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| Agilent E7495 linux root account |
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| technogeeky:
--- Quote from: DogP on November 02, 2016, 05:48:59 am ---2) When I connect a GPS antenna with a good view of the sky, I easily get GPS (bottom left says GPS Locked), location usually shows ~8 satellites tracked, but the GPS icon in the bottom right never goes to the green dot (I've left it tracking for over 24 hours). It always stays at the yellow triangle. Because of that, I can't run the Time Base Adjustment (it requires me to wait for the green dot). Switching to the internal reference shows a green dot, and the frequency accuracy seems pretty good, so I don't think the TCXO is bad. Also, I noticed that it shows time on the screen, but it never gets set to the correct GPS time (and it appears that the time/date gets reset to the time/date that was set at boot every 30 seconds, even if I manually set it over telnet). The GPS location looks correct though (drops a dot right on my neighbors house :-P ). --- End quote --- I thought I might have some insight into this problem, but it appears you already noticed what I noticed. The GPS never goes GREEN, it stays at YELLOW TRIANGLE. I think the problem lies with the time/clock itself. Something is clearly fighting the GPS to reset the clock to some (arbitrary, it seems) earlier value. And I do mean arbitrary. I tried this procedure and I think this pretty well proves something is fighting it: * Turn on device, connect GPS antenna. * At any time (but for sake of argument, after you notice at least 5 satellites locked), log into the web interface (port 5000). Click on Date and Time, and tell the device to take the current time of the your computer. * It will update, but then after about 30 seconds, it will reset to this initial time. * No matter how long you wait, it will continue to allow you to set the time; but it will always rollback to this 1st clock set. * You can confirm this by changing the time zone on your host computer. This will set the clock to the same time, but it will suddenly be many hours ahead; and the device will still go back to whatever the initial setting was (this can sometimes be Jan 1 2004). However, I do have something additional to report: You can fool the device into launching the Time Base Adjustment (... sort of): * When you are at the Time Base Adjustment screen (the Calibrate button will be greyed out)... * Log onto the web interface. * Click on Active STIM. * Select and activate the GPS stim. * Click on Channel I/O. * Set the Frequency Reference parameter (10) to 0, using the Int 10M reference. * This will fool the unit into believing that the 10MHz reference (e.g. the one we are trying to calibrate) is the locked signal. It will bring up the menu we are all trying to see. It will show the ADC value for the reference, and where/when it was chosen (2053, and Initial Factory). This doesn't help us, but I think it must be the case that something is fighting us for the clock. So we just need to find what other processes/stims/whatever access/try to change the clock. Perhaps this is a sign of a hardware malfunction in a clock on the motherboard, or some other malfunction that could be tested/corrected if we could e.g. get into the BIOS? Is there a BIOS? --- Quote from: DogP on November 02, 2016, 05:48:59 am --- 3) I rebuilt my 2nd battery pack, and like the first one, going through the battery recalibration procedure never finished. It says that it'd take up to 12 hours, and on the first battery I left it running for almost 2 days and it never finished, so it aborted... on the 2nd battery, I left it running since I rebuilt the pack on Friday night... so almost 5 days. I finally aborted it tonight. The battery voltage was slowly creeping upward around 12.4 (going up around 10mV per day) but never hit 12.6V (4.2V per cell)... not sure if it didn't think it was done because of that, or something else. It almost always showed 0 mA current. The percentage shown is usually 99%, though it sometimes bounces down to 98% or up to 100%. The battery life seems fine (~1.5 - 2 hours per battery), so I'm not too worried about it... just seems strange (and my OCD would like that fuel gauge error to say 0%, not 10% ;) )... I also tried just running the batteries down and recharging them normally, but that didn't make a difference. Related to that... the 2nd battery rebuild went smoother than the first. I'll update my rebuild post above with a couple more notes/pics. --- End quote --- I rebuilt one of my battery packs, and I took pictures of the process. Unfortunately the 2nd one I rebuilt was actually already good, and I simply hadn't checked. I will be getting batteries in soon to replace the first pack. |
| TheSteve:
I was hoping you were on to something to help adjust the time base on the N1996A. On the N1996A there is a frequency/reference setting menu. It won't let you continue though unless the system is configured for GPS. However the N1996A doesn't support a GPS - it was never enabled and the receiver is not installed. I can set the external reference to "even second" but it locks just fine to a 1 PPS signal(even second doesn't lock). Not a big deal but it would have been fun to adjust the timebase without using the crazy expensive calibration software Keysight sells for the N1996A. |
| technogeeky:
--- Quote from: TheSteve on March 08, 2017, 04:36:06 am ---I was hoping you were on to something to help adjust the time base on the N1996A. On the N1996A there is a frequency/reference setting menu. It won't let you continue though unless the system is configured for GPS. However the N1996A doesn't support a GPS - it was never enabled and the receiver is not installed. I can set the external reference to "even second" but it locks just fine to a 1 PPS signal(even second doesn't lock). Not a big deal but it would have been fun to adjust the timebase without using the crazy expensive calibration software Keysight sells for the N1996A. --- End quote --- Well, this may be a route toward that (if a circuitous one). I really don't know that hardware (or this hardware, to be honest). But this method let me see the the value stored somewhere (in firmware or eeprom or something) for the calibration setting (which is, in this case, an integer constant for the ADC). If we could use the screen in which this was displayed (I did not get a screenshot or photograph; I was actually driving my car at the time!) to find where it's writing a firmware setting to, perhaps we could translated this process back to your device? |
| DogP:
--- Quote from: technogeeky on March 08, 2017, 04:11:17 am ---This doesn't help us, but I think it must be the case that something is fighting us for the clock. So we just need to find what other processes/stims/whatever access/try to change the clock. --- End quote --- IIRC, I came to the conclusion that it's a script running in the background that's causing the time to constantly reset. I think it was keepTimeUpdated or something like that. I don't think the system clock is why GPS never goes green though (I don't think there's any code for the GPS to even try updating the system clock). --- Quote from: TheSteve on March 07, 2017, 05:18:34 pm ---I was able to extend both the power and frequency range of the signal source in a N1996A. The power range difference was only a few dB so I changed it back to stock as the real maximum output varied with frequency. I extended the frequency range down to 1 MHz from 10 MHz. I believe the E7495A has similar text files which can edited however I have read someone tried lowering the source range on an E7495A in the past and it would crash the unit when you tried to enter a lower frequency. --- End quote --- That'd be great to be able to extend the sig gen freq below 375 MHz... and if it could do that, maybe it could do the insertion loss test below 375 MHz as well. Those features would be very high on my wishlist (even though the arbitrary sig gen kinda sucks since it doesn't filter the LO or image). Does the N1996A have an arbitrary sig gen, or just a tracking generator? Pat |
| technogeeky:
--- Quote from: DogP on March 08, 2017, 06:35:27 am ---IIRC, I came to the conclusion that it's a script running in the background that's causing the time to constantly reset. I think it was keepTimeUpdated or something like that. I don't think the system clock is why GPS never goes green though (I don't think there's any code for the GPS to even try updating the system clock). --- End quote --- I think you are correct. I think I might have proof, but I don't think it's (yet) needed. In any case, when I was having trouble running the Calibrate Timebase thing, it turns out the hardware clock (as displayed by hwclock) was set to Jan 1 1970. In other words, it was just counting up from epoch. There is also an 'rtc' module, which could be the source of our problem: if the RTC is faulty or resetting, then it's possible the RTC or the manager of it is fighting attempts to set the clock. I have found some code regarding this in the GUI, so I can investigate further. Has anyone been able to decompile the ARM code? I assume there is little to no hope to decompile the firmware for the Dragonfly chips, but the ARM code (of elgato server) should be easy to decompile. I tried downloading and using snowman, but it is unfortunately stupid and it runs out of memory at the "regenerating types" stage. It seems to have generated all of the functions from two different binaries, but because I only have 8GB of memory I can't get much further. Does anyone know how to force a process to work from a disk instead of from memory? You can look at the elgato GUI (siege) source JAR linked here, and it's clear that there are a few checking conditions before you're allowed to enter the timebase recalibration. Also, there appears to be a direct command you can issue to some command listener to set the new timebase ADC value directly -- this may help N1996A owners. At the very least, you could GET the existing timebase ADC value and then SET a new one, then compare the clocks (though how one would go about this, I have no idea). |
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