[time-nuts] The Demise of LORAN (was Re: Reference oscillatoraccuracy)

[Magnus Danielson]

Bruce Rahn wrote:
> Magnus Danielson wrote:
>> The directional antenna needs to have their directional lobes towards 
>> each sat being tracked. If you try put the nulls towards the jammers 
>> then you need to have a fair knowledge of where it is. If you direct 
>> the loop, the side-loobs needs to be sufficiently suppressed. A single 
>> jammer and a fair idea of the heading will work, but it becomes 
>> complex and in the end you need more and more antennas to handle more 
>> jammers. 
> Ah...you really don't need any a prori knowledge of the location of a 
> jammer.
> A little reading on adaptive antenna technology as applied to GPS will 
> throw light on my comment and is also some interesting reading.  This 
> would be a starting point: 
> http://www.raytheon.com/businesses/stellent/groups/sas/documents/content/cms04_022900.pdf  

You can use different strategies yes. I was unclear on that.

Either you know the direction and then you can optimize for that or you 
just use the power of multiple antennas to create individual lobes for 
each receiver channels. You can balance lobe-gain to sat to that of the 
offender for best suppression. Setting lobes for each sat does not need 
the direction info on the jammer.

That link does not provide as much information as a number of online 
articles on directional antennas giving much more detail.

Cheers,
Magnus