Re: [time-nuts] time-nuts Digest, Vol 121, Issue 65
On Sat, 23 Aug 2014 16:51:06 -0500, Dave M wrote: Thanks for that suggestion, Ed. After a bit of reading in the X72 Reference Guide, it appears that the X72 does have a 1PPS input. That would be considerably easier than trying to interface the Rb into the GPSDO. Still trying to understand what the manual is telling me. Next thing is to determine if my unit has that option enabled (firmware option). That will be a chore for after the holiday... really busy next week. My X72 has firmware 4.xx , and does not support 1PPS. I seem to remember you need v 5.xx I'm quite sure i got it from here (*bay# 180791401271) , and after i complained about the missing 1PPS and told seller the fw. version i had in mine, he wrote the fw. version info on the page. /CFO Denmark ___ 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] time-nuts Digest, Vol 121, Issue 65
Hal there is not one straight answer, as mentioned before these units are intended for commercial applications with large temperature ranges. Most have added frequency compensation using heater current sensing for C field adjustment or in the case of the FE 5680A DDS control. Looking close at the 5680 you can expect 4 E-11 per 1 C. Bert Kehren In a message dated 8/23/2014 9:42:15 P.M. Eastern Daylight Time, hmur...@megapathdsl.net writes: kb...@n1k.org said: If you have a temperature stable environment (or create one) you can get some very good results with an (good) Rb locked to a (good) GPS via a proper long time constant setup. It’s not easy, but it can be done. What's the temperature sensitivity of the typical telco-surplus Rb unit? -- These are my opinions. 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] time-nuts Digest, Vol 121, Issue 65
Hi The typical small Rb’s are temperature compensated. They have a real tempco of a bit less than a ppb. It gets corrected to about 10X better than that using data from an internal temp sensor. Correction is often three point, so it may or may not track the actual performance of the unit at all temperatures. There are a couple of gotcha’s with this approach. The first is that the sensor needs to track what’s going on with the unit. If you do things that change the thermals (heat flow) of the unit, that may no longer be true. The next issue is the step size of the correction. It’s digital, if you vary back and forth barely over a step boundary, it will quite happily modulate your Rb. The net result will be a unit with worst ADEV than one with the correction disabled. This is very much a “your MPG may vary” sort of thing. If you happen to have a golden unit that is very flat before correction, the correction will not impact you much. If you have one with a third order curve to it’s pre-correction characteristic, the three point / two line segment correction isn’t gong be as effective as it might be. Also o the list of things to be aware of: Rb’s tune with a magnetic field. Changing the local field can change the output frequency. Rb’s have a sensitivity to barometric pressure. Eliminating this is a bit hard. Correcting for it may be the better approach. Again both of these effects vary unit to unit. Your part may not be as sensitive as my part. Lots of fun. Bob On Aug 23, 2014, at 9:41 PM, Hal Murray hmur...@megapathdsl.net wrote: kb...@n1k.org said: If you have a temperature stable environment (or create one) you can get some very good results with an (good) Rb locked to a (good) GPS via a proper long time constant setup. It’s not easy, but it can be done. What's the temperature sensitivity of the typical telco-surplus Rb unit? -- These are my opinions. 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] time-nuts Digest, Vol 121, Issue 65
Hi Bob: I think that's what's done in the SRS PRS10 http://www.prc68.com/I/PRS10.shtml Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html http://www.prc68.com/I/DietNutrition.html Bob Camp wrote: Hi If you lock an Rb to GPS, you need / want / should do it with a *very* long time constant. Numbers in the one day to several days range are commonly seen. If you lock it up with a tighter (shorter time constant) loop, it will just wander around as it follows the GPS input. That’s what would happen if you hook your Rb to your Trimble and turn on the disciplining on the Rb. It will significantly degrade the stability of the Rb. If you have a temperature stable environment (or create one) you can get some very good results with an (good) Rb locked to a (good) GPS via a proper long time constant setup. It’s not easy, but it can be done. Bob On Aug 23, 2014, at 6:31 PM, Ed Palmer ed_pal...@sasktel.net wrote: Hi Dave, On 8/23/2014 3:51 PM, Dave M wrote: Thanks for that suggestion, Ed. After a bit of reading in the X72 Reference Guide, it appears that the X72 does have a 1PPS input. That would be considerably easier than trying to interface the Rb into the GPSDO. Still trying to understand what the manual is telling me. Next thing is to determine if my unit has that option enabled (firmware option). That will be a chore for after the holiday... really busy next week. What would that (1PPS disciplining) do for me... in terms of maintaining the Rb frequency accurately set? Would it be as accurate as having the Rb disciplined via the EFC input? It's kind of overkill, but by connecting the 1 PPS from the NTBW50AA to the X72, the X72 will be disciplined to the 1 PPS so the frequency will be accurate. The question is how well will it be disciplined, i.e. what will the Allen Deviation graph look like. I have a few X72 and SA-22c (X72's cousin), but none of them have that option. I don't know of any published data on it. Maybe you can tell us how well it performs. In general, I just don't see the point of disciplining a Rb standard to GPS. I don't understand what will be gained by doing it. I have a Z3801A and a Tbolt plus a free-running FRK as a house standard. I occasionally compare the FRK to the Z3801A but the drift is so low (~1e-12 per month over 9 months) that I see no reason to link them. One exception that I recently discussed on another forum was a guy who lives in a ground floor, north-facing condo. He might need to have a disciplined Rb standard due to poor GPS visibility. Ed Thanks, Dave M Message: 5 Date: Fri, 22 Aug 2014 16:19:45 -0600 From: Ed Palmer ed_pal...@sasktel.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] EFC info on Trimble 34310-T OXCO Message-ID: 53f7c201.5070...@sasktel.net Content-Type: text/plain; charset=ISO-8859-1; format=flowed Have you checked your X72 to see if it has the 1 PPS discipline option? That would be a lot easier (and probably better) than your proposed transplant. Ed On 8/22/2014 12:39 PM, Dave M wrote: Does anyone have any info on the OXCO in the Nortel/Trimble NTBW50AA-17 GPSTM receiver? The OXCO is labeled as Trimble 34310-T. I see some Trimble 34310-T oscillators on Ebay with pinouts labeled, but no other info. Specifically, I'd like to know the EFC characteristics for it. I'm thinking of the possibility of pulling the OXCO out of the GPSTM and subbing in a 10 MHz Rubidium, and using the GPSTM to discipline the Rubidium. My Rubidium is a Symmetricom X72, recently purchased. It seems to be working well. Does anyone know the differences between the three OXCOs used in the GPSTM receivers (T, T2 and Oak)? Thanks for some insight, Dave M ___ 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] time-nuts Digest, Vol 121, Issue 65
Hi It is not what is done in the Efratom Rb’s. Their pps input is set up to get things on frequency / on time quickly. The assumption is that you plug it into a pps to get it “right” and then take off on your mission. That takes them into the short (for a Rb) time constant region. Bob On Aug 24, 2014, at 5:56 PM, Brooke Clarke bro...@pacific.net wrote: Hi Bob: I think that's what's done in the SRS PRS10 http://www.prc68.com/I/PRS10.shtml Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html http://www.prc68.com/I/DietNutrition.html Bob Camp wrote: Hi If you lock an Rb to GPS, you need / want / should do it with a *very* long time constant. Numbers in the one day to several days range are commonly seen. If you lock it up with a tighter (shorter time constant) loop, it will just wander around as it follows the GPS input. That’s what would happen if you hook your Rb to your Trimble and turn on the disciplining on the Rb. It will significantly degrade the stability of the Rb. If you have a temperature stable environment (or create one) you can get some very good results with an (good) Rb locked to a (good) GPS via a proper long time constant setup. It’s not easy, but it can be done. Bob On Aug 23, 2014, at 6:31 PM, Ed Palmer ed_pal...@sasktel.net wrote: Hi Dave, On 8/23/2014 3:51 PM, Dave M wrote: Thanks for that suggestion, Ed. After a bit of reading in the X72 Reference Guide, it appears that the X72 does have a 1PPS input. That would be considerably easier than trying to interface the Rb into the GPSDO. Still trying to understand what the manual is telling me. Next thing is to determine if my unit has that option enabled (firmware option). That will be a chore for after the holiday... really busy next week. What would that (1PPS disciplining) do for me... in terms of maintaining the Rb frequency accurately set? Would it be as accurate as having the Rb disciplined via the EFC input? It's kind of overkill, but by connecting the 1 PPS from the NTBW50AA to the X72, the X72 will be disciplined to the 1 PPS so the frequency will be accurate. The question is how well will it be disciplined, i.e. what will the Allen Deviation graph look like. I have a few X72 and SA-22c (X72's cousin), but none of them have that option. I don't know of any published data on it. Maybe you can tell us how well it performs. In general, I just don't see the point of disciplining a Rb standard to GPS. I don't understand what will be gained by doing it. I have a Z3801A and a Tbolt plus a free-running FRK as a house standard. I occasionally compare the FRK to the Z3801A but the drift is so low (~1e-12 per month over 9 months) that I see no reason to link them. One exception that I recently discussed on another forum was a guy who lives in a ground floor, north-facing condo. He might need to have a disciplined Rb standard due to poor GPS visibility. Ed Thanks, Dave M Message: 5 Date: Fri, 22 Aug 2014 16:19:45 -0600 From: Ed Palmer ed_pal...@sasktel.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] EFC info on Trimble 34310-T OXCO Message-ID: 53f7c201.5070...@sasktel.net Content-Type: text/plain; charset=ISO-8859-1; format=flowed Have you checked your X72 to see if it has the 1 PPS discipline option? That would be a lot easier (and probably better) than your proposed transplant. Ed On 8/22/2014 12:39 PM, Dave M wrote: Does anyone have any info on the OXCO in the Nortel/Trimble NTBW50AA-17 GPSTM receiver? The OXCO is labeled as Trimble 34310-T. I see some Trimble 34310-T oscillators on Ebay with pinouts labeled, but no other info. Specifically, I'd like to know the EFC characteristics for it. I'm thinking of the possibility of pulling the OXCO out of the GPSTM and subbing in a 10 MHz Rubidium, and using the GPSTM to discipline the Rubidium. My Rubidium is a Symmetricom X72, recently purchased. It seems to be working well. Does anyone know the differences between the three OXCOs used in the GPSTM receivers (T, T2 and Oak)? Thanks for some insight, Dave M ___ 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. ___ time-nuts mailing list -- time-nuts@febo.com To
Re: [time-nuts] time-nuts Digest, Vol 121, Issue 65
Bob which Efratom are you talking about? Bert In a message dated 8/24/2014 6:33:12 P.M. Eastern Daylight Time, kb...@n1k.org writes: Hi It is not what is done in the Efratom Rb’s. Their pps input is set up to get things on frequency / on time quickly. The assumption is that you plug it into a pps to get it “right” and then take off on your mission. That takes them into the short (for a Rb) time constant region. Bob On Aug 24, 2014, at 5:56 PM, Brooke Clarke bro...@pacific.net wrote: Hi Bob: I think that's what's done in the SRS PRS10 http://www.prc68.com/I/PRS10.shtml Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html http://www.prc68.com/I/DietNutrition.html Bob Camp wrote: Hi If you lock an Rb to GPS, you need / want / should do it with a *very* long time constant. Numbers in the one day to several days range are commonly seen. If you lock it up with a tighter (shorter time constant) loop, it will just wander around as it follows the GPS input. That’s what would happen if you hook your Rb to your Trimble and turn on the disciplining on the Rb. It will significantly degrade the stability of the Rb. If you have a temperature stable environment (or create one) you can get some very good results with an (good) Rb locked to a (good) GPS via a proper long time constant setup. It’s not easy, but it can be done. Bob On Aug 23, 2014, at 6:31 PM, Ed Palmer ed_pal...@sasktel.net wrote: Hi Dave, On 8/23/2014 3:51 PM, Dave M wrote: Thanks for that suggestion, Ed. After a bit of reading in the X72 Reference Guide, it appears that the X72 does have a 1PPS input. That would be considerably easier than trying to interface the Rb into the GPSDO. Still trying to understand what the manual is telling me. Next thing is to determine if my unit has that option enabled (firmware option). That will be a chore for after the holiday... really busy next week. What would that (1PPS disciplining) do for me... in terms of maintaining the Rb frequency accurately set? Would it be as accurate as having the Rb disciplined via the EFC input? It's kind of overkill, but by connecting the 1 PPS from the NTBW50AA to the X72, the X72 will be disciplined to the 1 PPS so the frequency will be accurate. The question is how well will it be disciplined, i.e. what will the Allen Deviation graph look like. I have a few X72 and SA-22c (X72's cousin), but none of them have that option. I don't know of any published data on it. Maybe you can tell us how well it performs. In general, I just don't see the point of disciplining a Rb standard to GPS. I don't understand what will be gained by doing it. I have a Z3801A and a Tbolt plus a free-running FRK as a house standard. I occasionally compare the FRK to the Z3801A but the drift is so low (~1e-12 per month over 9 months) that I see no reason to link them. One exception that I recently discussed on another forum was a guy who lives in a ground floor, north-facing condo. He might need to have a disciplined Rb standard due to poor GPS visibility. Ed Thanks, Dave M Message: 5 Date: Fri, 22 Aug 2014 16:19:45 -0600 From: Ed Palmer ed_pal...@sasktel.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] EFC info on Trimble 34310-T OXCO Message-ID: 53f7c201.5070...@sasktel.net Content-Type: text/plain; charset=ISO-8859-1; format=flowed Have you checked your X72 to see if it has the 1 PPS discipline option? That would be a lot easier (and probably better) than your proposed transplant. Ed On 8/22/2014 12:39 PM, Dave M wrote: Does anyone have any info on the OXCO in the Nortel/Trimble NTBW50AA-17 GPSTM receiver? The OXCO is labeled as Trimble 34310-T. I see some Trimble 34310-T oscillators on Ebay with pinouts labeled, but no other info. Specifically, I'd like to know the EFC characteristics for it. I'm thinking of the possibility of pulling the OXCO out of the GPSTM and subbing in a 10 MHz Rubidium, and using the GPSTM to discipline the Rubidium. My Rubidium is a Symmetricom X72, recently purchased. It seems to be working well. Does anyone know the differences between the three OXCOs used in the GPSTM receivers (T, T2 and Oak)? Thanks for some insight, Dave M ___ 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
Re: [time-nuts] time-nuts Digest, Vol 121, Issue 65
Hi The Efratom that the original poster was referring to. All of the Efratom’s with PPS in pretty much work the same way. It’s one of those options you go crazy trying to find an example of and when you do it’s “ho hum, let’s look for something else”. Bob On Aug 24, 2014, at 8:19 PM, ewkeh...@aol.com wrote: Bob which Efratom are you talking about? Bert In a message dated 8/24/2014 6:33:12 P.M. Eastern Daylight Time, kb...@n1k.org writes: Hi It is not what is done in the Efratom Rb’s. Their pps input is set up to get things on frequency / on time quickly. The assumption is that you plug it into a pps to get it “right” and then take off on your mission. That takes them into the short (for a Rb) time constant region. Bob On Aug 24, 2014, at 5:56 PM, Brooke Clarke bro...@pacific.net wrote: Hi Bob: I think that's what's done in the SRS PRS10 http://www.prc68.com/I/PRS10.shtml Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html http://www.prc68.com/I/DietNutrition.html Bob Camp wrote: Hi If you lock an Rb to GPS, you need / want / should do it with a *very* long time constant. Numbers in the one day to several days range are commonly seen. If you lock it up with a tighter (shorter time constant) loop, it will just wander around as it follows the GPS input. That’s what would happen if you hook your Rb to your Trimble and turn on the disciplining on the Rb. It will significantly degrade the stability of the Rb. If you have a temperature stable environment (or create one) you can get some very good results with an (good) Rb locked to a (good) GPS via a proper long time constant setup. It’s not easy, but it can be done. Bob On Aug 23, 2014, at 6:31 PM, Ed Palmer ed_pal...@sasktel.net wrote: Hi Dave, On 8/23/2014 3:51 PM, Dave M wrote: Thanks for that suggestion, Ed. After a bit of reading in the X72 Reference Guide, it appears that the X72 does have a 1PPS input. That would be considerably easier than trying to interface the Rb into the GPSDO. Still trying to understand what the manual is telling me. Next thing is to determine if my unit has that option enabled (firmware option). That will be a chore for after the holiday... really busy next week. What would that (1PPS disciplining) do for me... in terms of maintaining the Rb frequency accurately set? Would it be as accurate as having the Rb disciplined via the EFC input? It's kind of overkill, but by connecting the 1 PPS from the NTBW50AA to the X72, the X72 will be disciplined to the 1 PPS so the frequency will be accurate. The question is how well will it be disciplined, i.e. what will the Allen Deviation graph look like. I have a few X72 and SA-22c (X72's cousin), but none of them have that option. I don't know of any published data on it. Maybe you can tell us how well it performs. In general, I just don't see the point of disciplining a Rb standard to GPS. I don't understand what will be gained by doing it. I have a Z3801A and a Tbolt plus a free-running FRK as a house standard. I occasionally compare the FRK to the Z3801A but the drift is so low (~1e-12 per month over 9 months) that I see no reason to link them. One exception that I recently discussed on another forum was a guy who lives in a ground floor, north-facing condo. He might need to have a disciplined Rb standard due to poor GPS visibility. Ed Thanks, Dave M Message: 5 Date: Fri, 22 Aug 2014 16:19:45 -0600 From: Ed Palmer ed_pal...@sasktel.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] EFC info on Trimble 34310-T OXCO Message-ID: 53f7c201.5070...@sasktel.net Content-Type: text/plain; charset=ISO-8859-1; format=flowed Have you checked your X72 to see if it has the 1 PPS discipline option? That would be a lot easier (and probably better) than your proposed transplant. Ed On 8/22/2014 12:39 PM, Dave M wrote: Does anyone have any info on the OXCO in the Nortel/Trimble NTBW50AA-17 GPSTM receiver? The OXCO is labeled as Trimble 34310-T. I see some Trimble 34310-T oscillators on Ebay with pinouts labeled, but no other info. Specifically, I'd like to know the EFC characteristics for it. I'm thinking of the possibility of pulling the OXCO out of the GPSTM and subbing in a 10 MHz Rubidium, and using the GPSTM to discipline the Rubidium. My Rubidium is a Symmetricom X72, recently purchased. It seems to be working well. Does anyone know the differences between the three OXCOs used in the GPSTM receivers (T, T2 and Oak)? Thanks for some insight, Dave M ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and
Re: [time-nuts] time-nuts Digest, Vol 121, Issue 65
Thanks for that suggestion, Ed. After a bit of reading in the X72 Reference Guide, it appears that the X72 does have a 1PPS input. That would be considerably easier than trying to interface the Rb into the GPSDO. Still trying to understand what the manual is telling me. Next thing is to determine if my unit has that option enabled (firmware option). That will be a chore for after the holiday... really busy next week. What would that (1PPS disciplining) do for me... in terms of maintaining the Rb frequency accurately set? Would it be as accurate as having the Rb disciplined via the EFC input? Thanks, Dave M Message: 5 Date: Fri, 22 Aug 2014 16:19:45 -0600 From: Ed Palmer ed_pal...@sasktel.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] EFC info on Trimble 34310-T OXCO Message-ID: 53f7c201.5070...@sasktel.net Content-Type: text/plain; charset=ISO-8859-1; format=flowed Have you checked your X72 to see if it has the 1 PPS discipline option? That would be a lot easier (and probably better) than your proposed transplant. Ed On 8/22/2014 12:39 PM, Dave M wrote: Does anyone have any info on the OXCO in the Nortel/Trimble NTBW50AA-17 GPSTM receiver? The OXCO is labeled as Trimble 34310-T. I see some Trimble 34310-T oscillators on Ebay with pinouts labeled, but no other info. Specifically, I'd like to know the EFC characteristics for it. I'm thinking of the possibility of pulling the OXCO out of the GPSTM and subbing in a 10 MHz Rubidium, and using the GPSTM to discipline the Rubidium. My Rubidium is a Symmetricom X72, recently purchased. It seems to be working well. Does anyone know the differences between the three OXCOs used in the GPSTM receivers (T, T2 and Oak)? Thanks for some insight, Dave M ___ 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] time-nuts Digest, Vol 121, Issue 65
Hi Dave, On 8/23/2014 3:51 PM, Dave M wrote: Thanks for that suggestion, Ed. After a bit of reading in the X72 Reference Guide, it appears that the X72 does have a 1PPS input. That would be considerably easier than trying to interface the Rb into the GPSDO. Still trying to understand what the manual is telling me. Next thing is to determine if my unit has that option enabled (firmware option). That will be a chore for after the holiday... really busy next week. What would that (1PPS disciplining) do for me... in terms of maintaining the Rb frequency accurately set? Would it be as accurate as having the Rb disciplined via the EFC input? It's kind of overkill, but by connecting the 1 PPS from the NTBW50AA to the X72, the X72 will be disciplined to the 1 PPS so the frequency will be accurate. The question is how well will it be disciplined, i.e. what will the Allen Deviation graph look like. I have a few X72 and SA-22c (X72's cousin), but none of them have that option. I don't know of any published data on it. Maybe you can tell us how well it performs. In general, I just don't see the point of disciplining a Rb standard to GPS. I don't understand what will be gained by doing it. I have a Z3801A and a Tbolt plus a free-running FRK as a house standard. I occasionally compare the FRK to the Z3801A but the drift is so low (~1e-12 per month over 9 months) that I see no reason to link them. One exception that I recently discussed on another forum was a guy who lives in a ground floor, north-facing condo. He might need to have a disciplined Rb standard due to poor GPS visibility. Ed Thanks, Dave M Message: 5 Date: Fri, 22 Aug 2014 16:19:45 -0600 From: Ed Palmer ed_pal...@sasktel.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] EFC info on Trimble 34310-T OXCO Message-ID: 53f7c201.5070...@sasktel.net Content-Type: text/plain; charset=ISO-8859-1; format=flowed Have you checked your X72 to see if it has the 1 PPS discipline option? That would be a lot easier (and probably better) than your proposed transplant. Ed On 8/22/2014 12:39 PM, Dave M wrote: Does anyone have any info on the OXCO in the Nortel/Trimble NTBW50AA-17 GPSTM receiver? The OXCO is labeled as Trimble 34310-T. I see some Trimble 34310-T oscillators on Ebay with pinouts labeled, but no other info. Specifically, I'd like to know the EFC characteristics for it. I'm thinking of the possibility of pulling the OXCO out of the GPSTM and subbing in a 10 MHz Rubidium, and using the GPSTM to discipline the Rubidium. My Rubidium is a Symmetricom X72, recently purchased. It seems to be working well. Does anyone know the differences between the three OXCOs used in the GPSTM receivers (T, T2 and Oak)? Thanks for some insight, Dave M ___ 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] time-nuts Digest, Vol 121, Issue 65
Hi If you lock an Rb to GPS, you need / want / should do it with a *very* long time constant. Numbers in the one day to several days range are commonly seen. If you lock it up with a tighter (shorter time constant) loop, it will just wander around as it follows the GPS input. That’s what would happen if you hook your Rb to your Trimble and turn on the disciplining on the Rb. It will significantly degrade the stability of the Rb. If you have a temperature stable environment (or create one) you can get some very good results with an (good) Rb locked to a (good) GPS via a proper long time constant setup. It’s not easy, but it can be done. Bob On Aug 23, 2014, at 6:31 PM, Ed Palmer ed_pal...@sasktel.net wrote: Hi Dave, On 8/23/2014 3:51 PM, Dave M wrote: Thanks for that suggestion, Ed. After a bit of reading in the X72 Reference Guide, it appears that the X72 does have a 1PPS input. That would be considerably easier than trying to interface the Rb into the GPSDO. Still trying to understand what the manual is telling me. Next thing is to determine if my unit has that option enabled (firmware option). That will be a chore for after the holiday... really busy next week. What would that (1PPS disciplining) do for me... in terms of maintaining the Rb frequency accurately set? Would it be as accurate as having the Rb disciplined via the EFC input? It's kind of overkill, but by connecting the 1 PPS from the NTBW50AA to the X72, the X72 will be disciplined to the 1 PPS so the frequency will be accurate. The question is how well will it be disciplined, i.e. what will the Allen Deviation graph look like. I have a few X72 and SA-22c (X72's cousin), but none of them have that option. I don't know of any published data on it. Maybe you can tell us how well it performs. In general, I just don't see the point of disciplining a Rb standard to GPS. I don't understand what will be gained by doing it. I have a Z3801A and a Tbolt plus a free-running FRK as a house standard. I occasionally compare the FRK to the Z3801A but the drift is so low (~1e-12 per month over 9 months) that I see no reason to link them. One exception that I recently discussed on another forum was a guy who lives in a ground floor, north-facing condo. He might need to have a disciplined Rb standard due to poor GPS visibility. Ed Thanks, Dave M Message: 5 Date: Fri, 22 Aug 2014 16:19:45 -0600 From: Ed Palmer ed_pal...@sasktel.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] EFC info on Trimble 34310-T OXCO Message-ID: 53f7c201.5070...@sasktel.net Content-Type: text/plain; charset=ISO-8859-1; format=flowed Have you checked your X72 to see if it has the 1 PPS discipline option? That would be a lot easier (and probably better) than your proposed transplant. Ed On 8/22/2014 12:39 PM, Dave M wrote: Does anyone have any info on the OXCO in the Nortel/Trimble NTBW50AA-17 GPSTM receiver? The OXCO is labeled as Trimble 34310-T. I see some Trimble 34310-T oscillators on Ebay with pinouts labeled, but no other info. Specifically, I'd like to know the EFC characteristics for it. I'm thinking of the possibility of pulling the OXCO out of the GPSTM and subbing in a 10 MHz Rubidium, and using the GPSTM to discipline the Rubidium. My Rubidium is a Symmetricom X72, recently purchased. It seems to be working well. Does anyone know the differences between the three OXCOs used in the GPSTM receivers (T, T2 and Oak)? Thanks for some insight, Dave M ___ 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] time-nuts Digest, Vol 121, Issue 65
kb...@n1k.org said: If you have a temperature stable environment (or create one) you can get some very good results with an (good) Rb locked to a (good) GPS via a proper long time constant setup. Its not easy, but it can be done. What's the temperature sensitivity of the typical telco-surplus Rb unit? -- These are my opinions. 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] time-nuts Digest, Vol 121, Issue 65
actually if the oscillator is stabil enough, with a very long time constant one could kill the phase modulation of the new WWVB format 73 Alex On 8/23/2014 6:27 PM, Bob Camp wrote: Hi If you lock an Rb to GPS, you need / want / should do it with a *very* long time constant. Numbers in the one day to several days range are commonly seen. If you lock it up with a tighter (shorter time constant) loop, it will just wander around as it follows the GPS input. That’s what would happen if you hook your Rb to your Trimble and turn on the disciplining on the Rb. It will significantly degrade the stability of the Rb. If you have a temperature stable environment (or create one) you can get some very good results with an (good) Rb locked to a (good) GPS via a proper long time constant setup. It’s not easy, but it can be done. Bob On Aug 23, 2014, at 6:31 PM, Ed Palmer ed_pal...@sasktel.net wrote: Hi Dave, On 8/23/2014 3:51 PM, Dave M wrote: Thanks for that suggestion, Ed. After a bit of reading in the X72 Reference Guide, it appears that the X72 does have a 1PPS input. That would be considerably easier than trying to interface the Rb into the GPSDO. Still trying to understand what the manual is telling me. Next thing is to determine if my unit has that option enabled (firmware option). That will be a chore for after the holiday... really busy next week. What would that (1PPS disciplining) do for me... in terms of maintaining the Rb frequency accurately set? Would it be as accurate as having the Rb disciplined via the EFC input? It's kind of overkill, but by connecting the 1 PPS from the NTBW50AA to the X72, the X72 will be disciplined to the 1 PPS so the frequency will be accurate. The question is how well will it be disciplined, i.e. what will the Allen Deviation graph look like. I have a few X72 and SA-22c (X72's cousin), but none of them have that option. I don't know of any published data on it. Maybe you can tell us how well it performs. In general, I just don't see the point of disciplining a Rb standard to GPS. I don't understand what will be gained by doing it. I have a Z3801A and a Tbolt plus a free-running FRK as a house standard. I occasionally compare the FRK to the Z3801A but the drift is so low (~1e-12 per month over 9 months) that I see no reason to link them. One exception that I recently discussed on another forum was a guy who lives in a ground floor, north-facing condo. He might need to have a disciplined Rb standard due to poor GPS visibility. Ed Thanks, Dave M Message: 5 Date: Fri, 22 Aug 2014 16:19:45 -0600 From: Ed Palmer ed_pal...@sasktel.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] EFC info on Trimble 34310-T OXCO Message-ID: 53f7c201.5070...@sasktel.net Content-Type: text/plain; charset=ISO-8859-1; format=flowed Have you checked your X72 to see if it has the 1 PPS discipline option? That would be a lot easier (and probably better) than your proposed transplant. Ed On 8/22/2014 12:39 PM, Dave M wrote: Does anyone have any info on the OXCO in the Nortel/Trimble NTBW50AA-17 GPSTM receiver? The OXCO is labeled as Trimble 34310-T. I see some Trimble 34310-T oscillators on Ebay with pinouts labeled, but no other info. Specifically, I'd like to know the EFC characteristics for it. I'm thinking of the possibility of pulling the OXCO out of the GPSTM and subbing in a 10 MHz Rubidium, and using the GPSTM to discipline the Rubidium. My Rubidium is a Symmetricom X72, recently purchased. It seems to be working well. Does anyone know the differences between the three OXCOs used in the GPSTM receivers (T, T2 and Oak)? Thanks for some insight, Dave M ___ 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.
