4 ms·

This all just makes it clear that a military version of Starlink is needed, and that's what the DoD and others are building. I also think UWB radio is going to

This all just makes it clear that a military version of Starlink is needed, and that's what the DoD and others are building. I also think UWB radio is going to be big in the future for communicating with nearby devices in warzones.

morphle 3y ago
And lasers, both in space and in free space.
lxgr 3y ago
What makes UWB better positioned than other modulation/transmission technologies?
- morphle 3y ago
  most receivers see it as white noise, if they don't know the timing
  - lxgr 3y ago
    Is that fundamentally different from e.g. CDMA using cryptographic spreading sequences, though? In the end, any sufficiently efficient signal is indistinguishable from noise to anybody but the intended receiver(s), no?
    - morphle 3y ago
      Yes fundamentally different[1]. There are dozens of implementations under the Ultra Wide Band definition. [1] https://en.wikipedia.org/wiki/Ultra-wideband https://en.wikipedia.org/wiki/Ultra-wideband
      - lxgr 3y ago
        Can you say how, specifically with regards to "receivers seeing it as white noise without knowing the timing"? As I understand it, the same is true for e.g. DSSS (for receivers not knowing the spreading code), and the primary advantage of UWB is its precise ranging capability (due to its ability to reject multipath propagation errors and the generally high bandwidth, yielding better spatial resolution).
        dkjaudyeqooe 3y ago
        UWB radio transmits below the noise floor, you're going to have a hard time finding any signal there or even know if a signal is being transmitted. You can go crazy misidentifying noise combinations as signals. In that sense you need to know almost everything about it to intercept it.
        lxgr 3y ago
        That's the same for (wide) spectrum spreading though, right? Some of these signals are also below the noise floor before correlation, and you need to know the spreading code to detect them.
        morphle 3y ago
        I studied ultra wideband decades before they started to write papers refering to UWB standard definitions [1] so I might be out of tune (pun intended) with current definitions. A transceiver could use attosecond 10^−18, femtosecond 10^−15 picosecond 10^−12 or nanosecond 10^−9 pulses at very irregularly intervals. That seems (almost) random to any observer but not to a receiver which has pre-agreed those irregularly intervals with the transmitter (for example with quantum key distribution, with entangled particles). The receiver measures if there was a signal or not. It does not use power level, frequency, or phase (or a combination of these) of a sinusoidal wave but by generating radio energy at specific time intervals and occupying a large bandwidth, thus enabling pulse-position or time modulation. Not just spacial distribution can be used. You could use polarised photons, electron spin, etc. In my wafer scale integration [2] I use very few free space photos to flip a 1 v transistor in an ultra wideband mode. I refer you to [3] for [4] for a better explanation, even though ultra wideband is not mentioned specifically. Contact me directly, I'll be happy to lecture for a few hours to answer your question. [1] https://scholar.google.com/scholar?hl=en&as_sdt=0,5&q=ultra+wideband https://scholar.google.com/scholar?hl=en&as_sdt=0,5&q=ultra+... [2] Smalltalk and Self Hardware https://vimeo.com/731037615 https://vimeo.com/731037615 [3] Stanford Seminar - Saving energy and increasing density in information processing using photonics https://www.youtube.com/watch?v=7hWWyuesmhs&t=272s https://www.youtube.com/watch?v=7hWWyuesmhs&t=272s [4] Attojoule Optoelectronics for Low-Energy Information Processing and Communications: a Tutorial Review https://arxiv.org/abs/1609.05510 https://arxiv.org/abs/1609.05510

morphle 3y ago

And lasers, both in space and in free space.

lxgr 3y ago

What makes UWB better positioned than other modulation/transmission technologies?

morphle 3y ago
most receivers see it as white noise, if they don't know the timing
- lxgr 3y ago
  Is that fundamentally different from e.g. CDMA using cryptographic spreading sequences, though? In the end, any sufficiently efficient signal is indistinguishable from noise to anybody but the intended receiver(s), no?
  - morphle 3y ago
    Yes fundamentally different[1]. There are dozens of implementations under the Ultra Wide Band definition. [1] https://en.wikipedia.org/wiki/Ultra-wideband https://en.wikipedia.org/wiki/Ultra-wideband
    - lxgr 3y ago
      Can you say how, specifically with regards to "receivers seeing it as white noise without knowing the timing"? As I understand it, the same is true for e.g. DSSS (for receivers not knowing the spreading code), and the primary advantage of UWB is its precise ranging capability (due to its ability to reject multipath propagation errors and the generally high bandwidth, yielding better spatial resolution).
      - dkjaudyeqooe 3y ago
        UWB radio transmits below the noise floor, you're going to have a hard time finding any signal there or even know if a signal is being transmitted. You can go crazy misidentifying noise combinations as signals. In that sense you need to know almost everything about it to intercept it.
        lxgr 3y ago
        That's the same for (wide) spectrum spreading though, right? Some of these signals are also below the noise floor before correlation, and you need to know the spreading code to detect them.
      - morphle 3y ago
        I studied ultra wideband decades before they started to write papers refering to UWB standard definitions [1] so I might be out of tune (pun intended) with current definitions. A transceiver could use attosecond 10^−18, femtosecond 10^−15 picosecond 10^−12 or nanosecond 10^−9 pulses at very irregularly intervals. That seems (almost) random to any observer but not to a receiver which has pre-agreed those irregularly intervals with the transmitter (for example with quantum key distribution, with entangled particles). The receiver measures if there was a signal or not. It does not use power level, frequency, or phase (or a combination of these) of a sinusoidal wave but by generating radio energy at specific time intervals and occupying a large bandwidth, thus enabling pulse-position or time modulation. Not just spacial distribution can be used. You could use polarised photons, electron spin, etc. In my wafer scale integration [2] I use very few free space photos to flip a 1 v transistor in an ultra wideband mode. I refer you to [3] for [4] for a better explanation, even though ultra wideband is not mentioned specifically. Contact me directly, I'll be happy to lecture for a few hours to answer your question. [1] https://scholar.google.com/scholar?hl=en&as_sdt=0,5&q=ultra+wideband https://scholar.google.com/scholar?hl=en&as_sdt=0,5&q=ultra+... [2] Smalltalk and Self Hardware https://vimeo.com/731037615 https://vimeo.com/731037615 [3] Stanford Seminar - Saving energy and increasing density in information processing using photonics https://www.youtube.com/watch?v=7hWWyuesmhs&t=272s https://www.youtube.com/watch?v=7hWWyuesmhs&t=272s [4] Attojoule Optoelectronics for Low-Energy Information Processing and Communications: a Tutorial Review https://arxiv.org/abs/1609.05510 https://arxiv.org/abs/1609.05510