On 4/25/08, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > Send time-nuts mailing list submissions to > [email protected] > > To subscribe or unsubscribe via the World Wide Web, visit > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > or, via email, send a message with subject or body 'help' to > [EMAIL PROTECTED] > > You can reach the person managing the list at > [EMAIL PROTECTED] > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of time-nuts digest..." > > > Today's Topics: > > 1. Re: GSyncQ GPS Evalution Kits && NTPns (Bruce Griffiths) > 2. Re: Disciplining Rubidium (Bruce Griffiths) > 3. Re: GSyncQ GPS Evalution Kits && NTPns ( Pekka Niemel? ) > 4. Re: GSyncQ GPS Evalution Kits && NTPns (Bruce Griffiths) > 5. Re: GSyncQ GPS Evalution Kits && NTPns (Bruce Griffiths) > 6. Re: GSyncQ GPS Evalution Kits && NTPns (Didier Juges) > 7. Re: GSyncQ GPS Evalution Kits && NTPns (Bruce Griffiths) > 8. RS485/422/232 Chip (Don Bradbury) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Fri, 25 Apr 2008 20:12:22 +1200 > From: Bruce Griffiths <[EMAIL PROTECTED]> > Subject: Re: [time-nuts] GSyncQ GPS Evalution Kits && NTPns > To: Discussion of precise time and frequency measurement > <[email protected]> > Message-ID: <[EMAIL PROTECTED]> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > Pekka Niemel? wrote: > > Hi, and thanks for your replies PHK and Bruce, > > > > > > > > Yes, I'm looking for a Quatech card from a Finnish dealer. So, I need the 2 > > serial port version of the card to get everything I need? I'm not sure how > > and what should be fed to the rs-422 connector, can't I use a rs-232c from > > the computer run through a max232? Sorry for asking these stupid questions, > > but I'm kindof out of luck. Synergy says they have something called Deutsch > > connectors from the antenna and receiver. I'm not familiar with this kind of > > connector. Synergy says there is a rs-422 connector, do they provide > > something like a adapter which will turn the Deutsch thing into a RS-422 > > connector and separate wires for 1PPS and apparently a second power source? > > > > I'm thrilled that NTPns will work with this setup. :) > > > > warm regards, > > P. Niemel? > > > > > Pekka > > If you want, you can easily construct your own external RS422 to RS232 > transceiver. > Just use a Max 232 to convert the RS232 signals to TTL/CMOS and connect > RS422 receiver and transmitter chips to that. > RS 485 transceivers chips can also be used instead of RS422 transmitters > and receivers, just connect them as drivers or receivers as required. > If you need a circuit schematic I can send you one. > > Novatel also use Deutsch connectors on some of their enclosures. > > Bruce > > > > > ------------------------------ > > Message: 2 > Date: Fri, 25 Apr 2008 20:36:38 +1200 > From: Bruce Griffiths <[EMAIL PROTECTED]> > Subject: Re: [time-nuts] Disciplining Rubidium > To: Discussion of precise time and frequency measurement > <[email protected]> > Message-ID: <[EMAIL PROTECTED]> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > Said > [EMAIL PROTECTED] wrote: > > Hi Bruce, > > > > the 1ns performance per second was mentioned by someone else in the > > previous > > threads. > > > > When you lock a BVA OCXO to carrier phase, I would still expect the PLL > > loop > > time constant to be >>20s, thus the 8E-014 / 2s you mentioned is very > > likely > > the performance of the BVA Crystal, not likely the carrier phase real-time > > system output. > > > More complete specs are: > 8E-14 @ 1 sec > 8E-14 @ 10 sec > 2E-13 @ 100 sec > 5E-13 @ 1000 sec > 4E-14 @ 10,000 sec > 1E-14 @ 1 day > > Loop time constant is probably somewhere around 1000 sec or so. > > > > > For example, our Fury with double oven has an ADEV of a couple of parts per > > E-012 1s to 20s, but that performance is entirely generated by the OCXO, > > not > > the M12+. > > > > I would expect the carrier phase to improve things at the point where the > > BVA starts having a rising ADEV. Maybe around a couple 100s? If for > > example the > > phase comparator has 1ps resolution (that's really quite a high resolution) > > to compare the OCXO and carrier phases (1E-012) then it would take >12s > > averaging intervals in the PLL just to prevent the measurement errors from > > affecting the system performance above 8E-014. > > > > It's late, and I may just be wrong about all this. > > > > bye, > > Said > > > Yes the carrier phase measurement resolution is very high (typically 1/4000 > of a ~635ps L1 carrier period) however the measurement noise is around 20ps > the oscillator performance is so good in comparison a very large time > constant is used. > > However if one had an OCXO whose performance ADEV was around 1E-11 for tau > from 1 to 100 sec or so then a much shorter time constant would be > appropriate. > > When the GPS receiver LO is phase locked to the OCXO, the GPS receiver has > all the hardware necessary to do the phase comparisons using either via code > phase or carrier phase methods. > > The following Chinese implementation appears to use a commercial receiver, > they just replaced its crystal oscillator: > > http://ieeexplore.ieee.org/Xplore/login.jsp?url=/iel5/19/30540/01408297.pdf?arnumber=1408297 > > > They also use a neural net for modeling prediction of atmospheric delays. > > > Perhaps the ultimate is to implement a custom GPS receiver (apart from the RF > front end and ADC) in a large FPGA. > One could then use L1, L2C, L5 etc plus the Galileo signals when they become > available. > > Bruce > > > > > ------------------------------ > > Message: 3 > Date: Fri, 25 Apr 2008 12:47:13 +0300 > From: " Pekka Niemel? " <[EMAIL PROTECTED]> > Subject: Re: [time-nuts] GSyncQ GPS Evalution Kits && NTPns > To: "Discussion of precise time and frequency measurement" > <[email protected]> > Message-ID: > <[EMAIL PROTECTED]> > Content-Type: text/plain; charset=ISO-8859-1 > > Hi Bruce, thanks for bearing with me. :) > > On 4/25/08, Bruce Griffiths <[EMAIL PROTECTED]> wrote: > > > > > > Pekka > > > > If you want, you can easily construct your own external RS422 to RS232 > > transceiver. > > Just use a Max 232 to convert the RS232 signals to TTL/CMOS and connect > > RS422 receiver and transmitter chips to that. > > RS 485 transceivers chips can also be used instead of RS422 transmitters > > and receivers, just connect them as drivers or receivers as required. > > If you need a circuit schematic I can send you one. > > > Hmm, if you would have schematics that would be really great. Can I download > them from somewhere? I'm not 100% that I understand what you're saying, but > I guess the schematics talk more than thousand words. :) > > The other option is ofcourse to just buy the transciever. But even in that > case I would need to drop the voltage with the max 232? That is, the 1PPS > signal that we drive into the Soekris? > > > Novatel also use Deutsch connectors on some of their enclosures. > > > Hmm, so it's an industry standard? Wikipedia doesn't know anything about it. > Strange. > > warm regards, > P. Niemel? > > > Bruce > > > > > > > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > > > > ------------------------------ > > Message: 4 > Date: Fri, 25 Apr 2008 22:06:58 +1200 > From: Bruce Griffiths <[EMAIL PROTECTED]> > Subject: Re: [time-nuts] GSyncQ GPS Evalution Kits && NTPns > To: Discussion of precise time and frequency measurement > <[email protected]> > Message-ID: <[EMAIL PROTECTED]> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > Pekka Niemel? wrote: > > Hi Bruce, thanks for bearing with me. :) > > > > On 4/25/08, Bruce Griffiths <[EMAIL PROTECTED]> wrote: > > > >> Pekka > >> > >> If you want, you can easily construct your own external RS422 to RS232 > >> transceiver. > >> Just use a Max 232 to convert the RS232 signals to TTL/CMOS and connect > >> RS422 receiver and transmitter chips to that. > >> RS 485 transceivers chips can also be used instead of RS422 transmitters > >> and receivers, just connect them as drivers or receivers as required. > >> If you need a circuit schematic I can send you one. > >> > > > > > > Hmm, if you would have schematics that would be really great. Can I download > > them from somewhere? I'm not 100% that I understand what you're saying, but > > I guess the schematics talk more than thousand words. :) > > > > > I need to create them first, I can then place them with my collection of > circuits, references etc on Didier's site: > http://www.eds-fl.com/~bruce/ <http://www.eds-fl.com/%7Ebruce/> > > Should be ready by 1200 UTC. > > What I am really saying is that if one uses a few chips on a circuit > board one can just connect the GPS cable to the 2 RS422 receivers and RS > 422 transmitters on the card. > A Soekris serial port would then connect to the RS232 transceiver chip. > The TTL/CMOS signals from the 2nd RS422 chip would connect to the > appropriate Soekris header pin so you can use the higher resolution timer. > > No plug in RS422 card is then required. > > Remember of course that the RS422 signal is differential and the cable > pair associated with each RS 422 signal has to be terminated in in the > correct characteristic impedance at the receiver (~100 ohms). > > Can you buy components from Farnell or RS components these appear to be > good sources for some parts of Europe (for Germany at least)? > If so I can easily check the availability of the required parts. > > The other option is ofcourse to just buy the transciever. But even in that > > case I would need to drop the voltage with the max 232? That is, the 1PPS > > signal that we drive into the Soekris? > > > > > > Novatel also use Deutsch connectors on some of their enclosures. > > > > > > Hmm, so it's an industry standard? Wikipedia doesn't know anything about it. > > Strange. > > > > warm regards, > > P. Niemel? > > > > > > Bruce > > > > > > > ------------------------------ > > Message: 5 > Date: Fri, 25 Apr 2008 23:58:15 +1200 > From: Bruce Griffiths <[EMAIL PROTECTED]> > Subject: Re: [time-nuts] GSyncQ GPS Evalution Kits && NTPns > To: Discussion of precise time and frequency measurement > <[email protected]> > Message-ID: <[EMAIL PROTECTED]> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > Pekka > > Circuit schematic now at: > http://www.eds-fl.com/~bruce/GPS_RS232_RS422_Transceiver.html > <http://www.eds-fl.com/%7Ebruce/GPS_RS232_RS422_Transceiver.html> > > Bruce > > > > ------------------------------ > > Message: 6 > Date: Fri, 25 Apr 2008 07:01:55 -0500 > From: "Didier Juges" <[EMAIL PROTECTED]> > Subject: Re: [time-nuts] GSyncQ GPS Evalution Kits && NTPns > To: "'Discussion of precise time and frequency measurement'" > <[email protected]> > Message-ID: <[EMAIL PROTECTED]> > Content-Type: text/plain; charset="windows-1250" > > One issue with RS-485 is that the Tx and Rx lines are shared and the driver > chip has to be told which direction it is supposed to work. This is usually > done in the serial driver code using one of the modem control lines. I am > not sure if the NTP code provides that signal. If that signal is not > available, you can use a 555 timer to turn the driver around when it is done > transmitting. Of course, if data flows in only one direction (I do not see > why the PC should talk to the GPS receiver for an NTP application, but there > may be good reasons for that), you can simply tie the driver so that it > works in that direction only. > > In a pinch, I have made a RS-485 (one pair Rx/Tx) to RS-232 bi-directional > "converter" with only 3 resistors... I would not pretend it is good > engineering practice, but it works over a few feet (very useful for a quick > verification) and it requires the software in the PC being able to get back > what it sends without throwing its arms up in the air (the human equivalent > of an exception)... I use that "solution" for a project I am working on > right now, and it is nice not to have to carry a bunch of cables/wall warts > and assorted hardware when I carry my project from work to home back and > forth every day. > > http://www.ko4bb.com/Test_Equipment/RS-485_Converter.jpg > > On that schematic, the right side connector would be the standard serial > connector of a PC. When the RS-485 driver is in the receive mode, it > receives data on the inverting input through the 1k resistor and the other > input is biased to a fixed DC level with the other two resistors. When the > RS-485 driver is talking, it swamps the 1k resistor and drives the Rx pin of > the RS-232 connector directly. > > Didier KO4BB > > > -----Original Message----- > > From: [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED] On Behalf Of Bruce Griffiths > > Sent: Friday, April 25, 2008 3:12 AM > > To: Discussion of precise time and frequency measurement > > Subject: Re: [time-nuts] GSyncQ GPS Evalution Kits && NTPns > > > > Pekka > > > > If you want, you can easily construct your own external RS422 > > to RS232 transceiver. > > Just use a Max 232 to convert the RS232 signals to TTL/CMOS > > and connect > > RS422 receiver and transmitter chips to that. > > RS 485 transceivers chips can also be used instead of RS422 > > transmitters and receivers, just connect them as drivers or > > receivers as required. > > If you need a circuit schematic I can send you one. > > > > Novatel also use Deutsch connectors on some of their enclosures. > > > > Bruce > > > > Internal Virus Database is out-of-date. > Checked by AVG. > Version: 7.5.519 / Virus Database: 269.22.5/1358 - Release Date: 4/3/2008 > 6:36 PM > > > > > > ------------------------------ > > Message: 7 > Date: Sat, 26 Apr 2008 00:16:46 +1200 > From: Bruce Griffiths <[EMAIL PROTECTED]> > Subject: Re: [time-nuts] GSyncQ GPS Evalution Kits && NTPns > To: Discussion of precise time and frequency measurement > <[email protected]> > Message-ID: <[EMAIL PROTECTED]> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > Didier Juges wrote: > > One issue with RS-485 is that the Tx and Rx lines are shared and the driver > > chip has to be told which direction it is supposed to work. This is usually > > done in the serial driver code using one of the modem control lines. I am > > not sure if the NTP code provides that signal. If that signal is not > > available, you can use a 555 timer to turn the driver around when it is done > > transmitting. Of course, if data flows in only one direction (I do not see > > why the PC should talk to the GPS receiver for an NTP application, but there > > may be good reasons for that), you can simply tie the driver so that it > > works in that direction only. > > > > In a pinch, I have made a RS-485 (one pair Rx/Tx) to RS-232 bi-directional > > "converter" with only 3 resistors... I would not pretend it is good > > engineering practice, but it works over a few feet (very useful for a quick > > verification) and it requires the software in the PC being able to get back > > what it sends without throwing its arms up in the air (the human equivalent > > of an exception)... I use that "solution" for a project I am working on > > right now, and it is nice not to have to carry a bunch of cables/wall warts > > and assorted hardware when I carry my project from work to home back and > > forth every day. > > > > http://www.ko4bb.com/Test_Equipment/RS-485_Converter.jpg > > > > On that schematic, the right side connector would be the standard serial > > connector of a PC. When the RS-485 driver is in the receive mode, it > > receives data on the inverting input through the 1k resistor and the other > > input is biased to a fixed DC level with the other two resistors. When the > > RS-485 driver is talking, it swamps the 1k resistor and drives the Rx pin of > > the RS-232 connector directly. > > > > Didier KO4BB > > > > > Didier > > Look at the new circuit I've just added to the miscellaneous section. > I've just used the RS485 drivers not the RS485 standard. > > The GPS receiver actually uses dedicated RS422 transmit, PPS, and > receive pairs. > I've merely used RS485 transceiver chips for convenience and their > higher current drive capability. > The RS485 transceiver signal levels are RS422 compatible. > > Bruce > > > > > ------------------------------ > > Message: 8 > Date: Fri, 25 Apr 2008 23:17:27 +1000 > From: "Don Bradbury" <[EMAIL PROTECTED]> > Subject: [time-nuts] RS485/422/232 Chip > To: "Discussion of precise time and frequency measurement" > <[email protected]> > Message-ID: <[EMAIL PROTECTED]> > Content-Type: text/plain; charset="iso-8859-1" > > The MAXIM MAX3162E will do RS485/422 and RS232 in the one chip , get samples > from maxim.com. > Don VK3YV.... > > ------------------------------ > > _______________________________________________ > time-nuts mailing list > [email protected] > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > End of time-nuts Digest, Vol 45, Issue 55 > ***************************************** >
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