Re: [time-nuts] Very Accurate Delta Time RF Pulse
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
Hi Jerome:
Some time ago a company called Opto Electronics made a frequency counter with a small antenna that would count the
frequency of a nearby signal. They call these Near Field Receivers.
Some modern scanner radios incorporate some of these ideas.
http://www.prc68.com/I/BC125AT.html
--
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
The lesser of evils is still evil.
-------- Original Message --------
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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I have an Optoelectronics 3000A and as far as I know, the only thing
distinguishing this capability from any other frequency counter is
discrimination on the digital side which filters unstable counts. In
practice it operates like an FM receiver where the strongest signal
captures the input. If I put the same antenna on one of my other good
frequency counters, they perform about as well but will not hold the
last clear reading.
The Optoelectronics counters also have better signal conditioning than
many dedicated frequency counters which are intended to be used where
the input signal is well defined.
I think their later counters intended for this type of application
took this a step further by sweeping their input frequency range for
better selectivity. I assume this was done with superheterodyne block
conversion but maybe they had something else going on like a
switchable swept RF preselector.
On Fri, 29 Jul 2016 23:18:07 -0700, you wrote:
Hi Jerome:
Some time ago a company called Opto Electronics made a frequency counter with a small antenna that would count the
frequency of a nearby signal. They call these Near Field Receivers.
Some modern scanner radios incorporate some of these ideas.
http://www.prc68.com/I/BC125AT.html
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@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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