Re: Using mobile phone masts to track things
Steve Schear wrote: At 06:33 PM 10/15/2002 +1300, [EMAIL PROTECTED] (Peter Gutmann) wrote: Scribe [EMAIL PROTECTED] writes: The technology 'sees' the shapes made when radio waves emitted by mobile phone masts meet an obstruction. Signals bounced back by immobile objects, such as walls or trees, are filtered out by the receiver. This allows anything moving, such as cars or people, to be tracked. [snip] Isn't this what CDMA already does using RAKE receivers (different fingers track multiple signals, so it uses multipath as a feature rather than a problem). [snip] Yes, this is very similar to a RAKE receiver. Its also similar to the passive radar systems the U.S. recently accused a former Soviet republic of selling to Iraq. Passive radars are particularly good at spotting current generation stealth aircraft. Being passive, typically using distant powerful shortwave broadcast signals, means its much harder to spot the receiving sites. Nice explanatory picture at... http://www.pcquest.com/content/technology/101081001.asp The (over-a-year-old) article also states: The downside is that you cant make out whether the plane is a spy plane or not. However various companies are working on making it viable for detecting stealth aircraft. For instance, Roke Manor Research (www.roke.co.uk), UK-based has developed sensor technologies which can work with cellphone base stations to detect stealth aircraft. Detecting moving objects is one (simple) thing. Tracking them while identifying the type of object (stealth plane vs civilian, motorbike vs car, etc) is a different issue, naturally. What kind of resolution can be obtained from a few hundred meters (say, for mass-public-monitoring-services) if grounded base stations can make out high-altitude aircraft? Further, are there any known defenses against this kind of passive technology yet? Solitary surveillance aircrafts would surely have a harder time achieving countermeasures than a person on a cellphone amongst a crowd of bystanders. Intereference? Decoys?
Re: Using mobile phone masts to track things
Steve Schear wrote: At 06:33 PM 10/15/2002 +1300, [EMAIL PROTECTED] (Peter Gutmann) wrote: Scribe [EMAIL PROTECTED] writes: The technology 'sees' the shapes made when radio waves emitted by mobile phone masts meet an obstruction. Signals bounced back by immobile objects, such as walls or trees, are filtered out by the receiver. This allows anything moving, such as cars or people, to be tracked. [snip] Isn't this what CDMA already does using RAKE receivers (different fingers track multiple signals, so it uses multipath as a feature rather than a problem). [snip] Yes, this is very similar to a RAKE receiver. Its also similar to the passive radar systems the U.S. recently accused a former Soviet republic of selling to Iraq. Passive radars are particularly good at spotting current generation stealth aircraft. Being passive, typically using distant powerful shortwave broadcast signals, means its much harder to spot the receiving sites. Nice explanatory picture at... http://www.pcquest.com/content/technology/101081001.asp The (over-a-year-old) article also states: The downside is that you cant make out whether the plane is a spy plane or not. However various companies are working on making it viable for detecting stealth aircraft. For instance, Roke Manor Research (www.roke.co.uk), UK-based has developed sensor technologies which can work with cellphone base stations to detect stealth aircraft. Detecting moving objects is one (simple) thing. Tracking them while identifying the type of object (stealth plane vs civilian, motorbike vs car, etc) is a different issue, naturally. What kind of resolution can be obtained from a few hundred meters (say, for mass-public-monitoring-services) if grounded base stations can make out high-altitude aircraft? Further, are there any known defenses against this kind of passive technology yet? Solitary surveillance aircrafts would surely have a harder time achieving countermeasures than a person on a cellphone amongst a crowd of bystanders. Intereference? Decoys?
Re: Using mobile phone masts to track things
At 06:33 PM 10/15/2002 +1300, [EMAIL PROTECTED] (Peter Gutmann) wrote: Scribe [EMAIL PROTECTED] writes: The technology 'sees' the shapes made when radio waves emitted by mobile phone masts meet an obstruction. Signals bounced back by immobile objects, such as walls or trees, are filtered out by the receiver. This allows anything moving, such as cars or people, to be tracked. Previously, radar needed massive fixed equipment to work and transmissions from mobile phone masts were thought too weak to be useful. Isn't this what CDMA already does using RAKE receivers (different fingers track multiple signals, so it uses multipath as a feature rather than a problem). Presumably, with rather more signal processing than is simply used to improve signal quality, it'd be possible to use the capability to track interfering objects. Yes, this is very similar to a RAKE receiver. Its also similar to the passive radar systems the U.S. recently accused a former Soviet republic of selling to Iraq. Passive radars are particularly good at spotting current generation stealth aircraft. Being passive, typically using distant powerful shortwave broadcast signals, means its much harder to spot the receiving sites. steve
Re: Using mobile phone masts to track things
At 06:33 PM 10/15/2002 +1300, [EMAIL PROTECTED] (Peter Gutmann) wrote: Scribe [EMAIL PROTECTED] writes: The technology 'sees' the shapes made when radio waves emitted by mobile phone masts meet an obstruction. Signals bounced back by immobile objects, such as walls or trees, are filtered out by the receiver. This allows anything moving, such as cars or people, to be tracked. Previously, radar needed massive fixed equipment to work and transmissions from mobile phone masts were thought too weak to be useful. Isn't this what CDMA already does using RAKE receivers (different fingers track multiple signals, so it uses multipath as a feature rather than a problem). Presumably, with rather more signal processing than is simply used to improve signal quality, it'd be possible to use the capability to track interfering objects. Yes, this is very similar to a RAKE receiver. Its also similar to the passive radar systems the U.S. recently accused a former Soviet republic of selling to Iraq. Passive radars are particularly good at spotting current generation stealth aircraft. Being passive, typically using distant powerful shortwave broadcast signals, means its much harder to spot the receiving sites. steve
Re: Using mobile phone masts to track things
Scribe [EMAIL PROTECTED] writes: The technology 'sees' the shapes made when radio waves emitted by mobile phone masts meet an obstruction. Signals bounced back by immobile objects, such as walls or trees, are filtered out by the receiver. This allows anything moving, such as cars or people, to be tracked. Previously, radar needed massive fixed equipment to work and transmissions from mobile phone masts were thought too weak to be useful. Isn't this what CDMA already does using RAKE receivers (different fingers track multiple signals, so it uses multipath as a feature rather than a problem). Presumably, with rather more signal processing than is simply used to improve signal quality, it'd be possible to use the capability to track interfering objects. Peter.
Using mobile phone masts to track things
The technology 'sees' the shapes made when radio waves emitted by mobile phone masts meet an obstruction. Signals bounced back by immobile objects, such as walls or trees, are filtered out by the receiver. This allows anything moving, such as cars or people, to be tracked. Previously, radar needed massive fixed equipment to work and transmissions from mobile phone masts were thought too weak to be useful. Not enough detail in there to answer many questions - anyone have any more info on this? http://www.observer.co.uk/uk_news/story/0,6903,811027,00.html
Re: Using mobile phone masts to track things
You can find refs about this fucking up Stealth(tm) aircraft's stealthiness during one of the recent wars... possibly in England? Basically you have lots of emitters (basestations) probing the RF reflectance of their environment over time, reporting back to central stations... even angular dissipatively-clothed airframes will have signatures. One could do classroom tabletop experiments with e.g., some gunn devices, adsorbtive foam, metal foil, and simple diode detectors. Scripted Mr Scribe: The technology 'sees' the shapes made when radio waves emitted by mobile phone masts meet an obstruction. Signals bounced back by immobile objects, such as walls or trees, are filtered out by the receiver. This allows anything moving, such as cars or people, to be tracked. Previously, radar needed massive fixed equipment to work and transmissions from mobile phone masts were thought too weak to be useful. Not enough detail in there to answer many questions - anyone have any more info on this?
Using mobile phone masts to track things
The technology 'sees' the shapes made when radio waves emitted by mobile phone masts meet an obstruction. Signals bounced back by immobile objects, such as walls or trees, are filtered out by the receiver. This allows anything moving, such as cars or people, to be tracked. Previously, radar needed massive fixed equipment to work and transmissions from mobile phone masts were thought too weak to be useful. Not enough detail in there to answer many questions - anyone have any more info on this? http://www.observer.co.uk/uk_news/story/0,6903,811027,00.html
