[time-nuts] 10Mhz TXCO for LTE-Lite?
Did anyone implement an external 10Mhz TXCO for the Jackson-Labs LTE Lite? I'm finally getting around to trying to get 10Mhz out of this with a low enough impedance to drive a 50ohm cable. Thanks jim ab3cv ___ 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] LTE-Lite Plans
I have one of the LTE-Lite 20Mhz units and plan to use it as a frequency reference for my ham radio gear. My planned setup is as follows: I'm putting it in the recommended Hammond enclosure powered by a USB cable from my PC. I had originally planned to use the wall wart provided but I want to get status from the unit without hacking a window in the top to see the LEDs so I plan to use TBD software to provide a status check. I briefly thought about doing something with an Arduino and display shields but that seemed like too much work for now. I'm using a inverting D FF from TI (SN74aup1g80) as a divide by 2 to provide 10Mhz. The chip and associated passives will be on a little circuit board mounted in the open area normally reserved for the external oscillator. The output of the chip will be connected via a series resistor of about 400 ohms to a SMA connector. This resistor will limit the load on the FF and the LTE-Lite power source. Power will be taken from C6. This output will only go a few inches to a DEMI 10Mhz 4 way splitter The input of the splitter will be equipped with an additional ERA-2+ amplifier (50 ohm input) which will restore the signal levels lost due to the series resistor in the LTE-Lite addon. The DEMI splitter will also be equipped with a manual power switch which will allow me to kill the output of the box if the GPSDO fails for some reason. The little hockey puck antenna will be mounted directly outside the shack wall near a south facing wall which will limit the visibility to only half the horizon. I'm assuming this will be enough for my modest needs. The four outputs will be used as follows: One will go to the K3 ExtREF to provide an external reference. Two will go to separate TX/RX converters for low frequency (600Khz) use and be used with the transverter I/O on the K3. The last will be used as a general calibration reference. When the power switch on the DEMI splitter is turned off the K3 will revert to using its internal TXCO. I leave the PC running 24/7 and the power to the LTE-Lite would only be interrupted when the PC is rebooted. I don't need a frequency reference during the reboot time since I always operate my rig with the PC on and running. The TBD status software will tell me when the LTE-Lite is synched up again. The PC is served by a UPS and the shack circuit is one which is served by our whole house generator. I have the DEMI splitter built up and working. Now just waiting on enclosure from Digikey. I should have everything running by mid December. I still need to figure out what to use for the status software. Ideally I'd like an applet to display appropriate status indications on my monitor for now I'll examine the uBlox and Putty and if not satisfactory perhaps I'll write something in VB. Feedback and suggestions welcome. 73 Jim ab3cv ___ 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] New timing receivers?
I spent some time reading the uBlox-6 documentation. I found the TIM-TP ubx message and format. I see that there is also the ability to feed back to the uBlox-6 time shift info for the PPS in 1ns increments. Does it make sense to feed the TIM-TP info back this way to provide correction? Or is an external delay line or TIC plus software the only way? Thanks jim ab3cv On Sat, Apr 26, 2014 at 7:59 PM, Jim Miller j...@jtmiller.com wrote: I'm reading though the manual for my recently acquired M12+T which I'm looking forward to using. I notice that the manual is dated 09FEB05. So the M12+T has been around for about a decade. Are there more recent timing receivers available now or has the ubiquity of the consumer GPS market distracted all investment from timing receivers except at the high end? Thanks Jim AB3CV ___ 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] New timing receivers?
I'm reading though the manual for my recently acquired M12+T which I'm looking forward to using. I notice that the manual is dated 09FEB05. So the M12+T has been around for about a decade. Are there more recent timing receivers available now or has the ubiquity of the consumer GPS market distracted all investment from timing receivers except at the high end? Thanks Jim AB3CV ___ 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] M12+T module questions
Jim/Chris Thanks for the connector/cable info. Regarding the battery: I used a 2032 coin cell battery and holder I un-soldered from an dead PC motherboard. Even a coin cell will last its shelf life at least. According to the manual the module is designed for a rechargeable type while the lithium coin cells I'm aware of (e.g. 2032) are primary and not rechargeable. There is already a battery holder there which is perhaps 6mm in diameter. There is a tiny marking next to it UV-R1 or UV-M1. I'm aware of the need to shift the levels from the PC. Thanks for the reminder however. 73 jim ab3cv ___ 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] M12+T module questions
Received my M12+T and would like to gather parts to get it running and tested. I've looked through the manual for a battery type description and couldn't find one. Anyone know of a part number for the onboard battery I could reference? Also looking for a mating cable/connector for the 10pin header. Thanks Jim ab3cv ___ 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] Hanging bridge question
Thanks for all the helpful replies! Lots to learn. 73 jim ab3cv ___ 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] Hanging bridge question
The lowest cost solution is to do the correct entirely in software. After the measure the phase, simply add the correction. All you need to know is the phase. There is not point in correcting the pulse, you don't need a corrected pulse. What you want is a measurement of the phase. Chris I'm baffled as to how one would do this in software without a ton of expensive hardware to give phase information. Could you provide in words a simple block diagram of where you would get phase information without a Ghz TIC to read? Thanks Jim ___ 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] Hanging bridge question
Right now I'm planning to use a DS1123 driven by the PIC in my system to provide sawtooth correction. The phase measurement is strictly binary with a D FF. The PIC reads the value once a second and integrates with a bit of feedforward for stability. The numerical result will be fed to a DAC which controls the OCXO. The DS1123 is about $14, not unreasonable. The same PIC is used to setup the M12+T and read the status and sawtooth info, do the math for the PI filter, drive the D/A and communicate optionally with a PC to log D/A commands and relay any M12+T communication. It will also maintain a few simple indicator lights for status. Jim ___ 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] Hanging bridge question
Bob I'm not sure who you're responding to but I have a couple of questions: TDC = Time Delay Correlator? Could you point me to one of these 50 cent threads? I've read a ton of this list from 2007 forward but must have missed that. Thanks jim ab3cv (much to learn) Hi There have been multiple posts about analog TDC's of various designs that get you into the sub 100 ps range without costing very much money. I believe the cheapest posted so far adds 50 cents to a basic PIC based design. Bob ___ 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] M12+T Timing specs
I'm reading the Rev6.x Users guide from the Synergy website. The timing accuracy quoted on Page 21 indicates 20ns 6sigma average without the clock granularity message which I interpret to mean the user is not correcting for sawtooth errors. The timing granularity message from Page 167 is shown as one byte with a range of -128 to +127ns. So from that I presume the correct DS1123 to order would be one which capable of 1ns resolution. Is there any reason to select one with a finer resolution to implement sawtooth correction? I was thinking perhaps if the range of needed correction is actually much smaller than 128ns, ie more like 1/4th of that then the DS1123 with 0.25ns granularity and much smaller range might have better integral linearity performance. 73 jim ab3cv ___ 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] Hanging bridge question
I've spent a good part of the afternoon looking at all the plots, websites and the few papers I could find mentioning the hanging bridge. As far as I can tell as long as one is correcting for sawtooth there's nothing additional to do about hanging bridges. They merely show up as funny waveforms in the data that has not been corrected for sawtooth. Am I correct? Thanks jim ab3cv (still learning...) ___ 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] GPSDO simulation tool
To handle higher tau performance I think we want a higher degree loop. Cheers, Magnus Is a higher degree loop possible while maintaining stability? Commanding frequency while measuring phase is one pole, integrating the result of the phase comparison is a second pole and closing the loop will result in oscillation unless a zero is inserted (the P in PID). How would stability be maintained? Thanks jim ab3cv (newbie...) ___ 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] Range of Sawtooth values?
Just curious as to the range of sawtooth values that are typical for timing receivers. What's the maximum correction needed? Thanks jim ab3cv ___ 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] Another atomic clock question
Hi Hal Not arguing for or against sawtooth or hanging bridges, etc. My needs for GPSDO performance are unquantified but likely quite modest. I just want to get something working that's a bit better than my OCXO. I don't think I need the sawtooth stuff to get started. Thanks jim ab3cv Date: Fri, 07 Mar 2014 21:28:31 -0800 From: Hal Murray hmur...@megapathdsl.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Cc: hmur...@megapathdsl.net Subject: Re: [time-nuts] Another atomic clock question Message-ID: 20140308052831.40d3e406...@ip-64-139-1-69.sjc.megapath.net Content-Type: text/plain; charset=us-ascii j...@jtmiller.com said: I may switch the GPS module at a later date to one which provides sawtooth info if I really feel the need and add a delay line. Frankly I think I'll never get around to it. One nasty problem with hanging bridges is that if you don't believe in them, then you won't setup your monitoring system to notice them. ___ 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] Another atomic clock question
I think the hardware delay line approach is the only solution for a simple D FF lead/lag phase comparator. It would be placed ahead of the FF. Which GPS being built now provide sawtooth info? 73 jim ab3cv ___ 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] Another atomic clock question
I'm new at this obviously. I was just looking at the uBlox-6 info and I don't see where in the NMEA sentences the sawtooth info is contained. Is it a manufacturer specific option that needs be turned on? Or is it contained within a standard NMEA sentence somewhere. I also didn't see it mentioned in the uBlox u-Center software users guide. Thanks Jim ab3cv Message: 3 Date: Fri, 7 Mar 2014 16:26:35 +0100 From: Azelio Boriani azelio.bori...@screen.it To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Another atomic clock question Message-ID: cal8xpmmstyj2gczpdimzr1bqbhavq4a6r0kjtwaal521t+6...@mail.gmail.com Content-Type: text/plain; charset=ISO-8859-1 Every timing GPS receiver has the sawtooth information: uBlox, iLotus, SkyTraq, Trimble just to name someone ___ 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] Another atomic clock question
Didn't mean to cause a firestorm. Just used the term simple to describe a Lead/Lag D FF phase comparator. I view it as simple compared to a high speed counter. My GPSDO will have just such a FF whose state will be read by the micro which will implement a PI filter in software and drive a 20bit TI sigma delta DAC to apply corrections to the OCXO. Micro and all other clocks on the design are driven from the OCXO. I may switch the GPS module at a later date to one which provides sawtooth info if I really feel the need and add a delay line. Frankly I think I'll never get around to it. I'll publish a schematic, code and test results once I have something working. Thanks Jim ab3cv Date: Fri, 7 Mar 2014 09:23:54 -0800 From: Chris Albertson albertson.ch...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Another atomic clock question Message-ID: CABbxVHuc41UQMhgWNyCXdW=ichdg6taxeoka+zdv0hrrmo1...@mail.gmail.com Content-Type: text/plain; charset=ISO-8859-1 On Fri, Mar 7, 2014 at 5:25 AM, Jim Miller j...@jtmiller.com wrote: I think the hardware delay line approach is the only solution for a simple D FF lead/lag phase comparator. It would be placed ahead of the FF. Simple? You are going to need a micro controller and software to (1) tall the GPS to output the sawtooth function, they don't typically output it untell you tell it to. then (2) recover the sawtooth function from the serial data. Then(3) convert it to the counts that units used in the delay line. Finally (4) you need to interface the delay line to the processor and send the current sawtooth function value over that interface once per second. Also when I do stuff like this I always want some kind of LCD display or at least blink LEDS so I know what's going on inside and then it is at least running. Your simple analog devices no longer a simple analog device. Do a full up parts count for both designes. I think the digital correction comes in lower. Both solutions need the same micro controller and it's support circuitry. As to which GPSes send sawtooth. It's a common feature but typically you need to enable it, the same way you'd enable a self-survey or set a minimum elevation angle or whatever. 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] Software Sawtooth correction prerequisites?
$31 is certainly a reasonable price and would allow flexibility in the phase comparator design. I had forgotten that Maxim had a direct sale page. My bad... tnx jim miller ab3cv - Original Message - From: Dr Bruce Griffiths [EMAIL PROTECTED] To: Jim Miller [EMAIL PROTECTED]; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, May 12, 2007 9:18 AM Subject: Re: [time-nuts] Software Sawtooth correction prerequisites? Jim DS1021-15 (SOIC package) price is about $31 (1 off) from the Maxim-Dallas on line shop Bruce ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
[time-nuts] Software Sawtooth correction prerequisites?
My first post...newbie...be gentle... I spent the last several evenings reading the archives and saw mention of sawtooth error correction in software. Since the corrections to be applied are on the order of 1e-9 seconds it would seem that the phase detector outputs to which these are applied must be similar in resolution. That would seem to require a pretty hefty phase detector and a pretty substantial computing resource. Doesn't sound inexpensive. Is there a way around this? OTOH, the Dallas Semi delay line pushes the computation out into the input of the phase detector at the cost of a $17 chip (1k qty) which in small quantities is likely $50 or so. This would seem to allow for a wider variety of phase measurement techniques. Do I have this right? tnx jim miller ab3cv ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Software Sawtooth correction prerequisites?
Brooke Thanks for the quick response. I'm definitely in the amateur/hobbyist, frequency quadrant of the spectrum of posters/lurkers here. I'm mostly interested in the homebrew M12M/GPSDO activities so the HP counter doesn't appear applicable. tnx jim miller ab3cv ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Software Sawtooth correction prerequisites?
Hi Tom I thought the 1ns resolution phase detector combined with a significant phase error in a PLL could generate a number large enough to need a 4 byte representation which would then need signed arithmetic done on it. Accumulating many of those over the integration period means even greater precision in the PI software. Lots of work for a little PIC. Lesser resolution means easier computation although 1 second is a long time. I finally found where the sawtooth info comes from: the RAIM message...I mentioned I was a newbie. Since it is just an signed 8bit number in nanoseconds and is in the 50ns range it doesn't seem too useful if a low resolution phase detector has already quantized the phase sample. I suppose it could be accumulated anyway in the off chance the mean of the errors was significantly non-zero. I'm strictly an amateur looking at building a GPSDO for a workbench frequency standard and perhaps for occasional use on a ham rig. My oscillator will most likely be a HP10811 or similar. Your simulator sounds interesting. Would it need to be built on a commercial package? tnx jim miller ab3cv ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Re; Lucent RFTG-m-XO
On Feb 6, 2007, at 4:05 PM, Phil Staton wrote: data on pin 9 (5) :10020032f3ac52E109cc starts with a colon cc seems to be a checksum the first 2 changes to a 1 if gps ant disconnected and reconnected, at the same time the no gps led comes on the zero after the 1st 2 changes to 4 if their really is no gps The first digit is the talker - 0 for RB and 1 for XO. The second digit is status - 0 for active, 1 for inactive The third digit has always been 0 during my experiments. The fourth digit is 0=warmup, 1=GPS lock, 2=holdover?, 3=fault/fail the block 32...52 seems to be a count from last power up The 32F3AC52 is GPS time; it represents the number of seconds elapsed since 6-Jan-1980:00:00:00. The two digits before the time are a counter showing the number of hours the module has been in its present state. Max count 0xff. the E109 has been constant throughout all tests Mine say E004. The ROM version on my mezannine board is 4. Would your ROM version happen to be 9? Jim ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Lucent RFTG-m-XO
On Feb 6, 2007, at 11:27 AM, Robert E. Martinson wrote: I'm about to conclude that I have a defective unit and will order another unless anyone has any further suggestions (PLEASE)? Did you have the RB connected via the crossover cable and 10 MHz cable as described in previous emails? Jim ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Lucent RFTG-m-XO
On Feb 6, 2007, at 7:24 PM, Robert E. Martinson wrote: No, I was running the XO unit all by itself. My guess is that the XO should be able to run all by itself??? Perhaps they can, perhaps they can't, but why not prove them in their intended configuration before attempting to use a non-standard setup? I have previously run with the XO the RB interconnected (J5 10 MHz Ref). Not for 24 hours, but at least over night, but No GPS stayed ON on both units, Fault was ON only on the XO. NO GPS has always extinguished on mine after a half hour or so. Previously I have seen no activity on any pins of J6 on the XO, will check again also check J6 on the RB unit. Maybe I really do have a serious fault?? Data does not immediately appear after power up. It takes a while (15 minutes or more) to start coming out. Am I correct in assuming that the data continuously streams out of each J6 connector without any interrogation being sent from a PC?? That is correct - no interrogation is necessary. The data comes out gratuitously at 1 second intervals at 9600 8N1 via differential signalling on pins J6-5,9. Note also that J6 1PPS and SMA 15MHz outputs are not present on a unit that assumes a STDBY mode after completing its warmup. 73 de JIM N8ECI ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Lucent RFTG Units
On Jan 30, 2007, at 1:22 PM, Robert E. Martinson wrote: Hope everyone has not stopped experimenting with these nicely made, reasonably priced, units, but certainly the email regarding them has fallen to almost zero these last few weeks. I posted a few emails with the results of my reverse engineering but didn't get any significant response so I haven't posted any more. Investigation goes on however. They both power up, but both indicate No GPS, and the XO also indicates Fault, the RB unit indicates ON. I have the two J5 connectors interconnected per Jim Miller's email of 12/30/06 at 3:34pm, and the Ref In/Outs with an SMA cable. They should come out of NO GPS after 15-30 minutes. Even with the receiver plugged back into the XO unit, the data on the front panel J5-2 is clearly visible with HyperTerminal also Visual GPS is happy with this data. Be careful not to load the interconnect lines down with probes or external level changers. It is easy to knock one or both units into FAULT by aggressively probing signals on the interconnect cable. Even after many hours the RFTG units continue to indicate No GPS, and the XO unit also shows Fault. I tried the XO unit by itself (no connections to the RB unit) and the XO is still unable to obtain lock. I have been monitoring the crystal frequency (using a clip lead directly from the crystal) of the XO unit for 8 hours with an HP 5370B locked to my HP Z3801A Again, be careful of your probe loads. I found this out the hard way - too many loads (50Z on my 5370, freq counters on the oscillator, inverters on the serial lines etc) will spoil your results. I recommend initially bringing the units up in their original, as-designed configuration in order to establish a baseline. As mentioned earlier, you should get GPS lock in 15-30 minutes. Do you have a good DC voltage on the TNC GPS antenna connector when the receiver is installed in the RFTG? The RFTG has its own DC injection circuitry. I see commands initially being sent to the GPS receiver (monitoring its header pin 9 with an oscilloscope), however by simultaneously monitoring the calculated position using VisualGPS, its obvious that the receiver is not going into position hold mode. It takes 12 hours or so to transition into position hold mode. I use TAC32 for monitoring the receiver and TAC32's Receiver ID screen will show the status messages about the mode changes. Have you been able to capture and decode the motorola binary messages going from the CPU to the receiver during initialization? This would be useful. Don't we have any helpful Lucent employees in the group? I do not know about any Lucent employees in the group but it is very possible that company policy is not to release documentation to the public - and those that do have access to it might like their jobs more than they like the timenuts. It is also possible that the only docs available are written at a high level and would not be very useful in these pursuits. 73 de JIM N8ECI ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] New pics of RFTG-m-Rb, and some comparison details
On Dec 30, 2006, at 2:24 PM, John Ackermann N8UR wrote: My RFTG-m-Rb arrived yesterday, so of course it's in pieces on the bench today. Photos (along with those of the -XO) are at http://www.febo.com/time-freq/hardware/Lucent_GPSDO/ I did some reverse engineering on my RFTG-m-RB last night. The information below is what I've found so far. Upon power-up the unit will sit for a while, sometimes 10 minutes or more, presumably allowing the Rb to lock and settle. During this time there is a 10MHz square wave output from TP but no output from the 10 MHz REF nor the 15 MHz connector. The FAULT and NOGPS lights are illuminated. After the warmup period the FAULT light extinguishes, the ON light illuminates, and the 10 and 15 MHz connectors become active. The 10MHz REF OUT is squarewave, the 15 MHz is sine. Note that this behavior is fundamentally identical to the older stainless box units containing three boards and an FRS-C that have made their way around Ebay for a year or two. Could the RFTG have been the replacement for the stainless box units? Connectors J5 INTERFACE: J5-1: Comes high (+5) after the warmup period is complete and the reference outputs are enabled. J5-2: Unknown, maybe N/C J5-3: Unknown but appears connected to something. GPS IN? J5-4: GPS TX DATA (GPS header, pad 8) J5-5: Unknown but appears connected to something. GPS IN? J5-6: Unknown, maybe N/C J5-7: PPS output from internal source (not GPS) J5-8: Unknown, maybe N/C J5-9: GPS PPS OUT (GPS header, pad 6) Stimuli to GPS pin 8 (TX DATA) appears on J5-4. Stimuli to GPS pin 6 (PPS OUT) appears on J5-9. Since GPS TX and PPS show up on J5, I am betting that GPS RX is also available on this connector. See below. RS-485/1PPS connector: J6-1: diff. output - 1 PPS+ from internal source J6-2: ? J6-3: ? J6-4: ? believed to be diff. serial RXD input. J6-5: diff. output - TXD serial - J6-6: diff. output - 1 PPS- from internal source J6-7: ? J6-8: ? believed to be diff serial RXD input J6-9: diff output - TXD serial + Data on J6 TXD+/- is 9600 8N1 and is of the form: :000101E004E6 These updates come once per second and a couple of the nybbles change when it moves from warmup mode to online. The last byte is a CRC check of some sort as it changes by exactly one as previous nybbles change from 0 to 1 or 1 to 0. I didn't bother with a differential-to-RS232 converter, I just ran J6-9 into a PC serial port RXD. J6-4 and J6-8 may be the serial input to the 80188 processor. U101 (the 75174 differential receiver on the mezzanine board) has some of its inputs connected to J5-4, J5-9, J6-4, and J6-8. I have not yet traced the 75175 driver next to it. I have found no outputs on the ALARM connector. My mezzanine board looks identical to the one in John's pictures except the GPS 10 pin header and the antenna bias circuitry is unpopulated. There is +5 present on the header pads where the GPS would go at at least GPS TXD and PPS make it out to J5. I don't have an XO unit to experiment with but it looks almost identical to the RB as John has noted. Like the Z3801 and 3816, there must be a way for a technician to check the operation of the GPS at deployment time at the cell site - and maybe to put it in position-hold mode following a survey. As the GPS TXD and PPS lines are tied right to J5 on the front panel, I am betting that J5 provided a craft interface to the GPS. I cannot, however, find a path for the GPS RXD from the front panel to the 10 pin header. I watched GPS RXD during power up to see if the processor on the mezzanine might be sending initialization or status query commands and there were none. At this time I am wondering if the mezz. board was only interested in 1 PPS OUT for XO disciplining purposes, and TX/RX was carried right to the front panel for setup/ testing purposes. Hope this helps. YMMV! 73 de JIM N8ECI ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Repair of 5370B input channels
On Jun 14, 2006, at 11:05 PM, Randy Smith wrote: I got a dead 5370A from Ebay to work by taking the input board (and high-stability oscillator) from a dead 5345. HI Randy, Thanks for your reply to my question. I too noticed that there were 5345 parts in the input section of my dead 5370B. I'm going to try to make one good 5370B out of my two that have input problems. It is mighty difficult to chase down the problems, though, since there's almost no access to the input boards and test points while the unit is assembled! Jim ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Three subjects.
On Jan 3, 2006, at 3:32 PM, Dennis O'Keefe wrote: The Accutron was advertised to be accurate to a minute a month. Mine was +47 1/2 seconds at the end of the month. I no longer have that watch. My father used to work at a small (200 MW) municipal power plant and when I was young (1970s) I would occasionally go along with him to work. They had a Telechron clock and an Accutron right next to each other in the control room next to the synchroscope meter for each boiler/generator unit. The Telechron with its synchronous AC motor was hooked to the generator main output and the Accutron was naturally a standalone device. When off the grid they would trim the steam throttles to adjust the frequency of their generators to make the Telechron stay in agreement with the Accutron. Once it was time to go back on the grid they would use the synchroscope to assure that they were in phase with the grid. As you can imagine it would be a very, very bad day if they were to close the tie breaker to the grid while out of phase. The accutron / telechron arrangement was to keep the clocks in the town accurate during the off-grid interval. Jim ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
[time-nuts] GPS timing receivers - what now?
Hi, Now that the future of the Motorola timing receivers is uncertain due to the SiRF sale, does anyone have a favorite replacement receiver for timing? Synergy quoted me 2-4 weeks on an M12+ and eval board but did not sound certain that it would even be available at all. Thanks, Jim ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] GPS timing receivers - what now?
On Jul 20, 2005, at 3:06 PM, Poul-Henning Kamp wrote: The really interesting one would be to get a pci board with the host-assisted SiRF GPS chip and be able to do our own math on the raw measurements :-) That would be neat. ISTR that the Garmin GPS-25 boards could be coerced to give raw data on their second serial port. Jim ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] GPS timing receivers - what now?
On Jul 20, 2005, at 3:06 PM, Poul-Henning Kamp wrote: The really interesting one would be to get a pci board with the host-assisted SiRF GPS chip and be able to do our own math on the raw measurements :-) Another (probably crazy) thought came to mind... I wonder if the GNURadio can be used to demodulate signals at L1 either directly or through a downconverter/LNB.. We could make a software defined GPS receiver - a GNUGPS! Twiddling the software could make it support Galileo..or Glonass.. or the new civilian GPS frequencies. Jim ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] glossa7 being whiney on eBay...
On Jun 14, 2005, at 5:33 PM, Poul-Henning Kamp wrote: Special for TIME-NUTS complainers, I will sell some at this price. RUBIDIUM FREQUENCY STANDARD FROM STANFORD RESEARCH SYSTEMS PRS10, Power up with an input of 24 Volts DC. It has an output [...] Hi, I guess I'm missing the context... why would this seller have a beef with the time-nuts? Seems like a fair (albeit not spectacular) price for used rubidiums. Jim ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
