Re: WWV Broadcast Outages
"Majdi S. Abbas" <msa@latt.net> said:
That said, I and many others "still use" WWV -- there aren't exactly a surplus of suitable backup methods to GPS these days.
Any suggestions for gear and/or software that works with WWV (or CHU)? Or general suggestions for non GPS sources of time? Dave Mills had a driver in ntpd that used a PC audio port to listen to WWV. I don't know anybody who ever used it. I think there was code to tell some brand of receiver with a serial/USB port how to change frequencies so you could use the one that worked best for that time of day. There used to be WWVB (60 KHz) receivers. The good ones phase locked to the carrier. The general rise in EMI made those close to useless in most locations. NIST finished the job when they changed the modulation format a few years ago. As far as I know, there aren't any replacements for the old gear that take advantage of the new modulation format. GPS works too well. There are some boxes that recover the time from nearby cell phone towers. I think they will stop working as the towers get upgraded to the newer protocols that use a different form of timing. That will probably take many years. But the cell phone towers depend on GPS. (You can ususlly spot the conical antenna(s) if you look around a bit.) -- These are my opinions. I hate spam.
On Wed, Feb 22, 2017 at 04:59:53AM -0800, Hal Murray wrote:
Any suggestions for gear and/or software that works with WWV (or CHU)? Or general suggestions for non GPS sources of time?
Hey Hal! In North America, WWV and CHU are pretty much it for accessible backups these days. Unfortunately time and frequency distribution is a niche that tends to get neglected (if not actively gutted) in US budgets.
Dave Mills had a driver in ntpd that used a PC audio port to listen to WWV. I don't know anybody who ever used it. I think there was code to tell some brand of receiver with a serial/USB port how to change frequencies so you could use the one that worked best for that time of day.
You do now. The WWV and CHU audio drivers work fine. If you want the auto-tuning functionality, you need to use an Icom receiver that supports their CI-V protocol. (This can be a full fledged tabletop like the R-75, or a more compact receiver like their PCR-100 or 1000. Some of these are no longer produced, but they're easy to come by on the secondary markets. I picked up multiple PCR-100s off eBay at $25 ea a while ago.) You can always use any shortwave receiver, and just tune it to a good frequency. There are also kit and prebuilt 10 MHz receivers out there in the $30-$40 range which will work. You accept a slight loss in daily coverage by selecting a compromise frequency, but it's better than nothing and independent of GPS. If you (or anyone else on NANOG) needs some help getting the audio refclocks working; drop me a line.
There used to be WWVB (60 KHz) receivers. The good ones phase locked to the carrier. The general rise in EMI made those close to useless in most locations. NIST finished the job when they changed the modulation format a few years ago. As far as I know, there aren't any replacements for the old gear that take advantage of the new modulation format. GPS works too well.
It's not so much that GPS works so well, as there's no way to produce a commercial receiver that uses the enhanced format. By gifting the developed IP back to the developer as part of the SIPR grant, it is all sitting under a patent umbrella. Unfortunately, the startup that developed it appears to have failed (at least, they've mostly vanished, folks seem to have moved on, and they're late on corporate reports at this point.) -- leaving the new format only usable by hackers and not something that can be rolled into a commercial timing receiver. My biggest beef with the new format was the rollout, 5 years ago now, before a commercial receiver was available on the market. I'm not sure why NIST has stuck with it.
There are some boxes that recover the time from nearby cell phone towers. I think they will stop working as the towers get upgraded to the newer protocols that use a different form of timing. That will probably take many years. But the cell phone towers depend on GPS. (You can ususlly spot the conical antenna(s) if you look around a bit.)
CDMA was only ever good to +/- 10ms anyway, at least any of the boxes I ever used. You can actually outperform it with classic WWV or CHU, and those get you a real backup, rather than an indirect dependancy on GPS. --msa
On 3/6/2017 3:55 AM, Majdi S. Abbas wrote:
On Wed, Feb 22, 2017 at 04:59:53AM -0800, Hal Murray wrote:
Any suggestions for gear and/or software that works with WWV (or CHU)? Or general suggestions for non GPS sources of time? Hey Hal!
In North America, WWV and CHU are pretty much it for accessible backups these days. Unfortunately time and frequency distribution is a niche that tends to get neglected (if not actively gutted) in US budgets.
Agreed, but I'll share this- the recent FCC CSRIC V had a working group (4B) that studied the reliability of time and frequency distribution. https://www.fcc.gov/about-fcc/advisory-committees/communications-security-re... It may be of interest.
On Mon, Mar 6, 2017 at 5:12 AM, Andrew Gallo <akg1330@gmail.com> wrote:
On 3/6/2017 3:55 AM, Majdi S. Abbas wrote:
On Wed, Feb 22, 2017 at 04:59:53AM -0800, Hal Murray wrote:
Any suggestions for gear and/or software that works with WWV (or CHU)? Or general suggestions for non GPS sources of time?
Hey Hal!
In North America, WWV and CHU are pretty much it for accessible backups these days. Unfortunately time and frequency distribution is a niche that tends to get neglected (if not actively gutted) in US budgets.
Agreed, but I'll share this- the recent FCC CSRIC V had a working group (4B) that studied the reliability of time and frequency distribution. https://www.fcc.gov/about-fcc/advisory-committees/communications-security-re...
It may be of interest.
Specifically, the "Network Timing Single Source Risk Reduction - Final Report" part: https://transition.fcc.gov/bureaus/pshs/advisory/csric5/WG4B_FinalReport_122... My summary of its points: * Analysis of vulnerabilities in the "supply chain" of GPS * Assertion that GPS mitigations and alternatives are needed to reduce risk * Some likely characteristics of good mitigations and alternatives * A list of potential alternatives, their features, and their current state (L2C & L5 GPS, Galileo & GLONASS, LEO satelltes, commercial RF, antenna pattern optimization, NMA on L2C, sync over fiber, eLORAN, other RF sync, terrestrial beacons, and hybrid DME)
From the executive summary:
The U.S. communications sector relies heavily on the Global Positioning System (GPS) to provide network time. GPS is a widely available, extremely precise timing source that is used across multiple infrastructure sectors. However, given the high dependence of the communications sector on GPS, the Federal Communications Commission (Commission) is interested in identifying ways to increase the resilience of communications networks by exploring complementary or backup solutions that could be employed to offer similar time precision as GPS in the event that GPS signals are lost. These solutions also need to be completely independent of GPS to significantly reduce any risk. This report addresses the problems associated with relying on GPS solutions, the ideal technical characteristics for systems to backup or supplement GPS, and our recommendations for possible backup solutions by the communications industry and others reliant on communications network timing sources. Royce
participants (4)
-
Andrew Gallo -
Hal Murray -
Majdi S. Abbas -
Royce Williams