Re: [time-nuts] Solstice Puzzle
Brooke, Looks like we came up with almost exactly the same ideas. Maybe there is only one solution? You said accelerometer and tube sensor and I said gravity sensor. I think both are really an accelerometer with one bit resolution. You said and End Code, I said beep. Pretty much the same ideas but different words. OK there is another solution, expensive but it could work: Each block contains a precision inertial navigation system and it transmits it's exact position. Each block listens to the other five blocks when no movement is detected each block displays the correct digit. But now we have each block costing $100K but now they don't need to be in a neat row. Dumb idea: Build ether design by building each cube from six iPads. On Fri, Dec 16, 2011 at 10:39 PM, Brooke Clarke bro...@pacific.net wrote: Hi Nevelle: Have each face of each cube contain an LED digit display. They are battery powered. If one is rolled like a dice an accelerometer (or better set of ball in a tube sensors) knows where the top and bottom faces are and so they are not to be turned on. There's an assumption that after all six have been rolled someone will push them together into a sort of tight row. To sense that they are now grouped into a row you use one LED on the four possible active faces to measure the light. There are two possible answers, either three faces are open (an end cube) or two faces are open (a middle cube). If a cube is an end it blinks an LED on the dark face with the I'm an end pattern. If a cube is a middle cube it looks for a blinking LED. When a middle cube sees a blinking LED it makes note of the code. It remembers the code it's seen and adds one to it and blinks the opposite face unless the code is saying in 4 meaning that the cube seeing this is the tail cube. Now each cube has two IDs which is as it should be. After a head end cube has received an in 4 message then it knows it's also a tail end cube. When the time is displayed the 10 hours digit will be on the face of a starting cube that's CW from the adjacent cube when looking down on the string. If the cubes are numbered 1 to 6 left to right then the 10 hours digit will be on the 1 (left most) cube and on the front face. When looking at the back of the string, i.e. cubes 6 to 1. the 10 hours digit will be on the 6 cube on the left facing to the back. At this point the cubes assume they know where they are but they also know that they may be rearranged so . . cube 1 not only displays the current 10 hour digit it also sends the position message to cube 2 and makes the light measurements to confirm that it's still an end cube. If these fail then the cube un registers both it's IDs and we got back to the top. If the tests pass (cubes are still in order) then cube 1 sends the 1 hour time to cube 2. Cube 2 displays it and does the have I been moved test as above, if not it sends the 10 minutes message to cube 3, etc. etc. It may be possible to detect movement with other sensors, such ball in a tube making it easier to tell when that's happened. In any case when any cube knows that it has been moved it can cry out by blinking the LEDs on all faces in a we're being moved pattern. Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/Brooke4Congress.html Neville Michie wrote: At this time of the year many people look for frivolous puzzles to solve. My puzzle is to design a clock. This clock consists of 6 cubes, each has a digit display on one face. It does not matter how you arrange them, if they are in a line they will display the right time. (there may also be a nearby box containing a Rb or GPS time standard.) A second or two may be needed for them to reorganise if they are moved. It must be possible to design them, but an elegant design has eluded me. Merry Solstice, Neville Michie ___ 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. -- Chris Albertson Redondo Beach, California ___ 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] metric / English
Which works very well, but unlike all of the English thread combinations, you must keep the lathe's half-nuts engaged to the lead screw ALWAYS. That means when you reach the end of the thread, you must stop the lathe, and back it up to the beginning of the thread to make the next cut. With English threads the following rules exist for using the thread dial indicator: Even threads - engage half-nuts anytime Odd threads - engage half-nuts on any numbered line 1/2 threads - engage half-nuts on any odd numbered line 1/4 threads - engage half-nuts on the line you started with. Metric threads are miserable to cut on English lathes... and not much better on Metric lathes. Metric thread dial indicators are complicated and easy to get wrong devices. With English threads, you would have to work to get it wrong. -Chuck Harris Don Couch wrote: Hi, Brooke, To cut metric threads on an inch machine, I mesh the 127 tooth gear with the 100 tooth gear that came with my Sherline lathe threading attachment. Works great. Don Couch ___ 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] how good an oscillator do you need for a GPS simulator
Jim, you're right a DAC is not needed: I was thinking of generating the BPSK by a DAC but it is not necessary. I have seen some BPSK hardware modulators: easier than generating samples and feeding a DAC. On Fri, Dec 16, 2011 at 7:42 PM, Hal Murray hmur...@megapathdsl.net wrote: http://www.ti.com/product/lmk03806 If anybody is collecting a list of common frequencies, there is a table in the data sheet for that chip. -- 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. ___ 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] how good an oscillator do you need for a GPS simulator
On 12/17/2011 02:37 PM, Azelio Boriani wrote: Jim, you're right a DAC is not needed: I was thinking of generating the BPSK by a DAC but it is not necessary. I have seen some BPSK hardware modulators: easier than generating samples and feeding a DAC. For a single bird a digital output could be made to work, but for a constellation you would need individual bits which would then be mixed together using a resistor network since the birds will not have the same information due to different PN-cods, same rate since they will have different doppler rates etc. etc. Having a three or four bit DAC would be an alternative. Also, the square carrier waves would require more filtering than what a few-bit sine would require. So, saving a DAC is not necesserilly as smart as it looks. Looks like there is room for a GPS/GNSS receiver and simulator list. 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] Solstice Puzzle
At 01:04 AM 12/17/2011, Neville Michie wrote... This clock consists of 6 cubes, each has a digit display on one face. It does not matter how you arrange them, if they are in a line they will display the right time. (there may also be a nearby box containing a Rb or GPS time standard.) Wow. Looks like nobody takes time to read anymore. All the responses so far act as if the line each has a digit display on one face wasn't even there, and assume the boxes have to figure which side is up and which side to use as a display. They just need to figure out where they are in sequence. I'd use a microcontroller in each, to drive the display, and also to monitor an IR sensor and drive an IR LED. Sensor on the right of each box (as you face the arrangement of boxes), LED on the left. Box on the right (seconds - ones digit) receives no input from the sensor, knows it's the rightmost box. It's also the one that keeps time. Displays last digit, passes 5 remaining digits out the IR LED to the next box. Each box strips the last digit, displays it, sends the remaining ones on. Repeat. Last box receives one digit, displays it, done. Every time the seconds increment, the rightmost box passes the new time along. Obviously, if you're thinking of some type of electrical connection between them, it's the same, only different. The rest is just details, like how to modulate the signal, receive time from your standard, etc. If you want the digit changes closely sync'd, figure out the delay through each box, and each one delays the display by the delay time*number of digits it's passing on (and the first one starts the update sooner to accomodate). ___ 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] how good an oscillator do you need for a GPS simulator
Correct: I was thinking how to simulate an only bird. The RACAL GPS101 is a single channel simulator and maybe made that way. Then it is possible to place a number of 1 channel simulators at a distance... On Sat, Dec 17, 2011 at 3:18 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 12/17/2011 02:37 PM, Azelio Boriani wrote: Jim, you're right a DAC is not needed: I was thinking of generating the BPSK by a DAC but it is not necessary. I have seen some BPSK hardware modulators: easier than generating samples and feeding a DAC. For a single bird a digital output could be made to work, but for a constellation you would need individual bits which would then be mixed together using a resistor network since the birds will not have the same information due to different PN-cods, same rate since they will have different doppler rates etc. etc. Having a three or four bit DAC would be an alternative. Also, the square carrier waves would require more filtering than what a few-bit sine would require. So, saving a DAC is not necesserilly as smart as it looks. Looks like there is room for a GPS/GNSS receiver and simulator list. 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. ___ 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] how good an oscillator do you need for a GPS simulator
On 12/17/11 6:58 AM, Azelio Boriani wrote: Correct: I was thinking how to simulate an only bird. The RACAL GPS101 is a single channel simulator and maybe made that way. Then it is possible to place a number of 1 channel simulators at a distance... I was thinking more along the lines of how would one do a indoor test setup. Magnus's comment was a good one.. if you want to simulate multiple channels, you'd probably want some sort of resistive combiner. ___ 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] Solstice Puzzle
Hi Mike: Yes, I thought that cube implied any face could be the face with the display. The container that holds the single digit display could be a thin rectangle. Your reading is more practical and makes the problem much easier and far lower in cost. Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/Brooke4Congress.html Mike S wrote: At 01:04 AM 12/17/2011, Neville Michie wrote... This clock consists of 6 cubes, each has a digit display on one face. It does not matter how you arrange them, if they are in a line they will display the right time. (there may also be a nearby box containing a Rb or GPS time standard.) Wow. Looks like nobody takes time to read anymore. All the responses so far act as if the line each has a digit display on one face wasn't even there, and assume the boxes have to figure which side is up and which side to use as a display. They just need to figure out where they are in sequence. I'd use a microcontroller in each, to drive the display, and also to monitor an IR sensor and drive an IR LED. Sensor on the right of each box (as you face the arrangement of boxes), LED on the left. Box on the right (seconds - ones digit) receives no input from the sensor, knows it's the rightmost box. It's also the one that keeps time. Displays last digit, passes 5 remaining digits out the IR LED to the next box. Each box strips the last digit, displays it, sends the remaining ones on. Repeat. Last box receives one digit, displays it, done. Every time the seconds increment, the rightmost box passes the new time along. Obviously, if you're thinking of some type of electrical connection between them, it's the same, only different. The rest is just details, like how to modulate the signal, receive time from your standard, etc. If you want the digit changes closely sync'd, figure out the delay through each box, and each one delays the display by the delay time*number of digits it's passing on (and the first one starts the update sooner to accomodate). ___ 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] Solstice Puzzle
On 12/16/11 10:04 PM, Neville Michie wrote: At this time of the year many people look for frivolous puzzles to solve. My puzzle is to design a clock. This clock consists of 6 cubes, each has a digit display on one face. It does not matter how you arrange them, if they are in a line they will display the right time. (there may also be a nearby box containing a Rb or GPS time standard.) A second or two may be needed for them to reorganise if they are moved. It must be possible to design them, but an elegant design has eluded me. If you impose the minor requirement that you cast off the shackles of Babylon and sexigesimality.. and just read decimal seconds. Each block has a divide by 10 driving the display. it has a LED on the left side, and a photosensor on the right side. If the box detects pulses coming in from the sensor it uses those to drive the counter, if it detects nothing, it uses an internal 1 pps source. In any event sensor on the right, emitter on the left, is the basic strategy. The one widget detecting nothing uses an internal oscillator. You could have it send an entire timecode (in HH:MM:SS form), and receiver blocks just have to count where they are in the chain to know which digits to display. A simple way would be to do heat or tail deletion right hand unit sends out SMMHH. Each block displays the first byte, sends the remaining ones on. ___ 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] metric / English
On Sat, Dec 17, 2011 at 4:48 AM, Chuck Harris cfhar...@erols.com wrote: Which works very well, but unlike all of the English thread combinations, you must keep the lathe's half-nuts engaged to the lead screw ALWAYS. That means when you reach the end of the thread, you must stop the lathe, and back it up to the beginning of the thread to make the next cut. That method always works. But another might. There will always be some integer number of pitches that get you back exactly without error. But it might be say 5 inches back so there is almost always a way to run only forward you method might be the best. But are people still using these old machines for production work? Chris Albertson Redondo Beach, California ___ 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] how good an oscillator do you need for a GPS simulator
On 12/17/2011 05:10 PM, Jim Lux wrote: On 12/17/11 6:58 AM, Azelio Boriani wrote: Correct: I was thinking how to simulate an only bird. The RACAL GPS101 is a single channel simulator and maybe made that way. Then it is possible to place a number of 1 channel simulators at a distance... I was thinking more along the lines of how would one do a indoor test setup. Magnus's comment was a good one.. if you want to simulate multiple channels, you'd probably want some sort of resistive combiner. Yes, but if you have them all in the same sample clock, adding them together you can do a smaller resistor chain DAC. Three or four bits can be done without much performance setback. Jim, would you be satisfied with L1 C/A only or do you need L1/L2 P-code or even pseudo-P(Y)? 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] metric / English
I suspect turret lathes are still used for shortish runs of some of the simpler parts, like bushings and similar parts. Not every shop looks like a NASA facility. -John == On Sat, Dec 17, 2011 at 4:48 AM, Chuck Harris cfhar...@erols.com wrote: Which works very well, but unlike all of the English thread combinations, you must keep the lathe's half-nuts engaged to the lead screw ALWAYS. That means when you reach the end of the thread, you must stop the lathe, and back it up to the beginning of the thread to make the next cut. That method always works. But another might. There will always be some integer number of pitches that get you back exactly without error. But it might be say 5 inches back so there is almost always a way to run only forward you method might be the best. But are people still using these old machines for production work? Chris Albertson Redondo Beach, California ___ 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] metric / English
Chris, You must be kidding! How old are you? Lee K9WRU - Original Message - From: Chris Albertson albertson.ch...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, December 17, 2011 11:00 AM Subject: Re: [time-nuts] metric / English But are people still using these old machines for production work? Chris Albertson Redondo Beach, California ___ 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] Solstice Puzzle
Just read decimal seconds... Now that's interesting. It would be like visiting another country that uses a different temperature scale. After a while you'd be able to relate the numbers to your own sense of temperature. Similarly, you'd be able to relate the count of seconds to your sense of time of day. You'd be the only one on the block (and maybe in your house) that could look at the seconds count and know the time of day. There would have to be a reset message from the lowest order block when the seconds roll over at midnight. Ah, and a pushbutton to tell the low order block to add a leap second at midnight. Neat puzzle. Has anyone come up with an arrangement that would make it useful to separate the blocks? If they are separate, each has to have its own power supply. Or you could use RF to supply enough power to a nanoprocessor and a liquid crystal digit. Modulate the RF with 1 PPS and you can clock the simultaneous change of the digits. Although, there is a certain charm to watching the change propagate at some low serial message baud rate. Head or tail deletion is a pretty good idea, too. Bill Hawkins -Original Message- From: Jim Lux Sent: Saturday, December 17, 2011 10:54 AM To: time-nuts@febo.com Subject: Re: [time-nuts] Solstice Puzzle On 12/16/11 10:04 PM, Neville Michie wrote: At this time of the year many people look for frivolous puzzles to solve. If you impose the minor requirement that you cast off the shackles of Babylon and sexigesimality.. and just read decimal seconds. Each block has a divide by 10 driving the display. it has a LED on the left side, and a photosensor on the right side. If the box detects pulses coming in from the sensor it uses those to drive the counter, if it detects nothing, it uses an internal 1 pps source. In any event sensor on the right, emitter on the left, is the basic strategy. The one widget detecting nothing uses an internal oscillator. You could have it send an entire timecode (in HH:MM:SS form), and receiver blocks just have to count where they are in the chain to know which digits to display. A simple way would be to do head or tail deletion [where the] right hand unit sends out SMMHH. Each block displays the first byte, sends the remaining ones on. ___ 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] Solstice Puzzle
On 12/17/11 10:41 AM, Bill Hawkins wrote: Just read decimal seconds... Now that's interesting. It would be like visiting another country that uses a different temperature scale. After a while you'd be able to relate the numbers to your own sense of temperature. Similarly, you'd be able to relate the count of seconds to your sense of time of day. You'd be the only one on the block (and maybe in your house) that could look at the seconds count and know the time of day. It's like those clocks that read in binary... There would have to be a reset message from the lowest order block when the seconds roll over at midnight. Ah, and a pushbutton to tell the low order block to add a leap second at midnight. Neat puzzle. Has anyone come up with an arrangement that would make it useful to separate the blocks? If they are separate, each has to have its own power supply. Or you could use RF to supply enough power to a nanoprocessor and a liquid crystal digit. Modulate the RF with 1 PPS and you can clock the simultaneous change of the digits. Although, there is a certain charm to watching the change propagate at some low serial message baud rate. If you used an LCD display, and a tritium illuminator, you could run it on a battery for a very, very long time. Optical sensor or inductive coupling. Inductive coupling seems interesting.. When the block is directly adjacent, it would couple quite well, especially with an iron core (and one side could have a ring magnet, so the blocks would stick together) ___ 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] how good an oscillator do you need for a GPS simulator
On 12/17/11 9:01 AM, Magnus Danielson wrote: On 12/17/2011 05:10 PM, Jim Lux wrote: On 12/17/11 6:58 AM, Azelio Boriani wrote: Correct: I was thinking how to simulate an only bird. The RACAL GPS101 is a single channel simulator and maybe made that way. Then it is possible to place a number of 1 channel simulators at a distance... I was thinking more along the lines of how would one do a indoor test setup. Magnus's comment was a good one.. if you want to simulate multiple channels, you'd probably want some sort of resistive combiner. Yes, but if you have them all in the same sample clock, adding them together you can do a smaller resistor chain DAC. Three or four bits can be done without much performance setback. Jim, would you be satisfied with L1 C/A only or do you need L1/L2 P-code or even pseudo-P(Y)? L1 C/A But the real question isn't how to generate the signals (that's straight forward).. it's how good does the oscillator have to be to effectively test the receiver, in the sense of measuring it's timing performance. ___ 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] how good an oscillator do you need for a GPS simulator
On 12/17/2011 11:10 AM, Jim Lux wrote: On 12/17/11 6:58 AM, Azelio Boriani wrote: Correct: I was thinking how to simulate an only bird. The RACAL GPS101 is a single channel simulator and maybe made that way. Then it is possible to place a number of 1 channel simulators at a distance... I was thinking more along the lines of how would one do a indoor test setup. Magnus's comment was a good one.. if you want to simulate multiple channels, you'd probably want some sort of resistive combiner. ___ 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] how good an oscillator do you need for a GPS simulator
On 12/17/2011 09:57 PM, Jim Lux wrote: L1 C/A But the real question isn't how to generate the signals (that's straight forward).. it's how good does the oscillator have to be to effectively test the receiver, in the sense of measuring it's timing performance. A decent OCXO should be able to pull it off. Your receiver should long-term follow your OCXO. Take one of these 40 dollar rubidiums if you are worried. Any drift of a good OCXO will be way within the bandwidth of the GPS channels. This drift would show up as added drift of the GPS oscillator, which is then being tracked and compensated. 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] My Racal-Dana 1992
On 12/16/2011 2:31 PM, gandal...@aol.com wrote: Hi David It's part of the resolution settings, whereby you alter the number of displayed digits using the up down arrows, holding the up arrow for over two seconds will shift the display left and increase the gate time so you effectively get a 10 digit display with the left most digit concealed. Page 4-21 of the combined ops and service from 1985. or Page 3-22 para 3.5.2 of the 1995 manual Publication No.980647 dr ___ 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] how good an oscillator do you need for a GPS simulator
On 12/17/11 2:56 PM, Magnus Danielson wrote: On 12/17/2011 09:57 PM, Jim Lux wrote: L1 C/A But the real question isn't how to generate the signals (that's straight forward).. it's how good does the oscillator have to be to effectively test the receiver, in the sense of measuring it's timing performance. A decent OCXO should be able to pull it off. Your receiver should long-term follow your OCXO. Take one of these 40 dollar rubidiums if you are worried. Any drift of a good OCXO will be way within the bandwidth of the GPS channels. This drift would show up as added drift of the GPS oscillator, which is then being tracked and compensated. that is precisely what I was thinking.. I was just wondering if anyone had run across a reason why it wouldn't be the case. (short of actually doing the no doubt tedious analysis) ___ 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] metric / English
On 12/17/11 9:14 AM, J. Forster wrote: I suspect turret lathes are still used for shortish runs of some of the simpler parts, like bushings and similar parts. Not every shop looks like a NASA facility. Oddly, NASA facilities aren't necessarily the most modern or sophisticated. It takes an act of Congress to build a new building or make non-repair improvements. My office and lab at JPL is in an 3600 square meter 2 story semi-temporary building (161) built in 1954 (before NASA even existed). The frequency and timing lab is in building 298, an 1800 square meter building built in and was built in the 70s. Our big highbay spacecraft assembly building was built in 1961. (To be fair, there is a general plan to demolish a bunch of small buildings and replace them with larger buildings sometime in 2020-2030 time frame, if Congress approves). Much of the infrastructure at Johnson Spaceflight Center (and KSC, as well) was built for Apollo and followons in the 60s and early 70s We don't depreciate equipment, it's bought with capital expenditure or project funds, and then we pay for maintenance and calibration. A big project might buy a whole bunch of some piece of gear (e.g. HP8663A) which we will then use for the next 20-30 years (I just counted about 30 HP8663As in inventory.). I think we bought a whole pile of those 8663s in connection with upgrades for Voyager or maybe Cassini. As a result, we tend to keep gear forever.. Students coming on interviews are always amazed (and not necessarily in a good way). At least we've moved beyond slotted lines for the most part. ___ 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] how good an oscillator do you need for a GPS simulator
Hi Jim, On 12/18/2011 01:25 AM, Jim Lux wrote: On 12/17/11 2:56 PM, Magnus Danielson wrote: On 12/17/2011 09:57 PM, Jim Lux wrote: L1 C/A But the real question isn't how to generate the signals (that's straight forward).. it's how good does the oscillator have to be to effectively test the receiver, in the sense of measuring it's timing performance. A decent OCXO should be able to pull it off. Your receiver should long-term follow your OCXO. Take one of these 40 dollar rubidiums if you are worried. Any drift of a good OCXO will be way within the bandwidth of the GPS channels. This drift would show up as added drift of the GPS oscillator, which is then being tracked and compensated. that is precisely what I was thinking.. I was just wondering if anyone had run across a reason why it wouldn't be the case. (short of actually doing the no doubt tedious analysis) I can offer you several evidence of this: 1) None of the GPS simulators come with very special oscillator, but you may hook up your cesium if you need to for some reason. 2) A typical channel bandwidth typically measures in the Hz range. Tracking drift would not be too hard. 3) While we consider for all practical matter GPS time is stable and the GPS internal reference has incorrect frequency complete with drift, the GPS receiver uses the time-solution of the position to continuously correct the time, frequency and drift of the TCXO (or OCXO). Now, if we move a little of frequency error and drift over to the GPS time of the GPS simulator the receiver won't be able to say as long as the GPS simulator reference isn't drifting like a maniac so that the correction routines can't keep up with it. So, there is my rough analysis for you. 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] how good an oscillator do you need for a GPS simulator
Hi Magnus: Exactly. The main problem with the Transit system was that the receiver needed a Cs clock for the system to work at all. GPS removed that requirement. It's my understanding that a GPS receiver that uses a Cs clock has much more capability. Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/Brooke4Congress.html Magnus Danielson wrote: Hi Jim, On 12/18/2011 01:25 AM, Jim Lux wrote: On 12/17/11 2:56 PM, Magnus Danielson wrote: On 12/17/2011 09:57 PM, Jim Lux wrote: L1 C/A But the real question isn't how to generate the signals (that's straight forward).. it's how good does the oscillator have to be to effectively test the receiver, in the sense of measuring it's timing performance. A decent OCXO should be able to pull it off. Your receiver should long-term follow your OCXO. Take one of these 40 dollar rubidiums if you are worried. Any drift of a good OCXO will be way within the bandwidth of the GPS channels. This drift would show up as added drift of the GPS oscillator, which is then being tracked and compensated. that is precisely what I was thinking.. I was just wondering if anyone had run across a reason why it wouldn't be the case. (short of actually doing the no doubt tedious analysis) I can offer you several evidence of this: 1) None of the GPS simulators come with very special oscillator, but you may hook up your cesium if you need to for some reason. 2) A typical channel bandwidth typically measures in the Hz range. Tracking drift would not be too hard. 3) While we consider for all practical matter GPS time is stable and the GPS internal reference has incorrect frequency complete with drift, the GPS receiver uses the time-solution of the position to continuously correct the time, frequency and drift of the TCXO (or OCXO). Now, if we move a little of frequency error and drift over to the GPS time of the GPS simulator the receiver won't be able to say as long as the GPS simulator reference isn't drifting like a maniac so that the correction routines can't keep up with it. So, there is my rough analysis for you. 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. ___ 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] metric / English
The manual machines are still in use for limited production runs, such as are used in prototype manufacture. Screw machines, and second op lathes see extensive use in manufacturing because they are quicker than CNC machines... that and very cheap to use. I use manual machines because it is quicker to whittle out a prototype chassis or do-dad on manual machines than it is to do a formal CAD drawing, and then work out the tool paths to do it on a CNC machine... and then find you have made it a mistake... wash rinse repeat... CNC machines are like printers. In theory they save time and materials, but in practice, they can burn time and waste materials like no human running a manual machine ever would. [As a tree farmer, who sells trees into pulp production, computers and printers have been a godsend. More trees go into paper production today then ever did before the advent of the paperless office.] -Chuck Harris Chris Albertson wrote: On Sat, Dec 17, 2011 at 4:48 AM, Chuck Harriscfhar...@erols.com wrote: Which works very well, but unlike all of the English thread combinations, you must keep the lathe's half-nuts engaged to the lead screw ALWAYS. That means when you reach the end of the thread, you must stop the lathe, and back it up to the beginning of the thread to make the next cut. That method always works. But another might. There will always be some integer number of pitches that get you back exactly without error. But it might be say 5 inches back so there is almost always a way to run only forward you method might be the best. But are people still using these old machines for production work? Chris Albertson Redondo Beach, California ___ 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] how good an oscillator do you need for a GPS simulator
Hi Brooke, On 12/18/2011 03:30 AM, Brooke Clarke wrote: Hi Magnus: Exactly. The main problem with the Transit system was that the receiver needed a Cs clock for the system to work at all. GPS removed that requirement. Indeed. Most of that was due to the long observations times as I recall it. The 4 satellite requirement of a normal navigation GPS receiver is there to allow for a complete (X, Y, Z, T) solution for a portable receiver which can't afford the weight and continuous power consumption of atomic references... at it's time of design. It's my understanding that a GPS receiver that uses a Cs clock has much more capability. The main capability would be to either provide correction/ephemeris data (widely used) or to provide good navigation even under severe methods, as well as direct-Y locking. 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] how good an oscillator do you need for a GPS simulator
jim...@earthlink.net said: But the real question isn't how to generate the signals (that's straight forward).. it's how good does the oscillator have to be to effectively test the receiver, in the sense of measuring it's timing performance. My 2 cents, which could be way off... One of the things the receiver has to solve for is the actual frequency of the local oscillator. In the process of doing that, the receiver can't tell the difference between an offset in the local crystal and a coordinated offset that's the same in all the transmitter frequencies. So the actual accuracy on a fake transmitter only has to be good enough to fall within the band the receiver thinks is OK. That's a software vs manufacturing/testing issue. If the software will take X ppm but the manufacturing guys are buying crystals good for X/2, the transmitter can be off by X/2. If the software will take X but the manufacturing guys are buying junk crystals, it may not even work with a transmitter that is right on. -- One thing I don't understand about this area. Is the receiver clock offset an independent unknown? The usual reasoning goes that a receiver needs 4 satellites to solve for 4 unknowns: X, Y, Z, and T. If you are willing to assume you are on the surface of the earth, you can get away with only 3 satellites. That's a simple application of N independent unknowns needs N equations. (That's assuming the receiver isn't moving.) Is the receiver frequency another unknown? Do I need another satellite? Or does it drop out somehow? It might drop out. For example, take the 1D case with two satellites. (I know where they are and where they are going.) After I correct for the satellite Doppler, the velocity of the satellites should be zero. I guess that's another equation, so it drops out. -- 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] metric / English
You might want to consider the possibility that there is a whole world of manufacturing that does not deal with millions of a single item. And prototypes are not part of the process. When a product life might extend over ten years and you can expect to get orders for two or three per year (you know there are products that cost tens of millions of dollars) then high volume is of much less interest. Of course, a single part might require a five axis machine and then things are again different. I vividly recall one sales visit when I was only 35 or 40, and still hadn't learned anything, and found that a very familiar product was still being manufactured in a room with a dirt floor. Lee - Original Message - From: Chuck Harris cfhar...@erols.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, December 17, 2011 9:31 PM Subject: Re: [time-nuts] metric / English The manual machines are still in use for limited production runs, such as are used in prototype manufacture. Screw machines, and second op lathes see extensive use in manufacturing because they are quicker than CNC machines... that and very cheap to use. I use manual machines because it is quicker to whittle out a prototype chassis or do-dad on manual machines than it is to do a formal CAD drawing, and then work out the tool paths to do it on a CNC machine... and then find you have made it a mistake... wash rinse repeat... CNC machines are like printers. In theory they save time and materials, but in practice, they can burn time and waste materials like no human running a manual machine ever would. [As a tree farmer, who sells trees into pulp production, computers and printers have been a godsend. More trees go into paper production today then ever did before the advent of the paperless office.] -Chuck Harris Chris Albertson wrote: On Sat, Dec 17, 2011 at 4:48 AM, Chuck Harriscfhar...@erols.com wrote: Which works very well, but unlike all of the English thread combinations, you must keep the lathe's half-nuts engaged to the lead screw ALWAYS. That means when you reach the end of the thread, you must stop the lathe, and back it up to the beginning of the thread to make the next cut. That method always works. But another might. There will always be some integer number of pitches that get you back exactly without error. But it might be say 5 inches back so there is almost always a way to run only forward you method might be the best. But are people still using these old machines for production work? Chris Albertson Redondo Beach, California ___ 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] how good an oscillator do you need for a GPS simulator
Maybe they used a Cs standard for the original experimental units, but the first commercial Transit unit I saw (Magnavox MX700?) just had a big OCXO in it - it was also all controlled by a HP2100 computer and output the fix data onto a teletype. The MX1102/1107 (which were pretty much standard equipment on big ships for years) used a rather smaller OCXO, and the MX4102 used a high-grade TCXO. Regards, Pete On Sun, Dec 18, 2011 at 10:30 AM, Brooke Clarke bro...@pacific.net wrote: Hi Magnus: Exactly. The main problem with the Transit system was that the receiver needed a Cs clock for the system to work at all. GPS removed that requirement. It's my understanding that a GPS receiver that uses a Cs clock has much more capability. Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/Brooke4Congress.html Magnus Danielson wrote: Hi Jim, On 12/18/2011 01:25 AM, Jim Lux wrote: On 12/17/11 2:56 PM, Magnus Danielson wrote: On 12/17/2011 09:57 PM, Jim Lux wrote: L1 C/A But the real question isn't how to generate the signals (that's straight forward).. it's how good does the oscillator have to be to effectively test the receiver, in the sense of measuring it's timing performance. A decent OCXO should be able to pull it off. Your receiver should long-term follow your OCXO. Take one of these 40 dollar rubidiums if you are worried. Any drift of a good OCXO will be way within the bandwidth of the GPS channels. This drift would show up as added drift of the GPS oscillator, which is then being tracked and compensated. that is precisely what I was thinking.. I was just wondering if anyone had run across a reason why it wouldn't be the case. (short of actually doing the no doubt tedious analysis) I can offer you several evidence of this: 1) None of the GPS simulators come with very special oscillator, but you may hook up your cesium if you need to for some reason. 2) A typical channel bandwidth typically measures in the Hz range. Tracking drift would not be too hard. 3) While we consider for all practical matter GPS time is stable and the GPS internal reference has incorrect frequency complete with drift, the GPS receiver uses the time-solution of the position to continuously correct the time, frequency and drift of the TCXO (or OCXO). Now, if we move a little of frequency error and drift over to the GPS time of the GPS simulator the receiver won't be able to say as long as the GPS simulator reference isn't drifting like a maniac so that the correction routines can't keep up with it. So, there is my rough analysis for you. 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. ___ 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] My Racal-Dana 1992
It turns out that I unfairly maligned the 1992 (and the 9462 oscillator, option 04E) when I accused it of poor oscillator settability. I was inspired by the recent discussions to have another crack at mine, and they can, in fact, be set very accurately. One of mine has been reading 000.00 E-3 for about 24 hours now, hooked to a Thunderbolt and using the 10-second gate. The other has been toggling between 999.99 E-3 and 000.00 E-3. (This is how mine are used --- perpetually reading the shop standards to give an independent reality check on their condition.) Walking the oscillators to 0 is tedious and time-consuming, but not difficult. I think I must not have been sufficiently patient in the past. The fine adjustment has detents -- if you adjust it slowly, you can count the clicks. On both of mine, each click adjusts the oscillator frequency about 3 mHz (CW lowers the oscillator frequency/raises the displayed frequency). Interestingly, when you are close to zero and adjusting the oscillator only a few clicks at a time, it takes off in the opposite direction and peaks at a MUCH greater offset than the eventual increment, then returns and overshoots in the direction of the adjustment (again, quite a bit further than the eventual increment), and finally settles to its new value, with another cycle or two of smaller +/- overshoots around the final value. It takes at least 1/2 hour to settle within a count or two of the eventual final value, and several hours before you can be confident that it has settled to its new value. Best regards, Charles ___ 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.
