4 ms·

An adjustable filter that can prevent interference in the range 600 MHz to 6 GHz

lrasinen 2y ago
Not quite: "As a result, the new filter can be tuned to any frequency between 3.4 GHz and 11.1 GHz..." The 600 MHz to 6 GHz referred to currently used communication frequencies.
- giuliomagnifico 2y ago
  I was referring to the interferences range where the filter can work, not where it can be tuned. If I correct understood.
  - nestes 2y ago
    The 600-6GHz range is a rough approximation for some of the most used bands in telecommunications, e.g. Wi-Fi and 5G NR FR1. It's worth noting that the article explicitly mentions that this filter will be useful for FR3, which is "7 GHz to 24 GHz". They do not claim full 600 MHz-6 GHz operation, and as the previous poster noted, the filter was demonstrated from 3.4-11.1 GHz. More critically: you want to be very very careful about trying to extrapolate this filter down to lower frequencies. We're dealing with "weird physics" here. I am not an expert on spin-wave devices by any means, but a guy in my lab during grad school was working with them, so I do know that the resonant frequencies of the spin-waves are a function of the magnetic bias and the material. The researchers here are tuning the filter by tuning the magnetic bias. Someone more knowledgeable can correct me, but I believe YIG would have trouble propagating spin-waves down at 600 MHz, and so this kind of filter would not be practical.
FuckButtons 2y ago
I wonder if you could use this to overcome electronic warfare jamming of gps.
- gmrple 2y ago
  No, this is about preventing unwanted jamming/interference by a transmitter on frequencies it isn't intending or needing to transmit on as part of the design phase of a product. Overcoming intentional jamming is an entirely different ballgame.
- instagib 2y ago
  There’s a lot of strategies for this but a basic one is using direction find on the jammer. then electronically or manually moving antenna nulls (bad spots of a directional antenna) to face the jammer(s) which would then increase the gain for directed non-jammer areas. GPS is a very low amplitude signal that can easily be jammed. Dropping WP (white phosphorus) or a missile on the suspected jammer would be a better bet.
  - willcipriano 2y ago
    > Dropping WP (white phosphorus) "Your GPS jammer prevented my war crime so here's a bigger war crime." - The good guys
    - stoltzmann 2y ago
      The use of WP against military targets is not prohibited. A jammer is a military target. As long as it's not causing undue damage to civilians, this is not a war crime.
      - littlestymaar 2y ago
        I don't understand the expected military effect of white phosphorus on a RF jammer though…
        mrguyorama 2y ago
        You don't understand the expected effect of very hot, inextinguishable fire on an electronic device?
lnsru 2y ago
It might be cool, but I wasn’t able to find price comparison to existing technologies. The modules containing dozens of specified filters are dirt cheap. Since band frequencies for 5G are known no fine tuning needed. Also no fab wants exotic materials and a new process.
- RachelF 2y ago
  Yes, this article is marketing. They've just made a prototype smaller filter. YIG filters have been around for decades. They are electrically tunable. However, they are slow to change frequency and can have an odd phase response.
mikewarot 2y ago
The main innovation here seems to be the elimination of a bias electromagnet that consumes a constant current to generate a desired amount of magnetic flux. These apparently can consume 250 milliamp, if my quick Google is right. Here's a paper[1] that might be how they are doing it. [1] https://ieeexplore.ieee.org/document/7529113 https://ieeexplore.ieee.org/document/7529113
benkuykendall 2y ago
This kind of work sounds potentially (?) important for continuing to improve network technology. Unfortunately I don't have the background to understand why it works in the slightest. However, it reminded me of an older approach to signal filtering that I just recently learned about: the superheterodyne radio receiver. It's a simple idea that enabled us to build cheap, tunable radios. YouTube video if you're curious: https://www.youtube.com/watch?v=hz_mMLhUinw https://www.youtube.com/watch?v=hz_mMLhUinw. Definitely an accessible introduction to a neat trick in signal processing!

Not quite: "As a result, the new filter can be tuned to any frequency between 3.4 GHz and 11.1 GHz..." The 600 MHz to 6 GHz referred to currently used communication frequencies.

giuliomagnifico 2y ago
I was referring to the interferences range where the filter can work, not where it can be tuned. If I correct understood.
- nestes 2y ago
  The 600-6GHz range is a rough approximation for some of the most used bands in telecommunications, e.g. Wi-Fi and 5G NR FR1. It's worth noting that the article explicitly mentions that this filter will be useful for FR3, which is "7 GHz to 24 GHz". They do not claim full 600 MHz-6 GHz operation, and as the previous poster noted, the filter was demonstrated from 3.4-11.1 GHz. More critically: you want to be very very careful about trying to extrapolate this filter down to lower frequencies. We're dealing with "weird physics" here. I am not an expert on spin-wave devices by any means, but a guy in my lab during grad school was working with them, so I do know that the resonant frequencies of the spin-waves are a function of the magnetic bias and the material. The researchers here are tuning the filter by tuning the magnetic bias. Someone more knowledgeable can correct me, but I believe YIG would have trouble propagating spin-waves down at 600 MHz, and so this kind of filter would not be practical.

FuckButtons 2y ago

I wonder if you could use this to overcome electronic warfare jamming of gps.

gmrple 2y ago
No, this is about preventing unwanted jamming/interference by a transmitter on frequencies it isn't intending or needing to transmit on as part of the design phase of a product. Overcoming intentional jamming is an entirely different ballgame.
instagib 2y ago
There’s a lot of strategies for this but a basic one is using direction find on the jammer. then electronically or manually moving antenna nulls (bad spots of a directional antenna) to face the jammer(s) which would then increase the gain for directed non-jammer areas. GPS is a very low amplitude signal that can easily be jammed. Dropping WP (white phosphorus) or a missile on the suspected jammer would be a better bet.
- willcipriano 2y ago
  > Dropping WP (white phosphorus) "Your GPS jammer prevented my war crime so here's a bigger war crime." - The good guys
  - stoltzmann 2y ago
    The use of WP against military targets is not prohibited. A jammer is a military target. As long as it's not causing undue damage to civilians, this is not a war crime.
    - littlestymaar 2y ago
      I don't understand the expected military effect of white phosphorus on a RF jammer though…
      - mrguyorama 2y ago
        You don't understand the expected effect of very hot, inextinguishable fire on an electronic device?

lnsru 2y ago

It might be cool, but I wasn’t able to find price comparison to existing technologies. The modules containing dozens of specified filters are dirt cheap. Since band frequencies for 5G are known no fine tuning needed. Also no fab wants exotic materials and a new process.

RachelF 2y ago
Yes, this article is marketing. They've just made a prototype smaller filter. YIG filters have been around for decades. They are electrically tunable. However, they are slow to change frequency and can have an odd phase response.

mikewarot 2y ago

The main innovation here seems to be the elimination of a bias electromagnet that consumes a constant current to generate a desired amount of magnetic flux. These apparently can consume 250 milliamp, if my quick Google is right. Here's a paper[1] that might be how they are doing it. [1] https://ieeexplore.ieee.org/document/7529113 https://ieeexplore.ieee.org/document/7529113

benkuykendall 2y ago

This kind of work sounds potentially (?) important for continuing to improve network technology. Unfortunately I don't have the background to understand why it works in the slightest. However, it reminded me of an older approach to signal filtering that I just recently learned about: the superheterodyne radio receiver. It's a simple idea that enabled us to build cheap, tunable radios. YouTube video if you're curious: https://www.youtube.com/watch?v=hz_mMLhUinw https://www.youtube.com/watch?v=hz_mMLhUinw. Definitely an accessible introduction to a neat trick in signal processing!