5 ms·

You are right that Radar follows an inverse 4th power with distance (inverse 2th power for the light to go to the reflected object then 2th power for the reflec

You are right that Radar follows an inverse 4th power with distance (inverse 2th power for the light to go to the reflected object then 2th power for the reflected wave to go back to your antenna). For 3$ https://fr.aliexpress.com/item/32786483344.html https://fr.aliexpress.com/item/32786483344.html a 6Ghz radar that goes 12meters using 30mA, so my range claims are not that silly. When there is no obstacle 6Ghz or 60Ghz doesn't matter.

mlyle 7y ago
> When there is no obstacle 6Ghz or 60Ghz doesn't matter. Power amplifier efficiency for 6GHz and 60GHz is not the same-- not even close. > For 3$ https://fr.aliexpress.com/item/32786483344.html https://fr.aliexpress.com/item/32786483344.html a 6Ghz radar that goes 12meters using 30mA, so my range claims are not that silly. This is a deflection and ridiculous. We're talking about spotting e.g. gestures. It falls apart with distance because of both angular resolution and inverse-fourth power. I've been involved in the design of mmwave radars. If it was easy to spot and precisely track small objects at 10m, we'd be doing it...
- GistNoesis 7y ago
  >If it was easy to spot and precisely track small objects at 10m, That's not the claim I'm making. I agree that this chip won't do the gesture recognition at 10m, but I'm quite convinced that it can pick up human movement signal if they try to do so. >I've been involved in the design of mmwave radars I don't have this level of expertise. But I'll be really surprised if we couldn't reach the same levels of amplification. Gaining 12 dB will double the range. We can extend the antenna array or use more expensive low noise amplifiers. For cars there are 30Ghz Doppler radar, and the distance can go at least 50m. From the referenced paper ( A Highly Integrated 60 GHz 6-Channel Transceiver With Antenna in Package for Smart Sensing and Short-Range Communications https://sci-hub.tw/https://doi.org/10.1109/JSSC.2016.2585621 https://sci-hub.tw/https://doi.org/10.1109/JSSC.2016.2585621 ) : "In this work a 60 GHz 4-channel receiver 2-channel transmitter packaged chip targeting high resolution sensing systems and capable of supporting large bandwidth communication channels is presented. The SiGe technology used offers a low 1/f noise which is essential to the functionality of the chip in frequency modulated continues wave systems (FMCW)and Doppler radar with a sensing range below 10 m." "While we have not explored this in-depth we would like to highlight the similarities to re-cent work exploiting FMCW RF technology to coarsely ‘image’ users through a wall [1]"
  - mlyle 7y ago
    Your second quote seems out of context and doesn't occur in the paper you cite. Your first quote says "sensing range below 10m". Yes, it is possible to make long range 60GHz systems-- largely through antenna gain and lenses. Yes, we could build an entirely different radar to track peoples' gross movement--- and could have 20 years ago, too-- but that has largely nothing to do with the original system or your original claim. If I wanted to image people at low resolution through a wall, 60GHz is about the last thing I'd pick. Drywall alone has an attenuation of about 3 dB/cm, and remember we have to cross the wall twice. You run out of loss budget really quick. Suggesting one can go 10x as far (10000x power alone) and through walls is... creative. If you want to track people through a wall, use UHF. It works pretty well and is pretty easy.
    - GistNoesis 7y ago
      Sorry I mismanaged my tabs, the second citation is just above the conclusion in the referenced paper (https://dl.acm.org/citation.cfm?id=2984565 https://dl.acm.org/citation.cfm?id=2984565 ) "Interacting with Soli: Exploring Fine-Grained Dynamic Gesture Recognition in the Radio-Frequency Spectrum" > Suggesting one can go 10x as far (10000x power alone) and through walls is... creative. I was going for conservative. Typically thinking about open-space work environment. The device doesn't need line of sight like a camera would, it can be in your coworker pocket and listening to you. They are well founded and doing their own radio chips, I give them the credit they deserve and assume they can replicate a somewhat similar technology (6Ghz radar). It is better to use a logarithmic scale. The 10000x power (40dB gain) doesn't mean you will need to emit 10000x more power, in practice you will amplify the signal, by focusing the beam via antenna design, and amplifying which theoretically you can do relatively easily as long as you are above the Cosmic Microwave Background Radiation noise. Then you need to do some trickery to trade bandwidth for signal strength (which they do : FMCW). Then you still can integrate over time. A radar typically scan its whole surrounding, but if instead you chose to focus it at one place you can gather for longer.
    - GistNoesis 7y ago
      >10000x power alone Sorry to dig this up so late, there is a usual misconception when reasoning with power (which you might suffer from) : What matters is not power, what matter is what we measure. We are measuring electric field in volts whose square is proportional to the power. Going 10x as far, mean measuring a voltage 100x smaller. Even with just the dynamic range if your analog digital converter is reading you 8-bits values (values going to 256) with a 100x voltage reduction you get a smaller blip going from 0 to 2.
- ozymandias12 7y ago
  Not an mmwave radar guy as well, but afaik, this little chip is quite capable of counting how many people are IN a room, if they're standing or laying down, etc, but of course, without the granular control of its factory NUI [natural user interface] proximity calibration. And here I'm not even considering if this solid state radar chip cross reference its data with Wifi radio signals or the dot projector, boosting its ML recognition capabilities to be able to "blob" (and possibly identify) moving things as far as 50m.
deleted 7y ago
[deleted]

mlyle 7y ago

> When there is no obstacle 6Ghz or 60Ghz doesn't matter. Power amplifier efficiency for 6GHz and 60GHz is not the same-- not even close. > For 3$ https://fr.aliexpress.com/item/32786483344.html https://fr.aliexpress.com/item/32786483344.html a 6Ghz radar that goes 12meters using 30mA, so my range claims are not that silly. This is a deflection and ridiculous. We're talking about spotting e.g. gestures. It falls apart with distance because of both angular resolution and inverse-fourth power. I've been involved in the design of mmwave radars. If it was easy to spot and precisely track small objects at 10m, we'd be doing it...

GistNoesis 7y ago
>If it was easy to spot and precisely track small objects at 10m, That's not the claim I'm making. I agree that this chip won't do the gesture recognition at 10m, but I'm quite convinced that it can pick up human movement signal if they try to do so. >I've been involved in the design of mmwave radars I don't have this level of expertise. But I'll be really surprised if we couldn't reach the same levels of amplification. Gaining 12 dB will double the range. We can extend the antenna array or use more expensive low noise amplifiers. For cars there are 30Ghz Doppler radar, and the distance can go at least 50m. From the referenced paper ( A Highly Integrated 60 GHz 6-Channel Transceiver With Antenna in Package for Smart Sensing and Short-Range Communications https://sci-hub.tw/https://doi.org/10.1109/JSSC.2016.2585621 https://sci-hub.tw/https://doi.org/10.1109/JSSC.2016.2585621 ) : "In this work a 60 GHz 4-channel receiver 2-channel transmitter packaged chip targeting high resolution sensing systems and capable of supporting large bandwidth communication channels is presented. The SiGe technology used offers a low 1/f noise which is essential to the functionality of the chip in frequency modulated continues wave systems (FMCW)and Doppler radar with a sensing range below 10 m." "While we have not explored this in-depth we would like to highlight the similarities to re-cent work exploiting FMCW RF technology to coarsely ‘image’ users through a wall [1]"
- mlyle 7y ago
  Your second quote seems out of context and doesn't occur in the paper you cite. Your first quote says "sensing range below 10m". Yes, it is possible to make long range 60GHz systems-- largely through antenna gain and lenses. Yes, we could build an entirely different radar to track peoples' gross movement--- and could have 20 years ago, too-- but that has largely nothing to do with the original system or your original claim. If I wanted to image people at low resolution through a wall, 60GHz is about the last thing I'd pick. Drywall alone has an attenuation of about 3 dB/cm, and remember we have to cross the wall twice. You run out of loss budget really quick. Suggesting one can go 10x as far (10000x power alone) and through walls is... creative. If you want to track people through a wall, use UHF. It works pretty well and is pretty easy.
  - GistNoesis 7y ago
    Sorry I mismanaged my tabs, the second citation is just above the conclusion in the referenced paper (https://dl.acm.org/citation.cfm?id=2984565 https://dl.acm.org/citation.cfm?id=2984565 ) "Interacting with Soli: Exploring Fine-Grained Dynamic Gesture Recognition in the Radio-Frequency Spectrum" > Suggesting one can go 10x as far (10000x power alone) and through walls is... creative. I was going for conservative. Typically thinking about open-space work environment. The device doesn't need line of sight like a camera would, it can be in your coworker pocket and listening to you. They are well founded and doing their own radio chips, I give them the credit they deserve and assume they can replicate a somewhat similar technology (6Ghz radar). It is better to use a logarithmic scale. The 10000x power (40dB gain) doesn't mean you will need to emit 10000x more power, in practice you will amplify the signal, by focusing the beam via antenna design, and amplifying which theoretically you can do relatively easily as long as you are above the Cosmic Microwave Background Radiation noise. Then you need to do some trickery to trade bandwidth for signal strength (which they do : FMCW). Then you still can integrate over time. A radar typically scan its whole surrounding, but if instead you chose to focus it at one place you can gather for longer.
  - GistNoesis 7y ago
    >10000x power alone Sorry to dig this up so late, there is a usual misconception when reasoning with power (which you might suffer from) : What matters is not power, what matter is what we measure. We are measuring electric field in volts whose square is proportional to the power. Going 10x as far, mean measuring a voltage 100x smaller. Even with just the dynamic range if your analog digital converter is reading you 8-bits values (values going to 256) with a 100x voltage reduction you get a smaller blip going from 0 to 2.
ozymandias12 7y ago
Not an mmwave radar guy as well, but afaik, this little chip is quite capable of counting how many people are IN a room, if they're standing or laying down, etc, but of course, without the granular control of its factory NUI [natural user interface] proximity calibration. And here I'm not even considering if this solid state radar chip cross reference its data with Wifi radio signals or the dot projector, boosting its ML recognition capabilities to be able to "blob" (and possibly identify) moving things as far as 50m.

deleted 7y ago

[deleted]