[time-nuts] Source for DC-blocking 50-ohm terminators? (Spectracom 8140)
I'm looking at using a Spectracom 8140 for 10Mhz distribution, and they specify using a DC-blocking 50-ohm terminator on each run. These seem to be odd enough that none of my usual sources have them (75-ohm DC-blocking terminators yes, 50-ohm, no). While it's easy enough to chain a DC block and a terminator, I'd prefer a single module I can more obviously label as the line termination. ___ 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] nuts about position
Hi > On Jun 3, 2018, at 7:35 PM, Mark Sims wrote: > > As far as I'm concerned anything that you can do to improve the position > accuracy, environmental changes, noise environment, etc is a good thing. > Minimizing errors and disturbances can't hurt and may even improve things. > How much any improvement provides ... ??? But time nuts tend to be a bit > nutty about minimizing our therbligs ;-) > > Most receiver self-surveys seem to get your lat/lon to the 2-3 meter range. > Heather's median survey is in the 1-2 meter range. PPP data is in the < 0.25 > meter range... seems like something worthwhile. (altitude errors are usually > around twice the lat/lon error). > > There is always the possibility that some receiver model's computation of > lat/lon/alt could have some intrinsic bias in it. If so, a position > calculated by an external source could possibly degrade performance... If you go back to the NIST papers where they were testing timing modules, they indeed did find “gotcha’s” with putting in survey based coordinates. I don’t think they ever did PPP on the modules they published data on. Bob > > > >> Is this applicable to a Thunderbolt, and would this improved position > accuracy be expected to improve the time accuracy from a Thunderbolt > compared to using the older Lady Heather 24 hour self survey method? > ___ > 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] nuts about position
As far as I'm concerned anything that you can do to improve the position accuracy, environmental changes, noise environment, etc is a good thing. Minimizing errors and disturbances can't hurt and may even improve things. How much any improvement provides ... ??? But time nuts tend to be a bit nutty about minimizing our therbligs ;-) Most receiver self-surveys seem to get your lat/lon to the 2-3 meter range. Heather's median survey is in the 1-2 meter range. PPP data is in the < 0.25 meter range... seems like something worthwhile. (altitude errors are usually around twice the lat/lon error). There is always the possibility that some receiver model's computation of lat/lon/alt could have some intrinsic bias in it. If so, a position calculated by an external source could possibly degrade performance... > Is this applicable to a Thunderbolt, and would this improved position accuracy be expected to improve the time accuracy from a Thunderbolt compared to using the older Lady Heather 24 hour self survey method? ___ 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] HP 53131A Power Off Mod
I had also modified my HP 53132A but kept it extra simple and the modification allows me to use the counter normally.. On my HP 53132A I just mounted a toggle switch in one of the unused holes for the back panel BNC input connectors and wired the switch in series with the power connector. The front panel power/standby switch is unmodified and works as usual and if I want to completely power down I can reach around to the back and turn the added switch to the off position. Much easier than the other modifications I've seen and is easily removable if you want to sell the unit unmodified. -Arthur ___ 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] Fwd: HP 53131A Power Off Mod
*Important Update:* due to a mistake in my thinking, I had to upgrade the fuse I added to a 220V, 3A model to match the fuses on the internal switching power supply. My original plans were to mount the fuse on the power supply PCB and use it only to fuse the small power adapter used to power the relay. But, when there was not enough space, I decided to use the in-line fuse adapter, instead. Completely overlooking the fact that the in-line fuse would then need to handle the full power load. The project page at https://sites.google.com/site/wayneholder/hp-53131a-power-off-mod has been updated accordingly. Sorry for the mistake and I hope this hasn't inconvenienced anyone. *Wayne* On Fri, May 18, 2018 at 4:56 PM, Wayne Holder wrote: > The PCBs and Parts arrived and, after putting everything together and > testing it, it all seems to work fine. And, to document everything, I've > put up a web page at my web site that describes the mod and how to > implement it: > > https://sites.google.com/site/wayneholder/hp-53131a-power-off-mod > > I had two spare board sets left. One is claimed, but if someone would > like the other set, send me your address and I'll send them your way. > > Wayne > > On Mon, May 7, 2018 at 10:27 PM, Tim Tuck wrote: > >> Hi Wayne, >> >> Congrats on a nice simple mod ! >> >> I have both a 53131 and 181 in need of these :) >> >> Can you share the gerbers for your PCBs and then I can cut them out on my >> mill. >> >> I could probably make a few for any interested Australians, to save on >> cross pond postage. >> >> thanks >> >> Tim >> >> On 8/05/2018 9:08 AM, Wayne Holder wrote: >> >>> I recently purchased a surplus HP 53131A and was surprised to see that >>> it's >>> designed to stay partially powered on, with the fan running, even when >>> the >>> power switch is in standby. The manual says this is for timebase >>> temperature stability but, since I plan to use with my Trimble >>> Thunderbolt >>> as the reference source, I don't really need this feature. So, I decided >>> to see if I could change this. >>> >> >> >> --- >> This email has been checked for viruses by Avast antivirus software. >> https://www.avast.com/antivirus >> >> ___ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/m >> ailman/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] nuts about position
Hi Location will always impact things a bit. At some point it does become a minor contributor. What point that is varies with a lot of things. One of them is indeed the propagation path to the satellites. How much the ionosphere and troposphere mess things up is very much a “that depends” sort of thing. There are corrections applied to the data as part of normal GPS L! operation. The degree to which these corrections work depends on how close things are to the “normal model”. That in turn depends to some degree on how active the sunspot cycle is at the time. Right now we are in a period of relatively low activity. That equates to the models mostly fitting better most of the time. If solar activity was somewhat higher, then things get more dynamic. The magic models and the broadcast data can’t keep up as well. That translates to more noise on the estimates and worse timing ( as well as an impact on location). Bob > On Jun 3, 2018, at 4:07 PM, Chris Caudle wrote: > > On Sun, June 3, 2018 12:57 am, Mark Sims wrote: >> Well, with a little prodding and help from Magnus, I now have the >> Trimble devices outputting RINEX files. > > Is this applicable to a Thunderbolt, and would this improved position > accuracy be expected to improve the time accuracy from a Thunderbolt > compared to using the older Lady Heather 24 hour self survey method? Or > is ionospheric noise the limiting factor so determining more accurate > position doesn't really help? > > -- > Chris Caudle > > > > > ___ > 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] nuts about position
Hi, On 06/03/2018 10:07 PM, Chris Caudle wrote: > On Sun, June 3, 2018 12:57 am, Mark Sims wrote: >> Well, with a little prodding and help from Magnus, I now have the >> Trimble devices outputting RINEX files. > > Is this applicable to a Thunderbolt, and would this improved position > accuracy be expected to improve the time accuracy from a Thunderbolt > compared to using the older Lady Heather 24 hour self survey method? Or > is ionospheric noise the limiting factor so determining more accurate > position doesn't really help? > Actual ionospheric and corrections isn't matching up too well, so this can be a way to achieve a better fixed location. Exactly how the Thunderbolt uses the data in its steering I don't know, it would be interesting to figure that out. Cheers, Magnus ___ 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] nuts about position
On Sun, June 3, 2018 12:57 am, Mark Sims wrote: > Well, with a little prodding and help from Magnus, I now have the > Trimble devices outputting RINEX files. Is this applicable to a Thunderbolt, and would this improved position accuracy be expected to improve the time accuracy from a Thunderbolt compared to using the older Lady Heather 24 hour self survey method? Or is ionospheric noise the limiting factor so determining more accurate position doesn't really help? -- Chris Caudle ___ 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] HP 5372A TIA Question
Hi Adam, OK, good to hear about the progress. Let us know about what you learn and if you need additional input. I'm curious what is the cause of this error. Cheers, Magnus On 06/03/2018 04:09 AM, Adam MacDonald wrote: > Thanks Gents, > I ran the additional tests recommended by Poul and Magnus and I concur that > the interpolator board is not the likely culprit. I reversed the input > cables as well as the pods in separate experiments to rule out those > contributors with no different results. I thought it may be a trigger > circuit error so I fed the inputs with a locked TTL signal rather than a sine > wave using Manual Trigger with no difference. It seems to be a coarse count > error so I'll investigate the start/stop logic chain. > > Adam > > > ___ > 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] nuts about position
I did a test on a 1 second vs a stripped out 10 second rate from the same 24 hour run. The differences were down in the noise. Some people have actually reported slightly better results with 30 second vs 1 second data... but I doubt that... I suspect they used different data sets and the differences were just due to different data. --- If you are doing a longer run into one of the data analysis services - it does not seem to matter much what the spacing on the readings is ___ 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] nuts about position
Hi If you are doing a longer run into one of the data analysis services - it does not seem to matter much what the spacing on the readings is. One second data does not seem to produce any better result than 30 second data. I don’t think that the 3 second rate on the Trimble will have much impact on a 24 hour data set. Bob > On Jun 3, 2018, at 1:57 AM, Mark Sims wrote: > > Well, with a little prodding and help from Magnus, I now have the Trimble > devices outputting RINEX files. They have pseudorange, doppler, and signal > strength observations. A 5 hour 1Hz run was sent to CSRS-PPP and the > lat/lon/alt error ellipses were in the 250/250/700 mm range... that should > improve with a longer run. > > Firmware issues in the original Resolution-T limit those to a 3 second > observation rate. > ___ > 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] nuts about position
I haven't done any extensive testing of how accurate the results are, but comparing them to the position produced by a L1/L2 (error ellipses < 50mm) they seem to be correct. One issue to be aware of is that some receivers want altitude in othometric height (MSL) and others use geoid (GPS) height. If you are transferring the PPP results to a receiver you need to watch out for what the receiver wants. Also MSL based receivers may be using different orthometric models, so knowing how to convert GPS height to what the receiver uses can be problematic. - > Does the position agree with other chip sets? ___ 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.
