[time-nuts] Pulsars (was: 60 KHz Receiver)
jim...@earthlink.net said: If you want something that isn't run by governments,and is a technical challenge, how about pulsars? I'd guess (not having looked into it at all) that is would be cheaper to set up a station to receive pulsars than to run a Cs standard. What sort of gear does it take to hear a pulsar? What sort of spectrum are they sending? What frequencies would I listen to? What sort of bandwidth would the receiver use? If I have a setup that can hear Pulsar A, will it also be useful for Pulsar B and C and ...? Or do I need to listen on widely different frequencies? One problem with pulsars is that they might go below the horizon for part of the day. Is there a convenient one up near the north pole? I assume that they are weak enough that I need a steerable dish. Is there a catalog of pulsars that might be interesting to use for amateur timekeeping? I assume a strong signal would be the primary consideration. Any chance of hearing one without a dish? -- These are my opinions, not necessarily my employer's. 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] Pulsars (was: 60 KHz Receiver)
Receiving setup - pretty standard amateur eme/radio astromony kit, good antenna, LNA, downconverter. Antenna choice depends on frequency, pulsars are broadband but generally 300 MHz to as many GHz as you can build an LNA. Amateur attempts seem to be 406, ~600, ~1400MHz. 3m dish minimum or equivalent yagi arrays (better at lf end). Bandwidth of a few 10s of KHZ or more - there are trade-offs due to dispersion, high frequencies travel faster than the low ones so the pulse form is 'spread' but signal levels are higher at the lower frequencies. De-dispersion can be done in dsp but probably not real time unless you have lots of cpu power. Best pulsars for timing would seem to be be the millisecond ones but these are seriously faint. For getting the signal out of the noise a gated sampling approach is used locked to the repetition rate and divided down (so a system can be theoretically used for any pulsar) and driven from a Rb source or better (the pros use H-masers). There are lists of these things - try CSIRO in Australia, they have a good on-line database. The Japanese have looked at pulsars as a replacement for national standards but not sure of the results. They are (naturally...) slowing down but should be good for a while yet ;-) regards, Paul Reeves G8GJA -Original Message- From: Hal Murray [mailto:hmur...@megapathdsl.net] Sent: 05 October 2010 07:30 To: Discussion of precise time and frequency measurement Subject: [time-nuts] Pulsars (was: 60 KHz Receiver) jim...@earthlink.net said: If you want something that isn't run by governments,and is a technical challenge, how about pulsars? I'd guess (not having looked into it at all) that is would be cheaper to set up a station to receive pulsars than to run a Cs standard. What sort of gear does it take to hear a pulsar? What sort of spectrum are they sending? What frequencies would I listen to? What sort of bandwidth would the receiver use? If I have a setup that can hear Pulsar A, will it also be useful for Pulsar B and C and ...? Or do I need to listen on widely different frequencies? One problem with pulsars is that they might go below the horizon for part of the day. Is there a convenient one up near the north pole? I assume that they are weak enough that I need a steerable dish. Is there a catalog of pulsars that might be interesting to use for amateur timekeeping? I assume a strong signal would be the primary consideration. Any chance of hearing one without a dish? -- These are my opinions, not necessarily my employer's. 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. This email, including any attachment, is a confidential communication intended solely for the use of the individual or entity to whom it is addressed. It contains information which is private and may be proprietary or covered by legal professional privilege. If you have received this email in error, please notify the sender upon receipt, and immediately delete it from your system. Anything contained in this email that is not connected with the businesses of this company is neither endorsed by nor is the liability of this company. Whilst we have taken reasonable precautions to ensure that any attachment to this email has been swept for viruses, we cannot accept liability for any damage sustained as a result of software viruses, and would advise that you carry out your own virus checks before opening any attachment. ___ 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] Pulsars
Hal Murray wrote: What sort of gear does it take to hear a pulsar? ... Is there a convenient one up near the north pole? A potential target is PSR0329+54, 1.5 Jansky at 400Mhz, which corresponds to about 1.5E-26 W/m^2/Hz. I did some rough calculations and concluded that with a 16dB gain beam, a 120 hour epoch-folding integration might be enough for it to show up on a 'periodgram'. This was with 150kHz bandwidth, 40K front-end temperature. I tried this about 10 years ago, with no success but I didn't have very good antenna steering - I used a bank of four phased high-gain UHF TV antennas, polar mount clamped at +54 declination. It was necessary to write software to continuously re-time the received signal to barycentric coordinates before the integration. I injected a 1PPS from MSF 60kHz as the timing reference. A fun project, one that I will return to one day. -- Paul Nicholson -- ___ 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] 60 KHz Receiver
Hi The bandwidth of anything close to a Loran signal is a *lot* wider than any of the ham bands contemplated below 1 MHz. There's the minor issue of getting the power company to put in a cable to the house for your 1 Mw (capital M not lower case M) transmitter. Even though it's pule, the RF power is way beyond the sub 1 W outputs currently contemplated on those bands. Signal to noise *does* matter. Bob On Oct 5, 2010, at 12:20 AM, J. Forster wrote: a) broadcasts aren't legal for US hams b) ionospheric uncertainty in the skywave path makes this no better than WWV c) Whats wrong with GPS and/or WWV and/or CHU or whatever? d) A cheap Rb would give you a local reference that is much better than what you could do with receiving something via skywave. If you want something that isn't run by governments,and is a technical challenge, how about pulsars? I'd guess (not having looked into it at all) that is would be cheaper to set up a station to receive pulsars than to run a Cs standard. Pulsars take a big dish and they aren't all that good as a standard. A friend of mine proved that at Aricebo years and years ago. While I fully sympathize with the stand alone approach (that's one of the appeals of HF comms in general.. you aren't depending on anyone else's infrastructure), I don't know that setting up a time standards station fits in with that.. I've vaguely heard that there are some new ham allocations in the works below 500 KHz. How about setting up a beacon network that works like LORAN, but at a different frequency. A simple downconverter could then feed the signal into a LORAN receiver? FWIW, -John == ___ 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] 60 KHz Receiver
In message b69fdcaf-2b39-4575-b5cd-66a87fa1b...@rtty.us, Bob Camp writes: Even though it's pule, the RF power is way beyond the sub 1 W outputs currently contemplated on those bands. Signal to noise *does* matter. You know, there are other ways to skin that cat these days. Old-time signals had to be grossly inefficient because the receivers were inefficient, in particular the ear-wristwatch kind of time receivers. These days we have spread-spectrum modulation, and if our only goal is to transmit a timestamp, you can spread pretty wide and far and need very little power to produce a receiveable signal at long distances. The QRSS hams are playing around with numbers like 17,840,000 miles per watt, and all it takes to turn that into a time/frequency services is a spreading function with a really good autocorrelation. Obviously, you will not get second by second measurements, but the measurements you do get, say once per hour, will have much higher precision because of the averaging that goes into them. And equally obvious: propagation effects will take their toll, but still... Somebody with a license should try that on 137kHz... Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Pulsars (was: 60 KHz Receiver)
Hi folks, Well I'm studying pulsars for my Masters at the moment so here's a few hints and tips. My weekend toy is a 26m radio dish with H masers for timing. For the southern hemisphere the Vela pulsar is your best bet. J0835-4510. It's about a Jansky at 1440 MHz. With the 26m dish I can see individual pulses - that and the Crab pulsar are about the only ones available for single pulses with a 26m dish. The receiver is cooled to about 20K. Vela, my main subject, is not the best for timing. It glitches sometimes and only recently sped up. J0437-4715 is the brightest millisecond pulsar and is very good for timing. Too faint for individual pulses for me though. For software look up dspsr and psrchive. These are open source and will do all the work for you. Dedispersion is essential. Don't forget that Vela is highly polarized too. Hot off the presses from a conference last week is that a group of millisecond pulsars is starting to look like they may outdo earth based time standards. I saw some very impressive Allan variance curves. Oh and for bragging rights go to jimpalfreyman.com and look at The Dish folder where you can see us playing cricket on the famous 60m dish at Parkes. Jim Palfreyman On Tuesday, October 5, 2010, Reeves Paul paul.ree...@uk.thalesgroup.com wrote: Receiving setup - pretty standard amateur eme/radio astromony kit, good antenna, LNA, downconverter. Antenna choice depends on frequency, pulsars are broadband but generally 300 MHz to as many GHz as you can build an LNA. Amateur attempts seem to be 406, ~600, ~1400MHz. 3m dish minimum or equivalent yagi arrays (better at lf end). Bandwidth of a few 10s of KHZ or more - there are trade-offs due to dispersion, high frequencies travel faster than the low ones so the pulse form is 'spread' but signal levels are higher at the lower frequencies. De-dispersion can be done in dsp but probably not real time unless you have lots of cpu power. Best pulsars for timing would seem to be be the millisecond ones but these are seriously faint. For getting the signal out of the noise a gated sampling approach is used locked to the repetition rate and divided down (so a system can be theoretically used for any pulsar) and driven from a Rb source or better (the pros use H-masers). There are lists of these things - try CSIRO in Australia, they have a good on-line database. The Japanese have looked at pulsars as a replacement for national standards but not sure of the results. They are (naturally...) slowing down but should be good for a while yet ;-) regards, Paul Reeves G8GJA -Original Message- From: Hal Murray [mailto:hmur...@megapathdsl.net] Sent: 05 October 2010 07:30 To: Discussion of precise time and frequency measurement Subject: [time-nuts] Pulsars (was: 60 KHz Receiver) jim...@earthlink.net said: If you want something that isn't run by governments,and is a technical challenge, how about pulsars? I'd guess (not having looked into it at all) that is would be cheaper to set up a station to receive pulsars than to run a Cs standard. What sort of gear does it take to hear a pulsar? What sort of spectrum are they sending? What frequencies would I listen to? What sort of bandwidth would the receiver use? If I have a setup that can hear Pulsar A, will it also be useful for Pulsar B and C and ...? Or do I need to listen on widely different frequencies? One problem with pulsars is that they might go below the horizon for part of the day. Is there a convenient one up near the north pole? I assume that they are weak enough that I need a steerable dish. Is there a catalog of pulsars that might be interesting to use for amateur timekeeping? I assume a strong signal would be the primary consideration. Any chance of hearing one without a dish? -- These are my opinions, not necessarily my employer's. 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. This email, including any attachment, is a confidential communication intended solely for the use of the individual or entity to whom it is addressed. It contains information which is private and may be proprietary or covered by legal professional privilege. If you have received this email in error, please notify the sender upon receipt, and immediately delete it from your system. Anything contained in this email that is not connected with the businesses of this company is neither endorsed by nor is the liability of this company. Whilst we have taken reasonable precautions to ensure that any attachment to this email has been swept for viruses, we cannot accept liability for any damage sustained as a result of software viruses, and would advise that you carry out your own virus checks before opening any attachment.
Re: [time-nuts] 60 KHz Receiver
Hi If you were starting from scratch there are a lot of things you could do. If the intent is to put out something a Loran receiver will recognize ... not so much. Bob On Oct 5, 2010, at 6:44 AM, Poul-Henning Kamp wrote: In message b69fdcaf-2b39-4575-b5cd-66a87fa1b...@rtty.us, Bob Camp writes: Even though it's pule, the RF power is way beyond the sub 1 W outputs currently contemplated on those bands. Signal to noise *does* matter. You know, there are other ways to skin that cat these days. Old-time signals had to be grossly inefficient because the receivers were inefficient, in particular the ear-wristwatch kind of time receivers. These days we have spread-spectrum modulation, and if our only goal is to transmit a timestamp, you can spread pretty wide and far and need very little power to produce a receiveable signal at long distances. The QRSS hams are playing around with numbers like 17,840,000 miles per watt, and all it takes to turn that into a time/frequency services is a spreading function with a really good autocorrelation. Obviously, you will not get second by second measurements, but the measurements you do get, say once per hour, will have much higher precision because of the averaging that goes into them. And equally obvious: propagation effects will take their toll, but still... Somebody with a license should try that on 137kHz... Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Radio based time stations
-Original Message- Chuck wrote - _ Date: Tue, 05 Oct 2010 00:16:29 -0400 From: Chuck Harris cfhar...@erols.com Subject: Re: [time-nuts] 60 KHz Receiver To: Discussion of precise time and frequency measurement snip And if you are worried about the station being in North America, there are time stations in virtually every corner of the world. _ Sad to say, Chuck, those stations are fading fast. Many nations have dropped out of the business of providing time in that fashion in the last decade or so. Australia was one of the more notable recent losses. I don't believe that the African continent has a single station left. Even CHU was being eyed speculatively by the Canadian powers a while back. Overall, we probably now have a quarter to a third of the SW time stations compared to those that that existed 20 years ago. I suspect that the increasing availability of cheap GPSDO gear to the average Joe had a lot to do with it. Lee ___ 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] Radio based time stations
Lee Reynolds writes: Overall, we probably now have a quarter to a third of the SW time stations compared to those that that existed 20 years ago. I think too many radio-controlled alarmclocks have been sold for the remaning big VLF stations to disappear any time soon... Shortwave ? I can live without those, as far as I know we never really had any here in europe... Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Radio based time stations
Hi I believe that we have 1/4 the shortwave services we had 20 years ago. Not just for time, but the whole set of commercial / governmental transmitting setups. Bob On Oct 5, 2010, at 7:30 AM, Lee Reynolds wrote: -Original Message- Chuck wrote - _ Date: Tue, 05 Oct 2010 00:16:29 -0400 From: Chuck Harris cfhar...@erols.com Subject: Re: [time-nuts] 60 KHz Receiver To: Discussion of precise time and frequency measurement snip And if you are worried about the station being in North America, there are time stations in virtually every corner of the world. _ Sad to say, Chuck, those stations are fading fast. Many nations have dropped out of the business of providing time in that fashion in the last decade or so. Australia was one of the more notable recent losses. I don't believe that the African continent has a single station left. Even CHU was being eyed speculatively by the Canadian powers a while back. Overall, we probably now have a quarter to a third of the SW time stations compared to those that that existed 20 years ago. I suspect that the increasing availability of cheap GPSDO gear to the average Joe had a lot to do with it. Lee ___ 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] 60 KHz Receiver
A great thread by everyone. Oh to make the loran receivers work. But that is indeed the past. Can not hear Europe on east coast. But the question really is, what do you want to accomplish? I don't think its a time stamp. Its just to easy to get it from GPS or the network. But that could be a secondary use. I believe the primary goal would be frequency distribution with perhaps a tick. If this is the goal then I am 100% in agreement that there are far more efficient modulation and recovery methods today. The trick is you need something that does not effect the accuracy of the timing and may improve the various transmission issues at these frequencies. By the way this list has a heck of a brain trust so its very very possible. Someone mentioned spread spectrum. Thats very interesting as it is what GPS uses and could work at these lower frequencies. Like the Hey this is just telemetry comment. You know the FCC does indeed give temp authorization for quite long periods of time. Years in fact. So I would be in the keep it simple mode. Great a single carrier with a id every 10 min. Maybe that could be waved to 1 per hour or 24 hours. Unfortunately then we have nothing better then wwvb. The modulation method may be key and then what freq we would use. BPSK at higher frequencies is also impressive. My first contact was in the indian ocean on 5 whats from boston. Regards Paul WB8TSL On Tue, Oct 5, 2010 at 6:59 AM, Bob Camp li...@rtty.us wrote: Hi If you were starting from scratch there are a lot of things you could do. If the intent is to put out something a Loran receiver will recognize ... not so much. Bob On Oct 5, 2010, at 6:44 AM, Poul-Henning Kamp wrote: In message b69fdcaf-2b39-4575-b5cd-66a87fa1b...@rtty.us, Bob Camp writes: Even though it's pule, the RF power is way beyond the sub 1 W outputs currently contemplated on those bands. Signal to noise *does* matter. You know, there are other ways to skin that cat these days. Old-time signals had to be grossly inefficient because the receivers were inefficient, in particular the ear-wristwatch kind of time receivers. These days we have spread-spectrum modulation, and if our only goal is to transmit a timestamp, you can spread pretty wide and far and need very little power to produce a receiveable signal at long distances. The QRSS hams are playing around with numbers like 17,840,000 miles per watt, and all it takes to turn that into a time/frequency services is a spreading function with a really good autocorrelation. Obviously, you will not get second by second measurements, but the measurements you do get, say once per hour, will have much higher precision because of the averaging that goes into them. And equally obvious: propagation effects will take their toll, but still... Somebody with a license should try that on 137kHz... Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] 60 KHz Receiver
One other comment Would be great to be on 100KC But I might guess some one in gov will wake up to suggest that it could interfere with europe and not allow it. Or the treaties exist to forbid reuse. On Tue, Oct 5, 2010 at 8:57 AM, paul swed paulsw...@gmail.com wrote: A great thread by everyone. Oh to make the loran receivers work. But that is indeed the past. Can not hear Europe on east coast. But the question really is, what do you want to accomplish? I don't think its a time stamp. Its just to easy to get it from GPS or the network. But that could be a secondary use. I believe the primary goal would be frequency distribution with perhaps a tick. If this is the goal then I am 100% in agreement that there are far more efficient modulation and recovery methods today. The trick is you need something that does not effect the accuracy of the timing and may improve the various transmission issues at these frequencies. By the way this list has a heck of a brain trust so its very very possible. Someone mentioned spread spectrum. Thats very interesting as it is what GPS uses and could work at these lower frequencies. Like the Hey this is just telemetry comment. You know the FCC does indeed give temp authorization for quite long periods of time. Years in fact. So I would be in the keep it simple mode. Great a single carrier with a id every 10 min. Maybe that could be waved to 1 per hour or 24 hours. Unfortunately then we have nothing better then wwvb. The modulation method may be key and then what freq we would use. BPSK at higher frequencies is also impressive. My first contact was in the indian ocean on 5 whats from boston. Regards Paul WB8TSL On Tue, Oct 5, 2010 at 6:59 AM, Bob Camp li...@rtty.us wrote: Hi If you were starting from scratch there are a lot of things you could do. If the intent is to put out something a Loran receiver will recognize ... not so much. Bob On Oct 5, 2010, at 6:44 AM, Poul-Henning Kamp wrote: In message b69fdcaf-2b39-4575-b5cd-66a87fa1b...@rtty.us, Bob Camp writes: Even though it's pule, the RF power is way beyond the sub 1 W outputs currently contemplated on those bands. Signal to noise *does* matter. You know, there are other ways to skin that cat these days. Old-time signals had to be grossly inefficient because the receivers were inefficient, in particular the ear-wristwatch kind of time receivers. These days we have spread-spectrum modulation, and if our only goal is to transmit a timestamp, you can spread pretty wide and far and need very little power to produce a receiveable signal at long distances. The QRSS hams are playing around with numbers like 17,840,000 miles per watt, and all it takes to turn that into a time/frequency services is a spreading function with a really good autocorrelation. Obviously, you will not get second by second measurements, but the measurements you do get, say once per hour, will have much higher precision because of the averaging that goes into them. And equally obvious: propagation effects will take their toll, but still... Somebody with a license should try that on 137kHz... Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Interesting time interval measuring chip....
Hello, Time-Nutters-- A friend pointed me to an interesting chip for time interval measurement and related time and temperature measurement functions: A general purpose TDC: The TDC-GP2 I think the chip is around $20 in single-unit quantity. www.acam.de Measurement range 3.5 ns to 1.8 us 2 channels with resolution of 50 ps 4 events can be measured against each other 15 ns pulse-pair resolution - It also has a temperature measurement function: 2 or 4 sensors 16 bit resolution 0.004 Deg C resolution for platinum sensors --- Mike Baker ___ 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] 60 KHz Receiver
Were it me, I would change the model from a few high power transmitters netted together to a ton of WiFi routers running special software and netted together. -Chuck Harris paul swed wrote: A great thread by everyone. Oh to make the loran receivers work. But that is indeed the past. Can not hear Europe on east coast. But the question really is, what do you want to accomplish? I don't think its a time stamp. Its just to easy to get it from GPS or the network. But that could be a secondary use. I believe the primary goal would be frequency distribution with perhaps a tick. If this is the goal then I am 100% in agreement that there are far more efficient modulation and recovery methods today. The trick is you need something that does not effect the accuracy of the timing and may improve the various transmission issues at these frequencies. By the way this list has a heck of a brain trust so its very very possible. Someone mentioned spread spectrum. Thats very interesting as it is what GPS uses and could work at these lower frequencies. Like the Hey this is just telemetry comment. You know the FCC does indeed give temp authorization for quite long periods of time. Years in fact. So I would be in the keep it simple mode. Great a single carrier with a id every 10 min. Maybe that could be waved to 1 per hour or 24 hours. Unfortunately then we have nothing better then wwvb. The modulation method may be key and then what freq we would use. BPSK at higher frequencies is also impressive. My first contact was in the indian ocean on 5 whats from boston. Regards Paul ___ 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] 60 KHz Receiver
Hi The bandwidth of anything close to a Loran signal is a *lot* wider than any of the ham bands contemplated below 1 MHz. There's the minor issue of getting the power company to put in a cable to the house for your 1 Mw (capital M not lower case M) transmitter. I was not contemplating a global navigation system. Just enough to get a LORAN type timing, not navigation, lock over a few hundred mile radius. -John = Even though it's pule, the RF power is way beyond the sub 1 W outputs currently contemplated on those bands. Signal to noise *does* matter. Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 60 KHz Receiver
Millisecond pulsars have been proposed as being suitable as comparable to atomic clocks. I don't know how much power they put out, but there are stories about people with backyard size dishes receiving pulsars. Not sure if they're the right kind of pulsar, though. But hey, when fabricating your own Cs fountain or H maser seems boring. On Oct 4, 2010, at 9:20 PM, J. Forster j...@quik.com wrote: Pulsars take a big dish and they aren't all that good as a standard. A friend of mine proved that at Aricebo years and years ago. While I fully sympathize with the stand alone approach (that's one of the appeals of HF comms in general.. you aren't depending on anyone else's infrastructure), I don't know that setting up a time standards station fits in with that.. I've vaguely heard that there are some new ham allocations in the works below 500 KHz. How about setting up a beacon network that works like LORAN, but at a different frequency. A simple downconverter could then feed the signal into a LORAN receiver? FWIW, -John == ___ 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] 60 KHz Receiver
Paul, I'd bet there are 50+ LORAN timing receivers in the Boston area that could receive and lock to an erzatz 5W signal from a simulator and small amp. -John = A great thread by everyone. Oh to make the loran receivers work. But that is indeed the past. Can not hear Europe on east coast. But the question really is, what do you want to accomplish? I don't think its a time stamp. Its just to easy to get it from GPS or the network. But that could be a secondary use. I believe the primary goal would be frequency distribution with perhaps a tick. If this is the goal then I am 100% in agreement that there are far more efficient modulation and recovery methods today. The trick is you need something that does not effect the accuracy of the timing and may improve the various transmission issues at these frequencies. By the way this list has a heck of a brain trust so its very very possible. Someone mentioned spread spectrum. Thats very interesting as it is what GPS uses and could work at these lower frequencies. Like the Hey this is just telemetry comment. You know the FCC does indeed give temp authorization for quite long periods of time. Years in fact. So I would be in the keep it simple mode. Great a single carrier with a id every 10 min. Maybe that could be waved to 1 per hour or 24 hours. Unfortunately then we have nothing better then wwvb. The modulation method may be key and then what freq we would use. BPSK at higher frequencies is also impressive. My first contact was in the indian ocean on 5 whats from boston. Regards Paul WB8TSL On Tue, Oct 5, 2010 at 6:59 AM, Bob Camp li...@rtty.us wrote: Hi If you were starting from scratch there are a lot of things you could do. If the intent is to put out something a Loran receiver will recognize ... not so much. Bob On Oct 5, 2010, at 6:44 AM, Poul-Henning Kamp wrote: In message b69fdcaf-2b39-4575-b5cd-66a87fa1b...@rtty.us, Bob Camp writes: Even though it's pule, the RF power is way beyond the sub 1 W outputs currently contemplated on those bands. Signal to noise *does* matter. You know, there are other ways to skin that cat these days. Old-time signals had to be grossly inefficient because the receivers were inefficient, in particular the ear-wristwatch kind of time receivers. These days we have spread-spectrum modulation, and if our only goal is to transmit a timestamp, you can spread pretty wide and far and need very little power to produce a receiveable signal at long distances. The QRSS hams are playing around with numbers like 17,840,000 miles per watt, and all it takes to turn that into a time/frequency services is a spreading function with a really good autocorrelation. Obviously, you will not get second by second measurements, but the measurements you do get, say once per hour, will have much higher precision because of the averaging that goes into them. And equally obvious: propagation effects will take their toll, but still... Somebody with a license should try that on 137kHz... Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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 unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 60 KHz Receiver
On Oct 4, 2010, at 9:43 PM, Heathkid heath...@heathkid.com wrote: Wow you really missed my point and by having someone listening/monitoring it is not broadcasting. Especially if it is in reality for the most part... telemetry. The FCC is kind of down on transmissions not intended for a specific recipient. There are some exceptions, and informal agreements (e.g. Aprs isnt to a specific recipient, but is intended for one of a group) Not a big deal though, you can get an. Experimental license, though... Maybe I wasn't clear or maybe my message could have been misunderstood. For that, I am truly sorry. I was thinking along the lines of what John stated, a beacon network that works like LORAN You could do an experiment like that with a group, but I don't think it's viable as a continuing operation. And besides, I don't know that it really fills a need... HF isn't great for time distribution, and there aren't suitable bands for hams down low. * I'll shut up now and go back to just reading the posts for another month or so... Naah All ideas are interesting, and just because *I* don't think it's great doesn't mean that someone else might not think it's the bees knees 73 Brice KA8MAV - Original Message - From: jimlux jim...@earthlink.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Monday, October 04, 2010 11:39 PM Subject: Re: [time-nuts] 60 KHz Receiver Heathkid wrote: Doesn't someone on here with a Ham license have a Cs standard and could put up a 1pps signal? Simply transmit your callsign within the 1pps (there has to be a way) and we have a non-Govt. time standard if needed. A simple 1pps PSK-31 (or other digital mode) signal would probably work and be completely legal. Let's do this on our own and not rely on Govt. or GPS... Several throughout the world acting together (I'm not a programmer so someone could step up and figure out the logistics for a receiver) and we would have an alternative to GPS (IF/when it stops working). a) broadcasts aren't legal for US hams b) ionospheric uncertainty in the skywave path makes this no better than WWV c) Whats wrong with GPS and/or WWV and/or CHU or whatever? d) A cheap Rb would give you a local reference that is much better than what you could do with receiving something via skywave. If you want something that isn't run by governments,and is a technical challenge, how about pulsars? I'd guess (not having looked into it at all) that is would be cheaper to set up a station to receive pulsars than to run a Cs standard. While I fully sympathize with the stand alone approach (that's one of the appeals of HF comms in general.. you aren't depending on anyone else's infrastructure), I don't know that setting up a time standards station fits in with that.. ___ 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] 60 KHz Receiver
In message aanlkti=-rejgqkaobgshqz=jfhcb5bd6zezy596ua...@mail.gmail.com, paul swed writes: Great a single carrier with a id every 10 min. Maybe that could be waved to 1 per hour or 24 hours. There is no reason the ID could not be worked into your spreading function so the time to send it would not be lost. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] 60 KHz Receiver
In message aanlktinnoch7bsqsovhpn3qdohapg2pi2w5ynryjf...@mail.gmail.com, paul swed writes: One other comment Would be great to be on 100KC But I might guess some one in gov will wake up to suggest that it could interfere with europe and not allow it. Or the treaties exist to forbid reuse. Here in Denmark 100KHz is dual-licensed and open for low power unlicensed use, because nobody in their right mind would expect a few watts to ever be able to drown out Loran-C... Poul-Henning Exact text from Danish frequencyplan, will not attempt translation to avoid corrupting meaning: Mobile tjenester er begrænset til laveffekts radioanlæg. Laveffekts radioanlæg: Radiogrænseflade nr. 00 008 for laveffekts radioanlæg med spoleformede antenner. Radiogrænseflade nr. 00 023 for aktive medicinske implantater med ultra lav sendeeffekt. Anvendelse af radiofrekvenser i radioanlæg som nævnt i radiogrænseflade nr. 00 008 og nr. 00 023 må ske uden individuel tilladelse til frekvensanvendelse, jf. bekendtgørelse nr. 1119 af 27. november 2009 om anvendelse af radiofrekvenser uden tilladelse samt om amatørradioprøver og kaldesignaler m.v. 100 kHz: ATC. Militær anvendelse. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] 60 KHz Receiver
On Oct 4, 2010, at 10:26 PM, Heathkid heath...@heathkid.com wrote: One more note before I just read the posts for a while... a) broadcasts aren't legal for US hams Do some reading on telemetry and when broadcasts ARE allowed. I've been a Ham for more than 30+ years. Telemetry is allowed only in the sense that it is to a specific recipient(s). That's sort of different from a beacon on hf... I don't know how the ncdxf beacons are licensed.. They may have a STA But legality is the least of the issues.. If you set it up and you're not annoying anyone, I doubt you'll get hassled much.. b) ionospheric uncertainty in the skywave path makes this no better than WWV No kidding... but without GPS (and assuming no Internet as well) how do we sync our clocks besides RF? The way it's been done for centuries... Astronomical or traveling clocks or wireline. How close do you want to sync.. HF paths are probably only good to milliseconds. c) Whats wrong with GPS and/or WWV and/or CHU or whatever? Nothing as long as they are TRANSMITTING. Sure.. As an academic exercise I can see wanting to figure it out, and even doing it as an experiment for the thrill. But If wwv isn't on the air, I don't see hams stepping in to fill the need. And if it's self reliance,then a local atomic reference seems a better approach. d) A cheap Rb would give you a local reference that is much better than what you could do with receiving something via skywave. I have three Rb standards to go along with my two Thunderbolts. So you want to be able to sync your local ref to some other standard? That is more of an ad hoc thing than setting up a beacon, etc. If you want something that isn't run by governments,and is a technical challenge, how about pulsars? I'd guess (not having looked into it at all) that is would be cheaper to set up a station to receive pulsars than to run a Cs standard. Are you serious? Cheaper? Really? I'll trade you a Thunderbolt... complete kit! for a full Pulsar time/frequency reference receiving station that is reliable (and the real-estate plus equipment for a dish large enough for it!). ;) Were not comparing to Tbolts here.. You suggested that someone connect a Cs to some stable transmitter, etc. I think an amateur pulsar receiving system is comparable to the Cs setup. Now, if it's that you want someone else to put up the station, so you don't have to spend the time and moneygrin, You've got some selling to do... What time is it? *that wasn't my point* it's relative and I'm not going to go further with this discussion. I just thought a time-nuts based time system was an interesting prospect. It is interesting.. And figuring out how to do precision time/frequency in an infrastructure-lite environment is challenging, Especially if you want to do it in an adhoc way fairly quickly. It might be cloudy/smoky. Gps and wwv might be unavailable because of interference, locally. So there is value in thinking about it. What I don't think there is value in is someone trying to set up a wwv light using psk31 on a continuing basis. And that's just my opinion. There are lots of things other hams do that I think aren't particularly useful or valuable, just as there are things that I do ham-wise that others think are wastes of time. Jim ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 60 KHz Receiver
c) Whats wrong with GPS and/or WWV and/or CHU or whatever? Nothing as long as they are TRANSMITTING. Have you ever tried to adjust a local standard to better than 1 in 10E7 using WWV or CHU? I have three Rb standards to go along with my two Thunderbolts. And which one do you believe? If any? -John == ___ 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] Radio based time stations
Hi Poul-HenningOh yes we did ! but the closed a long time ago. MSF was on 2.5, 5 and 10 Mc/s:-)) (It only hertz when I laugh) OMA similar HBG there may have been others. I seem to remember the HF stations took it in turns to transmit Alan G3NYK - Original Message - From: Poul-Henning Kamp p...@phk.freebsd.dk To: kd...@spamcop.net; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tuesday, October 05, 2010 12:34 PM Subject: Re: [time-nuts] Radio based time stations Lee Reynolds writes: Overall, we probably now have a quarter to a third of the SW time stations compared to those that that existed 20 years ago. I think too many radio-controlled alarmclocks have been sold for the remaning big VLF stations to disappear any time soon... Shortwave ? I can live without those, as far as I know we never really had any here in europe... Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] 60 KHz Receiver
Speaking of LORAN receivers, I have two Stanford Research Systems FS700 receivers here at work (in central VA) that I have been asked to dispose of. They both have ovenized oscillators, and I have one original manual. The antenna is on the roof, but I think it'll stay there ;-). Any offers for one or both? 73, geo - n4ua On Tue, Oct 5, 2010 at 8:57 AM, paul swed paulsw...@gmail.com wrote: A great thread by everyone. Oh to make the loran receivers work. But that is indeed the past. Can not hear Europe on east coast. But the question really is, what do you want to accomplish? I don't think its a time stamp. Its just to easy to get it from GPS or the network. But that could be a secondary use. I believe the primary goal would be frequency distribution with perhaps a tick. If this is the goal then I am 100% in agreement that there are far more efficient modulation and recovery methods today. The trick is you need something that does not effect the accuracy of the timing and may improve the various transmission issues at these frequencies. By the way this list has a heck of a brain trust so its very very possible. Someone mentioned spread spectrum. Thats very interesting as it is what GPS uses and could work at these lower frequencies. Like the Hey this is just telemetry comment. You know the FCC does indeed give temp authorization for quite long periods of time. Years in fact. So I would be in the keep it simple mode. Great a single carrier with a id every 10 min. Maybe that could be waved to 1 per hour or 24 hours. Unfortunately then we have nothing better then wwvb. The modulation method may be key and then what freq we would use. BPSK at higher frequencies is also impressive. My first contact was in the indian ocean on 5 whats from boston. Regards Paul WB8TSL On Tue, Oct 5, 2010 at 6:59 AM, Bob Camp li...@rtty.us wrote: Hi If you were starting from scratch there are a lot of things you could do. If the intent is to put out something a Loran receiver will recognize ... not so much. Bob On Oct 5, 2010, at 6:44 AM, Poul-Henning Kamp wrote: In message b69fdcaf-2b39-4575-b5cd-66a87fa1b...@rtty.us, Bob Camp writes: Even though it's pule, the RF power is way beyond the sub 1 W outputs currently contemplated on those bands. Signal to noise *does* matter. You know, there are other ways to skin that cat these days. Old-time signals had to be grossly inefficient because the receivers were inefficient, in particular the ear-wristwatch kind of time receivers. These days we have spread-spectrum modulation, and if our only goal is to transmit a timestamp, you can spread pretty wide and far and need very little power to produce a receiveable signal at long distances. The QRSS hams are playing around with numbers like 17,840,000 miles per watt, and all it takes to turn that into a time/frequency services is a spreading function with a really good autocorrelation. Obviously, you will not get second by second measurements, but the measurements you do get, say once per hour, will have much higher precision because of the averaging that goes into them. And equally obvious: propagation effects will take their toll, but still... Somebody with a license should try that on 137kHz... Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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 unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 60 KHz Receiver
In message aanlktikt7xxjganyxgada1kqn4mkmq0xcw=b_2vln...@mail.gmail.com, Geor ge Dubovsky writes: Speaking of LORAN receivers, I have two Stanford Research Systems FS700 receivers here at work (in central VA) that I have been asked to dispose of. I would love to lay my hands on one of them, so I can compare the performance to my home-built stuff. I'm willing to pay for the shipping across the pond. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] 60 KHz Receiver
John I would be interested but with loran down fo ever. Inexpensive. On Tue, Oct 5, 2010 at 1:24 PM, George Dubovsky n4ua...@gmail.com wrote: Speaking of LORAN receivers, I have two Stanford Research Systems FS700 receivers here at work (in central VA) that I have been asked to dispose of. They both have ovenized oscillators, and I have one original manual. The antenna is on the roof, but I think it'll stay there ;-). Any offers for one or both? 73, geo - n4ua On Tue, Oct 5, 2010 at 8:57 AM, paul swed paulsw...@gmail.com wrote: A great thread by everyone. Oh to make the loran receivers work. But that is indeed the past. Can not hear Europe on east coast. But the question really is, what do you want to accomplish? I don't think its a time stamp. Its just to easy to get it from GPS or the network. But that could be a secondary use. I believe the primary goal would be frequency distribution with perhaps a tick. If this is the goal then I am 100% in agreement that there are far more efficient modulation and recovery methods today. The trick is you need something that does not effect the accuracy of the timing and may improve the various transmission issues at these frequencies. By the way this list has a heck of a brain trust so its very very possible. Someone mentioned spread spectrum. Thats very interesting as it is what GPS uses and could work at these lower frequencies. Like the Hey this is just telemetry comment. You know the FCC does indeed give temp authorization for quite long periods of time. Years in fact. So I would be in the keep it simple mode. Great a single carrier with a id every 10 min. Maybe that could be waved to 1 per hour or 24 hours. Unfortunately then we have nothing better then wwvb. The modulation method may be key and then what freq we would use. BPSK at higher frequencies is also impressive. My first contact was in the indian ocean on 5 whats from boston. Regards Paul WB8TSL On Tue, Oct 5, 2010 at 6:59 AM, Bob Camp li...@rtty.us wrote: Hi If you were starting from scratch there are a lot of things you could do. If the intent is to put out something a Loran receiver will recognize ... not so much. Bob On Oct 5, 2010, at 6:44 AM, Poul-Henning Kamp wrote: In message b69fdcaf-2b39-4575-b5cd-66a87fa1b...@rtty.us, Bob Camp writes: Even though it's pule, the RF power is way beyond the sub 1 W outputs currently contemplated on those bands. Signal to noise *does* matter. You know, there are other ways to skin that cat these days. Old-time signals had to be grossly inefficient because the receivers were inefficient, in particular the ear-wristwatch kind of time receivers. These days we have spread-spectrum modulation, and if our only goal is to transmit a timestamp, you can spread pretty wide and far and need very little power to produce a receiveable signal at long distances. The QRSS hams are playing around with numbers like 17,840,000 miles per watt, and all it takes to turn that into a time/frequency services is a spreading function with a really good autocorrelation. Obviously, you will not get second by second measurements, but the measurements you do get, say once per hour, will have much higher precision because of the averaging that goes into them. And equally obvious: propagation effects will take their toll, but still... Somebody with a license should try that on 137kHz... Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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 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] 60 KHz Receiver
There's the minor issue of getting the power company to put in a cable to the house for your 1 Mw (capital M not lower case M) transmitter. I can't resist citing a personal anecdote regarding power distribution. A few years back, I was working on a proposal for a high power (1MW) power supply system. Our building currently has about 750kW service, so I asked the facility engineer to call the power company to find out how much it would cost and how long it would take to get another MW in our building. He called me back quickly. He was told that because he called after 2PM, they could not do it that day and the soonest we could have it would be the next day. He was laughing so much, he never got to ask how much it would cost... Didier Sent from my Verizon Wireless BlackBerry -Original Message- From: Bob Camp li...@rtty.us Sender: time-nuts-boun...@febo.com Date: Tue, 5 Oct 2010 06:34:29 To: Discussion of precise time and frequency measurementtime-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] 60 KHz Receiver Hi The bandwidth of anything close to a Loran signal is a *lot* wider than any of the ham bands contemplated below 1 MHz. There's the minor issue of getting the power company to put in a cable to the house for your 1 Mw (capital M not lower case M) transmitter. Even though it's pule, the RF power is way beyond the sub 1 W outputs currently contemplated on those bands. Signal to noise *does* matter. Bob On Oct 5, 2010, at 12:20 AM, J. Forster wrote: a) broadcasts aren't legal for US hams b) ionospheric uncertainty in the skywave path makes this no better than WWV c) Whats wrong with GPS and/or WWV and/or CHU or whatever? d) A cheap Rb would give you a local reference that is much better than what you could do with receiving something via skywave. If you want something that isn't run by governments,and is a technical challenge, how about pulsars? I'd guess (not having looked into it at all) that is would be cheaper to set up a station to receive pulsars than to run a Cs standard. Pulsars take a big dish and they aren't all that good as a standard. A friend of mine proved that at Aricebo years and years ago. While I fully sympathize with the stand alone approach (that's one of the appeals of HF comms in general.. you aren't depending on anyone else's infrastructure), I don't know that setting up a time standards station fits in with that.. I've vaguely heard that there are some new ham allocations in the works below 500 KHz. How about setting up a beacon network that works like LORAN, but at a different frequency. A simple downconverter could then feed the signal into a LORAN receiver? FWIW, -John == ___ 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] 60 KHz Receiver
That is basically the sauce behind GPS. What is the power of the transmitters on the satellites? It can't be much, and the signal on the ground is quite a bit below the noise floor before correlation. Didier Sent from my Verizon Wireless BlackBerry -Original Message- From: Poul-Henning Kamp p...@phk.freebsd.dk Sender: time-nuts-boun...@febo.com Date: Tue, 05 Oct 2010 10:44:39 To: Discussion of precise time and frequency measurementtime-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] 60 KHz Receiver In message b69fdcaf-2b39-4575-b5cd-66a87fa1b...@rtty.us, Bob Camp writes: Even though it's pule, the RF power is way beyond the sub 1 W outputs currently contemplated on those bands. Signal to noise *does* matter. You know, there are other ways to skin that cat these days. Old-time signals had to be grossly inefficient because the receivers were inefficient, in particular the ear-wristwatch kind of time receivers. These days we have spread-spectrum modulation, and if our only goal is to transmit a timestamp, you can spread pretty wide and far and need very little power to produce a receiveable signal at long distances. The QRSS hams are playing around with numbers like 17,840,000 miles per watt, and all it takes to turn that into a time/frequency services is a spreading function with a really good autocorrelation. Obviously, you will not get second by second measurements, but the measurements you do get, say once per hour, will have much higher precision because of the averaging that goes into them. And equally obvious: propagation effects will take their toll, but still... Somebody with a license should try that on 137kHz... Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] 60 KHz Receiver
On Oct 5, 2010, at 1:15 PM, shali...@gmail.com wrote: That is basically the sauce behind GPS. What is the power of the transmitters on the satellites? It can't be much, and the signal on the ground is quite a bit below the noise floor before correlation. If I recall correctly, the transmit power is around 15W. A received signal of -130dbm is considered strong, and tracking (but not acquisition or data decoding) can still be done at signals approaching -160dbm. -- Mark J. Blair, NF6X n...@nf6x.net Web page: http://www.nf6x.net/ GnuPG public key available from my web page. ___ 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] 60 KHz Receiver
It is a pulse transmitter. It makes short bursts of 10 or 12 pulses, and then waits one GRI, and then does it again. I would think the actual continuous power draw is around 10Kw. The floor is open to anyone that wants to make the calculation. -Chuck Harris shali...@gmail.com wrote: There's the minor issue of getting the power company to put in a cable to the house for your 1 Mw (capital M not lower case M) transmitter. I can't resist citing a personal anecdote regarding power distribution. A few years back, I was working on a proposal for a high power (1MW) power supply system. Our building currently has about 750kW service, so I asked the facility engineer to call the power company to find out how much it would cost and how long it would take to get another MW in our building. He called me back quickly. He was told that because he called after 2PM, they could not do it that day and the soonest we could have it would be the next day. He was laughing so much, he never got to ask how much it would cost... Didier ___ 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] 60 KHz Receiver
In message 4cab888b.4040...@erols.com, Chuck Harris writes: It is a pulse transmitter. It makes short bursts of 10 or 12 pulses, and then waits one GRI, and then does it again. I would think the actual continuous power draw is around 10Kw. http://phk.freebsd.dk/photos/L9007M/dscf0458.jpg.html About 50kW for Eiði (400kW, 9007M) -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] 60 KHz Receiver
Ok, but that is no megawatt! Also, most of the transmitters were doing multi duty, handling several chains simultaneously. That would up the average power proportionately. -Chuck Harris Poul-Henning Kamp wrote: In message4cab888b.4040...@erols.com, Chuck Harris writes: It is a pulse transmitter. It makes short bursts of 10 or 12 pulses, and then waits one GRI, and then does it again. I would think the actual continuous power draw is around 10Kw. http://phk.freebsd.dk/photos/L9007M/dscf0458.jpg.html About 50kW for Ei�i (400kW, 9007M) ___ 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] 60 KHz Receiver
That's why I think an amateur timing LORAN network might be quite feasable. Imagine a dozen 1 KW PEP A-LORAN stations with Rb and GPS scattered around the US. There is no reason why a single transmitter could not spoof a whole chain as it would not be used for navigation. FWIW, -John = It is a pulse transmitter. It makes short bursts of 10 or 12 pulses, and then waits one GRI, and then does it again. I would think the actual continuous power draw is around 10Kw. The floor is open to anyone that wants to make the calculation. -Chuck Harris shali...@gmail.com wrote: There's the minor issue of getting the power company to put in a cable to the house for your 1 Mw (capital M not lower case M) transmitter. I can't resist citing a personal anecdote regarding power distribution. A few years back, I was working on a proposal for a high power (1MW) power supply system. Our building currently has about 750kW service, so I asked the facility engineer to call the power company to find out how much it would cost and how long it would take to get another MW in our building. He called me back quickly. He was told that because he called after 2PM, they could not do it that day and the soonest we could have it would be the next day. He was laughing so much, he never got to ask how much it would cost... Didier ___ 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] 60 KHz Receiver
And the Power Factor sucks, so there is a lot less real power being used. -John = Ok, but that is no megawatt! Also, most of the transmitters were doing multi duty, handling several chains simultaneously. That would up the average power proportionately. -Chuck Harris Poul-Henning Kamp wrote: In message4cab888b.4040...@erols.com, Chuck Harris writes: It is a pulse transmitter. It makes short bursts of 10 or 12 pulses, and then waits one GRI, and then does it again. I would think the actual continuous power draw is around 10Kw. http://phk.freebsd.dk/photos/L9007M/dscf0458.jpg.html About 50kW for Ei�i (400kW, 9007M) ___ 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] 60 KHz Receiver
In message 50213.12.6.201.2.1286311041.squir...@popaccts.quikus.com, J. Fors ter writes: And the Power Factor sucks, so there is a lot less real power being used. Yeah, 0.75 inductive is not exactly stellar, but it may not matter in this case, as the Faroese power-grid is pretty sparse. Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] 60 KHz Receiver
Not necessarily, on 3 phase systems, you would have to be creative to get below .9 You can easily get to .95 with a simple multipulse rectification. Beyond that, other than regulatory compliance, you do not gain much efficiency. I can't imagine these systems running on anything other than 3 phase power. Didier Sent from my Verizon Wireless BlackBerry -Original Message- From: J. Forster j...@quik.com Sender: time-nuts-boun...@febo.com Date: Tue, 5 Oct 2010 13:37:21 To: Discussion of precise time and frequency measurementtime-nuts@febo.com Reply-To: j...@quik.com, Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] 60 KHz Receiver And the Power Factor sucks, so there is a lot less real power being used. -John = Ok, but that is no megawatt! Also, most of the transmitters were doing multi duty, handling several chains simultaneously. That would up the average power proportionately. -Chuck Harris Poul-Henning Kamp wrote: In message4cab888b.4040...@erols.com, Chuck Harris writes: It is a pulse transmitter. It makes short bursts of 10 or 12 pulses, and then waits one GRI, and then does it again. I would think the actual continuous power draw is around 10Kw. http://phk.freebsd.dk/photos/L9007M/dscf0458.jpg.html About 50kW for Ei�i (400kW, 9007M) ___ 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 unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 60 KHz Receiver
Well crazy as it sounds if you are at 100 KC you might just want 1 loran tower in a chain or even fewer. You only need 1 station not 3. Timing rcvrs worked on one signal. On Tue, Oct 5, 2010 at 4:46 PM, shali...@gmail.com wrote: Not necessarily, on 3 phase systems, you would have to be creative to get below .9 You can easily get to .95 with a simple multipulse rectification. Beyond that, other than regulatory compliance, you do not gain much efficiency. I can't imagine these systems running on anything other than 3 phase power. Didier Sent from my Verizon Wireless BlackBerry -Original Message- From: J. Forster j...@quik.com Sender: time-nuts-boun...@febo.com Date: Tue, 5 Oct 2010 13:37:21 To: Discussion of precise time and frequency measurement time-nuts@febo.com Reply-To: j...@quik.com, Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] 60 KHz Receiver And the Power Factor sucks, so there is a lot less real power being used. -John = Ok, but that is no megawatt! Also, most of the transmitters were doing multi duty, handling several chains simultaneously. That would up the average power proportionately. -Chuck Harris Poul-Henning Kamp wrote: In message4cab888b.4040...@erols.com, Chuck Harris writes: It is a pulse transmitter. It makes short bursts of 10 or 12 pulses, and then waits one GRI, and then does it again. I would think the actual continuous power draw is around 10Kw. http://phk.freebsd.dk/photos/L9007M/dscf0458.jpg.html About 50kW for Ei�i (400kW, 9007M) ___ 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 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] 60 KHz Receiver
In message 63077.12.6.201.2.1286310871.squir...@popaccts.quikus.com, J. Fors ter writes: That's why I think an amateur timing LORAN network might be quite feasable. Imagine a dozen 1 KW PEP A-LORAN stations with Rb and GPS scattered around the US. There is no reason why a single transmitter could not spoof a whole chain as it would not be used for navigation. Why try to emulate technology from WWII ? I would find it much more interesting to invent a good spread-spectrum modulation, and see if we could do world wide time-transmission with just a single 1W tranmistter per continent, which could be received with a simple down-converter frontend and a soundcard. Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] 60 KHz Receiver
?? Paul, I've said that at least twice. A single Tx can emulate all the Txs in a chain, since it is not used for navigation. Just emulating the Master station would be fine, but I'm not certain that all LORAN receivers would lock up, absent two or three received stations. I'd set up my time differences to put the fake position on top of the Prudential or Bunker Hill Monument or some other landmark, if I were in Boston. FWIW, -John Well crazy as it sounds if you are at 100 KC you might just want 1 loran tower in a chain or even fewer. You only need 1 station not 3. Timing rcvrs worked on one 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.
Re: [time-nuts] 60 KHz Receiver
Yup running in circles. Not in favor of soundblaster. Looses accuracy Am in favor of spreadspct On Tue, Oct 5, 2010 at 5:06 PM, J. Forster j...@quik.com wrote: ?? Paul, I've said that at least twice. A single Tx can emulate all the Txs in a chain, since it is not used for navigation. Just emulating the Master station would be fine, but I'm not certain that all LORAN receivers would lock up, absent two or three received stations. I'd set up my time differences to put the fake position on top of the Prudential or Bunker Hill Monument or some other landmark, if I were in Boston. FWIW, -John Well crazy as it sounds if you are at 100 KC you might just want 1 loran tower in a chain or even fewer. You only need 1 station not 3. Timing rcvrs worked on one 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.
Re: [time-nuts] 60 KHz Receiver
Because there is a now-useless installed base of high grade LORAN receivers and comparators out there. IMO, one Tx site could make them all live again. -John === Why try to emulate technology from WWII ? I would find it much more interesting to invent a good spread-spectrum modulation, and see if we could do world wide time-transmission with just a single 1W tranmistter per continent, which could be received with a simple down-converter frontend and a soundcard. Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] 60 KHz Receiver
On 10/5/2010 3:59 PM, paul swed wrote: Well crazy as it sounds if you are at 100 KC you might just want 1 loran tower in a chain or even fewer. You only need 1 station not 3. Timing rcvrs worked on one signal. Frequency recovery works with master only, timing requires ranging data, so three stations are required to locate the receiver. -- mailto:o...@ozindfw.net Oz POB 93167 Southlake, TX 76092 (Near DFW Airport) ___ 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] 60 KHz Receiver
A loop around the house? -John == Hi Ok, the next layer to this onion is the antenna. At 100KC your antenna is 35X smaller than it is on 80 meters foot for foot. In other words, your 100' tall vertical on 80 equates to a 3 foot tall antenna at 100 KC. QRP on 80 with a 3' transmit antenna anybody? Been there done that, not much range at all. At VLF forget about transmitting with a horizontal antenna unless you are airborne. It's not just the antenna, the ground counts as well. If you are by the seashore that may not be a big deal. If you are inland, prepare to lay many very long radials. -- After that you hit signal to noise. The receivers worked as well as they did because they had an enormous signal to work with. There's an amazing amount of crud running around down below 200 KHz these days. Even for timing you need a lot of signal to get good results. Bob KB8TQ Ham for way more than 30 years On Oct 5, 2010, at 4:59 PM, paul swed wrote: Well crazy as it sounds if you are at 100 KC you might just want 1 loran tower in a chain or even fewer. You only need 1 station not 3. Timing rcvrs worked on one signal. On Tue, Oct 5, 2010 at 4:46 PM, shali...@gmail.com wrote: Not necessarily, on 3 phase systems, you would have to be creative to get below .9 You can easily get to .95 with a simple multipulse rectification. Beyond that, other than regulatory compliance, you do not gain much efficiency. I can't imagine these systems running on anything other than 3 phase power. Didier Sent from my Verizon Wireless BlackBerry -Original Message- From: J. Forster j...@quik.com Sender: time-nuts-boun...@febo.com Date: Tue, 5 Oct 2010 13:37:21 To: Discussion of precise time and frequency measurement time-nuts@febo.com Reply-To: j...@quik.com, Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] 60 KHz Receiver And the Power Factor sucks, so there is a lot less real power being used. -John = Ok, but that is no megawatt! Also, most of the transmitters were doing multi duty, handling several chains simultaneously. That would up the average power proportionately. -Chuck Harris Poul-Henning Kamp wrote: In message4cab888b.4040...@erols.com, Chuck Harris writes: It is a pulse transmitter. It makes short bursts of 10 or 12 pulses, and then waits one GRI, and then does it again. I would think the actual continuous power draw is around 10Kw. http://phk.freebsd.dk/photos/L9007M/dscf0458.jpg.html About 50kW for Ei�i (400kW, 9007M) ___ 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 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 unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 60 KHz Receiver
Hi I've had similar experiences with commercial power (we can't get the new transformers up on the pole this evening, but we can have it done by noon tomorrow...). The same call on a residential circuit gets you endless grief about tariffs and their poor aching back. Lucky if you can even double the circuit in under a couple months. Bob On Oct 5, 2010, at 4:13 PM, shali...@gmail.com wrote: There's the minor issue of getting the power company to put in a cable to the house for your 1 Mw (capital M not lower case M) transmitter. I can't resist citing a personal anecdote regarding power distribution. A few years back, I was working on a proposal for a high power (1MW) power supply system. Our building currently has about 750kW service, so I asked the facility engineer to call the power company to find out how much it would cost and how long it would take to get another MW in our building. He called me back quickly. He was told that because he called after 2PM, they could not do it that day and the soonest we could have it would be the next day. He was laughing so much, he never got to ask how much it would cost... Didier Sent from my Verizon Wireless BlackBerry -Original Message- From: Bob Camp li...@rtty.us Sender: time-nuts-boun...@febo.com Date: Tue, 5 Oct 2010 06:34:29 To: Discussion of precise time and frequency measurementtime-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] 60 KHz Receiver Hi The bandwidth of anything close to a Loran signal is a *lot* wider than any of the ham bands contemplated below 1 MHz. There's the minor issue of getting the power company to put in a cable to the house for your 1 Mw (capital M not lower case M) transmitter. Even though it's pule, the RF power is way beyond the sub 1 W outputs currently contemplated on those bands. Signal to noise *does* matter. Bob On Oct 5, 2010, at 12:20 AM, J. Forster wrote: a) broadcasts aren't legal for US hams b) ionospheric uncertainty in the skywave path makes this no better than WWV c) Whats wrong with GPS and/or WWV and/or CHU or whatever? d) A cheap Rb would give you a local reference that is much better than what you could do with receiving something via skywave. If you want something that isn't run by governments,and is a technical challenge, how about pulsars? I'd guess (not having looked into it at all) that is would be cheaper to set up a station to receive pulsars than to run a Cs standard. Pulsars take a big dish and they aren't all that good as a standard. A friend of mine proved that at Aricebo years and years ago. While I fully sympathize with the stand alone approach (that's one of the appeals of HF comms in general.. you aren't depending on anyone else's infrastructure), I don't know that setting up a time standards station fits in with that.. I've vaguely heard that there are some new ham allocations in the works below 500 KHz. How about setting up a beacon network that works like LORAN, but at a different frequency. A simple downconverter could then feed the signal into a LORAN receiver? FWIW, -John == ___ 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 unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 60 KHz Receiver
Hi Same gotcha as the horizontal dipole - most of the energy is shorted out by the ground. Think of a transformer with a shorted turn. Bob On Oct 5, 2010, at 5:58 PM, J. Forster wrote: A loop around the house? -John == Hi Ok, the next layer to this onion is the antenna. At 100KC your antenna is 35X smaller than it is on 80 meters foot for foot. In other words, your 100' tall vertical on 80 equates to a 3 foot tall antenna at 100 KC. QRP on 80 with a 3' transmit antenna anybody? Been there done that, not much range at all. At VLF forget about transmitting with a horizontal antenna unless you are airborne. It's not just the antenna, the ground counts as well. If you are by the seashore that may not be a big deal. If you are inland, prepare to lay many very long radials. -- After that you hit signal to noise. The receivers worked as well as they did because they had an enormous signal to work with. There's an amazing amount of crud running around down below 200 KHz these days. Even for timing you need a lot of signal to get good results. Bob KB8TQ Ham for way more than 30 years On Oct 5, 2010, at 4:59 PM, paul swed wrote: Well crazy as it sounds if you are at 100 KC you might just want 1 loran tower in a chain or even fewer. You only need 1 station not 3. Timing rcvrs worked on one signal. On Tue, Oct 5, 2010 at 4:46 PM, shali...@gmail.com wrote: Not necessarily, on 3 phase systems, you would have to be creative to get below .9 You can easily get to .95 with a simple multipulse rectification. Beyond that, other than regulatory compliance, you do not gain much efficiency. I can't imagine these systems running on anything other than 3 phase power. Didier Sent from my Verizon Wireless BlackBerry -Original Message- From: J. Forster j...@quik.com Sender: time-nuts-boun...@febo.com Date: Tue, 5 Oct 2010 13:37:21 To: Discussion of precise time and frequency measurement time-nuts@febo.com Reply-To: j...@quik.com, Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] 60 KHz Receiver And the Power Factor sucks, so there is a lot less real power being used. -John = Ok, but that is no megawatt! Also, most of the transmitters were doing multi duty, handling several chains simultaneously. That would up the average power proportionately. -Chuck Harris Poul-Henning Kamp wrote: In message4cab888b.4040...@erols.com, Chuck Harris writes: It is a pulse transmitter. It makes short bursts of 10 or 12 pulses, and then waits one GRI, and then does it again. I would think the actual continuous power draw is around 10Kw. http://phk.freebsd.dk/photos/L9007M/dscf0458.jpg.html About 50kW for Ei�i (400kW, 9007M) ___ 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 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 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] 60 KHz Receiver
Poul, Please explain to me how spread spectrum would enhance any process of frequency or time recovery ? I just do not see it. The reason for the spread spectrum used with the GPS is because all of the Birds are in the same base frequency. Thus the spreading codes allow for distinction between the different signals. At 100 kHz the system bandwidth is very, very limited compared to the very wide spectrum of the GPS. Stepping up into the HF area brings in the sky wave propagation issues. The whole purpose of suggesting an amateur approach is to utilize the large base of existing LORAN receivers as someone pointed out. However, as the number of people needing such a service is quite small it does not make economical sense, as the cost would certainly be prohibitive. The only feasible way would be to have many lower power 100 kHz transmitters and there are just not enough people around to construct, install and maintain such an operation; not to mention the licensing issues. Besides, you would achieve nothing above what is already provided by operations such as the 60 kHz WWVB and similar in other countries. So I see it as a pie in the sky nice idea but no cigar. BillWB6BNQ Poul-Henning Kamp wrote: In message 63077.12.6.201.2.1286310871.squir...@popaccts.quikus.com, J. Fors ter writes: That's why I think an amateur timing LORAN network might be quite feasable. Imagine a dozen 1 KW PEP A-LORAN stations with Rb and GPS scattered around the US. There is no reason why a single transmitter could not spoof a whole chain as it would not be used for navigation. Why try to emulate technology from WWII ? I would find it much more interesting to invent a good spread-spectrum modulation, and see if we could do world wide time-transmission with just a single 1W tranmistter per continent, which could be received with a simple down-converter frontend and a soundcard. Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] 60 KHz Receiver
Depends on your soil. New England is mainly rock with very poor conductivity. -John == Hi Same gotcha as the horizontal dipole - most of the energy is shorted out by the ground. Think of a transformer with a shorted turn. Bob On Oct 5, 2010, at 5:58 PM, J. Forster wrote: A loop around the house? -John == Hi Ok, the next layer to this onion is the antenna. At 100KC your antenna is 35X smaller than it is on 80 meters foot for foot. In other words, your 100' tall vertical on 80 equates to a 3 foot tall antenna at 100 KC. QRP on 80 with a 3' transmit antenna anybody? Been there done that, not much range at all. At VLF forget about transmitting with a horizontal antenna unless you are airborne. It's not just the antenna, the ground counts as well. If you are by the seashore that may not be a big deal. If you are inland, prepare to lay many very long radials. -- After that you hit signal to noise. The receivers worked as well as they did because they had an enormous signal to work with. There's an amazing amount of crud running around down below 200 KHz these days. Even for timing you need a lot of signal to get good results. Bob KB8TQ Ham for way more than 30 years On Oct 5, 2010, at 4:59 PM, paul swed wrote: Well crazy as it sounds if you are at 100 KC you might just want 1 loran tower in a chain or even fewer. You only need 1 station not 3. Timing rcvrs worked on one signal. On Tue, Oct 5, 2010 at 4:46 PM, shali...@gmail.com wrote: Not necessarily, on 3 phase systems, you would have to be creative to get below .9 You can easily get to .95 with a simple multipulse rectification. Beyond that, other than regulatory compliance, you do not gain much efficiency. I can't imagine these systems running on anything other than 3 phase power. Didier Sent from my Verizon Wireless BlackBerry -Original Message- From: J. Forster j...@quik.com Sender: time-nuts-boun...@febo.com Date: Tue, 5 Oct 2010 13:37:21 To: Discussion of precise time and frequency measurement time-nuts@febo.com Reply-To: j...@quik.com, Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] 60 KHz Receiver And the Power Factor sucks, so there is a lot less real power being used. -John = Ok, but that is no megawatt! Also, most of the transmitters were doing multi duty, handling several chains simultaneously. That would up the average power proportionately. -Chuck Harris Poul-Henning Kamp wrote: In message4cab888b.4040...@erols.com, Chuck Harris writes: It is a pulse transmitter. It makes short bursts of 10 or 12 pulses, and then waits one GRI, and then does it again. I would think the actual continuous power draw is around 10Kw. http://phk.freebsd.dk/photos/L9007M/dscf0458.jpg.html About 50kW for Ei�i (400kW, 9007M) ___ 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 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 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] 60 KHz Receiver
The localized LORAN is not that hard, IMO: Many TNs have GPS Rbs. At least one simulator has been built. RF amps are easily available (ENI) for 100W pulse at 100 KHz. Home Depot has 250' rolls of #14 THHN. FWIW, -John Poul, Please explain to me how spread spectrum would enhance any process of frequency or time recovery ? I just do not see it. The reason for the spread spectrum used with the GPS is because all of the Birds are in the same base frequency. Thus the spreading codes allow for distinction between the different signals. At 100 kHz the system bandwidth is very, very limited compared to the very wide spectrum of the GPS. Stepping up into the HF area brings in the sky wave propagation issues. The whole purpose of suggesting an amateur approach is to utilize the large base of existing LORAN receivers as someone pointed out. However, as the number of people needing such a service is quite small it does not make economical sense, as the cost would certainly be prohibitive. The only feasible way would be to have many lower power 100 kHz transmitters and there are just not enough people around to construct, install and maintain such an operation; not to mention the licensing issues. Besides, you would achieve nothing above what is already provided by operations such as the 60 kHz WWVB and similar in other countries. So I see it as a pie in the sky nice idea but no cigar. BillWB6BNQ Poul-Henning Kamp wrote: In message 63077.12.6.201.2.1286310871.squir...@popaccts.quikus.com, J. Fors ter writes: That's why I think an amateur timing LORAN network might be quite feasable. Imagine a dozen 1 KW PEP A-LORAN stations with Rb and GPS scattered around the US. There is no reason why a single transmitter could not spoof a whole chain as it would not be used for navigation. Why try to emulate technology from WWII ? I would find it much more interesting to invent a good spread-spectrum modulation, and see if we could do world wide time-transmission with just a single 1W tranmistter per continent, which could be received with a simple down-converter frontend and a soundcard. Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] 60 KHz Receiver
On 10/05/2010 03:17 PM, J. Forster wrote: Hi The bandwidth of anything close to a Loran signal is a *lot* wider than any of the ham bands contemplated below 1 MHz. There's the minor issue of getting the power company to put in a cable to the house for your 1 Mw (capital M not lower case M) transmitter. I was not contemplating a global navigation system. Just enough to get a LORAN type timing, not navigation, lock over a few hundred mile radius. However, consider that a few of these transmitters if wisely used could be kept running by guys like us on electricity bills we could handle and provide a grid network. This way the navigation aspect could be embedded into the system and propagation delay be cancelled. Fixed location could then be used to provide multiple observations of time-indication. A particular aspect of spread spectrum is that we could have several transmitters on the same center frequency which has the benefit that equipment delays become common mode to a first degree. This is a benefit of GPS over GLONASS. Multiple carrier systems provide means for frequency diversity as well as dispersion observations. There is many options to consider for such a system. Cheers, Magnus ___ 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] Spread Spectrum LF Time Code (Was: 60 KHz Receiver)
On 10/5/2010 5:14 PM, WB6BNQ wrote: Poul, Please explain to me how spread spectrum would enhance any process of frequency or time recovery ? I can see a lot of reasons, but it's an answer requiring lots of thought. I'm not certain that it'd be an advantage. Some things that come to mind are: 1. non-gaussian interferers would be reduced by the spread processing gain. (Yay!) 2. With a long enough code you can discriminate against multipath (skywave.) as well as Loran - really limiting diurnal shift. 3. With a high chip rate you can potentially get really fine time resolution. 4. Most of the processing goes right to bits - Moore's law becomes our buddy. -- mailto:o...@ozindfw.net Oz POB 93167 Southlake, TX 76092 (Near DFW Airport) ___ 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] 60 KHz Receiver
In message 4caba343.8c581...@cox.net, WB6BNQ writes: Please explain to me how spread spectrum would enhance any process of frequency or time recovery ? Ok, it is late and I'm probably going to botch this, but I'll try: The really short explanation is that your carrier transitions have random-ish looking signs, which, if properly designed, allows you to balance out pretty much any kind of CW or random noise. This is, in essence, why you can separate the different GPS sattelites, even though they all send on the same frequency. Technically speaking, Loran-C is spread spectrum, but they botched this aspect slightly, by not properly balancing the signs of (all) the codes. The Austron 2000 has a switch that allows you to disregard certain bits in the codes to balance them, this increases the imunity to CW interference. So given that you can trivially get a good OCXO today, I would design our low-power-time-transmitter to send one fix per hour. For instance 127 bits of PRNG at 28 seconds per bit with a four second gap before the next timestamp (send ID ?) On the receiver side, you know what time it is +/- one 28sec bit, so you digitize the signal and correlate the PRNG in a window around your local clock. After an hour, you pick the correlation bucket that correlated best and have an instant estimate of the difference between your local clock and the average of that hours transmissions. If xmitted as NFSK at around 100kHz and digitized at 1MSPS, you would get 1µsec resolution without resorting to interpolation. By choosing all your magic numbers to be nonprime to normal CW signals inside their respective periods, you supress those by averaging. This is why the NELS LORAN-C chains got new 4-digit GRI's: they are imune to pretty much traditional CW interference because they do not divide seconds or kHz on relevant timescales. Poul-Henning PS: DCF77 already does SS, but on a second to second basis. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] 60 KHz Receiver
A couple of comments. If loran c, I built the simulator for the transmitter and its available at this website Index of /simloran http://n4iqt.com/simloran/ But I left out various wave shaping filters because there was no intent to xmit on the air. KISS principal after all its all of $29 maybe. But is very optimized to preserve the accuracy of the 100kc signal and I did check its behaviors with the real loran stations it matched very well. Those filters also optimize ground and skywave propagation characteristics not a problem when the feed is coax and the endpoint the receiver. Good comments on spreadspectrum. I have to roll back up to the question asked a while ago. Goals of the interest. From there what frequency might be chosen and what method of delivery. Regards On Tue, Oct 5, 2010 at 6:32 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 10/05/2010 03:17 PM, J. Forster wrote: Hi The bandwidth of anything close to a Loran signal is a *lot* wider than any of the ham bands contemplated below 1 MHz. There's the minor issue of getting the power company to put in a cable to the house for your 1 Mw (capital M not lower case M) transmitter. I was not contemplating a global navigation system. Just enough to get a LORAN type timing, not navigation, lock over a few hundred mile radius. However, consider that a few of these transmitters if wisely used could be kept running by guys like us on electricity bills we could handle and provide a grid network. This way the navigation aspect could be embedded into the system and propagation delay be cancelled. Fixed location could then be used to provide multiple observations of time-indication. A particular aspect of spread spectrum is that we could have several transmitters on the same center frequency which has the benefit that equipment delays become common mode to a first degree. This is a benefit of GPS over GLONASS. Multiple carrier systems provide means for frequency diversity as well as dispersion observations. There is many options to consider for such a system. Cheers, Magnus ___ 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] 60 KHz Receiver
Hi Poor, but not poor enough in this case. A quarter wave at 100KC goes pretty deep. If you can drill a well there, you will hit the ground water with your antenna's ground side. The loss in getting there will be just as bad as anything else. Next issue would be stability over a poor ground when it rains. I suspect that they are going to pull a *lot* of copper out of the ground at some of the Loran stations. Bob On Oct 5, 2010, at 6:16 PM, J. Forster wrote: Depends on your soil. New England is mainly rock with very poor conductivity. -John == Hi Same gotcha as the horizontal dipole - most of the energy is shorted out by the ground. Think of a transformer with a shorted turn. Bob On Oct 5, 2010, at 5:58 PM, J. Forster wrote: A loop around the house? -John == Hi Ok, the next layer to this onion is the antenna. At 100KC your antenna is 35X smaller than it is on 80 meters foot for foot. In other words, your 100' tall vertical on 80 equates to a 3 foot tall antenna at 100 KC. QRP on 80 with a 3' transmit antenna anybody? Been there done that, not much range at all. At VLF forget about transmitting with a horizontal antenna unless you are airborne. It's not just the antenna, the ground counts as well. If you are by the seashore that may not be a big deal. If you are inland, prepare to lay many very long radials. -- After that you hit signal to noise. The receivers worked as well as they did because they had an enormous signal to work with. There's an amazing amount of crud running around down below 200 KHz these days. Even for timing you need a lot of signal to get good results. Bob KB8TQ Ham for way more than 30 years On Oct 5, 2010, at 4:59 PM, paul swed wrote: Well crazy as it sounds if you are at 100 KC you might just want 1 loran tower in a chain or even fewer. You only need 1 station not 3. Timing rcvrs worked on one signal. On Tue, Oct 5, 2010 at 4:46 PM, shali...@gmail.com wrote: Not necessarily, on 3 phase systems, you would have to be creative to get below .9 You can easily get to .95 with a simple multipulse rectification. Beyond that, other than regulatory compliance, you do not gain much efficiency. I can't imagine these systems running on anything other than 3 phase power. Didier Sent from my Verizon Wireless BlackBerry -Original Message- From: J. Forster j...@quik.com Sender: time-nuts-boun...@febo.com Date: Tue, 5 Oct 2010 13:37:21 To: Discussion of precise time and frequency measurement time-nuts@febo.com Reply-To: j...@quik.com, Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] 60 KHz Receiver And the Power Factor sucks, so there is a lot less real power being used. -John = Ok, but that is no megawatt! Also, most of the transmitters were doing multi duty, handling several chains simultaneously. That would up the average power proportionately. -Chuck Harris Poul-Henning Kamp wrote: In message4cab888b.4040...@erols.com, Chuck Harris writes: It is a pulse transmitter. It makes short bursts of 10 or 12 pulses, and then waits one GRI, and then does it again. I would think the actual continuous power draw is around 10Kw. http://phk.freebsd.dk/photos/L9007M/dscf0458.jpg.html About 50kW for Ei�i (400kW, 9007M) ___ 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 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 unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 60 KHz Receiver
Hi The other answer is that DSP was not really available when the original waveforms were developed. A modern system would not have a must be able to work with manual delay lines and an oscilloscope requirement on it. Bob On Oct 5, 2010, at 6:56 PM, Poul-Henning Kamp wrote: In message 4caba343.8c581...@cox.net, WB6BNQ writes: Please explain to me how spread spectrum would enhance any process of frequency or time recovery ? Ok, it is late and I'm probably going to botch this, but I'll try: The really short explanation is that your carrier transitions have random-ish looking signs, which, if properly designed, allows you to balance out pretty much any kind of CW or random noise. This is, in essence, why you can separate the different GPS sattelites, even though they all send on the same frequency. Technically speaking, Loran-C is spread spectrum, but they botched this aspect slightly, by not properly balancing the signs of (all) the codes. The Austron 2000 has a switch that allows you to disregard certain bits in the codes to balance them, this increases the imunity to CW interference. So given that you can trivially get a good OCXO today, I would design our low-power-time-transmitter to send one fix per hour. For instance 127 bits of PRNG at 28 seconds per bit with a four second gap before the next timestamp (send ID ?) On the receiver side, you know what time it is +/- one 28sec bit, so you digitize the signal and correlate the PRNG in a window around your local clock. After an hour, you pick the correlation bucket that correlated best and have an instant estimate of the difference between your local clock and the average of that hours transmissions. If xmitted as NFSK at around 100kHz and digitized at 1MSPS, you would get 1µsec resolution without resorting to interpolation. By choosing all your magic numbers to be nonprime to normal CW signals inside their respective periods, you supress those by averaging. This is why the NELS LORAN-C chains got new 4-digit GRI's: they are imune to pretty much traditional CW interference because they do not divide seconds or kHz on relevant timescales. Poul-Henning PS: DCF77 already does SS, but on a second to second basis. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] 60 KHz Receiver
If you want to see a R E A L L Y big vlf antenna check out thest two links. The first is about Soviet and US VLF antennas used for submarine communications during the cold war, and the second has a copule of photo's at the end of the powerpoint presentation of the installation in Cutler, Maine. http://coldwar-c4i.net/VLF/design.html www.eee.metu.edu.tr/~eekmekci/documents/vlf_antennas.ppt ___ 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] Alternative to GPS?
Hi, How far could you get passing time around from amateur station to station with a two way handshake system that establishes the instantaneous delay on the two way path and assumes a delay of half that value? A time relay. The stations would need their own short term clocks so they could keep their own time between contacts, and somewhere you would need heros with primary standards to synch the whole system. You would not be able to find a good position, because you would not know the propagation mode. cheers, Neville Michie ___ 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.
