[time-nuts] Very Accurate Delta Time RF Pulse

albertson.chris at gmail.com albertson.chris at gmail.com
Sat Jul 30 16:31:52 EDT 2016

You might be better off scanning than wide band. Even with a slow scanner you can cover the entire RF range every few meters of car travel. But I would sample as fast as you can. Hundreds of millions per second. This gives best sensitivity and noise  

Use gnu radio software and Their SDR radio hardware.  Some time ago someone built a passive radar with this. They were able to get Reflection from FM from passing aircraft. Not a lot different from your project

The algorithm is just scan a section of the band then do FFT the FFT will separate all that noise by transmitter frequency. Search the spectra for peaks

If you are moving and targets are fixed Doppler can actually help you sort it out. Radars take advantage of this too

> On Jul 29, 2016, at 6:54 PM, Jerome Blaha <jblaha at polariswireless.com> wrote:
> 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.
> Best Regards,
> -Jerome 
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