[Goose]

The failure to stop the GPS jamming, perhaps by HARM knocking out transmitters doing the jamming, has been perplexing.

I had presumed that GPS jamming was local.  That is, a jammer transmitter might protect some region near it.

You are exactly correct in that presumption. However, the definition of "near" is dependent on the Effective Radiated Power (ERP) of the jammer. The ERP can be directional, where all the jamming power is concentrated in a narrow beam aimed at the vehicle that is to be "jammed". It can also be spread over a defined area by using various forms of directional antennas. However, the easiest way to cover a large area is using a jammer that puts out LOTS of power. Russia is usually quite fond of this "solution". Another way of course is to have many jammers. In Ukraine, Russia seems to be going with quantity, not brute power. Brute power creates a vulnerability. Knock out one jammer and a broad area is unprotected. Lower power jammers are also easier to build. Commercial cell tower components work great in this application and they are easy to buy from many nations that don't care much about sanctions.

I just noticed this article from Wired: "The Dangerous Rise of GPS Attacks"

One open source intelligence analyst, going by the pseudonym Markus Jonsson, has located jamming in the Baltics, and that which impacted the Finnish airline this week, to Kaliningrad and other Russian locations.

I don't really know how long distance jamming might work.  But, if it can be done, perhaps that explains why the jammers haven't been hit.

Actually quite the opposite. The larger the ERP the easier it is to detect and geolocate the jammer. It is also easier to "home" on a signal that has a high signal to noise ratio (SNR).

The GPS jamming situation is complicated by the fact the actual received power from GPS satellites is very small. GPS wouldn't work at all if the GPS signal was not coded is such a way that digital signal processing can deliver "processing gain". The various types of jamming gets complicated pretty fast. That said, if a transmitter is delivering enough power to your location that it can jam a desired signal that you would normally detect and use, you can home in on the jammer. That is physics. The fact it isn't being done in Ukraine, especially since the US has known about this vulnerability for over 20 years, is a mystery.

[Goose]

The failure to stop the GPS jamming, perhaps by HARM knocking out transmitters doing the jamming, has been perplexing.

I had presumed that GPS jamming was local.  That is, a jammer transmitter might protect some region near it.

You are exactly correct in that presumption. However, the definition of "near" is dependent on the Effective Radiated Power (ERP) of the jammer. The ERP can be directional, where all the jamming power is concentrated in a narrow beam aimed at the vehicle that is to be "jammed". It can also be spread over a defined area by using various forms of directional antennas. However, the easiest way to cover a large area is using a jammer that puts out LOTS of power. Russia is usually quite fond of this "solution". Another way of course is to have many jammers. In Ukraine, Russia seems to be going with quantity, not brute power. Brute power creates a vulnerability. Knock out one jammer and a broad area is unprotected. Lower power jammers are also easier to build. Commercial cell tower components work great in this application and they are easy to buy from many nations that don't care much about sanctions.

I just noticed this article from Wired: "The Dangerous Rise of GPS Attacks"

One open source intelligence analyst, going by the pseudonym Markus Jonsson, has located jamming in the Baltics, and that which impacted the Finnish airline this week, to Kaliningrad and other Russian locations.

I don't really know how long distance jamming might work.  But, if it can be done, perhaps that explains why the jammers haven't been hit.

Actually quite the opposite. The larger the ERP the easier it is to detect and geolocate the jammer. It is also easier to "home" on a signal that has a high signal to noise ratio (SNR).

The GPS jamming situation is complicated by the fact the actual received power from GPS satellites is very small. GPS wouldn't work at all if the GPS signal was not coded is such a way that digital signal processing can deliver "processing gain". The various types of jamming gets complicated pretty fast. That said, if a transmitter is delivering enough power to your location that it can jam a desired signal that you would normally detect and use, you can home in on the jammer. That is physics. The fact it isn't being done in Ukraine, especially since the US has known about this vulnerability for over 20 years, is a mystery.