Re: [time-nuts] USB and Mouse conflict persists
quote: [On the tab "Port Settings" click "Advanced" and in that window uncheck the box next to "Serial Enumerator"] This is a feature of the FTDI driver. Not something generic. What worked for me was to disable (postpone actually) the Windows PnP device enumerator for a serial device. It works for hardware serial ports as well as the USBtoRS232 converters. This can be done with a registry patch which adds the "Skipenumerations" registry entry. Setting this to a big value skips the possible detection of any device (such as a serial mouse) on a COM port. Search the net for details. E.g. here : http://support.microsoft.com/default.aspx?scid=kb;en-us;283063 Lots of the USBtoRS232 converters do not contain EEPROM to store a unique serial number. Without it Windows cannot be sure you unplugged the same device as you re-plugged in another USB port. Its behaviour is to assign it a new COM port number. Re-plugging the converter in the original USB port should bring back the same COM port number. You will need to patch the registry again if a new COM port number is assigned. If you want to avoid this, look for USBtoRS232 converters that have the option to program a USB serial number (like the FTDI FT232R based ones) Joop - pe1cqp ___ 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] Hyperterminal with variable baud rate
A friend of mine had a need for a round 500Kbit baud rate. What he did was use some FDTI USB/RS232 chip. He could patch the timing values for an existing baud rate (300 baud or something else normally not used). I believe in the Windows registry. This way the (terminal) software can select the patched baud rate and it will in effect behave as the custom baud rate. Cheers, Joop ___ 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] Small quantity custom crystals
I have had good results with the part if this circuit around T1. http://www.qsl.net/on7yd/minitx2.htm Varying L1 selects the right overtone for basic operation. The collector circuit here has a coupled resonator tuned for the 144, but it will probably work equally well for 216. A cheap (fundamental) 24Mhz computer crystal operating at 72 MHz will get you there. Just alter the filter for 3 x 72 instead of 2 x 72. Note as someone else posted that the frequency at 72 may be tens of KHz higher than that. Each brand or even each individual crystal will vary here. You could also stick to the collector circuit from your tracker transmitter circuit if you want to keep things as small as possible. It worked down to 1.1V in bench tests with a MPSH10 transistor. Tuning the bias with R2 helps to optimize the power for the desired output frequency. More bias then necessary will only consume more battery power and not contribute to the output. Actually power output may be less. For more insight look here: http://www.wenzel.com/pdffiles1/pdfs/choose.pdf Cheers, Joop - pe1cqp ___ 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] Re frequency counters
>It is vain to do with more that which can be done with less. In that case have a look here: http://www.uploadarchief.net/files/download/freqlogger.zip A PIC12F629 based RS-232 frequency logger. No display and can be clocked by an external 10MHz clock if needed. My version worked to 60 MHz. Joop ___ 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] Function of cap to GND in isolation transformer circuit
Hi, I noticed in several circuits that the 10MHz isolation transformer in input and output circuits have a 6.8nF or 10nF capacitor to GND. How necessary is this for suppression of unwanted signals? Is the transformer itself not sufficient? I would expect common mode issues to be a bit worse with the cap in place. The circuit I refer to can be seen here: http://www.uploadarchief.net/files/download/cap2gnd.png The first one is an output as described in the Efratom FRK manual, the second one the input in the TADD-2 manual. Cheers, Joop ___ 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] More from the obsolete gps file: oncore nmea
Hi all!! Trying to get a gt+ setup(also tried one of my m12+t's) as a nmea receiver. @@Ci does not work. Did form the string correctly. Tried it with tac32, used Labview to send the hex string. Receiver ignores it and continues to send moto bin at 9600.. Any ideas?? Want to use this for a balloon flight with aprs. Good news is that we want to launch Friday, so it's not too pressing. Norm n3ykf + Norm, have you looked at the WinOncore software? http://www.synergy-gps.com/index.php?option=com_content&task=view&id=163&Itemid=115 >From memory (could be wrong): * you can open a window that shows all data that gets sent from the menu commands. * One can switch between NMEA / BIN (change baud rate in between) * It allows sending commands where the checksum is calculated for you. Cheers, Joop ___ 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] injection locking
Kit VK2LL wrote: >Theory suggests that lock sensitivity could be improved in this instance >if the 10MHz duty cycle was changed from 1:1 to 6 or 7:1, the idea being >that the narrower pulse should be <0.5 period of the frequency of the >oscillator to be locked. Ah, that triggers some thought. I know from (ARDF) experiments that sub-critical oscillators can be used as very narrow filters. Just as the Q-multiplier circuits. Even at the point where there is enough gain and oscillation starts, I found the oscillator tracks and locks onto the incoming frequency. Thinking this way of injection locking, it makes sense to increase harmonic content of the injected signal. In essence it will then not lock onto the fundamental frequency, but on some harmonic part of it. In my SPICE investigation I injected a clean sine signal. Perhaps I should try with some clipped or digital signal. That might also explain why James G1PVZ was so successful. The bottom 2N918 might cause a lot of harmonics if driven into the collector cut-off. Joop PE1CQP ___ 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] injection locking
Yes, I wrote I searched for that too. This indeed is one circuit I found. At first glance the biasing does not give me the impression it might be a very good oscillator by itself. But then again, that might be a requirement in order to allow it to lock to another signal. James G1PVZ wanted to see how far he could pull it (>10% it seems). And tested how it tracked FM modulation. For purposes of a very pure harmonic frequency one might have to start with a better oscillator. I played a bit with SPICE to see if I could make a high Q oscillator lock, but with limited success. Perhaps it needs much more time to start locking. I guess building something and measure it might be faster. Joop >Joop, > >you may also search for "synchronous oscillator". You will find for example: > >http://www.amalgamate2000.com/radio-hobbies/radio/synchronous_oscillator.htm > >Best regards >Ulrich > >> -Ursprungliche Nachricht- >> Von: time-nuts-bounces at febo.com >> [mailto:time-nuts-bounces at febo.com] Im Auftrag von Joop >> Gesendet: Mittwoch, 10. Februar 2010 13:50 >> An: time-nuts at febo.com >> Betreff: [time-nuts] injection locking >> >> >> >You can even build an injection locked divide by 5 stage. >> Choosing the >> >right oscillator topology and injection method allows high level >> >injection to be used with an LC oscillator. >> > >> >Bruce >> > >> >> Are there references to some practical circuits? That would be great. >> >> A google search on "injection locking" and "synchronous >> oscillator" results in a lot of conceptual descriptions but >> nothing that one can build, try out and study. Maybe some of >> the scientific articles or books contain circuits, but I am >> not a IEEE member. >> >> Cheers, >> Joop > ___ 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] injection locking
>You can even build an injection locked divide by 5 stage. >Choosing the right oscillator topology and injection method allows high >level injection to be used with an LC oscillator. > >Bruce > Are there references to some practical circuits? That would be great. A google search on "injection locking" and "synchronous oscillator" results in a lot of conceptual descriptions but nothing that one can build, try out and study. Maybe some of the scientific articles or books contain circuits, but I am not a IEEE member. Cheers, Joop ___ 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] Frequency comparison
??? I double checked the email I sent and it seems part of it did not end up in the time-nuts archive. Perhaps it did pass on in the emails to subscribers. Personally I find the traffic on this list a bit much and disabled the email/digest. Because of my moving around I use some webmail thingy. So I do not get the email itself. It would be nice to have a yahoo-type webform to post on this list. But hey, I am not complaining with all these knowledgeable people around. This is what I sent before of which only the first paragraph seemed to get through. hope it works now. If not I will quit trying to reduce the "noise". > > I can understand. But I will not need that high accuracy very often. > So I just wanted to examine what can be expected after power-on. Just > saving a bit of environment where possible. > > From a Datum LPRO specifications document I read: > > Warm-up: (at -20°C) (at 25°C) > Time to Lock: < 8.7 min < 5.4 min > Time to <1E-9: <10.2 min <7.3 min > Time to <4E-10: <12.7 min <10.6 min > > Frequency Retrace: <±2.5E-11 > (after 24 hrs power on @ 25°C & up to 48 hrs power off) > > I guess my readings are all within the above specs. The retrace value is > probably the limiting factor. 2.5E-11 translates in my setup to 90ns/hour. > Which looks being reached already in about 2 hours after power-on. So if > the Efratom is essentially the same as the Datum, then all looks fine. > > Joop ___ 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] Frequency comparison
>It is best to leave your stable quartz and Rubidium oscillators >running continuously, preferably on a UPS in case of power failure, >for best results. > >Best regards, > >Charles > I can understand. But I will not need that high accuracy very often. So I just wanted to examine what can be expected after power-on. Just saving a bit of environment where possible. From a Datum LPRO specifications document I read: Warm-up: (at -20°C) (at 25°C) Time to Lock: < 8.7 min < 5.4 min Time to <1E-9: <10.2 min <7.3 min Time to <4E-10: <12.7 min <10.6 min Frequency Retrace: <±2.5E-11 (after 24 hrs power on @ 25°C & up to 48 hrs power off) I guess my readings are all within the above specs. The retrace value is probably the limiting factor. 2.5E-11 translates in my setup to 90ns/hour. Which looks being reached already in about 2 hours after power-on. So if the Efratom is essentially the same as the Datum, then all looks fine. Joop ___ 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] Frequency comparison
>Since the GPSDO takes > 1 1/2 hours to give an adequately accurate reading >to calibrate 1x10^-11, there's no rushing the process. That's not warm up >time, or lock time on the GPSDO. It's the time you need to watch if for in >order to know it's output frequency to a sufficient level of precision. > >Bob > Yes, I noticed these things take time ;-) This is what I logged after everthing was powered on for over 24 hours and adjusted. It is a 2 hour period during which no adjustments were made. http://www.uploadarchief.net/files/download/lpro_24h.png And this is with the LPRO is cold started. About 5 minutes after lock. The GPS was already running for about an hour I have to guess. The LPRO was not adjusted anymore. http://www.uploadarchief.net/files/download/lpro_start7h.png It is less flat at the last two hours than what I was hoping for. Joop ___ 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] Frequency comparison
On Mon, 08 Feb 2010 22:26:44 +0100, Joop wrote: > The last point is guessing since my GPS signal is super stable. I thought Here I meant of course that my GPS 1Hz signal is NOT super stable. Well, I thought it was until I bought the LPRO ;-) Cheers, Joop ___ 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] Frequency comparison
At 07-02-10, John Ackermann wrote: >Hi Raj -- > >You've already gotten some good answers. If all you want to do is >measure the frequency offset rather than characterize the stability, a >simple approach is to first get as close as you can by adjust for >minimum march of the 10 MHz signals across the oscilloscope, then use >either the Racal counter or the digital o'scope to measure the delay >between the two signals and how it changes over time, preferably >measuring at 1 PPS rather than 10 MHz. > >In other words, measure the time difference between the leading edge of >the PPS signals, averaging for a while (depending on how close the two >already are) to improve resolution and reduce the noise. Write down the >delay figure, note the wall clock time, wait a while, then come back and >measure the delay again. The change in delay over the elapsed time will >tell you the frequency offset, e.g., if you see 1 microsecond per day, >that's 1.16x10e-11. > >Adjust and repeat. As others have mentioned, being a time-nut requires >patience. :-) > >It's best to do this at a lower frequency than 10 MHz, and ideally at 1 >PPS, as there's only 100 nanoseconds between cycle slips at 10 MHz, and >that limits how long you'll be able to measure before you've drifted a >complete cycle. > >73, >John > Ok, the past few days I have been working on exactly the same thing. That is, adjust an LPRO to my homemade GPSDO. Good to know I followed a proven procedure. Initially I wanted to build two PPSDIV/TADD circuits but did not have the right PICs. Instead I used two PIC12F devices and put them on the same veroboard. The software for only a single 1Hz output was not too complex. There was also a Racal 1992 I could use to measure and log the phase shift. If that would not have been the case I probably would have tried a XOR port to both (synched) outputs and use an R + C to measure the DC voltage. That would make a nice little gadget for people not having a high-res counter. Also the TADD 74AC04 drivers would not be needed this way. Anyway, I finally dared to adjust the LPRO. Can somebody tell if the following seems normal? * The LPRO measured 1.77 E-10 high (before any adjustment) * Lamp voltage is about 5.7V * The GPSDO 1Hz pulse seems to move (noise like) + or - 15ns around its linear regression line * The LPRO takes more than 8 hours (perhaps even 24) to reach the 1E-11 level? The last point is guessing since my GPS signal is super stable. I thought I managed to adjust it to that level after the LPRO had been powered on for more than 24 hours. But powering it on two days later shows a higher drift after 5 hours than where left before. Also I would like to know if I have to repeat this procedure once it is built into its final enclosure. Right now it is open on the bench and clamped to a heatsink. Temperature might be different inside a box. Cheers, Joop ___ 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] Racal 1992 input amplifier offset problem - fixed
I am happy to report that the offset problem I mentioned on Dec 28 is fixed. There were no responses to my request, but it might be helpful to others should their 1992 get faulty in the same way. Basically the A-input had a low leakage input protection diode (JPAD50) that was, well, not so low leakage anymore. Should it have broken down completely the problem would probably have been more easy to spot. Anyway, it is replaced with a BAS116. Offset and sensitivity calibration went fine and operation is back to normal. Joop ___ 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] Racal 1992 input amplifier offset problem
Hi, Sorry if this question is a bit out of place. It is not about timing, but more an electronics thing. But searching for Racal 1992 seems to get a lot of hits here on this list. I have just received a used Racal 1992 counter and are checking it for proper operation. All seem fine except the channel A only triggers properly on small signals with DC input or when in "auto-trigger" mode selecting AC. Checking the trigger level in this mode shows -1.08 (Volts I guess) I went through the protocol for channel-A adjustment with R192/R149 and channel-B adjustment with R193/R150. Channel B seems to work fine and needed only minor adjustment. The offset can be adjusted to 0V and the specified sensitivity levels of 13mV (count) and 7mV (gate off) are fine. Changing from AC to DC has no effect, both work fine here. However channel A seems to have a problem. It is not possible to adjust it to 0V in AC mode. Only with DC it can be adjusted to 0. Sensitivity is also a bit out of range. I get 17mV (count is steady) and 7mV (gate off). The trigger output levels at the back seem ok for both channels (about +5.1 to -5.1) So I guess the DAC is still OK. Looking at the schematics I suspect IC34 (CA3140E) might be having a problem, but I did not dare to open the module yet. Is it placed in a socket? Has anybody experienced a similar problem and fixed it? Are some capacitors known to go bad? Any help would be appreciated. Cheers, Joop ___ 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.
