The short version is this: Some US laws and regulations basically require a license for "receive-only earth stations," which operate with any non-US satellite service. This, unfortunately, includes GNSS systems such as GALILEO and GLONASS. The link Ken provided ( https://www.gps.gov/spectrum/foreign/ ) is a good spot to describe the government's position and provide links to the CFR sections about this and so on.
However, the problem is that the FCC only started making noise about GNSS being affected by this a few years ago. By then, thousands, if not millions, of GPS+GLONASS receivers were operating in the US. Trying to stuff that back in the bag is not really possible. And it's getting harder and harder as more are added every day. The official legal status is that GPS is fine (obviously). In addition, there is a waiver process that foreign systems can go through, and GALILEO (and only GALILEO) has completed that. So we're left with GPS+GALILEO being the only multi-GNSS system with the US government stamp of approval. I doubt we will ever see any enforcement actions here as almost every single American has an unlicensed ground station in their pocket (as you pointed out). There are other reasons why GLONASS, in particular, isn't an ideal GNSS system for the timing applications we use. The main technical one is that the specified GLONASS-UTC offset is up to 1ms (1/1000th of a second), whereas GPS and GALILEO are better than 1us (1 millionth of a second). In fairness to GLONASS, they are typically under 1uS as well, but their offset is usually bigger than either GPS or GALILEO (with GALILEO typically being the best). But the summary is that adding GLONASS to GPS tends to slightly reduce the precision of the timing signal, and adding GALILEO typically improves it. I've purposely ignored the geopolitical issues here, but I will state this: I'm also not 100% comfortable with using a system that relies on Russia not deciding to intentionally mess with the signals from GLONASS. This all adds up to the reason why I decided to switch the defaults to all GPS+GALILEO. It's guaranteed to be actually legal. Technically GPS+GLONASS is a better choice than GPS+GALILEO. And finally, GALILEO doesn't roll their date over every 4 years, causing issues. On Mon, Jan 1, 2024 at 3:14 PM Josh Luthman <j...@imaginenetworksllc.com> wrote: > US cell phones have GLONASS support. What makes you say there's a legal > question? > > On Sun, Dec 31, 2023 at 6:10 PM Forrest Christian (List Account) < > li...@packetflux.com> wrote: > >> Some customers wanted the added redundancy that comes with more >> satellites. The irony of the thing which we changed to improve reliability >> biting one in the rear with this issue is not lost on me. >> >> At this point, everything is going out with GPS+GALILEO since there is >> some question about if it is even legal to operate a GLONASS receiver in >> the USA. >> >> On Sun, Dec 31, 2023 at 2:26 PM Chuck McCown via AF <af@af.afmug.com> >> wrote: >> >>> What is the benefit to using glonass? >>> For timing is not GPS good enough? >>> >>> >>> *From:* Forrest Christian (List Account) >>> *Sent:* Sunday, December 31, 2023 10:10 AM >>> *To:* AnimalFarm Microwave Users Group >>> *Subject:* Re: [AFMUG] Ken Hohof >>> >>> Well hopefully most everything can be remotely handled. >>> >>> I'm really really hoping that the fix my current GPS vendor provided >>> actually survives the rollover. Otherwise this is going to be a much >>> bigger mess. >>> >>> I really wish multi GNSS simulators weren't so expensive. Like costs >>> more than we make on syncboxes for a couple/few years expensive. They're >>> also not available to lease for any reasonable price. As a result I get to >>> trust that my vendor did exactly the right thing here. >>> >>> I'm hanging around the phone for the inevitable panicked call from the >>> customer who ignored (or didn't get) all of the messages we sent out. >>> >>> On Sun, Dec 31, 2023, 9:07 AM Ken Hohhof <khoh...@kwom.com> wrote: >>> >>>> Hi all. Happy New Year. I have to do GLONASS fixups at 3pm today, the >>>> forecast is freezing rain. Yay! >>>> >>>> -----Original Message----- >>>> From: AF <af-boun...@af.afmug.com> On Behalf Of Chuck McCown via AF >>>> Sent: Sunday, December 31, 2023 12:08 AM >>>> To: af@af.afmug.com >>>> Cc: Chuck McCown <ch...@go-mtc.com> >>>> Subject: [AFMUG] Ken Hohof >>>> >>>> Everbuddy say welcome back Ken!!! >>>> >>>> Sent from my iPhone >>>> >>>> >>>> -- >>>> AF mailing list >>>> AF@af.afmug.com >>>> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >>>> >>>> >>>> >>>> -- >>>> AF mailing list >>>> AF@af.afmug.com >>>> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >>>> >>> ------------------------------ >>> -- >>> AF mailing list >>> AF@af.afmug.com >>> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >>> >>> -- >>> AF mailing list >>> AF@af.afmug.com >>> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >>> >> >> >> -- >> - Forrest >> -- >> AF mailing list >> AF@af.afmug.com >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >> > -- > AF mailing list > AF@af.afmug.com > http://af.afmug.com/mailman/listinfo/af_af.afmug.com > -- - Forrest
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