[time-nuts] Very Accurate Delta Time RF Pulse
jblaha at polariswireless.com
Fri Jul 29 21:54:08 EDT 2016
Thank you all who responded including Bob, Attila, Vlad, Brooke, and Chris for some great suggestions.
This is a fun side project of mine to passively detect RF emitters based upon strongest nearby signal using ToA pulses from cheap log power sensors or perhaps the Watson-Watt method. The hope is to use it in a vehicle with sufficient antenna spacing and time pulse accuracy to create a neighborhood plot with strongest TX locations.
Yes, there are major issues to be overcome. The super wide band input has no tuner and will pickup massive noise from many near-field sources, such as wi-fi, Bluetooth, or phones, however some can be filtered as noise. Additionally, very few omni antennas cover such a large input range and I don't think CW signals will be detected properly, as they don't use a distinct rising-edge pulse.
I'm leaning toward what Bob suggested with a single shot Ghz counter possibly with some type of pulse start/stop timer or a double input A/D with GS/s buffers that can be stopped and momentarily read off whenever a new strong signal is detected or after a set time each second. Vlad mentioned a phase comparator AD8302, which would also be interesting and allow for analog or possibly digital wideband multi-frequency comparison using phase. The AD8302 apparently comes with its own internal double log power RF input, which could save on purchasing additional power sensor ICs as well.
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