4 ms·

Yes, but we're not talking about Starlink. I'm talking about Othernet, which I mentioned above. It is receive only-- not an uplink. (I'm sure a tiny bit of R

by mlyle 4y ago

Yes, but we're not talking about Starlink. I'm talking about Othernet, which I mentioned above. It is receive only-- not an uplink. (I'm sure a tiny bit of RF leaks out of the LNB, but that could be mitigated as it is not designed for stealth).

lazide 4y ago
Sounds useless for the internet (where every protocol is fundamentally two way), but great for ‘Radio America’ type broadcasts. Of course, so is shortwave. definitely not solving the same ‘problem’ at all though.
- mlyle 4y ago
  You're replying to a thread where I started by saying "Maybe the internet as a whole is intractable."
  - runsWphotons 4y ago
    could you say this seven more times?
    - mlyle 4y ago
      I'm worried I'll have to :/
retrac 4y ago
> I'm sure a tiny bit of RF leaks out of the LNB Any receiver using the heterodyne principle (this includes most current digital radio modems) is trivially detected by its local oscillator, often to some considerable range (potentially hundreds of metres). In the UK, the BBC used to exploit this, with radio detection vans patrolling the streets for unauthorized receivers, to fine people for watching TV without a license. So did the USSR with shortwave receivers, where the penalty was potentially more than a fine. A satellite receiver is the same, in principle.
- mlyle 4y ago
  > Any receiver using the heterodyne principle (this includes most current digital radio modems) is trivially detected by its local oscillator, often to some considerable range (potentially hundreds of metres). I'm sorry. This is not intrinsic; this is a design choice. Yes, most LOs just care about getting under legal emission masks, but there's nothing to prevent one from bringing it much lower. Further, as I explained: the LO frequency of the LNB for the first conversion is often the exact same frequency as you'd use to downconvert digital TV broadcast. > In the UK, the BBC used to exploit this, with radio detection vans patrolling the streets for unauthorized receivers, to fine people for watching TV without a license. They never found anyone in a way that could be used for prosecution. "A freedom of information act has revealed that TV Detector vans have never to date provided evidence to be used in court against the TV Licence Non-payer, and have therefore never succeeded in enforcing the TV licence." https://en.wikipedia.org/wiki/TV_detector_van https://en.wikipedia.org/wiki/TV_detector_van
  - retrac 4y ago
    It's not intrinsic, no. It's possible to design a receiver with its local oscillator emissions to be down to an arbitrarily low emission standard. (But who actually does that?) And not all reception techniques require a local oscillator at all. Still. My point was merely that with an average radio, which was designed to just not be harmfully interfering, such as typical satellite TV receiver? It's quite possibly lit up like a beacon if you know what to look for.
    - mlyle 4y ago
      > with its local oscillator emissions to be down to an arbitrarily low emission standard. (But who actually does that?) Better testing to compliance standards has pushed LOs down way lower than they were in the 40s-60s. We have relatively cheap high quality spectrum analyzers and big integrated measurements. So-- kinda everyone pushes things down pretty low now. > My point was merely that with an average radio, which was designed to just not be harmfully interfering, such as typical satellite TV receiver? Yah-- this LNB looks just like a satellite TV receiver, with the exact same LO frequency. So your rogue downlink looks exactly like something that there's hundreds of innocent versions around. Then a SDR inside your house chooses a different signal from the transponder and gets the data.

by mlyle 4y ago

lazide 4y ago

Sounds useless for the internet (where every protocol is fundamentally two way), but great for ‘Radio America’ type broadcasts. Of course, so is shortwave. definitely not solving the same ‘problem’ at all though.

mlyle 4y ago
You're replying to a thread where I started by saying "Maybe the internet as a whole is intractable."
- runsWphotons 4y ago
  could you say this seven more times?
  - mlyle 4y ago
    I'm worried I'll have to :/

retrac 4y ago

> I'm sure a tiny bit of RF leaks out of the LNB Any receiver using the heterodyne principle (this includes most current digital radio modems) is trivially detected by its local oscillator, often to some considerable range (potentially hundreds of metres). In the UK, the BBC used to exploit this, with radio detection vans patrolling the streets for unauthorized receivers, to fine people for watching TV without a license. So did the USSR with shortwave receivers, where the penalty was potentially more than a fine. A satellite receiver is the same, in principle.

mlyle 4y ago
> Any receiver using the heterodyne principle (this includes most current digital radio modems) is trivially detected by its local oscillator, often to some considerable range (potentially hundreds of metres). I'm sorry. This is not intrinsic; this is a design choice. Yes, most LOs just care about getting under legal emission masks, but there's nothing to prevent one from bringing it much lower. Further, as I explained: the LO frequency of the LNB for the first conversion is often the exact same frequency as you'd use to downconvert digital TV broadcast. > In the UK, the BBC used to exploit this, with radio detection vans patrolling the streets for unauthorized receivers, to fine people for watching TV without a license. They never found anyone in a way that could be used for prosecution. "A freedom of information act has revealed that TV Detector vans have never to date provided evidence to be used in court against the TV Licence Non-payer, and have therefore never succeeded in enforcing the TV licence." https://en.wikipedia.org/wiki/TV_detector_van https://en.wikipedia.org/wiki/TV_detector_van
- retrac 4y ago
  It's not intrinsic, no. It's possible to design a receiver with its local oscillator emissions to be down to an arbitrarily low emission standard. (But who actually does that?) And not all reception techniques require a local oscillator at all. Still. My point was merely that with an average radio, which was designed to just not be harmfully interfering, such as typical satellite TV receiver? It's quite possibly lit up like a beacon if you know what to look for.
  - mlyle 4y ago
    > with its local oscillator emissions to be down to an arbitrarily low emission standard. (But who actually does that?) Better testing to compliance standards has pushed LOs down way lower than they were in the 40s-60s. We have relatively cheap high quality spectrum analyzers and big integrated measurements. So-- kinda everyone pushes things down pretty low now. > My point was merely that with an average radio, which was designed to just not be harmfully interfering, such as typical satellite TV receiver? Yah-- this LNB looks just like a satellite TV receiver, with the exact same LO frequency. So your rogue downlink looks exactly like something that there's hundreds of innocent versions around. Then a SDR inside your house chooses a different signal from the transponder and gets the data.