Re: [time-nuts] Thunderbolt antenna
Hi Like the Lucent antennas, they are ceramic patch antennas inside a fairly rugged enclosure. They are fine antennas, but they aren't choke ring designs. Bob On Mar 10, 2013, at 12:07 AM, Peter Gottlieb n...@verizon.net wrote: I'd like to get a better antenna for my Thunderbolt. I see Trimble bullet antennas type 57860-00 on ebay for $30 or so, specs look to be 5 volt 35 dB gain. Would something like this be a good choice? Peter ___ 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] frequency reference for portable operation
Asking here on behalf of a friend.. With respect to portable amateur microwave operation.. you want good close in phase noise (so you can use narrow band filters) AND good frequency accuracy (so you can find the signal) the typical operation is drive somewhere, operate a bit, drive somewhere operate a bit repeated (contacts from different grid squares/peaks/what haveyou My instinct is that this is an application for a nice quiet OCXO on a battery. Adjust the frequency before you set out against a good reference and just go from there. Surplus Rb references are apparently also popular, but I think they keep those on battery too (that is, you need to be ready to go 10 minutes after arriving, and I don't know that a Rb is settled in that quickly). So the question from my friend was with reference to GPS disciplined oscillators. Would that do any better? I'm used to GPSDOs in a fixed location where you have time to do long term averaging. And what about truly mobile operation (there are folks in the SF bay area apparently doing 10GHz mobile ops.. slotted WG radiator on the roof of the car, etc.) What sort of 1pps timing accuracy do you get from a GPS on the move. I assume it would have the usual 10ns sort of uncertainty (in that the mfr specs don't say only with the antenna fixed in one place for N hours). 10ns is only 1E-8 of a second. Presumably one can average a bit over many pps ticks. I've got a bunch of Wenzel Streamline units, and they typically do 1E-10/day aging and 1E-9 over temp. Assuming the temperature doesn't vary a lot, seems like the OCXO is better than the GPS, at least in a 1-2 day time frame. (and, of course, isn't that just what a GPSDO is, in holdover mode, anyway) The Rb is good to 1E-11 over the short run (assuming it's been calibrated recently) but I notice that the PRS10 data sheet says 7 minutes to 1E-9, so in the non continuously powered mode of operation, it's not all that wonderful. The Rb is definitely higher powered.. The PRS10 is 2+ amps at 28V to start, and 0.6 to run. 15-16 Watts is a lot to keep on a battery. (Assume you run off a pair of 7Ah 12V batteries.. that gives you 10-12 hours). The Wenzel is a couple watts (after a 5W warmup). The GPS is a LOT lower power. The Garmin GPS 18x is 0.45W, of course the 1pps on that receiver is only specified to 1 microsecond.. A moto Oncore UT is a bit less than a watt and claims 100ns (with SA.. showing the age of the datasheet I have). ___ 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] Thunderbolt antenna
Yes, the Trimble Bullet is the originally suggested antenna for the TBolt but it is nothing special. Any patch timing antenna can do (Symmetricom 58532, Motorola Timing2000, Panasonic VIC100 and similar). To deviate from the usual patch type antenna, there is the Procom GPS4 quadrifilar helix and, having the money to acquire one, the choke ring type antenna. The top antenna (in my opinion) is the Trimble Zephyr but this antenna is extremely expensive even on the popular auction site. On Sun, Mar 10, 2013 at 2:33 PM, Bob Camp li...@rtty.us wrote: Hi Like the Lucent antennas, they are ceramic patch antennas inside a fairly rugged enclosure. They are fine antennas, but they aren't choke ring designs. Bob On Mar 10, 2013, at 12:07 AM, Peter Gottlieb n...@verizon.net wrote: I'd like to get a better antenna for my Thunderbolt. I see Trimble bullet antennas type 57860-00 on ebay for $30 or so, specs look to be 5 volt 35 dB gain. Would something like this be a good choice? Peter ___ 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] frequency reference for portable operation
Hi Jim, There are a few different schools of thought. Here in New England, I use a very simple GPS locked 10 MHz oscillator. It's based on the Jupiter GPS series with 10 kHz out. It drives a Qualcomm 1152 MHz board. This board generates harmonics through 24 GHz. I don't lock any of my rigs up to 24 GHz. From 47 GHz and up (78, 122, 241 GHz) the rigs are locked mostly using Axtal Axiom 75 series OCXO's and GPS via VE1ALQ reflock boards. For my rigs up to 24 GHz, I use the Qualcomm board to generate accurate markers. From there, I can adjust my IF to compensate. The simple GPSDO driving the Qualcomm is accurate to about 2 Hz/GHz, so even at 24 GHz, I'm typically within about 50 Hz - well within my narrow CW filter on the IF. The added benefit of using the GPS is I have it hooked to an ON4IY RoverBox. This gives me grid square, and Sun position based on location/time for aligning my dish (if the sun is out...) Plus the simple GPSDO is locked and running in about 3 minutes or so from a cold start. I find I don't need ultimate accuracy from 24 GHz down. And not messing with the crystals in LO's keeps phase noise down etc... We've started to add Panadpaters to our IF rigs lately using the FUNCube SDR initially and now the cheaper sticks. These let us see 96 kHz or better at once, so finding the signal can be pretty easy. Remember, locking is great if both ends are locked. If not, you're back to tuning around to find the signal (that's where the panadapter is great!) KT1J and I did our first 2 km 122 GHz contact a while back. We were both locked and had rifle scopes calibrated for aiming. It was amazing to point our dishes and start sending and instantly hear the other station with no tuning! 73, Mike, N1JEZ A closed mouth gathers no feet - Original Message - From: Jim Lux jim...@earthlink.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, March 10, 2013 10:23 AM Subject: [time-nuts] frequency reference for portable operation Asking here on behalf of a friend.. With respect to portable amateur microwave operation.. you want good close in phase noise (so you can use narrow band filters) AND good frequency accuracy (so you can find the signal) ___ 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] Antenna Install - was Hello and new Project
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[time-nuts] Antenna Install - was Hello and new Project
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[time-nuts] Antenna Install - was Hello and new Project
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Re: [time-nuts] Thunderbolt antenna
Hi Peter, Why not. The antenna is optimized for that purpose (receiving GPS L1), omnidirectional and tuned to the GPS frequency, snow skids down, birds can't land on it. As N0UU affirms, there's nothing further sensational inside. I don't know, how proficient you are with radio frequency stuff, but a gain of 35dB does not guarantee a good reception. You primarily need gain to compensate (cable) losses. The noise figure (NF), for example, can get much more important. What antenna do you use at the time? If you are using a magnetic car roof antenna a Trimble Bullet surely will be a better choice... There are lots of GPS antennas on ebay for even less than 30 Dollars. I run four different antennas, which I purchased from ebay and none of them has failed so far. Volker Am 10.03.2013 06:07, schrieb Peter Gottlieb: I'd like to get a better antenna for my Thunderbolt. I see Trimble bullet antennas type 57860-00 on ebay for $30 or so, specs look to be 5 volt 35 dB gain. Would something like this be a good choice? Peter ___ 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] frequency reference for portable operation
Hi Remember - OCXO's are going to be acceleration sensitive. As you bump about on back roads, the oscillator is likely moving around by a few ppb. If you are after a hertz at 10 GHz, that's a lot. Your GPS will be off by a fairly predictable amount based on it's idea of it's location. If you have a 3M position accuracy, then you will likely have 10 ns of time error. With a 10 second loop, you are right back to a ppb. A good Rb should be able to hit a sub ppb accuracy at 10 minutes. No perfect answer. Bob On Mar 10, 2013, at 10:23 AM, Jim Lux jim...@earthlink.net wrote: Asking here on behalf of a friend.. With respect to portable amateur microwave operation.. you want good close in phase noise (so you can use narrow band filters) AND good frequency accuracy (so you can find the signal) the typical operation is drive somewhere, operate a bit, drive somewhere operate a bit repeated (contacts from different grid squares/peaks/what haveyou My instinct is that this is an application for a nice quiet OCXO on a battery. Adjust the frequency before you set out against a good reference and just go from there. Surplus Rb references are apparently also popular, but I think they keep those on battery too (that is, you need to be ready to go 10 minutes after arriving, and I don't know that a Rb is settled in that quickly). So the question from my friend was with reference to GPS disciplined oscillators. Would that do any better? I'm used to GPSDOs in a fixed location where you have time to do long term averaging. And what about truly mobile operation (there are folks in the SF bay area apparently doing 10GHz mobile ops.. slotted WG radiator on the roof of the car, etc.) What sort of 1pps timing accuracy do you get from a GPS on the move. I assume it would have the usual 10ns sort of uncertainty (in that the mfr specs don't say only with the antenna fixed in one place for N hours). 10ns is only 1E-8 of a second. Presumably one can average a bit over many pps ticks. I've got a bunch of Wenzel Streamline units, and they typically do 1E-10/day aging and 1E-9 over temp. Assuming the temperature doesn't vary a lot, seems like the OCXO is better than the GPS, at least in a 1-2 day time frame. (and, of course, isn't that just what a GPSDO is, in holdover mode, anyway) The Rb is good to 1E-11 over the short run (assuming it's been calibrated recently) but I notice that the PRS10 data sheet says 7 minutes to 1E-9, so in the non continuously powered mode of operation, it's not all that wonderful. The Rb is definitely higher powered.. The PRS10 is 2+ amps at 28V to start, and 0.6 to run. 15-16 Watts is a lot to keep on a battery. (Assume you run off a pair of 7Ah 12V batteries.. that gives you 10-12 hours). The Wenzel is a couple watts (after a 5W warmup). The GPS is a LOT lower power. The Garmin GPS 18x is 0.45W, of course the 1pps on that receiver is only specified to 1 microsecond.. A moto Oncore UT is a bit less than a watt and claims 100ns (with SA.. showing the age of the datasheet I have). ___ 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] GPS Antenna Install
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[time-nuts] GPS Antenna Install
Sorry about the blank messages - not sure why I could not reply to my own message... In any case, thanks to the help from kind folks on the list, the TS-2100L in in the rack at the N2MO amateur radio station at InfoAge. The N2MO team spent yesterday doing the prep work to mount a 27dB antenna on the gable end of the building, using 1/2 heliax for feed line, with a Polyphaser DGXZ + 06NFNF installed in the line before it enters the building. The antenna mount pipe and the Polyphaser are grounded via #2 copper cable that will be exothermic welded to the ground rod. Thanks again! Martin Flynn PS - Now that the precision time bug has bitten, the team, is considering a Rubidium standard! ___ 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] Rockwell PLGR GPS
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Could you give me a bit more description as to fair used condition? I live in western canada does the $300 include shipping out here? Iain On 2013-03-09, at 10:41 AM, Robert Atkinson wrote: Hi all, Not totally timenut, but I have a PLGR for sale and thought I' offer it here before putting it on ebay. it's a bit of an odd one, model HNV561A part no.822-0766-002. This appears to be the British version of the HMV560C. It is not stolen, I obtained it from official UK disposal channels. It works and is in fair used condition. Cost is $300 or £200 including postage. Ideal chance to get one with the SM without the DoD claiming it's theirs! Contact me OFF LIST if inerested. Robert G8RPI. Sent from Yahoo! Mail on Android ___ 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. -BEGIN PGP SIGNATURE- Version: GnuPG/MacGPG2 v2.0.18 (Darwin) Comment: GPGTools - http://gpgtools.org iQEcBAEBAgAGBQJRPKjjAAoJEEi8s8MVElu9tDcH/1gEXGz1tpOiZFXb9hue0xkp 5XHwxxWPMnRKOrcBnUiX7kB4geJ8ncBTW2DJ+dIna7+yb6fX0s+vT8ir6jKzJUPH UVOdVd1q/fIVWjXqkJLuYckUHGrJfFwh+3u/oIy4yeEziceMXNJBNF+F5rjEspwE acezD25AShScPaoN4BOgwWIaVTlqovG0YFwRmRZYiEw7CwRoeQYhNFjbD/mtcyiH U9pACTAHyEBL1ZALfqVgqwaXof3EDfbcdKhWhttuFzuKkNf7ebSIFs6BGPd7C3le cMfti3Njx/9S+05jR30Cs6wAKSL7yaS2OvPS9psc5rYQNgMlnSFT6qxXWUYcYxo= =YzpN -END PGP SIGNATURE- ___ 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] Thunderbolt antenna
The seller had a make offer so I tried $20 and it was set to auto accept. I figure for $25 (with shipping) it's worth a shot for a new unit. The Trimble data sheet says it is good for up to 75 feet of coax, I think I'll end up with about 50 here. The antenna I have been using is a no-name pole mount unit with 25 feet of attached RG-59 coax that came with the TBolt kit I initially got. I'm not a big fan of RG-59. So what coax should I use? Many people say use good RG-6, although the Dranetz power line units with GPS come with a 100 foot piece of 1/4 Heliax, I have to imagine that would be better. Here's some on epay: 360492678643, but with wrong connectors. Expensive, though, here are approx attenuation numbers at the frequency of interest: RG-5910.4 dB/100 ft RG-68.4 dB/100 ft Heliax 7.4 dB/100 ft FSJ1-50A RG-11 5.7 dB/100 ft (Yes, I'm aware of the impedance differences) It seems, just go with quad shield RG-6 and be done with it. I even have part of a spool of that laying around. Maybe more of an issue is how do you properly connect a TNC to that stuff (the antenna has a TNC). Peter On 3/10/2013 11:01 AM, Volker Esper wrote: Hi Peter, Why not. The antenna is optimized for that purpose (receiving GPS L1), omnidirectional and tuned to the GPS frequency, snow skids down, birds can't land on it. As N0UU affirms, there's nothing further sensational inside. I don't know, how proficient you are with radio frequency stuff, but a gain of 35dB does not guarantee a good reception. You primarily need gain to compensate (cable) losses. The noise figure (NF), for example, can get much more important. What antenna do you use at the time? If you are using a magnetic car roof antenna a Trimble Bullet surely will be a better choice... There are lots of GPS antennas on ebay for even less than 30 Dollars. I run four different antennas, which I purchased from ebay and none of them has failed so far. Volker Am 10.03.2013 06:07, schrieb Peter Gottlieb: I'd like to get a better antenna for my Thunderbolt. I see Trimble bullet antennas type 57860-00 on ebay for $30 or so, specs look to be 5 volt 35 dB gain. Would something like this be a good choice? Peter ___ 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. - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1430 / Virus Database: 2641/5660 - Release Date: 03/09/13 ___ 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] Thunderbolt antenna
Hi How long a run of coax will you have? Do you have a power splitter at the receiver end? You probably need 10 db of gain between the antenna and the receiver. If the antenna has 25 db of gain, you have 15 db to waste on cable loss and power splitting. With no power splitter, you could run about 200' of RG-6. You likely will spend less on that amount of cable (plus the F connectors) than you will just on the connectors for the Heliax… As mentioned in an earlier thread, RG-59 may or may not be what the tables say it should be. RG-6 quad shield is made for the same frequency range as GPS. Weather it works broadband or not - who knows. It's pretty likely that it will indeed work at satellite / GPS frequencies. In a receiving application, impedance isn't a big issue. Since the TBolt is designed for 75 ohms, it's probably happier with 75 ohm cable. The antenna - who knows. Either way 50 or 75 ohms - no big deal. Bob On Mar 10, 2013, at 12:04 PM, Peter Gottlieb n...@verizon.net wrote: The seller had a make offer so I tried $20 and it was set to auto accept. I figure for $25 (with shipping) it's worth a shot for a new unit. The Trimble data sheet says it is good for up to 75 feet of coax, I think I'll end up with about 50 here. The antenna I have been using is a no-name pole mount unit with 25 feet of attached RG-59 coax that came with the TBolt kit I initially got. I'm not a big fan of RG-59. So what coax should I use? Many people say use good RG-6, although the Dranetz power line units with GPS come with a 100 foot piece of 1/4 Heliax, I have to imagine that would be better. Here's some on epay: 360492678643, but with wrong connectors. Expensive, though, here are approx attenuation numbers at the frequency of interest: RG-5910.4 dB/100 ft RG-68.4 dB/100 ft Heliax 7.4 dB/100 ft FSJ1-50A RG-11 5.7 dB/100 ft (Yes, I'm aware of the impedance differences) It seems, just go with quad shield RG-6 and be done with it. I even have part of a spool of that laying around. Maybe more of an issue is how do you properly connect a TNC to that stuff (the antenna has a TNC). Peter On 3/10/2013 11:01 AM, Volker Esper wrote: Hi Peter, Why not. The antenna is optimized for that purpose (receiving GPS L1), omnidirectional and tuned to the GPS frequency, snow skids down, birds can't land on it. As N0UU affirms, there's nothing further sensational inside. I don't know, how proficient you are with radio frequency stuff, but a gain of 35dB does not guarantee a good reception. You primarily need gain to compensate (cable) losses. The noise figure (NF), for example, can get much more important. What antenna do you use at the time? If you are using a magnetic car roof antenna a Trimble Bullet surely will be a better choice... There are lots of GPS antennas on ebay for even less than 30 Dollars. I run four different antennas, which I purchased from ebay and none of them has failed so far. Volker Am 10.03.2013 06:07, schrieb Peter Gottlieb: I'd like to get a better antenna for my Thunderbolt. I see Trimble bullet antennas type 57860-00 on ebay for $30 or so, specs look to be 5 volt 35 dB gain. Would something like this be a good choice? Peter ___ 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. - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1430 / Virus Database: 2641/5660 - Release Date: 03/09/13 ___ 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] frequency reference for portable operation
Having built a few portable frequency sources my recommendation based on your application and what is reasonably available today would be a FE 5680A in combination with a 100 MHz clean up XO. We have very good results with a slightly modified what I call the Dorsten PLL-VCXO by W-H-Rech. I can send you the article and some plots, the article is in German but you would be able to understand or I would help you. Using an AGM battery and a $ 4 up converter I would plug it in to the car when driving and at home run it off AC and when in the field you will have plenty of time to operate. 9.8 A 12V Li-ion are available for $ 45. When home keep it running and use the RS 232 to update Rb frequency. Bert In a message dated 3/10/2013 10:23:21 A.M. Eastern Daylight Time, jim...@earthlink.net writes: Asking here on behalf of a friend.. With respect to portable amateur microwave operation.. you want good close in phase noise (so you can use narrow band filters) AND good frequency accuracy (so you can find the signal) the typical operation is drive somewhere, operate a bit, drive somewhere operate a bit repeated (contacts from different grid squares/peaks/what haveyou My instinct is that this is an application for a nice quiet OCXO on a battery. Adjust the frequency before you set out against a good reference and just go from there. Surplus Rb references are apparently also popular, but I think they keep those on battery too (that is, you need to be ready to go 10 minutes after arriving, and I don't know that a Rb is settled in that quickly). So the question from my friend was with reference to GPS disciplined oscillators. Would that do any better? I'm used to GPSDOs in a fixed location where you have time to do long term averaging. And what about truly mobile operation (there are folks in the SF bay area apparently doing 10GHz mobile ops.. slotted WG radiator on the roof of the car, etc.) What sort of 1pps timing accuracy do you get from a GPS on the move. I assume it would have the usual 10ns sort of uncertainty (in that the mfr specs don't say only with the antenna fixed in one place for N hours). 10ns is only 1E-8 of a second. Presumably one can average a bit over many pps ticks. I've got a bunch of Wenzel Streamline units, and they typically do 1E-10/day aging and 1E-9 over temp. Assuming the temperature doesn't vary a lot, seems like the OCXO is better than the GPS, at least in a 1-2 day time frame. (and, of course, isn't that just what a GPSDO is, in holdover mode, anyway) The Rb is good to 1E-11 over the short run (assuming it's been calibrated recently) but I notice that the PRS10 data sheet says 7 minutes to 1E-9, so in the non continuously powered mode of operation, it's not all that wonderful. The Rb is definitely higher powered.. The PRS10 is 2+ amps at 28V to start, and 0.6 to run. 15-16 Watts is a lot to keep on a battery. (Assume you run off a pair of 7Ah 12V batteries.. that gives you 10-12 hours). The Wenzel is a couple watts (after a 5W warmup). The GPS is a LOT lower power. The Garmin GPS 18x is 0.45W, of course the 1pps on that receiver is only specified to 1 microsecond.. A moto Oncore UT is a bit less than a watt and claims 100ns (with SA.. showing the age of the datasheet I have). ___ 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] Thunderbolt antenna
Thank you. The antenna spec is 35 dB gain and I'll end up with 50-75 feet of RG-6. Maybe I'll just put in a TNC-F adapter as there are F connectors made especially for RG-6, and probably no TNC connectors like that! Thanks again. Peter On 3/10/2013 12:35 PM, Bob Camp wrote: Hi How long a run of coax will you have? Do you have a power splitter at the receiver end? You probably need 10 db of gain between the antenna and the receiver. If the antenna has 25 db of gain, you have 15 db to waste on cable loss and power splitting. With no power splitter, you could run about 200' of RG-6. You likely will spend less on that amount of cable (plus the F connectors) than you will just on the connectors for the Heliax… As mentioned in an earlier thread, RG-59 may or may not be what the tables say it should be. RG-6 quad shield is made for the same frequency range as GPS. Weather it works broadband or not - who knows. It's pretty likely that it will indeed work at satellite / GPS frequencies. In a receiving application, impedance isn't a big issue. Since the TBolt is designed for 75 ohms, it's probably happier with 75 ohm cable. The antenna - who knows. Either way 50 or 75 ohms - no big deal. Bob On Mar 10, 2013, at 12:04 PM, Peter Gottlieb n...@verizon.net wrote: The seller had a make offer so I tried $20 and it was set to auto accept. I figure for $25 (with shipping) it's worth a shot for a new unit. The Trimble data sheet says it is good for up to 75 feet of coax, I think I'll end up with about 50 here. The antenna I have been using is a no-name pole mount unit with 25 feet of attached RG-59 coax that came with the TBolt kit I initially got. I'm not a big fan of RG-59. So what coax should I use? Many people say use good RG-6, although the Dranetz power line units with GPS come with a 100 foot piece of 1/4 Heliax, I have to imagine that would be better. Here's some on epay: 360492678643, but with wrong connectors. Expensive, though, here are approx attenuation numbers at the frequency of interest: RG-5910.4 dB/100 ft RG-68.4 dB/100 ft Heliax 7.4 dB/100 ft FSJ1-50A RG-11 5.7 dB/100 ft (Yes, I'm aware of the impedance differences) It seems, just go with quad shield RG-6 and be done with it. I even have part of a spool of that laying around. Maybe more of an issue is how do you properly connect a TNC to that stuff (the antenna has a TNC). Peter On 3/10/2013 11:01 AM, Volker Esper wrote: Hi Peter, Why not. The antenna is optimized for that purpose (receiving GPS L1), omnidirectional and tuned to the GPS frequency, snow skids down, birds can't land on it. As N0UU affirms, there's nothing further sensational inside. I don't know, how proficient you are with radio frequency stuff, but a gain of 35dB does not guarantee a good reception. You primarily need gain to compensate (cable) losses. The noise figure (NF), for example, can get much more important. What antenna do you use at the time? If you are using a magnetic car roof antenna a Trimble Bullet surely will be a better choice... There are lots of GPS antennas on ebay for even less than 30 Dollars. I run four different antennas, which I purchased from ebay and none of them has failed so far. Volker Am 10.03.2013 06:07, schrieb Peter Gottlieb: I'd like to get a better antenna for my Thunderbolt. I see Trimble bullet antennas type 57860-00 on ebay for $30 or so, specs look to be 5 volt 35 dB gain. Would something like this be a good choice? Peter ___ 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. - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1430 / Virus Database: 2641/5660 - Release Date: 03/09/13 ___ 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. - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1430 / Virus Database: 2641/5660 - Release Date: 03/09/13 ___ 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] Thunderbolt antenna
Exactly. I'll probably wait until NEARfest up here and pick one up there. You
know, more justification to go.
Peter
On 3/10/2013 12:45 PM, George Dubovsky wrote:
It seems, just go with quad shield RG-6 and be done with it. I even have
part of a spool of that laying around. Maybe more of an issue is how do
you properly connect a TNC to that stuff (the antenna has a TNC).
Peter
Here is one solution:
http://www.showmecables.com/Category/F-Connectors-Adapters.aspx?q=pg=1ps=25fq={attr_display2_sm:TNC%20to%20F}fq={attr_display2_sm:F%20to%20TNC}
http://www.showmecables.com/Category/F-Connectors-Adapters.aspx?q=pg=1ps=25fq=%7Battr_display2_sm:TNC%20to%20F%7Dfq=%7Battr_display2_sm:F%20to%20TNC%7D
73,
geo - n4ua
On 3/10/2013 11:01 AM, Volker Esper wrote:
Hi Peter,
Why not. The antenna is optimized for that purpose (receiving GPS L1),
omnidirectional and tuned to the GPS frequency, snow skids down, birds
can't land on it. As N0UU affirms, there's nothing further sensational
inside.
I don't know, how proficient you are with radio frequency stuff, but a
gain of 35dB does not guarantee a good reception. You primarily need
gain to compensate (cable) losses. The noise figure (NF), for example,
can get much more important.
What antenna do you use at the time? If you are using a magnetic car
roof antenna a Trimble Bullet surely will be a better choice...
There are lots of GPS antennas on ebay for even less than 30 Dollars.
I run four different antennas, which I purchased from ebay and none of
them has failed so far.
Volker
Am 10.03.2013 06:07, schrieb Peter Gottlieb:
I'd like to get a better antenna for my Thunderbolt.
I see Trimble bullet antennas type 57860-00 on ebay for $30 or so,
specs look to be 5 volt 35 dB gain.
Would something like this be a good choice?
Peter
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Re: [time-nuts] Thunderbolt antenna
It seems, just go with quad shield RG-6 and be done with it. I even have
part of a spool of that laying around. Maybe more of an issue is how do
you properly connect a TNC to that stuff (the antenna has a TNC).
Peter
Here is one solution:
http://www.showmecables.com/Category/F-Connectors-Adapters.aspx?q=pg=1ps=25fq={attr_display2_sm:TNC%20to%20F}fq={attr_display2_sm:F%20to%20TNC}http://www.showmecables.com/Category/F-Connectors-Adapters.aspx?q=pg=1ps=25fq=%7Battr_display2_sm:TNC%20to%20F%7Dfq=%7Battr_display2_sm:F%20to%20TNC%7D
73,
geo - n4ua
On 3/10/2013 11:01 AM, Volker Esper wrote:
Hi Peter,
Why not. The antenna is optimized for that purpose (receiving GPS L1),
omnidirectional and tuned to the GPS frequency, snow skids down, birds
can't land on it. As N0UU affirms, there's nothing further sensational
inside.
I don't know, how proficient you are with radio frequency stuff, but a
gain of 35dB does not guarantee a good reception. You primarily need gain
to compensate (cable) losses. The noise figure (NF), for example, can get
much more important.
What antenna do you use at the time? If you are using a magnetic car roof
antenna a Trimble Bullet surely will be a better choice...
There are lots of GPS antennas on ebay for even less than 30 Dollars. I
run four different antennas, which I purchased from ebay and none of them
has failed so far.
Volker
Am 10.03.2013 06:07, schrieb Peter Gottlieb:
I'd like to get a better antenna for my Thunderbolt.
I see Trimble bullet antennas type 57860-00 on ebay for $30 or so, specs
look to be 5 volt 35 dB gain.
Would something like this be a good choice?
Peter
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Re: [time-nuts] Thunderbolt antenna
On Sat, Mar 9, 2013 at 9:07 PM, Peter Gottlieb n...@verizon.net wrote: I'd like to get a better antenna for my Thunderbolt. I see Trimble bullet antennas type 57860-00 on ebay for $30 or so, specs look to be 5 volt 35 dB gain. Would something like this be a good choice? Yes. They work well and it has more than enough gain as long as the cable leength is reasonable.Use the cable TV type RG6 with waterproof F connectors. Those really are waterproof. Then get a F to whatever adaptor for the cable to antenna. Actually it hardly matters if the connection is water proof because it is make inside the 1 inch pipe. That is the other advantage of this type antenna: It mounts on a pipe. So get the longest pipe you can manage and get the antenna out into free space and far from reflections and so on and with a good view of the horizon.Location is far more importance then the brand of antenna or the type of cable. Put with the abilty to mount on a tall mast you can get a good location. If this antenna works better it will be because of the better location more so then because of the antenna The pipe is not that expensive and doubles as a conduit for the cable. But do remember to ground the pipe. Give lightening an easy and direct path to ground and it will follow that route. 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] frequency reference for portable operation
Hi The FE Rb's are dirty enough that you may need a second stage of PLL filtering in the system. Possibly a cheap 10 MHz low power OCXO and a sub 1Hz loop. A lot depends on just how good you want the close in noise and spurs to be. Put another way - is this PSK-32 at 10 GHz or conventional AM or …? Do we want to tune a bit to find the guy or not? The flip side to the fancy stuff would be SSB at 10 GHz. If I'm within a couple of KHz, I can hear you / you can hear me. We can tune to match things up. That drops the accuracy on the mobile end to 100's of ppb. A $30 eBay OCXO will handle 1/10th of that nicely. A cell phone TCXO might also do the trick over a narrow range. I'd much rather have the OCXO's stability once I tune on frequency. Bob On Mar 10, 2013, at 12:36 PM, ewkeh...@aol.com wrote: Having built a few portable frequency sources my recommendation based on your application and what is reasonably available today would be a FE 5680A in combination with a 100 MHz clean up XO. We have very good results with a slightly modified what I call the Dorsten PLL-VCXO by W-H-Rech. I can send you the article and some plots, the article is in German but you would be able to understand or I would help you. Using an AGM battery and a $ 4 up converter I would plug it in to the car when driving and at home run it off AC and when in the field you will have plenty of time to operate. 9.8 A 12V Li-ion are available for $ 45. When home keep it running and use the RS 232 to update Rb frequency. Bert In a message dated 3/10/2013 10:23:21 A.M. Eastern Daylight Time, jim...@earthlink.net writes: Asking here on behalf of a friend.. With respect to portable amateur microwave operation.. you want good close in phase noise (so you can use narrow band filters) AND good frequency accuracy (so you can find the signal) the typical operation is drive somewhere, operate a bit, drive somewhere operate a bit repeated (contacts from different grid squares/peaks/what haveyou My instinct is that this is an application for a nice quiet OCXO on a battery. Adjust the frequency before you set out against a good reference and just go from there. Surplus Rb references are apparently also popular, but I think they keep those on battery too (that is, you need to be ready to go 10 minutes after arriving, and I don't know that a Rb is settled in that quickly). So the question from my friend was with reference to GPS disciplined oscillators. Would that do any better? I'm used to GPSDOs in a fixed location where you have time to do long term averaging. And what about truly mobile operation (there are folks in the SF bay area apparently doing 10GHz mobile ops.. slotted WG radiator on the roof of the car, etc.) What sort of 1pps timing accuracy do you get from a GPS on the move. I assume it would have the usual 10ns sort of uncertainty (in that the mfr specs don't say only with the antenna fixed in one place for N hours). 10ns is only 1E-8 of a second. Presumably one can average a bit over many pps ticks. I've got a bunch of Wenzel Streamline units, and they typically do 1E-10/day aging and 1E-9 over temp. Assuming the temperature doesn't vary a lot, seems like the OCXO is better than the GPS, at least in a 1-2 day time frame. (and, of course, isn't that just what a GPSDO is, in holdover mode, anyway) The Rb is good to 1E-11 over the short run (assuming it's been calibrated recently) but I notice that the PRS10 data sheet says 7 minutes to 1E-9, so in the non continuously powered mode of operation, it's not all that wonderful. The Rb is definitely higher powered.. The PRS10 is 2+ amps at 28V to start, and 0.6 to run. 15-16 Watts is a lot to keep on a battery. (Assume you run off a pair of 7Ah 12V batteries.. that gives you 10-12 hours). The Wenzel is a couple watts (after a 5W warmup). The GPS is a LOT lower power. The Garmin GPS 18x is 0.45W, of course the 1pps on that receiver is only specified to 1 microsecond.. A moto Oncore UT is a bit less than a watt and claims 100ns (with SA.. showing the age of the datasheet I have). ___ 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] Thunderbolt antenna
On 3/10/2013 12:04 PM, Peter Gottlieb wrote: RG-5910.4 dB/100 ft RG-68.4 dB/100 ft Heliax 7.4 dB/100 ft FSJ1-50A RG-11 5.7 dB/100 ft (Yes, I'm aware of the impedance differences) I used LMR-400. 5.1 dB @1.5 GHz /100 ft, 90 dB shield. And, it's 50 ohms. ___ 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] Thunderbolt antenna
Also available from Times Microwave in 75 Ohm. Google LMR400-754.9 dB per 100 ft. @ 1.5 GHz. -- FL --- Den søn 10/3/13 skrev Mike S mi...@flatsurface.com: Fra: Mike S mi...@flatsurface.com Emne: Re: [time-nuts] Thunderbolt antenna Til: time-nuts@febo.com Dato: søndag 10. marts 2013 11.22 On 3/10/2013 12:04 PM, Peter Gottlieb wrote: RG-59 10.4 dB/100 ft RG-6 8.4 dB/100 ft Heliax 7.4 dB/100 ft FSJ1-50A RG-11 5.7 dB/100 ft (Yes, I'm aware of the impedance differences) I used LMR-400. 5.1 dB @1.5 GHz /100 ft, 90 dB shield. And, it's 50 ohms. ___ 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] Need info on Trimble 4000S GPS Surveyor
I recently acquired a junker Trimble 4000S GPS surveying unit. It's mid-1980s technology, so very big, but nice to salvage various RF and signal processing goodies from. I have no plan to get it working, and no need for the function - it's just for parts/subsection use. I found that this unit is way beyond obsolete, and found no support info on-line. I'm just wondering if anyone has or knows of info on it - even a block diagram would help, or anything to fill in some blanks. I've saved the RF/PLL modules intact, and recorded the interconnections and supplies, so I can (eventually) figure out what everything does. This unit uses both the L1 and L2 carriers, and has eight canned function modules plus an OCXO to do the front-end work. Other than the power supplies, the entire interconnection appears to be just two IFs and two references going to the control/DSP board assembly (four huge boards), and a 16-bit parallel DAC drive from there to control the EFC line to the OCXO. The L1 1575.42 MHz chain uses a 16.368 MHz VCXO locked to the 10 MHz reference, running an LO of some integer multiple that results in a reference around 38.4 MHz labeled ECL 38.4 F0 on the main board, and an unlabeled signal IF called TTL LIMITER. Internal markings 768 and 384 may indicate PLL IFs of 76.8 and 38.4 (76.8/2) MHz. The L2 1227.6 MHz chain uses a 28.644 MHz VCXO locked to the 16.368 MHz reference, and LO that results in another unknown IF that runs through a similar TTL limiter. It appears that the LO is an integer multiple of the 28.644 MHz, with a PLL IF possibly around 59.2 MHz, marked 592 FO. Only the unknown signal IF from this section goes to the processing boards - no PLL IF seems to go beyond these modules. The unknown signal IF goes only to one of two apparently identical DSP boards, unlike the others that all go to the main board. The L1 downconverter appears to use quadrature mixing, but I can't tell what happens after that - the I-Q signals go into a bunch of baseband circuitry. The L2 one also has a quadrature mixer, but only one output goes into its baseband circuits - the other is just terminated. As I understand, the L2 is always encrypted, so useless for data, but its carrier can be used to enhance overall accuracy - I recall studying that a few years ago, but forgot the details. So, maybe the L2 portion is only for carrier recovery of some sort. So, here's what goes between the RF section and the rest: RF to main board: 1. Main reference 16.368 MHz 2. L1 DSP reference approx 38.4 MHz 3. L1 IF unknown frequency RF to one DSP board: L2 IF (or recovered carrier?) unknown frequency Main board to RF: 16 bits DAC EFC tuning for 10 MHz reference Antenna to RF: Input to diplexer, with +15 VDC feed for preamp I'd appreciate any info or ideas on deciphering the rest of the way - maybe the modules will be useful for something as a system, rather than just parts. I'm especially interested in GPS carrier recovery techniques for frequency only - not time. Ed ___ 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] Thunderbolt antenna
I bought one of the 40 db gain GPS antennas that were on Ebay some time ago. I had been using a mushroom style antenna with an rg-59 lead that came with one of the Thunderbolts. I have maybe 75 feet of rg-6 lead in. Rg-6 sold for satellite dishes or cable companies should do just fine without requiring a second mortgage on one's house. Try to liberate some from your cable guy or order some from pchcables.com. -- Chuck Forsberg WA7KGX c...@omen.com www.omen.com Developer of Industrial ZMODEM(Tm) for Embedded Applications Omen Technology Inc The High Reliability Software 10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430 ___ 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] Thunderbolt antenna
Hi You do need to be a little careful with gain. Past a certain point, you do no more good for the noise figure of the system , but you do degrade the overload performance. Bob On Mar 10, 2013, at 3:40 PM, Chuck Forsberg WA7KGX N2469R c...@omen.com wrote: I bought one of the 40 db gain GPS antennas that were on Ebay some time ago. I had been using a mushroom style antenna with an rg-59 lead that came with one of the Thunderbolts. I have maybe 75 feet of rg-6 lead in. Rg-6 sold for satellite dishes or cable companies should do just fine without requiring a second mortgage on one's house. Try to liberate some from your cable guy or order some from pchcables.com. -- Chuck Forsberg WA7KGX c...@omen.com www.omen.com Developer of Industrial ZMODEM(Tm) for Embedded Applications Omen Technology Inc The High Reliability Software 10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430 ___ 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] Thunderbolt antenna
To me, that seems to be a much more important issue than suggestions about the right cable. Volker Am 10.03.2013 21:48, schrieb Bob Camp: Hi You do need to be a little careful with gain. Past a certain point, you do no more good for the noise figure of the system , but you do degrade the overload performance. Bob On Mar 10, 2013, at 3:40 PM, Chuck Forsberg WA7KGX N2469Rc...@omen.com wrote: I bought one of the 40 db gain GPS antennas that were on Ebay some time ago. I had been using a mushroom style antenna with an rg-59 lead that came with one of the Thunderbolts. I have maybe 75 feet of rg-6 lead in. Rg-6 sold for satellite dishes or cable companies should do just fine without requiring a second mortgage on one's house. Try to liberate some from your cable guy or order some from pchcables.com. -- Chuck Forsberg WA7KGX c...@omen.com www.omen.com Developer of Industrial ZMODEM(Tm) for Embedded Applications Omen Technology Inc The High Reliability Software 10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430 ___ 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] Loran again
Hi All; I hear Loran C signals back on again, I'll fire up the SRS FS-700 and check. RP ___ 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] Loran again
Yes, LORAN is in and I have been locked up to GRI 89700, for a few hours now. Stan, W1LE Cape Cod On 3/10/2013 6:55 PM, Rich and Marcia Putz wrote: Hi All; I hear Loran C signals back on again, I'll fire up the SRS FS-700 and check. RP ___ 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] Loran again
Where are you? -John === Hi All; I hear Loran C signals back on again, I'll fire up the SRS FS-700 and check. RP ___ 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] frequency reference for portable operation
I agree with using an OCXO for amateur radio operation. The main activity in the US is the 10 GHz and Up contest which takes place over two weekends, mid-August and mid-September. I've been active in most of them for the last 15 years. Full participation requires operating something like 12 hrs each of the two weekend days. Occasionally I have operated into the wee hours Saturday night. Some people go to a high location like a mountain top and stay there all weekend. Many rove, driving hundreds of miles, or some combination of the two strategies. Very few have AC power available so operate on batteries for the two days, though sometimes with the option of charging batteries between stops or by just running your engine or a generator. By contest rules, to count as a new contact, at least one of the two stations needs to move 10 miles or more from a previous location -- hence the rover strategy. To reduce your levels of uncertainty in making contacts, two things matter, antenna pointing accuracy and frequency accuracy and stability. Being exactly on frequency is nice, but being off a few hundred Hz at 10 GHz is usually in the radio passband and good enough. So in my experience a good OCXO is fine. It is accurate enough, very stable for many minutes of contact operation, has good phase noise and moderate power consumption. I think most people in the contest are using OCXOs. I never checked exact accuracy, but I think, even with a lot of driving and temperature extremes my rig stays within a few tens of Hz at 10 GHz. A few operators use rubidiums. To my thinking, the extra accuracy is not really needed and the extra power consumption is not worth going that way if you are running off batteries. Usually, the ones available tend to have a bit worse phase noise than a good OCXO too, though I'm not sure if enough worse to matter in real contacts. I have thought about taking a rubidium along to power on occasionally and calibrate the OCXO but never found my OCXO frequency to be an issue so never bothered to take the rubidium. There are applications like microwave EME where very weak signals are extracted by post-processing the data of a long contact in the noise level. In that case rubidium accuracy is needed for very narrow bandwidth contacts. You mentioned operating while driving. A few people have the omni antennas to do that and I have worked some of them. For that the frequency accuracy becomes moot. At freeway speeds the doppler shift at 10 GHz is very significant in the audio range. Because of that, the mobile-while-moving contacts are usually made in FM mode with wide bandwidths and no need for very accurate frequency. That mode can't do the long distances of dishes and narrow SSB or CW but it has worked better than I would have expected. Also, the 10-mile rule tends to make the FM mobile less useful and it usually happens as an experiment while someone is driving home at the end. One side note about doppler. Often several guys roam in small packs. To begin a contact, often one station will put up a steady carrier for the other end stations to find. Often the rovers are set up near a freeway and a station receiving near the guy sending steady carrier will hear whoops in the steady tone caused by doppler bouncing of the signal off the freeway traffic. In my view, using GPS locked oscillators has the same disadvantage of power consumption as the rubidiums. If you are in one location (a mountain top, etc.) for long periods of time, it might work, especially if you have AC available, but for roving, with the many locations, I would think it would either not give you much accuracy or would cause a big operational time penalty for multiple surveys. I'm not aware of any roving operators around here using GPS (except for location, which almost everyone now uses to determine their operating location). A few operators, get by with an only moderately stabilized frequency. This might be a brick oscillator with its so-so internal oven. It's better to get out than to stay home thinking about better options. The poor frequency control is usually on new operator's rigs and was more common 10 years back. If the frequency is fairly stable, then the drifting can be reined in by going out with other hams who have good frequency to calibrate from, or if you have a beacon in range that you can find to establish your offset. So, yes, OCXO is the way most hams lock their mobile microwave rigs. -Rex, KK6MK On 3/10/2013 7:23 AM, Jim Lux wrote: Asking here on behalf of a friend.. With respect to portable amateur microwave operation.. you want good close in phase noise (so you can use narrow band filters) AND good frequency accuracy (so you can find the signal) the typical operation is drive somewhere, operate a bit, drive somewhere operate a bit repeated (contacts from different grid squares/peaks/what haveyou My instinct is that this is an
Re: [time-nuts] frequency reference for portable operation
Hi If you go with one of the better DOCXO's on eBay (spend the full $30 not $15) you should get something that will hold 0.3 ppb for 48 hours. You would have to do a few things: 1) Keep it on power for a couple weeks ahead of time. 2) Keep it on power the whole weekend. 3) Make sure it's always in the same orientation (base down or whatever) 4) Put it in something like a cooler to keep the drafts off of it 5) Regulate the supply and efc tightly. You might have to buy three and sort them, but I suspect not. One ppb at 10 GHz would be 10 Hz. The carefully minded DOCXO should keep you within 3 Hz. Bob On Mar 10, 2013, at 6:24 PM, Rex r...@sonic.net wrote: I agree with using an OCXO for amateur radio operation. The main activity in the US is the 10 GHz and Up contest which takes place over two weekends, mid-August and mid-September. I've been active in most of them for the last 15 years. Full participation requires operating something like 12 hrs each of the two weekend days. Occasionally I have operated into the wee hours Saturday night. Some people go to a high location like a mountain top and stay there all weekend. Many rove, driving hundreds of miles, or some combination of the two strategies. Very few have AC power available so operate on batteries for the two days, though sometimes with the option of charging batteries between stops or by just running your engine or a generator. By contest rules, to count as a new contact, at least one of the two stations needs to move 10 miles or more from a previous location -- hence the rover strategy. To reduce your levels of uncertainty in making contacts, two things matter, antenna pointing accuracy and frequency accuracy and stability. Being exactly on frequency is nice, but being off a few hundred Hz at 10 GHz is usually in the radio passband and good enough. So in my experience a good OCXO is fine. It is accurate enough, very stable for many minutes of contact operation, has good phase noise and moderate power consumption. I think most people in the contest are using OCXOs. I never checked exact accuracy, but I think, even with a lot of driving and temperature extremes my rig stays within a few tens of Hz at 10 GHz. A few operators use rubidiums. To my thinking, the extra accuracy is not really needed and the extra power consumption is not worth going that way if you are running off batteries. Usually, the ones available tend to have a bit worse phase noise than a good OCXO too, though I'm not sure if enough worse to matter in real contacts. I have thought about taking a rubidium along to power on occasionally and calibrate the OCXO but never found my OCXO frequency to be an issue so never bothered to take the rubidium. There are applications like microwave EME where very weak signals are extracted by post-processing the data of a long contact in the noise level. In that case rubidium accuracy is needed for very narrow bandwidth contacts. You mentioned operating while driving. A few people have the omni antennas to do that and I have worked some of them. For that the frequency accuracy becomes moot. At freeway speeds the doppler shift at 10 GHz is very significant in the audio range. Because of that, the mobile-while-moving contacts are usually made in FM mode with wide bandwidths and no need for very accurate frequency. That mode can't do the long distances of dishes and narrow SSB or CW but it has worked better than I would have expected. Also, the 10-mile rule tends to make the FM mobile less useful and it usually happens as an experiment while someone is driving home at the end. One side note about doppler. Often several guys roam in small packs. To begin a contact, often one station will put up a steady carrier for the other end stations to find. Often the rovers are set up near a freeway and a station receiving near the guy sending steady carrier will hear whoops in the steady tone caused by doppler bouncing of the signal off the freeway traffic. In my view, using GPS locked oscillators has the same disadvantage of power consumption as the rubidiums. If you are in one location (a mountain top, etc.) for long periods of time, it might work, especially if you have AC available, but for roving, with the many locations, I would think it would either not give you much accuracy or would cause a big operational time penalty for multiple surveys. I'm not aware of any roving operators around here using GPS (except for location, which almost everyone now uses to determine their operating location). A few operators, get by with an only moderately stabilized frequency. This might be a brick oscillator with its so-so internal oven. It's better to get out than to stay home thinking about better options. The poor frequency control is usually on new operator's rigs and was more common 10 years back. If the frequency is fairly
Re: [time-nuts] GPS Antenna Install
Quite the nice QTH you have there! Wish I had an East Coast trip scheduled -- would love to visit. Dave -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Martin A Flynn Sent: Sunday, March 10, 2013 08:20 To: Discussion of precise time and frequency measurement Subject: [time-nuts] GPS Antenna Install Sorry about the blank messages - not sure why I could not reply to my own message... In any case, thanks to the help from kind folks on the list, the TS-2100L in in the rack at the N2MO amateur radio station at InfoAge. The N2MO team spent yesterday doing the prep work to mount a 27dB antenna on the gable end of the building, using 1/2 heliax for feed line, with a Polyphaser DGXZ + 06NFNF installed in the line before it enters the building. The antenna mount pipe and the Polyphaser are grounded via #2 copper cable that will be exothermic welded to the ground rod. Thanks again! Martin Flynn PS - Now that the precision time bug has bitten, the team, is considering a Rubidium standard! ___ 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] frequency reference for portable operation
I haven't researched this yet, but the SDR crowd is using GSM and LTE for tuning their sample clocks. https://github.com/steve-m/kalibrate-rtl https://github.com/Evrytania/LTE-Cell-Scanner I have no idea what kind of accuracy you can get from a tower. ___ 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 reference for portable operation
r...@sonic.net said: or if you have a beacon in range that you can find to establish your offset. What do you do after you determine the offset? Do you tweak it out with a trimmer (R or C)? Or tell the software? Or do the corrections with pencil and paper? -- 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] frequency reference for portable operation
Hi With GSM you *may* have 10 ppb, you may get a lot better. With LTE you *should* get better, but you don't always. That was the downfall of the Symmetricom 2700. You are very much at the mercy of the cellphone outfit. They may or may not be paying attention. Bob On Mar 10, 2013, at 8:37 PM, gary li...@lazygranch.com wrote: I haven't researched this yet, but the SDR crowd is using GSM and LTE for tuning their sample clocks. https://github.com/steve-m/kalibrate-rtl https://github.com/Evrytania/LTE-Cell-Scanner I have no idea what kind of accuracy you can get from a tower. ___ 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.
