Re: [time-nuts] Sending me Lady Heather screen-captures....
Mike Assuming you have learned to tame some of LH behavior issues, and that is not what is causing the problems then: MB) the temperature graph exhibits a sharp, which recovers over a period of a few minutes. ws)Likley a basic 'bug' in the LH Hardware. Best to ignore it. MB) blue PPS ADEV and the red OSC ADEV ws)The best thing I have found so far for most to do with the Blue and Red ADEV curves is to turn them off using GA They can provide some useful advanced information BUT they are not too comparable to 'standard' ADEV. MB) Periodically, the violet PPS graph and the green DAC graph will go off scale for 10-15 minutes. ws)The really LARGE jumps can and most likely are caused when the Tbolt goes into and returns from holdover. To verify if that is your cause, Look at the Sat Counts LH plot, if it goes to zero, then that is what is happing. Also check the 'holdover sec, That counts how many seconds has been spent in holdover. IF Holdover is the cause then setting the AMU down to around 1.0 from the default 4.0 can help IF you can not get a better signal and view from your antenna. If you set the Elevation up to around 25 to 30 and set the TC to 250 + from the default 100 both of these will help reduce the smaller jumps, even when your antenna has a good signal. And to reduce the Phase error that the Higher TC will cause with changing temperature and ageing reduce the Damping setting from the 1.2 default to 0.7. And before doing that set the 'Dac gain' correct. It's all a compromise, but with some effort and experience you can make things much better over the default settings. If you send me a LH screen dump or better yet a 24 hr log plot, I'd better be able to point out the causes of you problems without all the guessing. have fun ws From: Mark Sims Those spikes/decays in the temperature plot are due to false readings the Tbolt firmware gets from the temperature sensor chip. They are an artifact of how the temperature sensor works in its high resolution mode. They are actually single sample spikes of 1C (I think) in the output of the sensor chip. The reported amplitude/decay is due to the filtering the Tbolt firmware does on the temperature readings. Also, remember that the ADEV values calculated by Lady Heather are from its internal measurements of the oscillator and PPS signal against the rather-noisy-in-the-short-term GPS signal. They tend to depart from the true ADEV values measured against a real external reference particularly at shorter values of tau (like 100 secs). Turn on the satellite count display (G C from the keyboard in ver 3.0). The Tbolt reacts rather poorly to changes in the group of satellites that it is tracking. When the tracked satellite constellation changes, you can get big jumps in the osc/pps/dac signals. To minimize constellation changes, set the signal level mask to a low value (like AMU=1.0) and the satellite elevation mask to a high value (like 25 degrees). - Original Message - From: John Miles jmi...@pop.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Monday, December 28, 2009 10:26 PM Subject: Re: [time-nuts] Sending me Lady Heather screen-captures One mystery is that once or twice daily, the temperature graph exhibits a sharp, almost perfectly vertical spike which recovers over a period of a few minutes. The temperature cannot possibly change that rapidly so there is something else going on. Note that the existing (non-beta) version of LH has some pretty debatable serial-port code in it. You may just be seeing data corruption. If it happens with the 3.0 beta version, it's may be worth investigating. LH often indicates that the blue PPS ADEV and the red OSC ADEV are both in the high E-13 zone for several hours and then invariably, both will drop back to the mid E-12 zone and sometimes stay there for many hours. Nature of the beast, really. A single outlier can affect your whole ADEV plot. Periodically, the violet PPS graph and the green DAC graph will go off scale for 10-15 minutes and I cannot find a reason for this-- it does not seem to be either temperature related or have anything to do with how strong the signals from the birds are or where the birds are relative to any tall tree foliage blocking the antenna sky view. The auto-scaling has undergone some improvements, too... if you're not running the beta, give that a try. -- john, KE5FX *** From: Michael Baker Hello, Time-Nuts-- Many thanks to Warren S for sending me over 20 Lady Heather screen-captures showing different configurations!! I really appreciate seeing these and welcome anyone else on the list sending me their screen captures. John Miles commented that individual screenshots may not be very useful without specifying the timescale, filters, and graphs you're looking for. This is true, but I am not even sure what I am
[time-nuts] Sending me Lady Heather screen-captures....
Hello, Time-Nuts-- Many thanks to Warren S for sending me over 20 Lady Heather screen-captures showing different configurations!! I really appreciate seeing these and welcome anyone else on the list sending me their screen captures. John Miles commented that individual screenshots may not be very useful without specifying the timescale, filters, and graphs you're looking for. This is true, but I am not even sure what I am looking for,--and some of the filter configurations mean nothing to me!! At this stage, I am like the little boy on the sidewalk looking into the toy store window and saying, WOW!! How COOL!! Look at that, and that, and that!! Now I have some studying to do of the graphs of all the different filters and configurations-- this will take me a while as I am not really sure what I am looking at with some of the graphs. Thanks again Warren!! My Thunderbolt sits next to my desktop computer in the shop and I have made no attempt to thermally isolate it from ambient temperature excursions due to routine air-conditioner cycles in the summer and heat-pump cycles in the winter so I expect to see some regular variation of the temperature graph. I mainly use it's outputs to reference and lock my spectrum analyzer and frequency counters with. One mystery is that once or twice daily, the temperature graph exhibits a sharp, almost perfectly vertical spike which recovers over a period of a few minutes. The temperature cannot possibly change that rapidly so there is something else going on. LH often indicates that the blue PPS ADEV and the red OSC ADEV are both in the high E-13 zone for several hours and then invariably, both will drop back to the mid E-12 zone and sometimes stay there for many hours. Periodically, the violet PPS graph and the green DAC graph will go off scale for 10-15 minutes and I cannot find a reason for this-- it does not seem to be either temperature related or have anything to do with how strong the signals from the birds are or where the birds are relative to any tall tree foliage blocking the antenna sky view. Mike Baker --- ___ 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] Sending me Lady Heather screen-captures....
One mystery is that once or twice daily, the temperature graph exhibits a sharp, almost perfectly vertical spike which recovers over a period of a few minutes. The temperature cannot possibly change that rapidly so there is something else going on. Note that the existing (non-beta) version of LH has some pretty debatable serial-port code in it. You may just be seeing data corruption. If it happens with the 3.0 beta version, it's may be worth investigating. LH often indicates that the blue PPS ADEV and the red OSC ADEV are both in the high E-13 zone for several hours and then invariably, both will drop back to the mid E-12 zone and sometimes stay there for many hours. Nature of the beast, really. A single outlier can affect your whole ADEV plot. Periodically, the violet PPS graph and the green DAC graph will go off scale for 10-15 minutes and I cannot find a reason for this-- it does not seem to be either temperature related or have anything to do with how strong the signals from the birds are or where the birds are relative to any tall tree foliage blocking the antenna sky view. The auto-scaling has undergone some improvements, too... if you're not running the beta, give that a try. -- john, KE5FX ___ 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] Sending me Lady Heather screen-captures....
Those spikes/decays in the temperature plot are due to false readings the Tbolt firmware gets from the temperature sensor chip. They are an artifact of how the temperature sensor works in its high resolution mode. They are actually single sample spikes of 1C (I think) in the output of the sensor chip. The reported amplitude/decay is due to the filtering the Tbolt firmware does on the temperature readings. Also, remember that the ADEV values calculated by Lady Heather are from its internal measurements of the oscillator and PPS signal against the rather-noisy-in-the-short-term GPS signal. They tend to depart from the true ADEV values measured against a real external reference particularly at shorter values of tau (like 100 secs). Turn on the satellite count display (G C from the keyboard in ver 3.0). The Tbolt reacts rather poorly to changes in the group of satellites that it is tracking. When the tracked satellite constellation changes, you can get big jumps in the osc/pps/dac signals. To minimize constellation changes, set the signal level mask to a low value (like AMU=1.0) and the satellite elevation mask to a high value (like 25 degrees). _ Hotmail: Trusted email with powerful SPAM protection. http://clk.atdmt.com/GBL/go/177141665/direct/01/ ___ 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.
