Re: [time-nuts] Collecting raw timing data
Thanks so much, your description of collecting the raw timing data is really clear. I like the technique of doing timing interval measurements from a slower known reference on one channel to a DUT on a second channel. This definitely gets me started. jeff Didier Juges wrote: Jeff, I have a practical step by step example using the HP 5370, a reference oscillator (in my case, a Thunderbolt GPSDO, but you could use the counter's time base if you know it to be better than your UUT), a test oscillator (in my case an HP 10811) and the free Plotter software from Ulrich Bangert on mu web page: http://www.ko4bb.com/Timing/FAQ-1.html Look for Practical Example near the bottom. Didier KO4BB -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jeff Mock Sent: Monday, November 26, 2007 1:13 PM To: time-nuts@febo.com Subject: [time-nuts] Collecting raw timing data This is mostly a question for tvb. How are you collecting raw timing timing data to calculate a typical Allan deviation plot? Something like: http://www.leapsecond.com/museum/hp58503b/log19395v.gif I've been fiddling with my HP53132A to get the right combination of settings to collect useful timing data for making Allan deviation plots. Any information on your general workflow from collecting the raw data to making a plot is appreciated. thanks, jeff ___ 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] Collecting raw timing data
Jeff Mock wrote: Thanks so much, your description of collecting the raw timing data is really clear. I like the technique of doing timing interval measurements from a slower known reference on one channel to a DUT on a second channel. This definitely gets me started. jeff An algorithm for unabiguously unwrapping the rollovers can be found in: http://horology.jpl.nasa.gov/papers/picket_uffc.pdf Bruce ___ 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] 1Mhz to 1 PPS
You will need a clock shaper to convert the sine to a digital signal, and a series of dividers. You can look at my page on clock shapers for ideas: http://www.ko4bb.com/Timing/ClockShaper.html If you look through the archives, I believe earlier this year there was a thread about the respective noise performance of various logic technologies, but I am sure someone can recommend the current best-in-class divider for low noise. For any but the most demanding applications, I am sure that standard CMOS decade counters in the AC, HC, ACT or HCT series would work fine, such as the 74ACT162. Look at this page for comparison of CMOS technologies: http://www.solarbotics.net/bftgu/starting_elect_ic.html Didier KO4BB jshank [EMAIL PROTECTED] wrote: Hi, I would like to convert a 1 MHz sine wave to a 1 pps TTL. Any suggestions? Thanks, Jeff ___ 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] 1Mhz to 1 PPS
Jeff If you do a web search for frequency divider or standard, there are several good home brew type projects that are relatively simple and straight forward. Below are some of the sites I have visited. The first 2 explain more on the tech end and the last is a public domain schematic of a relatively simple divider. 2 more dividers would have to be added to get 1pps with a 1mhz input. I've seen the 390 chip used elsewhere and seems to work without a bunch of external components. Of course, all vcc lines to the chips should have capacitors to ground on all the chips. These are not normally shown or maybe they didn't use them. http://www.play-hookey.com/digital/ www.techlib.com/files/dividers.pdf http://www.g7ltt.com/10mhz/freqstd3.jpeg Good Luck Rix -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of jshank Sent: Tuesday, November 27, 2007 8:23 AM To: Discussion of precise time and frequency measurement Subject: [time-nuts] 1Mhz to 1 PPS Hi, I would like to convert a 1 MHz sine wave to a 1 pps TTL. Any suggestions? Thanks, Jeff ___ 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] 1Mhz to 1 PPS
Hi Jeff: Another way is using a PIC micro controller, see: http://www.prc68.com/I/PRC68COM.shtml#TVB http://www.leapsecond.com/tools/PPSDIV.ASM Have Fun, Brooke Clarke http://www.PRC68.com http://www.precisionclock.com http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam jshank wrote: Hi, I would like to convert a 1 MHz sine wave to a 1 pps TTL. Any suggestions? Thanks, Jeff ___ 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] 1Mhz to 1 PPS
I would like to convert a 1 MHz sine wave to a 1 pps TTL. I'm assuming you aren't too concerned about jitter. There are two issues. The first is converting your sine wave into a valid logic level. The second is dividing by a million. If your sine wave has a reasonable amplitude, I'd just feed it into a logic gate. If it's too big, I'd add a resistive divider. You probably want to AC couple the input. That needs something to bias it at the right level. A big resistor from an inverted output usually works well. It sets the bias point to give you a 50-50 duty cycle. If you want to get fancy, use a comparator. For home construction, a row of 74HC390s is the best divider I can think of. It gives you 2 divide by 10 stages in each package so you only need 3 chips. Are you tight for space? Do you like low level software? I'd probably do the dividing in software on a PIC or AVR. The 8 pin dips are easy to work with but they come in tiny packages too. They are usually setup to work with a raw crystal or external clock. You can probably find something that will work with your sine wave. Another alternative to a row of '390s is a CPLD or FPGA. They usually only come in packages with tiny pins which are hard for my old eyes to work with. They might make sense if you need some logic for something else. -- These are my opinions, not necessarily my employer's. I hate spam. ___ 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] 1Mhz to 1 PPS
Hal Murray wrote: I would like to convert a 1 MHz sine wave to a 1 pps TTL. I'm assuming you aren't too concerned about jitter. There are two issues. The first is converting your sine wave into a valid logic level. The second is dividing by a million. If your sine wave has a reasonable amplitude, I'd just feed it into a logic gate. If it's too big, I'd add a resistive divider. You probably want to AC couple the input. That needs something to bias it at the right level. A big resistor from an inverted output usually works well. It sets the bias point to give you a 50-50 duty cycle. A Schmitt trigger device 74xx14 is generally better than a simple logic gate. CMOS Schmitt trigger devices are easier to rive than TTL type devices especially if the source impedance is high. If you want to get fancy, use a comparator. For home construction, a row of 74HC390s is the best divider I can think of. It gives you 2 divide by 10 stages in each package so you only need 3 chips. The jitter and clock to output delay (along with its tempco) is increased when one cascades 390's. Synchronously cascaded 160's have lower jitter and lower clock to output delay. Are you tight for space? Do you like low level software? I'd probably do the dividing in software on a PIC or AVR. The 8 pin dips are easy to work with but they come in tiny packages too. They are usually setup to work with a raw crystal or external clock. You can probably find something that will work with your sine wave. Resynchronising the divided output with a D flipflop will minimise clock to output delay and associated jitter. Another alternative to a row of '390s is a CPLD or FPGA. They usually only come in packages with tiny pins which are hard for my old eyes to work with. They might make sense if you need some logic for something else. FPGAs are nice but jitter can be high, resynchronising the divided output with an external D flipflop will reduce this significantly. You could also resynchronise the output of a 390 divider chain, however the delay from clock in to output can be too large to reliably do this in one step, when the input frequency is too high or the divider chain too long. Bruce ___ 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] OT: Prologix GPIB and HP3478A...
Hi Gang! I just bought a Prologix GPIB - USB converter model, version 5.00, and I am having some problems. It works fine on some of my instruments, but it just locks up when I hook it to an HP3478A DVM. The DVM is known good, and works great with my HP85B (doesn't everything?). Basically, if I do any commands that require bus activity, the Prologix locks up and refuses to respond to even the ++ver command. When I unplug the HP3478A, the Prologix once again finds its happy spot, and responds normally. Any ideas? -Chuck Harris ___ 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] OT: Prologix GPIB and HP3478A...
Chuck, I have used my HP 3478A with my Prologix controller (and several other GPIB controllers), but I have not upgraded the firmware to 5.0 (I think I am still at 4.61 or something like that). I will try and let you know. The 3478 is a relatively recent instrument (as far as GPIB features/capability/compliance is concerned), so I am surprised you would have problems. Didier KO4BB -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Chuck Harris Sent: Tuesday, November 27, 2007 9:34 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] OT: Prologix GPIB and HP3478A... Hi Gang! I just bought a Prologix GPIB - USB converter model, version 5.00, and I am having some problems. It works fine on some of my instruments, but it just locks up when I hook it to an HP3478A DVM. The DVM is known good, and works great with my HP85B (doesn't everything?). Basically, if I do any commands that require bus activity, the Prologix locks up and refuses to respond to even the ++ver command. When I unplug the HP3478A, the Prologix once again finds its happy spot, and responds normally. Any ideas? -Chuck Harris ___ 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. -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.503 / Virus Database: 269.16.8/1154 - Release Date: 11/27/2007 11:40 AM ___ 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] OT: Prologix GPIB and HP3478A...
Hi Chuck: It may be timing. The 85 and the 3478 are old and slow. Have you tried adding wait statements after you send any command to give the 3478 time to think about it? Also it may be good to send CRLFEOI after each command then do the wait. Have Fun, Brooke Clarke http://www.PRC68.com http://www.precisionclock.com http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam Chuck Harris wrote: Hi Gang! I just bought a Prologix GPIB - USB converter model, version 5.00, and I am having some problems. It works fine on some of my instruments, but it just locks up when I hook it to an HP3478A DVM. The DVM is known good, and works great with my HP85B (doesn't everything?). Basically, if I do any commands that require bus activity, the Prologix locks up and refuses to respond to even the ++ver command. When I unplug the HP3478A, the Prologix once again finds its happy spot, and responds normally. Any ideas? -Chuck Harris ___ 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] OT: Prologix GPIB and HP3478A...
Hello Chuck, It appears that 3478A sends data continuously as soon as it is addressed to talk. Since the Prologix adapter is busy processing GPIB data it is unable to respond to USB commands. One solution is to turn read-after-write off (++auto 0) before connecting the adapter to 3478A, and then use ++read command to read one measurement at a time. Please see the manual (www.prologix.biz) for ++read command options. The other option is to set 3478A to one-reading-per-trigger mode using T3 device command. See HP3478 manual (pages 39, 59). Then use the ++trg command to trigger the device. ++auto must be set to 1 in this case. Regards, Abdul -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Chuck Harris Sent: Tuesday, November 27, 2007 7:34 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] OT: Prologix GPIB and HP3478A... Hi Gang! I just bought a Prologix GPIB - USB converter model, version 5.00, and I am having some problems. It works fine on some of my instruments, but it just locks up when I hook it to an HP3478A DVM. The DVM is known good, and works great with my HP85B (doesn't everything?). Basically, if I do any commands that require bus activity, the Prologix locks up and refuses to respond to even the ++ver command. When I unplug the HP3478A, the Prologix once again finds its happy spot, and responds normally. Any ideas? -Chuck Harris ___ 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] OT: Prologix GPIB and HP3478A...
On Tue, 27 Nov 2007, Prologix wrote: Hello Chuck, It appears that 3478A sends data continuously as soon as it is addressed to talk. Since the Prologix adapter is busy processing GPIB data it is unable to respond to USB commands. One solution is to turn read-after-write off (++auto 0) before connecting the adapter to 3478A, and then use ++read command to read one measurement at a time. Please see the manual (www.prologix.biz) for ++read command options. The other option is to set 3478A to one-reading-per-trigger mode using T3 device command. See HP3478 manual (pages 39, 59). Then use the ++trg command to trigger the device. ++auto must be set to 1 in this case. Regards, Abdul Excellent answer! I do not have either piece of equipment but I can certainly say that even though I am now using NI GPIB cards which are likely faster, I always program the instrument being queried to only send one response per trigger. I learned BASIC and also HPIB programming on a HP85 when it was the latest and greatest in 1980-81. Then later in another company I used the 9845 and then after that used the 9836. I think I must have learned from their wonderful documentation sets that this was the right way to take readings. It may well have been to avoid the timing issues you presented. Regards, Jeffrey Pawlan ___ 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] OT: Prologix GPIB and HP3478A...
Chuck, Sending ++addr 09; ++read 10; with my Prologix to the HP 3478A returns a single reading just fine. Didier KO4BB -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Chuck Harris Sent: Tuesday, November 27, 2007 9:34 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] OT: Prologix GPIB and HP3478A... Hi Gang! I just bought a Prologix GPIB - USB converter model, version 5.00, and I am having some problems. It works fine on some of my instruments, but it just locks up when I hook it to an HP3478A DVM. The DVM is known good, and works great with my HP85B (doesn't everything?). Basically, if I do any commands that require bus activity, the Prologix locks up and refuses to respond to even the ++ver command. When I unplug the HP3478A, the Prologix once again finds its happy spot, and responds normally. Any ideas? -Chuck Harris ___ 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] OT: Prologix GPIB and HP3478A...
Some instruments are pretty hard headed and can't be easily convinced to stop after just one piece of information. So Abdul implemented the ++read command. I know some people like that :-) Too bad ++read does not work with those... Didier KO4BB -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jeffrey Pawlan Sent: Tuesday, November 27, 2007 10:33 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] OT: Prologix GPIB and HP3478A... I always program the instrument being queried to only send one response per trigger. ... Jeffrey Pawlan ___ 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] OT: Prologix GPIB and HP3478A...
Prologix wrote: One solution is to turn read-after-write off (++auto 0) before connecting the adapter to 3478A, and then use ++read command to read one measurement at a time. Please see the manual (www.prologix.biz) for ++read command options. I nearly always turn off auto mode on the prologix. I've run into a number of slightly flaky problems when the prologix guesses to turn on the instrument to talk. I've never noticed a performance penalty because I need to issue a ++read command to the prologix whenever I want to read something back. I think the prologix device is great. I'm a linux guy, I haven't used windows in many years. NI has never really understood open source software. It was always a pain to have a reliable driver for the NI GPIB PCI cards, so I was quite happy to find something like the Prologix device that is reliable and has drivers that are totally open source and distributed as part of the linux kernel. I have a slightly off-topic question about reads. When issuing a ++read eoi, is it possible to tell whether an EOI was actually returned by the instrument or whether the read was terminated by timeout or block size limitation? jeff ___ 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] OT: Prologix GPIB and HP3478A...
Hi Brooke, I'm sending the commands as I type them in Kermit. Surely that is slow enough. I cannot send any commands to the 3478A. The simple act of asking the prologix to do anything other than ++ver, locks up the prologix so it ignores all USB traffic. The Prologix works fine with a 3438A, which is about as old as GPIB gets. Also with a 3437A, which is pretty old too. Something is broken here. The prologix is probably violating some timing requirement in the handshaking, and the 3478A isn't playing along. -Chuck Harris Brooke Clarke wrote: Hi Chuck: It may be timing. The 85 and the 3478 are old and slow. Have you tried adding wait statements after you send any command to give the 3478 time to think about it? Also it may be good to send CRLFEOI after each command then do the wait. Have Fun, Brooke Clarke ___ 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] OT: Prologix GPIB and HP3478A...
Chuck, The commands I copied in my previous post were sent very fast. My program sends the strings automatically when I click on a button, so fast timing is perfectly acceptable by the Prologix/3478A combination. Let me know if you need me to give you any particular configuration information of my setup. I use a program I wrote in Visual basic under XP, but I cannot see why it would not work from the keyboard, even though I have not tried... I have tried from the keyboard with the HP 3456A voltmeter at one time when Abdul asked me for testing purposes (the Prologix did not completely lock out, but was clearly overwhelmed by the amount of data returned by the meter), and after Abdul added the ++read eoi command, it worked fine too. I know you use Linux, so this program won't do you any good, and I do not have a Linux box handy in the shack at the moment, but if you wanted to try it, let me know. Didier KO4BB -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Chuck Harris Sent: Tuesday, November 27, 2007 11:55 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] OT: Prologix GPIB and HP3478A... Hi Brooke, I'm sending the commands as I type them in Kermit. Surely that is slow enough. I cannot send any commands to the 3478A. The simple act of asking the prologix to do anything other than ++ver, locks up the prologix so it ignores all USB traffic. The Prologix works fine with a 3438A, which is about as old as GPIB gets. Also with a 3437A, which is pretty old too. Something is broken here. The prologix is probably violating some timing requirement in the handshaking, and the 3478A isn't playing along. -Chuck Harris Brooke Clarke wrote: Hi Chuck: It may be timing. The 85 and the 3478 are old and slow. Have you tried adding wait statements after you send any command to give the 3478 time to think about it? Also it may be good to send CRLFEOI after each command then do the wait. Have Fun, Brooke Clarke ___ 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] Collecting raw timing data
Bruce Griffiths wrote: Jeff Mock wrote: Thanks so much, your description of collecting the raw timing data is really clear. I like the technique of doing timing interval measurements from a slower known reference on one channel to a DUT on a second channel. This definitely gets me started. jeff An algorithm for unabiguously unwrapping the rollovers can be found in: http://horology.jpl.nasa.gov/papers/picket_uffc.pdf Thanks, that's a nice paper, 3-pages, lots of short declarative sentences that make sense. As I understand the problem, Fig. 1 in this paper is the key for collecting good data for measuring Allan variance. jeff ___ 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] OT: Prologix GPIB and HP3478A...
Did you try sending ++auto 0 before powering up the 3478A? This setting is persistent, so you should only have to do it once to keep the board from automatically addressing the 3478A to talk. Also try disconnecting any/all other RS-232 devices from your PC during initial testing, and/or try a different USB port. -- john, KE5FX -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Chuck Harris Sent: Tuesday, November 27, 2007 9:55 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] OT: Prologix GPIB and HP3478A... Hi Brooke, I'm sending the commands as I type them in Kermit. Surely that is slow enough. I cannot send any commands to the 3478A. The simple act of asking the prologix to do anything other than ++ver, locks up the prologix so it ignores all USB traffic. ___ 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] OT: Prologix GPIB and HP3478A...
Hello Jeff, Thanks for the compliments. Much appreciated. You may configure the Prologix adapter (using ++eot_enable and ++eot_char) to send (append, really) a user-specified character to USB ouput when it detects EOI. By checking for the character you can determine if EOI was asserted. Regards, Abdul -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jeff Mock I have a slightly off-topic question about reads. When issuing a ++read eoi, is it possible to tell whether an EOI was actually returned by the instrument or whether the read was terminated by timeout or block size limitation? jeff ___ 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] OT: Prologix GPIB and HP3478A...
Prologix wrote: Hello Chuck, It appears that 3478A sends data continuously as soon as it is addressed to talk. Since the Prologix adapter is busy processing GPIB data it is unable to respond to USB commands. I don't think the 3478A is sending anything at all. If it was, it should be showing some of the annunciators on its LCD display, like TLK, LSTN, RMT, SRQ, or something. But it isn't. I think the Prologix isn't capable of driving the 3478A, logic level wise, and is waiting in vain for the 3478A to respond to a signal the 3478A cannot see. There truly is a reason why 488 bus driver chips exist. Something about the talker/controller's 220 ohm/330 ohm pull up/pull down terminator spec, and the 38ma pull down spec. One solution is to turn read-after-write off (++auto 0) before connecting the adapter to 3478A, and then use ++read command to read one measurement at a time. Please see the manual (www.prologix.biz) for ++read command options. Nope, doesn't work, locks it up on the first ++read command. The other option is to set 3478A to one-reading-per-trigger mode using T3 device command. See HP3478 manual (pages 39, 59). Then use the ++trg command to trigger the device. ++auto must be set to 1 in this case. Sending T3 locks up the Prologix. -Chuck Harris Regards, Abdul -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Chuck Harris Sent: Tuesday, November 27, 2007 7:34 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] OT: Prologix GPIB and HP3478A... Hi Gang! I just bought a Prologix GPIB - USB converter model, version 5.00, and I am having some problems. It works fine on some of my instruments, but it just locks up when I hook it to an HP3478A DVM. The DVM is known good, and works great with my HP85B (doesn't everything?). Basically, if I do any commands that require bus activity, the Prologix locks up and refuses to respond to even the ++ver command. When I unplug the HP3478A, the Prologix once again finds its happy spot, and responds normally. Any ideas? -Chuck Harris ___ 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] fury lock light?
In a message dated 11/27/2007 21:22:41 Pacific Standard Time, [EMAIL PROTECTED] writes: Under what criteria does the Fury turn on its lock light? Hi CH, good question, let me CC the time nuts on the answer. We are at the PTTI, so sorry for the sluggish communication. The Fury actually checks the temperature of the OCXO case. A lock LED requires that the OCXO has a minimum case temperature of 35 Deg C or higher. If the temperature falls below this value, an Alarm condition is given. The temperature in your plots is below 35C, so the unit does not give a lock indication. This is an oversight on our end, sorry for the issue. We will fix this, and post a software update for this (rev 1.15 firmware). That software update will also include a neat new feature: a fail-safe 1PPS external input. This gives the user the option to feed an external 1PPS signal (from another GPSDO, or any other good-stability source), and the Fury will automatically switch-over to the second 1PPS input if the GPS goes into holdover for whatever reason. A manual selection via SCPI is also possible. We also fixed a minor issue which could cause small glitches when going into holdover mode, your plots seem to show these glitches from time to time. Hope this helps, and that everyone will like this new feature and the fixes, Said **Check out AOL's list of 2007's hottest products. (http://money.aol.com/special/hot-products-2007?NCID=aoltop000301) ___ 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.
