Re: NTP question

Mel Beckman : > It’s hard to consider messing with signal converters and pricey > remotely-powered active antennas when you can solve the problem for $300. :) The recipe I posted a link to upthread is cheaper. https://www.ntpsec.org/white-papers/stratum-1-microserver-howto/ -- h

Re: NTP question

Alejandro Acosta : > "The built in high sensitivity GPS receiver is able to lock multiple > satellites from within multiple buildings or from a window location*, > eliminating the requirement that an outdoor antenna be installed*." Even relatively low-end GPS hardware can do this now. https://www

Re: NTP question

Brielle Bruns : > I've got a WWVB clock as well that I'd love to get hooked into my main NTP > server, but I worry they're going to finally kill that off in the next year > or so. Alas, your WWVB clock is probably already almost useless except as a wall decoration. The modulation of the subsecond

Re: NTP question

well, if they all go down, here is my backup clock. On Fri, May 3, 2019 at 10:04 AM Seth Mattinen wrote: > > On 5/1/19 8:35 PM, Mel Beckman wrote: > > But wait. What is the GPS constellation goes down? THEN we have bigger > problems > > > For timing if we lose the WWV stations and CDMA, then it

Re: NTP question

On 5/1/19 8:35 PM, Mel Beckman wrote: But wait. What is the GPS constellation goes down? THEN we have bigger problems For timing if we lose the WWV stations and CDMA, then it seems the diversity plan is going to be a combination of US GPS, Galileo, and GLONASS disciplined sources.

Re: NTP question

It is called Galileo :) Ge > Le 2 mai 2019 à 22:35, Scott Weeks a écrit : > > > >> But wait. What is the GPS constellation goes down? >> THEN we have bigger problems :) >> -- >> >> >> What if the US military intentionally messes with >> the s

Re: NTP question

> But wait. What is the GPS constellation goes down? > THEN we have bigger problems :) > -- > > > What if the US military intentionally messes with > the signal to thwart the advances of an enemy who > is using GPS in their attack? ;-) ---

Re: NTP question

Like I said, bigger problems. :) Enemies aren’t dependent on US GPS, by the way. lol! -mel via cell > On May 2, 2019, at 12:31 PM, Scott Weeks wrote: > > > > --- m...@beckman.org wrote: > From: Mel Beckman > > But wait. What is the GPS constellation goes down? > THEN we have bigger proble

Re: NTP question

--- m...@beckman.org wrote: From: Mel Beckman But wait. What is the GPS constellation goes down? THEN we have bigger problems :) -- What if the US military intentionally messes with the signal to thwart the advances of an enemy who is using

Re: NTP question

> On May 2, 2019, at 2:44 PM, Harlan Stenn wrote: > > > > On 5/2/2019 9:13 AM, James R Cutler wrote: >>> On May 2, 2019, at 10:59 AM, William Herrin >> > wrote: >>> >>> On Wed, May 1, 2019 at 7:03 PM Harlan Stenn >> > wrote: >>> >>>It's not

Re: NTP question

On 5/2/2019 7:59 AM, William Herrin wrote: > On Wed, May 1, 2019 at 7:03 PM Harlan Stenn > wrote: > > It's not clear to me that there's anything *wrong* with using the pool, > especially if you're using our 'pool' directive in your config file. > > > The one

Re: NTP question

On 5/2/2019 9:13 AM, James R Cutler wrote: >> On May 2, 2019, at 10:59 AM, William Herrin > > wrote: >> >> On Wed, May 1, 2019 at 7:03 PM Harlan Stenn > > wrote: >> >> It's not clear to me that there's anything *wrong* with using the >> poo

Re: NTP question

    First sorry for the gender goof, I did a lazy analog translation from "pompiers".     It is a true story that happened to a buddy of mine a few years back.     People saw smoke (diesel exhaust) coming from the roof of the building during a power outage and called 911.     They did follow

Building Integrated Timing System (was Re: NTP question)

On Thu, 2 May 2019, Carsten Bormann wrote: Why don’t data centers provide a GPS signal along with power and air conditioning? Installing a distribution amplifier for 1.5 GHz is not rocket science. (Or an Ethernet with IEEE1588 precise time, but that is probably asking too much.) They should

Re: NTP question

On 5/2/19 9:32 AM, Alain Hebert wrote: Unless the Firemen turn your roof generator off because someone in the street yelled fire =D The firemen & women that I've had the pleasure of working with did have more brains than that. Despite their reputation of brute force, they do think. -- Gra

Re: NTP question

> On May 2, 2019, at 10:59 AM, William Herrin wrote: > > On Wed, May 1, 2019 at 7:03 PM Harlan Stenn > wrote: > It's not clear to me that there's anything *wrong* with using the pool, > especially if you're using our 'pool' directive in your config file. > > The one tim

Re: NTP question

@nanog.org Sent: Wednesday, May 1, 2019 5:27:38 PM Subject: Re: NTP question On 01/05/2019 20:29, Job Snijders wrote: > The trick is to order a spot on the roof of the datacenter, have the > facility staff place the antenna there, and run a cable to the NTP > server in your rack.

Re: NTP question

Bill, I did say _today’s_ RTP chips :) Although as a Mac user with multiple types, many not Internet-connected, I’ve never seen any lose minutes per day. You might have a dead clock battery. -mel On May 2, 2019, at 7:57 AM, William Herrin mailto:b...@herrin.us>> wrote: On Wed, May 1, 2019 a

Re: NTP question

On 01/05/2019 20:29, Job Snijders wrote: > The trick is to order a spot on the roof of the datacenter, have the > facility staff place the antenna there, and run a cable to the NTP > server in your rack. Some DCs also offer GPS antenna feeds fed from a splitter, though it's important to get the to

Re: NTP question

The link you provided answers that question: "The built in high sensitivity GPS receiver is able to lock multiple satellites from within multiple buildings or from a window location, eliminating the requirement that an outdoor antenna be installed". If you're still worried about your specific use-

Re: NTP question

    Unless the Firemen turn your roof generator off because someone in the street yelled fire =D On 2019-05-02 11:21, Grant Taylor via NANOG wrote: On 5/2/19 8:03 AM, Kain, Rebecca (.) wrote: Or the fbi shuts off the power grid Na. Battery backup and generators with days ~> weeks worth of f

Re: NTP question

Once upon a time, William Herrin said: > The one time I relied on the pool I lost sync a year later when all three > servers the configuration picked withdrew time services and the > still-running ntp client didn't return to the names to find new ones. > Wonderful if that's fixed now but the pool

Re: NTP question

On 5/2/19 8:03 AM, Kain, Rebecca (.) wrote: Or the fbi shuts off the power grid Na. Battery backup and generators with days ~> weeks worth of fuel. }:-) -- Grant. . . . unix || die smime.p7s Description: S/MIME Cryptographic Signature

Re: NTP question

On Wed, May 1, 2019 at 7:03 PM Harlan Stenn wrote: > It's not clear to me that there's anything *wrong* with using the pool, > especially if you're using our 'pool' directive in your config file. > The one time I relied on the pool I lost sync a year later when all three servers the configuratio

Re: NTP question

On Wed, May 1, 2019 at 8:35 PM Mel Beckman wrote: > I can tell you how the GPS server behaves when it loses it signal: it > stops giving out verified time and lapses into Stratum-“goners” mode. But > today’s RTP chips don’t start losing seconds-per-day when they are free > running. Typically they

RE: NTP question

Or the fbi shuts off the power grid -Original Message- From: NANOG On Behalf Of Valdis Kletnieks Sent: Thursday, May 02, 2019 10:00 AM To: Tom Beecher Cc: NANOG list Subject: Re: NTP question On Thu, 02 May 2019 08:59:19 -0400, Tom Beecher said: > Passes the backhoe test, but mi

Re: NTP question

On Thu, 02 May 2019 08:59:19 -0400, Tom Beecher said: > Passes the backhoe test, but might have an issue with the Die Hard Elevator > Shaft Fight Scene checks. If your data center is suffering from both backhoe face and a Die Hard Fight Scene, the *real* question is whether you're going to care

Re: NTP question

Passes the backhoe test, but might have an issue with the Die Hard Elevator Shaft Fight Scene checks. :) On Thu, May 2, 2019 at 07:34 william manning wrote: > for our PCI-DSS audit, the rational for at least -one- local source, > instead of depending on pool.ntp.org, was "backhoe fade". > it wa

Re: NTP question

for our PCI-DSS audit, the rational for at least -one- local source, instead of depending on pool.ntp.org, was "backhoe fade". it was worth the $135 for an NTP source using GPS. the cable run up the elevator shaft for the antenna works without needing OSHPD permits. We are very happy with the res

Re: NTP question

Op 02-05-19 om 02:00 schreef Ask Bjørn Hansen: Though, on the topic of unusual requirements there are a bunch of contributors to the NTP Pool using this curious device It continues to surprise me that there is still hardware being sold that doesn't even support IPv6. -- Marco

Re: NTP question

On Thu, 02 May 2019 00:29:32 -0400, Keith Wallace said: > Good stuff, never had an issue with rollovers, software was upgradable. Did the vendor ever ship an actual software upgrade? pgpn6eFWHI5i6.pgp Description: PGP signature

Re: NTP question

issue with rollovers, software was upgradable. Sent from my android device. -Original Message- From: "Ask Bjørn Hansen" To: Mehmet Akcin Cc: nanog Sent: Wed, 01 May 2019 19:43 Subject: Re: NTP question > On May 1, 2019, at 12:22, Mehmet Akcin wrote: > > I am trying

Re: NTP question

On May 2, 2019, at 00:41, Alejandro Acosta wrote: > > As other have commented before, it looks you need an outdoor antenna, > however, reading the specs it says: > > > > “The built in high sensitivity GPS receiver is able to lock multiple > satellites from within multiple buildings or fro

Re: NTP question

For those wondering what a GPS certification letter for the rollover bug looks like, here’s Garmin’s. Note the phrase “for many years, Garmin has anticipated and prepared for this event...”: Garmin GPS Week Number Rollover Statement What is the GPS Week Number Rollover (WNRO)? The GPS system i

Re: NTP question

I’m talking about _my_ GPS server. I have no idea what you’ve cobbled up :) -mel > On May 1, 2019, at 8:41 PM, Gary E. Miller wrote: > > Yo Mel! > > On Thu, 2 May 2019 03:35:31 + > Mel Beckman wrote: > >> I can tell you how the GPS server behaves when it loses it signal: it >> stops gi

Re: NTP question

Gary, Gary, Gary, You don’t need a $30,000 GPS simulator to verify if a GPS product in your inventory has the rollover bug. You simply ask the supplier to certify that they don’t have the rollover bug. They use their _$100,000_ GPS simulator If needed, but usually it’s done with a trivial code

Re: NTP question

Yo Mel! On Thu, 2 May 2019 03:35:31 + Mel Beckman wrote: > I can tell you how the GPS server behaves when it loses it signal: it > stops giving out verified time and lapses into Stratum-“goners” mode. I happen to have a few GPS in my lab that do not agree with your statement. I'll spare th

Re: NTP question

Yo Mel! On Thu, 2 May 2019 03:30:03 + Mel Beckman wrote: > I’m also an FAA licensed A&P mechanic, and have worked for airlines > in fleet maintenance. Air carriers have extremely thorough systems > reviews, by law, through the Airworthiness Directive program, which > started identifying 201

Re: NTP question

I can tell you how the GPS server behaves when it loses it signal: it stops giving out verified time and lapses into Stratum-“goners” mode. But today’s RTP chips don’t start losing seconds-per-day when they are free running. Typically they might lose ten seconds per week on cheap systems. That’s

Re: NTP question

Yo Gary! Not only did I not sleep through it, I was one of the engineers who verified that every GPS clock source in a very large aviation support network didn’t have have this bug. I’m also an FAA licensed A&P mechanic, and have worked for airlines in fleet maintenance. Air carriers have ex

Re: NTP question

On 5/1/19 7:54 PM, Mel Beckman wrote: > Harlan, > > Why? The GPS NTP Server is Stratum-1. If it fails computer clocks will > freewheel for hours or days before losing significant time, during which > period you can simply order a replacement unit. If that isn’t fast enough, > buy two $300 b

Re: NTP question

Yo Mel! On Thu, 2 May 2019 02:54:25 + Mel Beckman wrote: > Why? The GPS NTP Server is Stratum-1. If it fails computer clocks > will freewheel for hours or days before losing significant time, > during which period you can simply order a replacement unit. If that > isn’t fast enough, buy two

Re: NTP question

Harlan, Why? The GPS NTP Server is Stratum-1. If it fails computer clocks will freewheel for hours or days before losing significant time, during which period you can simply order a replacement unit. If that isn’t fast enough, buy two $300 boxes. The “consensus” issue is moot, since a GPS serv

Re: NTP question

Hi Keith, On 5/1/19 6:17 PM, Keith Medcalf wrote: > >> If your network is air gapped from the Internet then sure. If it's >> not, you can run NTP against a reasonably reliable set of time >> sources (not random picks from Pool) and be able to say, "my log >> timestamps are accurate to +/- 10 mill

Re: NTP question

On 5/1/19 5:55 PM, William Herrin wrote: > On Wed, May 1, 2019 at 5:48 PM Keith Medcalf wrote: > >> If you have one such installation, then you really do not care about the >> "accuracy" of the time. However if you have multiple such installations >> then you want them all to have the same ti

Re: NTP question

> On May 1, 2019, at 9:45 PM, Harlan Stenn wrote: > > > > On 5/1/19 5:39 PM, William Herrin wrote: >> On Wed, May 1, 2019 at 12:23 PM Mehmet Akcin wrote: >> >>> I am trying to buy a GPS based NTP server like this one >>> >>> https://timemachinescorp.com/product/gps-time-server-tm1000a/ >>>

Re: NTP Question

On 5/1/19 4:28 PM, Mel Beckman wrote: > Harlan and Mehmet, > > I can expand on one important reason that James only alluded to with his > “Kepping the Auditors happy” comment. > > Passing NTP through a firewall and then using that as a critical time > reference source represents a huge secur

Re: NTP question

On 5/1/19 4:53 PM, Mel Beckman wrote: > Ask, > > But with a small compact server like the DC-powered TimeMachines Inc unit, > which costs something like $300, you simply put the server where the > visibility is and connect back to the nearest Ethernet port in your network, > up to 300’ away,

Re: NTP question

On 5/1/19 5:39 PM, William Herrin wrote: > On Wed, May 1, 2019 at 12:23 PM Mehmet Akcin wrote: > >> I am trying to buy a GPS based NTP server like this one >> >> https://timemachinescorp.com/product/gps-time-server-tm1000a/ >> >> but I will be placing this inside a data center, do these need a

Re: NTP question

On Wed, May 1, 2019, at 19:19, Brandon Martin wrote: > I've seen things like this when there's a sudden power loss across a > small site e.g. a remote PoP. Think a loss of utility power and UPS > fails to transfer for some unanticipated reason. Or in our case, a Canada Goose lands on the transf

Re: NTP question

Stephen, LOL. That’s not a real problem with today’s microprocessors. The TM1000A, for example: “...is capable of serving 135+ synchronizations per second. That provides support for over 120,000+ devices updating every 15 minutes on the network.” As for ARP traffic deluges, if that’s happenin

Re: NTP question

One word of caution when using a low-priced NTP appliance: your network activity could overwhelm the TCP/IP stack of the poor thing, especially if you want to sync your entire shop to it. In the case of the networks I set up, I set up a VLAN specific to the NTP appliance and to the two servers tha

RE: NTP question

>If your network is air gapped from the Internet then sure. If it's >not, you can run NTP against a reasonably reliable set of time >sources (not random picks from Pool) and be able to say, "my log >timestamps are accurate to +/- 10 milliseconds so it must be you who >is farked up." While my mill

Re: NTP question

On Wed, May 1, 2019 at 9:56 PM William Herrin wrote: > On Wed, May 1, 2019 at 5:48 PM Keith Medcalf wrote: > >> If you have one such installation, then you really do not care about the >> "accuracy" of the time. However if you have multiple such installations >> then you want them all to have t

Re: NTP question

On Wed, May 1, 2019 at 5:48 PM Keith Medcalf wrote: > If you have one such installation, then you really do not care about the > "accuracy" of the time. However if you have multiple such installations > then you want them all to have the same time (if you will be comparing logs > between them, f

RE: NTP question

On Wednesday, 1 May, 2019 15:36, Harlan Stenn wrote: >So I gotta ask, just as a reality check: >- Why do folks want to have one or more NTP server masters that have >at least 1 refclock on them in a data center, instead of having their >data center NTP server masters that only get time over th

Re: NTP question

Once upon a time, William Herrin said: > You sure you need a GPS NTP server? You understand that if you do, you need > two for reliability right That'd be 3 - a man with 2 clocks never know what time it is! :) -- Chris Adams

Re: NTP question

On Wed, May 1, 2019 at 12:23 PM Mehmet Akcin wrote: > I am trying to buy a GPS based NTP server like this one > > https://timemachinescorp.com/product/gps-time-server-tm1000a/ > > but I will be placing this inside a data center, do these need an actual > view of a sky to be able to get signal or

Re: NTP question

On 5/1/2019 6:12 PM, Mike Hammett wrote: Anyone know of a solution that doesn't require an external antenna, is NEBS compliant, and has T1-type outputs for me to hook into my Metaswitch gear? You forgot 'world peace' in there too. :) -- Brielle Bruns The Summit Open Source Development Grou

Re: NTP question

ssage - From: "Alejandro Acosta" To: nanog@nanog.org Sent: Wednesday, May 1, 2019 5:41:36 PM Subject: Re: NTP question Hello, As other have commented before, it looks you need an outdoor antenna, however, reading the specs it says: "The built in high sensitivity GPS

Re: NTP question

> On May 1, 2019, at 16:53, Mel Beckman wrote: > > It’s hard to consider messing with signal converters and pricey > remotely-powered active antennas when you can solve the problem for $300. :) As I said, it really depends on your requirements and expectations. :-) For my “normal” use cases

Re: NTP question

Ask, But with a small compact server like the DC-powered TimeMachines Inc unit, which costs something like $300, you simply put the server where the visibility is and connect back to the nearest Ethernet port in your network, up to 300’ away, or virtually any distance with fiber transceivers. W

Re: NTP question

> On May 1, 2019, at 12:22, Mehmet Akcin wrote: > > I am trying to buy a GPS based NTP server like this one > > https://timemachinescorp.com/product/gps-time-server-tm1000a/ > > but I will be placing this inside a data center, do these need an actual view > of a sky to be able to get signa

Re: NTP Question

Harlan and Mehmet, I can expand on one important reason that James only alluded to with his “Kepping the Auditors happy” comment. Passing NTP through a firewall and then using that as a critical time reference source represents a huge security risk. Here’s one detailed explanation of that risk

Re: NTP question

On 5/1/2019 4:17 PM, Brandon Martin wrote: > On 5/1/19 7:03 PM, Harald Koch wrote: >> Properly deployed NTP should calibrate the local hardware clocks to >> prevent drift even during connectivity outages. (I'm talking both the >> low resolution hardware clocks used for timing across power cycles

Re: NTP question

On 5/1/19 7:03 PM, Harald Koch wrote: Properly deployed NTP should calibrate the local hardware clocks to prevent drift even during connectivity outages. (I'm talking both the low resolution hardware clocks used for timing across power cycles and reboots, and the oscillators used while the OS

Re: NTP question

On Wed, May 1, 2019, at 18:46, Brandon Martin wrote: > Think about what might happen if you lost time sync as a result of the > incident causing said connectivity outage. Depending on your time > sources available, you might see rapid drift or, worst case, lose your > time reference entirely as

Re: NTP Question

On Wed, May 01, 2019 at 02:35:58PM -0700, Harlan Stenn wrote: > - Why do folks want to have one or more NTP server masters that have at > least 1 refclock on them in a data center, instead of having their data > center NTP server masters that only get time over the internet? Answers to that includ

Re: NTP question

On 5/1/19 5:35 PM, Harlan Stenn wrote: - Why do folks want to have one or more NTP server masters that have at least 1 refclock on them in a data center, instead of having their data center NTP server masters that only get time over the internet? It can be extremely useful to have known-good ti

Re: NTP question

Hello,   As other have commented before, it looks you need an outdoor antenna, however, reading the specs it says: "The built in high sensitivity GPS receiver is able to lock multiple satellites from within multiple buildings or from a window location*, eliminating the requirement that an outdoo

Re: NTP question

4:35:58 PM Subject: Re: NTP question So I gotta ask, just as a reality check: - Why do folks want to have one or more NTP server masters that have at least 1 refclock on them in a data center, instead of having their data center NTP server masters that only get time over the internet? - What

Re: NTP question

On 5/1/19 2:59 PM, Andreas Ott wrote: > On Wed, May 01, 2019 at 02:35:58PM -0700, Harlan Stenn wrote: >> - Why do folks want to have one or more NTP server masters that have at >> least 1 refclock on them in a data center, instead of having their data >> center NTP server masters that only get t

Re: NTP question

On Wed, May 01, 2019 at 02:35:58PM -0700, Harlan Stenn wrote: > - Why do folks want to have one or more NTP server masters that have at > least 1 refclock on them in a data center, instead of having their data > center NTP server masters that only get time over the internet? I had that discussion

Re: NTP question

Perhaps using a rubidium source instead of GPS ? The actual time can be obtained thru NTP, all you actually need is a precision source to keep time accurate thereafter. Rubens On Wed, May 1, 2019 at 4:24 PM Mehmet Akcin wrote: > hey there Nanog, > > I am trying to buy a GPS based NTP server l

Re: NTP question

So I gotta ask, just as a reality check: - Why do folks want to have one or more NTP server masters that have at least 1 refclock on them in a data center, instead of having their data center NTP server masters that only get time over the internet? - What % of data center operators provide time s

Re: NTP question

dnesday, May 1, 2019 3:58:57 PM *Subject: *Re: NTP question On 5/1/2019 2:50 PM, Andreas Ott wrote: >> If you can't get a good spot for an antenna, you could be on the lookout >> for a CDMA NTP clock. > CDMA service is about to be retired in several places, please check >

Re: NTP question

w.ics-il.com Midwest-IX http://www.midwest-ix.com - Original Message - From: "Brielle Bruns" To: nanog@nanog.org Sent: Wednesday, May 1, 2019 3:58:57 PM Subject: Re: NTP question On 5/1/2019 2:50 PM, Andreas Ott wrote: >> If you can't get a good spot for an an

Re: NTP question

On 5/1/2019 2:50 PM, Andreas Ott wrote: If you can't get a good spot for an antenna, you could be on the lookout for a CDMA NTP clock. CDMA service is about to be retired in several places, please check in your area before you install a "new" CDMA based time server. C.f.https://www.verizonwirele

Re: NTP question

Mehmet, I use the TimeMachines unit a lot. Usually we deploy these near any outside window, typically putting the box in the ceiling and the running the GPS antenna on its 20’ cable (or whatever it is) down to the window glass. Test different windows first before committing. Then use any of th

Re: NTP question

igent Computing Solutions http://www.ics-il.com Midwest-IX http://www.midwest-ix.com - Original Message - From: "Andreas Ott" To: nanog@nanog.org Sent: Wednesday, May 1, 2019 3:50:33 PM Subject: Re: NTP question Hi, On Wed, May 01, 2019 at 02:01:44PM -0600, Brielle Bruns w

Re: NTP question

Hi, On Wed, May 01, 2019 at 02:01:44PM -0600, Brielle Bruns wrote: > If you can't get a good spot for an antenna, you could be on the lookout > for a CDMA NTP clock. CDMA service is about to be retired in several places, please check in your area before you install a "new" CDMA based time server

Re: NTP question

If you can't get a good spot for an antenna, you could be on the lookout for a CDMA NTP clock. https://endruntechnologies.com/products/ntp-time-servers We've got one as a backup to our SyncServer S200. Doesn't need an outdoor antenna as long as you can get a cellular signal in the DC. EndRu

Re: NTP question

thank you guys, looks like GPS based NTP is the way to go. On Wed, May 1, 2019 at 3:36 PM Bryan Fields wrote: > On 5/1/19 3:22 PM, Mehmet Akcin wrote: > > hey there Nanog, > > > > I am trying to buy a GPS based NTP server like this one > > > > https://timemachinescorp.com/product/gps-time-server

Re: NTP question

On 5/1/19 3:22 PM, Mehmet Akcin wrote: > hey there Nanog, > > I am trying to buy a GPS based NTP server like this one > > https://timemachinescorp.com/product/gps-time-server-tm1000a/ > > but I will be placing this inside a data center, do these need an actual > view of a sky to be able to get s

Re: NTP question

Dear Mehmet, On Wed, May 01, 2019 at 03:22:57PM -0400, Mehmet Akcin wrote: > I am trying to buy a GPS based NTP server like this one > > https://timemachinescorp.com/product/gps-time-server-tm1000a/ > > but I will be placing this inside a data center, do these need an > actual view of a sky to b

NTP question

hey there Nanog, I am trying to buy a GPS based NTP server like this one https://timemachinescorp.com/product/gps-time-server-tm1000a/ but I will be placing this inside a data center, do these need an actual view of a sky to be able to get signal or will they work fine inside a data center build