I wonder if the many Starlink satellites can be used for this? True, the signals are low and are steered, but the nature of steering creates many side lobes that will be useable in this manner. It would be a complex computational task with satellites in motion as well as ground stations transmitting on offset frequencies. I suspect various research/military labs are playing with this?
How Passive Radar Works
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Re: How Passive Radar Works
#12What's this website? Who put it up?
Those have always been good questions to ask, but especially these days.
Re: How Passive Radar Works
#13I wonder if the many Starlink satellites can be used for this? True, the signals are low and are steered, but the nature of steering creates many side lobes that will be useable in this manner. It would be a complex computational task with satellites in motion as well as ground stations transmitting on offset frequencies. I suspect various research/military labs are playing with this?
Such radar would be a game changer.
Re: How Passive Radar Works
#14I read a lot about passive radars trying to leech off of opportunistic waves, and lots about actual troops preferring to play hide-and-seem with anti-radiation weapons just to use active machines.
A config that strikes me as obvious but doesn’t seem to be popular would be just bistatic where you fire your own transmitter far away from yourself?
There’s got to be a reason, but it seems like best of both worlds.
Re: How Passive Radar Works
#15I read a lot about passive radars trying to leech off of opportunistic waves, and lots about actual troops preferring to play hide-and-seem with anti-radiation weapons just to use active machines. A config that strikes me as obvious but doesn’t seem to be popular would be just bistatic where you fire your own transmitter far away from yourself? There’s got to be a reason, but it seems like best of both worlds.
Probably more complicated to setup in a hostile environment because you'd need multiple transmitters, which also need to remain stationary, or at least you need to accurately know when they move.
Re: How Passive Radar Works
#16I wonder if the many Starlink satellites can be used for this? True, the signals are low and are steered, but the nature of steering creates many side lobes that will be useable in this manner. It would be a complex computational task with satellites in motion as well as ground stations transmitting on offset frequencies. I suspect various research/military labs are playing with this?
I did some searching and seems like an active area of research: https://ieeexplore.ieee.org/document/8768105/ and https://ieeexplore.ieee.org/document/9905046/
Re: How Passive Radar Works
#17Are there any clever tricks for the data processing involved here, given that the delay is a shift in the time domain and the Doppler effect is a shift in the frequency domain? Maybe involving fractional Fourier transforms, or wavelets?
[deleted]
Re: How Passive Radar Works
#18What's this website? Who put it up? Those have always been good questions to ask, but especially these days.
The image screams Australia, the image title confirms ...
https://www.silentiumdefence.com.au/our-solutions/space-doma...
but whether they have any connection or are just getting image jacked ... couldn't say.
Re: How Passive Radar Works
#19I wonder if the many Starlink satellites can be used for this? True, the signals are low and are steered, but the nature of steering creates many side lobes that will be useable in this manner. It would be a complex computational task with satellites in motion as well as ground stations transmitting on offset frequencies. I suspect various research/military labs are playing with this?
With their movement you might get some strange SAR like effects. Computationally complex but could add another dimension over a static tower.
Re: How Passive Radar Works
#20I read a lot about passive radars trying to leech off of opportunistic waves, and lots about actual troops preferring to play hide-and-seem with anti-radiation weapons just to use active machines. A config that strikes me as obvious but doesn’t seem to be popular would be just bistatic where you fire your own transmitter far away from yourself? There’s got to be a reason, but it seems like best of both worlds.
Much more covert, and civilian infrastructure also less likely to be blown up.