workhorse and more than adequate for such things as transmitter or receiver adjustment etc and, at the give-away prices the 1904 and 1905 often seem to fetch on Ebay, they can be quite a bargain. regards Nigel GM8PZR ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] More Z3801/Tbolt comparisons
Yes, the sidereal day is definitely the proper interval to survey for. The technique that I am using analyzes the data over minute, hour, and 24 hour intervals. The Tbolt outputs data at one second intervals. There is not a good way to evenly divide those 236 seconds over those intervals, so I stick with the 24 hour day. The difference is not noticeable. If we are being this careful, I wonder if you should use a SIDEREAL day of averaging - 236 seconds short of a solar day ? _ Hotmail® is up to 70% faster. Now good news travels really fast. http://windowslive.com/online/hotmail?ocid=PID23391::T:WLMTAGL:ON:WL:en-US:WM_HYGN_faster:082009 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] More Z3801/Tbolt comparisons
Hi Mark, If we are being this careful, I wonder if you should use a SIDEREAL day of averaging - 236 seconds short of a solar day ? TTFN, Peter Vince (G8ZZR, London, England) On Thu Sep 3 19:40 , Mark Sims sent: >... > The next version of Lady Heather will have a very precise self-survey routine. > It takes data for 48 hours (which has 24 overlapping 24 hour intervals) and > statistically processes it to get a very precise location. Typically the > error > is around 1 foot lat/lon, 1 meter altitude (there he goes, mixing measurement > systems again). With good antennas in good locations it can get to under 4 > inches > of error. Poor antennas in bad locations might be 2 feet off. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] More Z3801/Tbolt comparisons
In a message dated 04/09/2009 11:18:07 GMT Daylight Time, phill...@btinternet.com writes: Racal 19## Counters are something else - - I got rid of mine some years back, not only the ongoing problems with the key-pad, but I don't think they put much cost into the oven osc. Perhaps you should consider moving on to an HP or other quality counter, "you deserve it" -- Even the best counters can sometimes suffer from poor internal oscillators. The basic onboard oscillator in the HP53132A for example has no practical use whatsoever, other than to demonstrate that the counter is functional, but I suspect most, if not all, list members will generally be operating counters with external references anyway Whilst I wouldn't even consider swapping my 53132A for a 199x I must be a glutton for punishment as I've just bought another 1991 after also selling my previous one some time ago. Aside from the reported key pad problems, which haven't affected me so far, and the lesser resolution, it's a good solid workhorse and, something not to be sneezed at, this one in very good condition cost me at least 80% less than I'd expect to pay for a similar condition 53132A:-) Earlier 19xx counters also strike me as being underrated these days. Although it's lacking in resolution for most of my current needs I've still got a 1905 I bought new in the late 70s/early 80s and that has served me very well as a general purpose counter. I'd suggest that too as an excellent workhorse and more than adequate for such things as transmitter or receiver adjustment etc and, at the give-away prices the 1904 and 1905 often seem to fetch on Ebay, they can be quite a bargain. regards Nigel GM8PZR ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] More Z3801/Tbolt comparisons
John Interesting stuff - - I'm not anti Racal, in fact I have a Racal T & F Mainframe, fed by a Trimble NTX, and the T&F Mainframe is very well made and performs in an excellent manner. But, - - - Racal 19## Counters are something else - - I got rid of mine some years back, not only the ongoing problems with the key-pad, but I don't think they put much cost into the oven osc. Perhaps you should consider moving on to an HP or other quality counter, "you deserve it" Roy - Original Message - From: "John Green" To: Sent: Thursday, September 03, 2009 8:05 PM Subject: [time-nuts] More Z3801/Tbolt comparisons Yesterday, I thought the Tbolt was wandering around too much. So, I did a factory reset and started a new 5K fix self survey. At about the same time, I started a new self survey on the Z3801 thinking that if they were both looking at the same satellites with the same antenna at the same time, they might be closer together. When I arrived back at work this morning, I looked at the final positions they had arrived at. The latitude difference was .17 deg. and Longitude was .26 deg. Great. This is probably within the margin of error of how they report. But, the altitude was 36.05 meters different. That, I can't explain. I have been looking at the time difference all morning and it seems to cycle +/- 6 ns every couple of minutes. It also seems to move maybe 30 nsec every hour or so.This also seems to be cyclic. I also see sudden jumps of around 4 to 5 nsec. I assume this is due to DAC voltage corrections. I thought some of this might be due to the Z3801 since I was using it as the reference to the 1992. I switched back to the internal reference and couldn't tell any difference. Could some of this still be the 1992? I noticed the Tbolt was set to not look at any satellites below 10 deg. I changed that to 0 deg. like the Z3801 and it didn't seem to make a difference. I am going to let a Rb start warming up and use it as a reference later to see if some of what I am seeing is the Z3801. Anyone have any ideas why the altitude is so much different? I am going to look at a topo map to see what it says. I might also change the disciplining constants of the Tbolt to see if it makes a difference. I can always do a factory reset later. None of this is meant to say that the Tbolt isn't as good as the Z3801. I just wanted to see what they looked like compared to each other. To folks used to seeing charts and exact numbers these casual observations may be a bit annoying. I haven't yet been able to use the GPIB facilities of my 1992. Hope to later. These are only meant to be casual observations. Though I trust what I see and read from my instruments, these aren't meant to be written in stone or quoted as specifications. Just some things to think about. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] More Z3801/Tbolt comparisons
The standard self-surveys in these units leaves MUCH to be desired. You need to do surveys for 24 hours to help mitigate satellite constellation and atmospheric effects. Note that due to periods of poor satellite geometry, you can't just survey for 24*60*60 fixes. You need the survey to be based upon absolute time. Altitude errors are typically at least three times as large as lat/lon errors, but can be very large. Luckily, altitude errors seem to have a much smaller effect on GPSDO performance than lat/lon errors. Be careful getting your altitude from topo maps. You need to make sure your map reference geoid matches the GPS WGS84 coordinate system. Geoid errors can be tens of meters. For instance the NGS OPUS system reports altitude as both ellipsoid height and orthometric height. The difference here is 25 meters. The next version of Lady Heather will have a very precise self-survey routine. It takes data for 48 hours (which has 24 overlapping 24 hour intervals) and statistically processes it to get a very precise location. Typically the error is around 1 foot lat/lon, 1 meter altitude (there he goes, mixing measurement systems again). With good antennas in good locations it can get to under 4 inches of error. Poor antennas in bad locations might be 2 feet off. _ Hotmail® is up to 70% faster. Now good news travels really fast. http://windowslive.com/online/hotmail?ocid=PID23391::T:WLMTAGL:ON:WL:en-US:WM_HYGN_faster:082009 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] More Z3801/Tbolt comparisons
Hi John, With regard to the altitude, what I have found is that it is never close ! I have seen variations all over the scale. What I did here is determine, to the best of my ability, from TOPO maps what my altitude is and measure the height of the antenna off of the ground where it is mounted and manually enter that number. BillWB6BNQ John Green wrote: > Yesterday, I thought the Tbolt was wandering around too much. So, I did a > factory reset and started a new 5K > fix self survey. At about the same time, I started a new self survey on the > Z3801 thinking that if they were > both looking at the same satellites with the same antenna at the same time, > they might be closer together. > When I arrived back at work this morning, I looked at the final positions > they had arrived at. The latitude > difference was .17 deg. and Longitude was .26 deg. Great. This is > probably within the margin of error > of how they report. But, the altitude was 36.05 meters different. That, I > can't explain. I have been looking > at the time difference all morning and it seems to cycle +/- 6 ns every > couple of minutes. It also seems to move > maybe 30 nsec every hour or so.This also seems to be cyclic. I also see > sudden jumps of around 4 to 5 nsec. I > assume this is due to DAC voltage corrections. I thought some of this might > be due to the Z3801 since I was using > it as the reference to the 1992. I switched back to the internal reference > and couldn't tell any difference. > Could some of this still be the 1992? I noticed the Tbolt was set to not > look at any satellites below 10 deg. > I changed that to 0 deg. like the Z3801 and it didn't seem to make a > difference. I am going to let a Rb start > warming up and use it as a reference later to see if some of what I am > seeing is the Z3801. Anyone have any ideas > why the altitude is so much different? I am going to look at a topo map to > see what it says. I might also change > the disciplining constants of the Tbolt to see if it makes a difference. I > can always do a factory reset later. None of this is > meant to say that the Tbolt isn't as good as the Z3801. I just wanted to see > what they looked like compared to each other. > To folks used to seeing charts and exact numbers these casual observations > may be a bit annoying. I haven't > yet been able to use the GPIB facilities of my 1992. Hope to later. These > are only meant to be casual > observations. Though I trust what I see and read from my instruments, these > aren't meant to be written in stone or quoted > as specifications. Just some things to think about. > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] More Z3801/Tbolt comparisons
Yesterday, I thought the Tbolt was wandering around too much. So, I did a factory reset and started a new 5K fix self survey. At about the same time, I started a new self survey on the Z3801 thinking that if they were both looking at the same satellites with the same antenna at the same time, they might be closer together. When I arrived back at work this morning, I looked at the final positions they had arrived at. The latitude difference was .17 deg. and Longitude was .26 deg. Great. This is probably within the margin of error of how they report. But, the altitude was 36.05 meters different. That, I can't explain. I have been looking at the time difference all morning and it seems to cycle +/- 6 ns every couple of minutes. It also seems to move maybe 30 nsec every hour or so.This also seems to be cyclic. I also see sudden jumps of around 4 to 5 nsec. I assume this is due to DAC voltage corrections. I thought some of this might be due to the Z3801 since I was using it as the reference to the 1992. I switched back to the internal reference and couldn't tell any difference. Could some of this still be the 1992? I noticed the Tbolt was set to not look at any satellites below 10 deg. I changed that to 0 deg. like the Z3801 and it didn't seem to make a difference. I am going to let a Rb start warming up and use it as a reference later to see if some of what I am seeing is the Z3801. Anyone have any ideas why the altitude is so much different? I am going to look at a topo map to see what it says. I might also change the disciplining constants of the Tbolt to see if it makes a difference. I can always do a factory reset later. None of this is meant to say that the Tbolt isn't as good as the Z3801. I just wanted to see what they looked like compared to each other. To folks used to seeing charts and exact numbers these casual observations may be a bit annoying. I haven't yet been able to use the GPIB facilities of my 1992. Hope to later. These are only meant to be casual observations. Though I trust what I see and read from my instruments, these aren't meant to be written in stone or quoted as specifications. Just some things to think about. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
