Re: [ntp:questions] Indirect GPS time source options
On Thursday, March 13, 2014 1:52:51 PM UTC-4, Olivier Drouin wrote: Diversity is really what I'm looking for and I dont really need microsecond accuracy. I'll talk with the facility owner and do some tests with handheld GPS so I can verify what kind of signal I can get (and where). I'm not sure what your goals and constraints are but ... You should test with a high sensitivity timing GPS receiver (e.g. u-blox or Resolution SMTx). I get acceptable performance in an inner office off a machine room on the ground floor of three-story building. In my case acceptable is 100s of microseconds. If you can sometimes get a GPS signal in your machine room (interior or exterior antenna) then run that into a GPS disciplined oscillator which should give 10-100microsec./day drift when there's no GPS signal -- O(10ms/yr) given stable temperature. The high sensitivity + timing constraints let you stay locked with just a single satellite fix. There are also some time transfer tricks you could do to periodically discipline an oscillator or you could just switch to a Rubidium/quasi-Cesium based free-running oscillator that you manually discipline if needed with NTP (e.g. approximate time2 from peer stats). Some of these things you can buy, some you would have to assemble from functional modules. There was a discussion in the last 12 months or so on the Time-Nuts list about doing time transfer into (really) RF free areas (i.e. secure bunkers). ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Indirect GPS time source options
Olivier Drouin wrote:
The thing with CDMA is that it looks like it'll not be
around for many years and I haven't seen any equipement
for 4g, hspa, LTE, etc...
IIRC, HSPA, UMB, UMTS, EVDO and EVDV are all CDMA based 3G?
LTE run with GSM or CDMA?
Can you get a modem with LTE, and neither GSM or CDMA?
I'm fairly certain you can get a WiMax Modem without either.
Verizon, Sprint, U.S. Cellular, Cricket, and MetroPCS all use CDMA
MetroPCS (T-Mobil CDMA), is supposed to be toast by 2016.
Cricket is getting borged by ATT
{Who knows what they will do with the CDMA, since ATT is GSM}.
--
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will be added to the BlackLists.
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Re: [ntp:questions] Indirect GPS time source options
On 03/14/2014 08:12 AM, E-Mail Sent to this address will be added to the BlackLists wrote: Olivier Drouin wrote: The thing with CDMA is that it looks like it'll not be around for many years and I haven't seen any equipement for 4g, hspa, LTE, etc... IIRC, HSPA, UMB, UMTS, EVDO and EVDV are all CDMA based 3G? LTE run with GSM or CDMA? Informative white paper here: https://www.aventasinc.com/whitepapers/WP-Timing-Sync-LTE-SEC.pdf Among other things, it compares the timing requirements of a number of cellular technologies. Warning: it also tries to sell you PTP grand master equipment. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Indirect GPS time source options
On Wed, Mar 12, 2014 at 3:59 PM, William Unruh un...@invalid.ca wrote: On 2014-03-12, Olivier Drouin ol.dro...@gmail.com wrote: Hello, I'm located in Canada and I'm trying to find indirect GPS time sources. I like the idea of using CDMA as a time source but it seems that this technology will not be around for a lot longer. What is an indirect gps timing source? How does that differ from using ntp to go to a level 1 server which gets its time from gps. While cdma uses accurate time, it is not really designed to deliver accurate time. GPS is. Well, from what I understand the cell networks are closely synchronized against the GPS constellation. So, synchronizing against the cellular network is called indirect gps, at least according to the endrun website (I haven't seen this nomenclature anywhere else). It is different of GPS because if your WAN links are down, which can happen once every few years, then, hopefully, you can still reach the cellular network in your neighborhood or else its the end of the world or something... Also, from what I understand and please correct me if I'm wrong but cellular networks are indeed designed to be accurately timed because it's needed for the normal operations of the cell network. Thank you for your reply, best regards, Olivier Drouin For exemple, Endrun Technologies sells the Sonoma N12 which seems to allow time synchronization against CDMA signal without the need for a carrier subscriptions. And a gps receiver with PPS output is probably 1/100 the price. Is the CDMA method still available with these other cellulare network technologies like HSPA or LTE? If not, do I have other options beside a GPS antenna with a sky view? CDMA also needs an antenna with cell tower view. What's the difference? (Note my gps on an east facing window through a large cedar tree works just fine.) As Terje is mentioning, the cell antenna doesnt need a line of sight to a cell antenna, so It can be installed inside the server room and you dont have to deal with the maintenance problems (lots of snow around here) of a GPS antenna on the roof... Thank you and best regards, Olivier Drouin. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions Thank you and best regards, Olivier Drouin. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Indirect GPS time source options
Oops, I said It is different of GPS because if your WAN links are down, which can happen once every few years, then, hopefully, you can still reach the cellular network in your neighborhood or else its the end of the world or something... but it should read It is different from using ntp to go to a level 1 server because if your WAN links are down, which can happen once every few years, then, hopefully, you can still reach the cellular network in your neighborhood or else its the end of the world or something... On Wed, Mar 12, 2014 at 3:59 PM, William Unruh un...@invalid.ca wrote: On 2014-03-12, Olivier Drouin ol.dro...@gmail.com wrote: Hello, I'm located in Canada and I'm trying to find indirect GPS time sources. I like the idea of using CDMA as a time source but it seems that this technology will not be around for a lot longer. What is an indirect gps timing source? How does that differ from using ntp to go to a level 1 server which gets its time from gps. While cdma uses accurate time, it is not really designed to deliver accurate time. GPS is. For exemple, Endrun Technologies sells the Sonoma N12 which seems to allow time synchronization against CDMA signal without the need for a carrier subscriptions. And a gps receiver with PPS output is probably 1/100 the price. Is the CDMA method still available with these other cellulare network technologies like HSPA or LTE? If not, do I have other options beside a GPS antenna with a sky view? CDMA also needs an antenna with cell tower view. What's the difference? (Note my gps on an east facing window through a large cedar tree works just fine.) Thank you and best regards, Olivier Drouin. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Indirect GPS time source options
On 2014-03-13, Olivier Drouin ol.dro...@gmail.com wrote: On Wed, Mar 12, 2014 at 3:59 PM, William Unruh un...@invalid.ca wrote: On 2014-03-12, Olivier Drouin ol.dro...@gmail.com wrote: Hello, I'm located in Canada and I'm trying to find indirect GPS time sources. I like the idea of using CDMA as a time source but it seems that this technology will not be around for a lot longer. What is an indirect gps timing source? How does that differ from using ntp to go to a level 1 server which gets its time from gps. While cdma uses accurate time, it is not really designed to deliver accurate time. GPS is. Well, from what I understand the cell networks are closely synchronized against the GPS constellation. So, synchronizing against the cellular network is called indirect gps, at least according to the endrun website (I haven't seen this nomenclature anywhere else). And in npt terms it would be called a stratum 1 server. It is different of GPS because if your WAN links are down, which can happen once every few years, then, hopefully, you can still reach the cellular network in your neighborhood or else its the end of the world or something... Or a power blackout, while the sattelites keep beeping away even if the whole eastern seaboard is in the dark. And except a gps receiver is far cheaper and more accurate than a cell timing receiver. Also, from what I understand and please correct me if I'm wrong but cellular networks are indeed designed to be accurately timed because it's needed for the normal operations of the cell network. Yes, but they are not designed to deliver accurate time to the rest of the world AFAIK. Thank you for your reply, best regards, Olivier Drouin For exemple, Endrun Technologies sells the Sonoma N12 which seems to allow time synchronization against CDMA signal without the need for a carrier subscriptions. And a gps receiver with PPS output is probably 1/100 the price. Is the CDMA method still available with these other cellulare network technologies like HSPA or LTE? If not, do I have other options beside a GPS antenna with a sky view? CDMA also needs an antenna with cell tower view. What's the difference? (Note my gps on an east facing window through a large cedar tree works just fine.) As Terje is mentioning, the cell antenna doesnt need a line of sight to a cell antenna, so It can be installed inside the server room and you dont have to deal with the maintenance problems (lots of snow around here) of a GPS antenna on the roof... Thank you and best regards, Olivier Drouin. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions Thank you and best regards, Olivier Drouin. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Indirect GPS time source options
On 13/03/2014 15:24, Jochen Bern wrote: [] (Personal opinion: I just don't get why there apparently are so many hosting/housing/colo providers where you *cannot* get access to a local NTP server or other central sync source even if you threaten to throw money at them. Tamperproofness-wise, two miniature PCs with GPS receivers on a roof your provider owns and controls run circles around everybody and his VMs talking to public no-crypto NTP servers through a plain Internet uplink ...) Regards, J. Bern Example of low-cost, low-power miniature NTP server as mentioned by Jochen: http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html -- Cheers, David Web: http://www.satsignal.eu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Indirect GPS time source options
Thank you Greg, Jochen, William, Great answers. Diversity is really what I'm looking for and I dont really need microsecond accuracy. CDMA seemed to be the most 'convenient' way to add diversity without a need for a working WAN link and/or line of sight view to the sky. Also, I already know that I get good cell signal from inside the server room. The thing with CDMA is that it looks like it'll not be around for many years and I haven't seen any equipement for 4g, hspa, LTE, etc... For your information, I think I can get away with a 10K budget but I need to be absolutely sure It'll work beforehand. I'll talk with the facility owner and do some tests with handheld GPS so I can verify what kind of signal I can get (and where). I'm a bit worried because I dont have roof access whenver I want and I dont know how the antenna will behave with the snow we get around here (quebec city). Ill also verify if I can synthonize the CHU radio frequency inside the server room if I can get my hand on a scanner. Olivier Drouin. On Thu, Mar 13, 2014 at 1:26 PM, Dowd, Greg greg.d...@microsemi.com wrote: You are not incorrect but I think that indirect GPS time may be more of a marketing term. Basically, GPS is the predominant method of time dissemination. When you think of a commercial ntp server, really you just moved the GPS antenna from your PC (getting rid of the receiver and coax cable) over to the ntp server, and then distributed the timing information over a different cable (your ethernet cable). Since NTP is layer 3, and the bus isn't dedicated, you introduce error but it's still GPS time. My term for the concept I understand you to be discussing is timing diversity. I prefer to have a number of different methods of accessing time data. GPS is the baseline but access to the L1 GPS signal is limited in some locations, particularly indoors. Keep in mind the analogy that the GPS broadcast is like a light bulb shining from 22000 km away. CDMA is nice as it's a powerful signal (compared to GPS) but it is limited in geographic deployment. Most 3G/LTE cellular systems these days are tightly syntonized (frequency) but not synchronized (time). So, no, you won't get microsecond level timing from GSM. Next gen LTE has a profile for LTE-TDD which will require about the same level of synchronization as CDMA. If you are looking to add diversity to an installation, your first best bet is to move to a GNSS receiver. Like your smartphone, a GNSS receiver typically works with both GPS and the Russian Glonass satellite systems. There's some diversity. For Canada, you could also look at eLoran. That operates on a completely different frequency plan to satellite timing. I think Canada has CHU radio timing as well (3330kHz). There are a number of signals of opportunity that require custom hardware to access either time or frequency. You mentioned CDMA. Digital television is another example. As someone mentioned earlier, to get a more precise answer you have to provide a more detailed analysis of your requirements and budget. Anything is possible. There are neutron stars out there dieing to provide you with a frequency reference :-) -Original Message- From: questions-bounces+gdowd=symmetricom@lists.ntp.org [mailto: questions-bounces+gdowd=symmetricom@lists.ntp.org] On Behalf Of Olivier Drouin Sent: Thursday, March 13, 2014 7:29 AM To: William Unruh Cc: questions@lists.ntp.org Subject: Re: [ntp:questions] Indirect GPS time source options On Wed, Mar 12, 2014 at 3:59 PM, William Unruh un...@invalid.ca wrote: On 2014-03-12, Olivier Drouin ol.dro...@gmail.com wrote: Hello, I'm located in Canada and I'm trying to find indirect GPS time sources. I like the idea of using CDMA as a time source but it seems that this technology will not be around for a lot longer. What is an indirect gps timing source? How does that differ from using ntp to go to a level 1 server which gets its time from gps. While cdma uses accurate time, it is not really designed to deliver accurate time. GPS is. Well, from what I understand the cell networks are closely synchronized against the GPS constellation. So, synchronizing against the cellular network is called indirect gps, at least according to the endrun website (I haven't seen this nomenclature anywhere else). It is different of GPS because if your WAN links are down, which can happen once every few years, then, hopefully, you can still reach the cellular network in your neighborhood or else its the end of the world or something... Also, from what I understand and please correct me if I'm wrong but cellular
Re: [ntp:questions] Indirect GPS time source options
On 2014-03-13, Hal Murray hal-use...@ip-64-139-1-69.sjc.megapath.net wrote: In article lfqeb1$m6$5...@dont-email.me, William Unruh un...@invalid.ca writes: CDMA also needs an antenna with cell tower view. What's the difference? 1/r-squared. The GPS satellites are way up in the air. A cell tower is a lot closer. You can get a signal from a cell tower into a lot of places where GPS doesn't work. There are loads of places here where the cell phone signal disappears. The gps signal is there everywhere outside. Agreed that in favourable circumstances, the cell signal may penetrate into the building much deeper, but it can also be non-existant even outdoors. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Indirect GPS time source options
On 2014-03-13, Steve Kostecke koste...@ntp.org wrote: On 2014-03-13, William Unruh un...@invalid.ca wrote: On 2014-03-13, Olivier Drouin ol.dro...@gmail.com wrote: Also, from what I understand and please correct me if I'm wrong but cellular networks are indeed designed to be accurately timed because it's needed for the normal operations of the cell network. Yes, but they are not designed to deliver accurate time to the rest of the world AFAIK. http://www.cdg.org/technology/cdma_technology/a_ross/systemtime.asp CDMA requires accurate time synchronization among all base stations and mobile stations. The accuracy must be within a few microseconds among base stations because the pilot code phase is used to distinguish them. When a mobile station is communicating with a base station they must be synchronized to within a fraction of a chip (814 ns). And the clocks (the PN generators) that must be synchronized have a period of 37 centuries. http://www.endruntechnologies.com/gps-cdma3.htm GPS Absolute timing accuracy of unit is under 30 nanoseconds. CDMA Absolute timing accuracy of unit is typically under 10 microseconds. Network timing accuracy 1/2 - 2 milliseconds, typical for both GPS and CDMA NTP products. Also see: http://www.endruntechnologies.com/cdma.htm Thanks. By the way, network timing I have found is much better than 1/2ms. If I get the time from a gps and a stratum 1 source 2000 miles away, the timing accuracy of that source is in the 50usec range. (the delay is clearly much larger than that ). From a local stratum 1 source (ie in the same building) it is more like 15usec. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Indirect GPS time source options
On 2014-03-13, Olivier Drouin ol.dro...@gmail.com wrote: Thank you Greg, Jochen, William, Great answers. Diversity is really what I'm looking for and I dont really need microsecond accuracy. CDMA seemed to be the most 'convenient' way to add diversity without a need for a working WAN link and/or line of sight view to the sky. Also, I already know that I get good cell signal from inside the server room. The thing with CDMA is that it looks like it'll not be around for many years and I haven't seen any equipement for 4g, hspa, LTE, etc... For your information, I think I can get away with a 10K budget but I need to be absolutely sure It'll work beforehand. A gps will cost you $50 assuming you have a computer already (if not another $50 for a Raspberry Pi +power source and ethernet cable. ) It will also cost a bit of wiring up time. I do agree that gps will almost certainly require an unalumized window, and in Quebec, not a north facing window. (gps avoids the north). Ie, you can try out the gps option with spare change. If that does not work, then you can go to the more expensive CDMA option. I have no idea how long Bell and Telus will continue their cdma offering. Rogers never used it, and all the newer players do not use G2 type offerings. I'll talk with the facility owner and do some tests with handheld GPS so I can verify what kind of signal I can get (and where). I'm a bit worried because I dont have roof access whenver I want and I dont know how the antenna will behave with the snow we get around here (quebec city). If it is on the roof, put the antenna onto a pole on the roof high enough that it will not get covered. But on a window, the chances are pretty slim that it will get covered in snow. Ill also verify if I can synthonize the CHU radio frequency inside the server room if I can get my hand on a scanner. Olivier Drouin. On Thu, Mar 13, 2014 at 1:26 PM, Dowd, Greg greg.d...@microsemi.com wrote: You are not incorrect but I think that indirect GPS time may be more of a marketing term. Basically, GPS is the predominant method of time dissemination. When you think of a commercial ntp server, really you just moved the GPS antenna from your PC (getting rid of the receiver and coax cable) over to the ntp server, and then distributed the timing information over a different cable (your ethernet cable). Since NTP is layer 3, and the bus isn't dedicated, you introduce error but it's still GPS time. My term for the concept I understand you to be discussing is timing diversity. I prefer to have a number of different methods of accessing time data. GPS is the baseline but access to the L1 GPS signal is limited in some locations, particularly indoors. Keep in mind the analogy that the GPS broadcast is like a light bulb shining from 22000 km away. CDMA is nice as it's a powerful signal (compared to GPS) but it is limited in geographic deployment. Most 3G/LTE cellular systems these days are tightly syntonized (frequency) but not synchronized (time). So, no, you won't get microsecond level timing from GSM. Next gen LTE has a profile for LTE-TDD which will require about the same level of synchronization as CDMA. If you are looking to add diversity to an installation, your first best bet is to move to a GNSS receiver. Like your smartphone, a GNSS receiver typically works with both GPS and the Russian Glonass satellite systems. There's some diversity. For Canada, you could also look at eLoran. That operates on a completely different frequency plan to satellite timing. I think Canada has CHU radio timing as well (3330kHz). There are a number of signals of opportunity that require custom hardware to access either time or frequency. You mentioned CDMA. Digital television is another example. As someone mentioned earlier, to get a more precise answer you have to provide a more detailed analysis of your requirements and budget. Anything is possible. There are neutron stars out there dieing to provide you with a frequency reference :-) -Original Message- From: questions-bounces+gdowd=symmetricom@lists.ntp.org [mailto: questions-bounces+gdowd=symmetricom@lists.ntp.org] On Behalf Of Olivier Drouin Sent: Thursday, March 13, 2014 7:29 AM To: William Unruh Cc: questions@lists.ntp.org Subject: Re: [ntp:questions] Indirect GPS time source options On Wed, Mar 12, 2014 at 3:59 PM, William Unruh un...@invalid.ca wrote: On 2014-03-12, Olivier Drouin ol.dro...@gmail.com wrote: Hello, I'm located in Canada and I'm trying to find indirect GPS time sources. I like the idea of using CDMA as a time source but it seems
Re: [ntp:questions] Indirect GPS time source options
On 2014-03-13, William Unruh un...@invalid.ca wrote: Ie, you can try out the gps option with spare change. If that does not work, then you can go to the more expensive CDMA option. I have no idea how long Bell and Telus will continue their cdma offering. Rogers never used it, and all the newer players do not use G2 type offerings. If you had thoroughly read all of the material at the links I previously posted you would know that CDMA is predicted to be available through 2020+ to support M2M (machine to machine) communications. [---=| TOFU protection by t-prot: 138 lines snipped |=---] ... -- Steve Kostecke koste...@ntp.org NTP Public Services Project - http://support.ntp.org/ ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Indirect GPS time source options
On 2014-03-13 11:52, Olivier Drouin wrote: Thank you Greg, Jochen, William, Great answers. Diversity is really what I'm looking for and I dont really need microsecond accuracy. CDMA seemed to be the most 'convenient' way to add diversity without a need for a working WAN link and/or line of sight view to the sky. Also, I already know that I get good cell signal from inside the server room. The thing with CDMA is that it looks like it'll not be around for many years and I haven't seen any equipement for 4g, hspa, LTE, etc... For your information, I think I can get away with a 10K budget but I need to be absolutely sure It'll work beforehand. I'll talk with the facility owner and do some tests with handheld GPS so I can verify what kind of signal I can get (and where). I'm a bit worried because I dont have roof access whenver I want and I dont know how the antenna will behave with the snow we get around here (quebec city). Ill also verify if I can synthonize the CHU radio frequency inside the server room if I can get my hand on a scanner. To test CHU reception you need a SW receiver to tune 3330, 7850, and 14670 kHz - 1kHz tones of different durations are broadcast every second except second 29 of each minute, data from seconds 31 to 39 ending at each half second, and voice is broadcast from seconds 50 to 59: see time signals at http://www.nrc-cnrc.gc.ca/eng/services/time/short_wave.html and data format at http://www.nrc-cnrc.gc.ca/eng/services/time/broadcast_codes.html. To use CHU, you need a SW receiver, possibly an external antenna, Bell 103 300 bps 8-N-2 compatible modem, an async serial UART port that will read it, and a system running NTP. For testing GPS, you could use any smart device with GPS, such as recent iP* or Android players, phones, or tablets, and a monitor app that shows satellite counts and visibility. To use GPS, you need a Sirf receiver module, like a Garmin 18x LVC, or uBlox NEO/ LEA-6T/M8F, ideally mounted inside a south facing roof space without steel, or window with no buildings in the way, or else an external active GPS antenna rated for -40C-+40C mounted above snow and obstruction level, hooked to an async serial UART port, on a system running NTP. See David Taylor's various devices, systems, and releases at http://www.satsignal.eu/ntp/. There are also a number of vendors who will sell you commercial GPS gear with antennas, and consultancies who will buy, install, and set it up for you. All OEM timing receivers typically perform much better than hand held devices, and the gold standard seems to be the Trimble Thunderbolt, available locally from Novotech in Pointe Claire near Montreal. -- Take care. Thanks, Brian Inglis ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
[ntp:questions] Indirect GPS time source options
Hello, I'm located in Canada and I'm trying to find indirect GPS time sources. I like the idea of using CDMA as a time source but it seems that this technology will not be around for a lot longer. For exemple, Endrun Technologies sells the Sonoma N12 which seems to allow time synchronization against CDMA signal without the need for a carrier subscriptions. Is the CDMA method still available with these other cellulare network technologies like HSPA or LTE? If not, do I have other options beside a GPS antenna with a sky view? Thank you and best regards, Olivier Drouin. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Indirect GPS time source options
On 2014-03-12, Olivier Drouin ol.dro...@gmail.com wrote: Hello, I'm located in Canada and I'm trying to find indirect GPS time sources. I like the idea of using CDMA as a time source but it seems that this technology will not be around for a lot longer. What is an indirect gps timing source? How does that differ from using ntp to go to a level 1 server which gets its time from gps. While cdma uses accurate time, it is not really designed to deliver accurate time. GPS is. For exemple, Endrun Technologies sells the Sonoma N12 which seems to allow time synchronization against CDMA signal without the need for a carrier subscriptions. And a gps receiver with PPS output is probably 1/100 the price. Is the CDMA method still available with these other cellulare network technologies like HSPA or LTE? If not, do I have other options beside a GPS antenna with a sky view? CDMA also needs an antenna with cell tower view. What's the difference? (Note my gps on an east facing window through a large cedar tree works just fine.) Thank you and best regards, Olivier Drouin. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Indirect GPS time source options
William Unruh wrote: On 2014-03-12, Olivier Drouin ol.dro...@gmail.com wrote: Is the CDMA method still available with these other cellulare network technologies like HSPA or LTE? If not, do I have other options beside a GPS antenna with a sky view? CDMA also needs an antenna with cell tower view. What's the difference? (Note my gps on an east facing window through a large cedar tree works just fine.) The Endrun unit worked very nicely inside the server room of our Tampa facility when I installed it 10+ years ago. There was no possible outside antenna location and at that time absolutely no gps units that would work from inside the metal glazed windows of the high rise building. Terje -- - Terje.Mathisen at tmsw.no almost all programming can be viewed as an exercise in caching ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
