[time-nuts] Re: UTC Backbone in Europe

[Magnus Danielson]

Hi Hal,

On 2024-11-21 03:58, Hal Murray via time-nuts wrote:
> W3AB said:
>> As y'all know, GPS jamming is easy. We need to have an alternative.
> How hard is it to jam Loran?  Or WWVB, JJY, MSF, and other low frequency
> time signals?  How about the not so low frequencies?
>
> What are the units of jamming difficulty?
>    watts per square kilometer?
> How would you scale that by the difficulty of building the antenna?

Well, signal-structure wise it's not that hard. For wide area it 
requires large antennas, so it's hard to hide, but for local area you 
can use much smaller setups such as H-field antennas.

Sweden had a top-secret array of LORAN-C / Chayka jammer/spoofer 
transmitters with 212 m antenna towers. It has since been declassified. 
So, it's been done. Search for "RT-02 Fredriksson" and you find a report 
in Swedish.

Cheers,
Magnus