Expected release date for Theia?

I anticipate a RAI/Theia RD from Radenso in - 1st quarter of 2020


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Token

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1950's technology is not the way to approach this problem.

Multiple coherent SDRs on multiple fixed antennas could provide instantaneous and continuous direction information in a mechanically "solid state" construction.

OK, it is Saturday night, and I may have had a Scotch or two already, but my ramblings on the subject....

Absolutely it could be done with multiple coherent receivers in an active phased array application. But that would greatly increase complexity, cost, and (assuming horn antennas with some gain) size. Such a system would be neat and all, but probably only affordable to an extremely small clientele.

I suspect it could be done a bit differently with existing receiver hardware (modified) and an added or plug in antenna section. Complexity and cost would also be increased, but I believe it would be fraction of the cost of the sexier active phased array solutions using multiple coherent receivers.

I believe it could be done at least two different ways (and I am sure there are others), those two being passive scanned phased array and pseudo Doppler scanning array. Both systems would require higher signal levels as I am assuming lower gain antennas making up the directional arrays. If you made it up of 4 antennas configured in a square, each with slightly overlapping coverage, just over 90 degrees azimuth and say 20 degrees elevation each, that would yield gains of over 7 dBi, and at least some improvement. If you cannot get enough gain to meet requirements you could increase the array element count, to 8 or even 16 elements, each with smaller beamwidths and higher gain. I can see some interesting PCB Vivaldi antenna type designs being applied.

In both cases you could use the existing core hardware to ID and alert to the threat, and once the threat signal level rises above a defined minimum point the target signal could then be sent to the AOA detection routine. You would use the core capability to queue the AOA system. By necessity the core system would then have to spend some periods of time processing the AOA data, and so you would have a reduced capability to alert to new threats. Not no capability, just reduced, depending on how much of your time you devote to AOA detection.

In both of my examples I envision a clip on / add on directional antenna array, probably clipped to the bottom of the detector and itself roughly the same size as the original detector. This add on would contain a set of antennas and the associated LNA's/LOs/Mixers, specific configuration depending on the techniques used.

In a passive scanned phased array you would have an array of 4 (or more) antennas which you control the feed phase of each, say using a digital controlled phase shifter in each feed line. Once queued from the main detection and identification systems you could rapidly "scan" the phase control, steering the beam, for each adjacent set of 2 antennas. This would mimic a physically spun antenna by establish direction based on the peak signal strength.

Off the top of my head I am not familiar enough with commercially available phase shift modules to say if this would be fiscally viable. I suspect there are several different paths to success here, but it would take a little research to determine the most cost effective way forward. My own experience with this hardware has never been based on trying to produce a piece of consumer electronics, it has always been more along the lines of "these are our performance specifications, tell me how much it will cost me", so having a custom built, one of a kind, solution, with the associated NRE, is just part and parcel of getting it done.

And the simplest way would be using a pseudo Doppler system. Use the same basic receiver and long range detection antennas that has been demonstrated to date. Detect and identify a signal of interest. Stare at the threat signal, switch to a different antenna input, use a pseudo Doppler based system to detect direction of arrival.

And again a caveat, I know this technique works and I have applied it myself as needed. However I have never done it trying to cover 3 different microwave bands in a single antenna module, indeed I have never done it above about 3 GHz. I am not aware of any limitations that would prevent its applications at such short wavelengths as Ka band, but that does not mean there are not any.

And I just thought of a third possibility. Maybe something like a multiple beam parallel plate stripline microwave lens array. I have no real idea if it could be done in a size that would be applicable, but I suspect it might be doable. I have seen that application at lower frequencies, and scaling it in my head ... maybe. If you are not familiar with what I mean look at how the directional antenna array of something like the AN/SLQ-32 ESM system works.

OK, this might all be pipe dream (or Scotch dream) stuff, but it is fun to brain storm.

T!
 
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Boozehound

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OK, it is Saturday night, and I may have had a Scotch or two already, but my ramblings on the subject....

Absolutely it could be done with multiple coherent receivers in an active phased array application. But that would greatly increase complexity, cost, and (assuming horn antennas with some gain) size. Such a system would be neat and all, but probably only affordable to an extremely small clientele.

I suspect it could be done a bit differently with existing receiver hardware (modified) and an added or plug in antenna section. Complexity and cost would also be increased, but I believe it would be fraction of the cost of the sexier active phased array solutions using multiple coherent receivers.

I believe it could be done at least two different ways (and I am sure there are others), those two being passive scanned phased array and pseudo Doppler scanning array. Both systems would require higher signal levels as I am assuming lower gain antennas making up the directional arrays. If you made it up of 4 antennas configured in a square, each with slightly overlapping coverage, just over 90 degrees azimuth and say 20 degrees elevation each, that would yield gains of over 7 dBi, and at least some improvement. If you cannot get enough gain to meet requirements you could increase the array element count, to 8 or even 16 elements, each with smaller beamwidths and higher gain. I can see some interesting PCB Vivaldi antenna type designs being applied.

In both cases you could use the existing core hardware to ID and alert to the threat, and once the threat signal level rises above a defined minimum point the target signal could then be sent to the AOA detection routine. You would use the core capability to queue the AOA system. By necessity the core system would then have to spend some periods of time processing the AOA data, and so you would have a reduced capability to alert to new threats. Not no capability, just reduced, depending on how much of your time you devote to AOA detection.

In both of my examples I envision a clip on / add on directional antenna array, probably clipped to the bottom of the detector and itself roughly the same size as the original detector. This add on would contain a set of antennas and the associated LNA's/LOs/Mixers, specific configuration depending on the techniques used.

In a passive scanned phased array you would have an array of 4 (or more) antennas which you control the feed phase of each, say using a digital controlled phase shifter in each feed line. Once queued from the main detection and identification systems you could rapidly "scan" the phase control, steering the beam, for each adjacent set of 2 antennas. This would mimic a physically spun antenna by establish direction based on the peak signal strength.

Off the top of my head I am not familiar enough with commercially available phase shift modules to say if this would be fiscally viable. I suspect there are several different paths to success here, but it would take a little research to determine the most cost effective way forward. My own experience with this hardware has never been based on trying to produce a piece of consumer electronics, it has always been more along the lines of "these are our performance specifications, tell me how much it will cost me", so having a custom built, one of a kind, solution, with the associated NRE, is just part and parcel of getting it done.

And the simplest way would be using a pseudo Doppler system. Use the same basic receiver and long range detection antennas that has been demonstrated to date. Detect and identify a signal of interest. Stare at the threat signal, switch to a different antenna input, use a pseudo Doppler based system to detect direction of arrival.

And again a caveat, I know this technique works and I have applied it myself as needed. However I have never done it trying to cover 3 different microwave bands in a single antenna module, indeed I have never done it above about 3 GHz. I am not aware of any limitations that would prevent its applications at such short wavelengths as Ka band, but that does not mean there are not any.

And I just thought of a third possibility. Maybe something like a multiple beam parallel plate stripline microwave lens array. I have no real idea if it could be done in a size that would be applicable, but I suspect it might be doable. I have seen that application at lower frequencies, and scaling it in my head ... maybe. If you are not familiar with what I mean look at how the directional antenna array of something like the AN/SLQ-32 ESM system works.

OK, this might all be pipe dream (or Scotch dream) stuff, but it is fun to brain storm.

T!
We share this pipe dream and the Scotch tonight. This is the stuff that makes RDF great. It took an innovative company like Radenso to launch a project like Theia to even get us thinking about these possibilities. Do you think the add-on could be done for $3G?

@Penumbrian I was mulling over how small I could make a rotator but wah, wahh, wahhhh. For the record there was lots of physical radar antenna movement going on in US fighter jets until not all that long ago. Even in this century. They were look down shoot down and they worked pretty well. An actively scanned phased array would be incredible but we'd like to do this for something less than a quarter mill...
 

fishing66

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Yesterday was an utter aPIEcalypse. It started off with consumption of an entire coconut custard pie. We had an outoor gathering and oh jeez, somebody brought a strawberry rhubarb pie. It became my new favorite. Between eating half of the strawberry rhubarb pie, half of the second coconut custard pie, some blueberry and pumpkin pie, the total was 2.75 pies for the day.

I might do an funky twist and make turkey Shepherd's pie with mashed sweet potatoes on top.
 

CarefulDriver

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OK, it is Saturday night, and I may have had a Scotch or two already, but my ramblings on the subject....

Absolutely it could be done with multiple coherent receivers in an active phased array application. But that would greatly increase complexity, cost, and (assuming horn antennas with some gain) size. Such a system would be neat and all, but probably only affordable to an extremely small clientele.

I suspect it could be done a bit differently with existing receiver hardware (modified) and an added or plug in antenna section. Complexity and cost would also be increased, but I believe it would be fraction of the cost of the sexier active phased array solutions using multiple coherent receivers.

I believe it could be done at least two different ways (and I am sure there are others), those two being passive scanned phased array and pseudo Doppler scanning array. Both systems would require higher signal levels as I am assuming lower gain antennas making up the directional arrays. If you made it up of 4 antennas configured in a square, each with slightly overlapping coverage, just over 90 degrees azimuth and say 20 degrees elevation each, that would yield gains of over 7 dBi, and at least some improvement. If you cannot get enough gain to meet requirements you could increase the array element count, to 8 or even 16 elements, each with smaller beamwidths and higher gain. I can see some interesting PCB Vivaldi antenna type designs being applied.

In both cases you could use the existing core hardware to ID and alert to the threat, and once the threat signal level rises above a defined minimum point the target signal could then be sent to the AOA detection routine. You would use the core capability to queue the AOA system. By necessity the core system would then have to spend some periods of time processing the AOA data, and so you would have a reduced capability to alert to new threats. Not no capability, just reduced, depending on how much of your time you devote to AOA detection.

In both of my examples I envision a clip on / add on directional antenna array, probably clipped to the bottom of the detector and itself roughly the same size as the original detector. This add on would contain a set of antennas and the associated LNA's/LOs/Mixers, specific configuration depending on the techniques used.

In a passive scanned phased array you would have an array of 4 (or more) antennas which you control the feed phase of each, say using a digital controlled phase shifter in each feed line. Once queued from the main detection and identification systems you could rapidly "scan" the phase control, steering the beam, for each adjacent set of 2 antennas. This would mimic a physically spun antenna by establish direction based on the peak signal strength.

Off the top of my head I am not familiar enough with commercially available phase shift modules to say if this would be fiscally viable. I suspect there are several different paths to success here, but it would take a little research to determine the most cost effective way forward. My own experience with this hardware has never been based on trying to produce a piece of consumer electronics, it has always been more along the lines of "these are our performance specifications, tell me how much it will cost me", so having a custom built, one of a kind, solution, with the associated NRE, is just part and parcel of getting it done.

And the simplest way would be using a pseudo Doppler system. Use the same basic receiver and long range detection antennas that has been demonstrated to date. Detect and identify a signal of interest. Stare at the threat signal, switch to a different antenna input, use a pseudo Doppler based system to detect direction of arrival.

And again a caveat, I know this technique works and I have applied it myself as needed. However I have never done it trying to cover 3 different microwave bands in a single antenna module, indeed I have never done it above about 3 GHz. I am not aware of any limitations that would prevent its applications at such short wavelengths as Ka band, but that does not mean there are not any.

And I just thought of a third possibility. Maybe something like a multiple beam parallel plate stripline microwave lens array. I have no real idea if it could be done in a size that would be applicable, but I suspect it might be doable. I have seen that application at lower frequencies, and scaling it in my head ... maybe. If you are not familiar with what I mean look at how the directional antenna array of something like the AN/SLQ-32 ESM system works.

OK, this might all be pipe dream (or Scotch dream) stuff, but it is fun to brain storm.

T!
Now that you have mentioned LOs and mixers, I gotta ask (yet again) something: if all current detectors are just "frequency detectors" and frequency is the only information they need/use in decision making, why do they need to downconvert the signal and sample it at all? I understand why Theia needs to do this (it uses more info than just frequency, it actually does analyze the signal) but legacy detectors, why?
 

SwankPeRFection

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Yesterday was an utter aPIEcalypse. It started off with consumption of an entire coconut custard pie. We had an outoor gathering and oh jeez, somebody brought a strawberry rhubarb pie. It became my new favorite. Between eating half of the strawberry rhubarb pie, half of the second coconut custard pie, some blueberry and pumpkin pie, the total was 2.75 pies for the day.

I might do an funky twist and make turkey Shepherd's pie with mashed sweet potatoes on top.
You don’t even need to worry about Theia.... you won’t fit in the car soon enough.
 

Token

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Now that you have mentioned LOs and mixers, I gotta ask (yet again) something: if all current detectors are just "frequency detectors" and frequency is the only information they need/use in decision making, why do they need to downconvert the signal and sample it at all? I understand why Theia needs to do this (it uses more info than just frequency, it actually does analyze the signal) but legacy detectors, why?

Sorry for the long answer here, but I can't think of a way to do it adequately in a short response.

Think of it like tuning an analog FM radio. You cannot hear these signals directly, despite the fact they are hitting you all the time. The signals need to be converted to something your ears can work with. The dial goes from 88 MHz on the left to 108 MHz on the right. The radio is capable of receiving 88 to 108 MHz, but not all at one time, it does it in smaller segments so that it can differentiate a station on 95.5 MHz from one on 95.7 MHz. To do this, as you tune the dial across the "band" it downconverts the signals in that range (88 to 108 MHz) from their frequency (called the RF, or Radio Frequency) to lower frequencies (called an IF, or Intermediate Frequency). They use an LO (Local Oscillator) and a mixer to do this. That IF is then passed through a filter to allow isolation of a specific frequency / channel, where lower cost hardware (in general, the lower the frequency the less expensive and critical the hardware) can make usable audio for your ears to hear.

As I understand it traditional detectors are normal superhetrodyne receivers, as I have described above. They tune a specific section (or multiple sections) of spectrum and down convert it/them to lower frequencies where the information in that spectrum can be "worked with". You cannot, with any fidelity and at a reasonable cost, work with a signal directly at something like 35.5 GHz, it needs to be at lower frequencies for affordable demodulation or analysis to be done.

I hear it now, "traditional detectors do no analysis", and that is wrong, they do, it just may be very simple analysis. Any modern detector that displays frequency at least measures amplitude vs frequency, so that they can tell, and display, a signal is X strong and at Y frequency. In order to do that you have to be able to look at each specific frequency (with some defined resolution or granularity) and differentiate it from the frequency "right next to it".

At the most simple level, you have to filter all the signals on frequencies you don't want to hear (say something at 40 GHz vs 34.7 GHz), and then detect / isolate the individual signals (when there may be many) in the desired band to alert/indicate on them. It would be very expensive to do that directly at 35.5 GHz, so it gets downconverted to a lower freqs for this effort.

I suspect many detectors do this whole thing by downconverting small segments of the RF into bins or buckets at the IF level. Something like this, and this is total guess work on my part, I have never deep dived any detector to find the real numbers. The detector is looking at K band, 24.05 to 24.25 GHz. To allow out of spec guns it includes a slightly wider 24.00 to 24.30 GHz range. The "front end" of the detector includes a bandpass filter that tries to narrow all of the passed through spectrum to this region. It then samples the desired frequency range. It does this by breaking that 300 MHz total bandwidth up into 30 (a number I picked at random for this example, I have no idea if any detectors use 30 segments in K band) smaller segments, each 0.01 GHz (10 MHz) wide (again, a number I picked totally at random for this example). It scans / samples "segment 0", 24.00 to 24.01, then it scans /samples segment 1, 24.01 to 24.02, then it scans / samples segment 2, 24.02 to 24.03, etc all the way up to 24.3 GHz.

This could take two LOs and two mixers, making the system "double conversion".

To do this each of these 10 MHz wide chunks are first downconverted to something like an 800 Mhz IF (again, a number I picked totally at random for this example). To tune the 24.000 to 24.010 bin a first LO is made at 23.205 GHz. This makes the 24.000 to 24.010 GHz frequency appear at, be converted to, 795 to 805 MHz.

And then again downconverted to something like a 60 Mhz second IF (again, a number I picked at random), a second LO, at 740 MHz, is applied to the 800 MHz IF. So now that 24.000 - 24.010 GHz / 795 - 805 MHz segment appears at, is downconverted to, a 55 - 65 MHz IF.

You do the detection, the limited analysis, at the 60 Mhz IF. Your analysis may be as simple as "is there energy in this bin". Or you can sweep the small bin and determine the peak energy in the bin. If the peak energy is at 61 MHz during "segment 2" then you know, via the conversion process, that the peak energy was at 24.026 GHz.

The first LO is the only one that has to change in the process. To do segment 0 (24.000 to 24.010 GHz) the first LO would tune to 23.205 GHz. To do segment 1 (24.010 to 24.020 GHz) the first LO would tune to 23.215 GHz, segment 2 (24.020 to 24.030 GHz) would make the first LO 23.225 GHz. Each of these combinations leaves the first IF at 800 MHz where the fixed second LO at 740 MHz downconverts everything to the 60 MHz second IF.

T!
 

thesilverbullet

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is it just me or are we off topic - 32 days and some change...
 

ILS27L

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@Penumbrian I was mulling over how small I could make a rotator but wah, wahh, wahhhh. For the record there was lots of physical radar antenna movement going on in US fighter jets until not all that long ago. Even in this century. They were look down shoot down and they worked pretty well. An actively scanned phased array would be incredible but we'd like to do this for something less than a quarter mill...

Physically moving antennas are still very much a thing, not everything is AESA or even PESA, although of course AESA is the way of the future. For example the F-16 is shifting to the APG-83, but most of them are not there yet. So the majority are still using the older, scanning, APG-66 or 68. Of course the Block 70/72 come out the door with the AESA. And older platforms, like the B-52, still use mechanically scanned antennas.

In the missile world (focused on lower cost and expendable) things have shifted to phased array a bit slower, something like the AIM-120 still uses a mechanically scanned antenna.

AIM120.jpg


T!
 

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Yesterday was an utter aPIEcalypse. It started off with consumption of an entire coconut custard pie. We had an outoor gathering and oh jeez, somebody brought a strawberry rhubarb pie. It became my new favorite. Between eating half of the strawberry rhubarb pie, half of the second coconut custard pie, some blueberry and pumpkin pie, the total was 2.75 pies for the day.

I might do an funky twist and make turkey Shepherd's pie with mashed sweet potatoes on top.
Well we might be off topic, but any discussion that involves coconut custard and strawberry rubarb pies is just fine. They are just wonderful.
 

CarefulDriver

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Sorry for the long answer here, but I can't think of a way to do it adequately in a short response.

Think of it like tuning an analog FM radio. You cannot hear these signals directly, despite the fact they are hitting you all the time. The signals need to be converted to something your ears can work with. The dial goes from 88 MHz on the left to 108 MHz on the right. The radio is capable of receiving 88 to 108 MHz, but not all at one time, it does it in smaller segments so that it can differentiate a station on 95.5 MHz from one on 95.7 MHz. To do this, as you tune the dial across the "band" it downconverts the signals in that range (88 to 108 MHz) from their frequency (called the RF, or Radio Frequency) to lower frequencies (called an IF, or Intermediate Frequency). They use an LO (Local Oscillator) and a mixer to do this. That IF is then passed through a filter to allow isolation of a specific frequency / channel, where lower cost hardware (in general, the lower the frequency the less expensive and critical the hardware) can make usable audio for your ears to hear.

As I understand it traditional detectors are normal superhetrodyne receivers, as I have described above. They tune a specific section (or multiple sections) of spectrum and down convert it/them to lower frequencies where the information in that spectrum can be "worked with". You cannot, with any fidelity and at a reasonable cost, work with a signal directly at something like 35.5 GHz, it needs to be at lower frequencies for affordable demodulation or analysis to be done.

I hear it now, "traditional detectors do no analysis", and that is wrong, they do, it just may be very simple analysis. Any modern detector that displays frequency at least measures amplitude vs frequency, so that they can tell, and display, a signal is X strong and at Y frequency. In order to do that you have to be able to look at each specific frequency (with some defined resolution or granularity) and differentiate it from the frequency "right next to it".

At the most simple level, you have to filter all the signals on frequencies you don't want to hear (say something at 40 GHz vs 34.7 GHz), and then detect / isolate the individual signals (when there may be many) in the desired band to alert/indicate on them. It would be very expensive to do that directly at 35.5 GHz, so it gets downconverted to a lower freqs for this effort.

I suspect many detectors do this whole thing by downconverting small segments of the RF into bins or buckets at the IF level. Something like this, and this is total guess work on my part, I have never deep dived any detector to find the real numbers. The detector is looking at K band, 24.05 to 24.25 GHz. To allow out of spec guns it includes a slightly wider 24.00 to 24.30 GHz range. The "front end" of the detector includes a bandpass filter that tries to narrow all of the passed through spectrum to this region. It then samples the desired frequency range. It does this by breaking that 300 MHz total bandwidth up into 30 (a number I picked at random for this example, I have no idea if any detectors use 30 segments in K band) smaller segments, each 0.01 GHz (10 MHz) wide (again, a number I picked totally at random for this example). It scans / samples "segment 0", 24.00 to 24.01, then it scans /samples segment 1, 24.01 to 24.02, then it scans / samples segment 2, 24.02 to 24.03, etc all the way up to 24.3 GHz.

This could take two LOs and two mixers, making the system "double conversion".

To do this each of these 10 MHz wide chunks are first downconverted to something like an 800 Mhz IF (again, a number I picked totally at random for this example). To tune the 24.000 to 24.010 bin a first LO is made at 23.205 GHz. This makes the 24.000 to 24.010 GHz frequency appear at, be converted to, 795 to 805 MHz.

And then again downconverted to something like a 60 Mhz second IF (again, a number I picked at random), a second LO, at 740 MHz, is applied to the 800 MHz IF. So now that 24.000 - 24.010 GHz / 795 - 805 MHz segment appears at, is downconverted to, a 55 - 65 MHz IF.

You do the detection, the limited analysis, at the 60 Mhz IF. Your analysis may be as simple as "is there energy in this bin". Or you can sweep the small bin and determine the peak energy in the bin. If the peak energy is at 61 MHz during "segment 2" then you know, via the conversion process, that the peak energy was at 24.026 GHz.

The first LO is the only one that has to change in the process. To do segment 0 (24.000 to 24.010 GHz) the first LO would tune to 23.205 GHz. To do segment 1 (24.010 to 24.020 GHz) the first LO would tune to 23.215 GHz, segment 2 (24.020 to 24.030 GHz) would make the first LO 23.225 GHz. Each of these combinations leaves the first IF at 800 MHz where the fixed second LO at 740 MHz downconverts everything to the 60 MHz second IF.

T!
This is very good explanation. But isn't it still possible to just add bandpass filters that filter out everything under 34.7Ghz and above 35.5Ghz and done, you have energy detector receiving only specific frequencies (without LO and mixer)?
 
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Token

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This is very good explanation. But isn't it still possible to just add bandpass filters that filter out everything under 34.7Ghz and above 35.5Ghz and done, you have energy detector receiving only specific frequencies (without LO and mixer)?

The bandpass filter is easy, but how do you detect that energy? Without down conversion there is no economical way to detect each individual signal in the band. It is cheaper, and easier, in the long run, to look at things at lower frequencies.

I suppose you could use a crystal detector based receiver to detect energy in the band, but the false alert rates would be even higher than todays decent level detectors. With such a broadbanded approach you would have no options of GPS lockouts based on location and frequency, since you cannot measure frequency. You would have no ability to detect multiple sources in a given band, since all the energy inside the band would just be lumped together.

T!
 

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Physically moving antennas are still very much a thing, not everything is AESA or even PESA, although of course AESA is the way of the future. For example the F-16 is shifting to the APG-83, but most of them are not there yet. So the majority are still using the older, scanning, APG-66 or 68. Of course the Block 70/72 come out the door with the AESA. And older platforms, like the B-52, still use mechanically scanned antennas.

In the missile world (focused on lower cost and expendable) things have shifted to phased array a bit slower, something like the AIM-120 still uses a mechanically scanned antenna.

View attachment 166146

T!
Very cool pic. The Super Hornets have had the AESA for a while now. That's the jet and radar used to track the Unidentified Famous TicTac. IIRC several advanced ship radars had also tracked it.

We might just have members who've never seen an analog FM radio. Hope we do! FM radio has become so irrelevant that it's difficult to find a tuner that receives the digital signal (HD Radio) for a component system. On FM you trade noise and separation for lossy digital compression. On AM it sounds a whole lot better.

I need pie.
 

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The bandpass filter is easy, but how do you detect that energy? Without down conversion there is no economical way to detect each individual signal in the band. It is cheaper, and easier, in the long run, to look at things at lower frequencies.

I suppose you could use a crystal detector based receiver to detect energy in the band, but the false alert rates would be even higher than todays decent level detectors. With such a broadbanded approach you would have no options of GPS lockouts based on location and frequency, since you cannot measure frequency. You would have no ability to detect multiple sources in a given band, since all the energy inside the band would just be lumped together.

T!
Yeah you are correct, I'm just thinking about battle between RDs and RDDs. Two decades ago, there weren't much false alerts, but lot of people got nailed by RDDs because for some reason LO was needed on detectors even thought they did not really use that.
 

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I went to the supermarket this morning and got four pies: two coconut custard, one blueberry and one pumpkin. They had some Dutch Apple and Sweet Potato pies that looked good but I'm already in trouble for bringing home four pies. Up next, massive pie consumption, a Godzilla movie and a nap.
Be glad it was pies and not cakes or you'd be a target.

lex-luthor-40-cakes-1131948.jpg
 

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OK, it is Saturday night, and I may have had a Scotch or two already, but my ramblings on the subject....

Absolutely it could be done with multiple coherent receivers in an active phased array application. But that would greatly increase complexity, cost, and (assuming horn antennas with some gain) size. Such a system would be neat and all, but probably only affordable to an extremely small clientele.

I suspect it could be done a bit differently with existing receiver hardware (modified) and an added or plug in antenna section. Complexity and cost would also be increased, but I believe it would be fraction of the cost of the sexier active phased array solutions using multiple coherent receivers.

I believe it could be done at least two different ways (and I am sure there are others), those two being passive scanned phased array and pseudo Doppler scanning array. Both systems would require higher signal levels as I am assuming lower gain antennas making up the directional arrays. If you made it up of 4 antennas configured in a square, each with slightly overlapping coverage, just over 90 degrees azimuth and say 20 degrees elevation each, that would yield gains of over 7 dBi, and at least some improvement. If you cannot get enough gain to meet requirements you could increase the array element count, to 8 or even 16 elements, each with smaller beamwidths and higher gain. I can see some interesting PCB Vivaldi antenna type designs being applied.

In both cases you could use the existing core hardware to ID and alert to the threat, and once the threat signal level rises above a defined minimum point the target signal could then be sent to the AOA detection routine. You would use the core capability to queue the AOA system. By necessity the core system would then have to spend some periods of time processing the AOA data, and so you would have a reduced capability to alert to new threats. Not no capability, just reduced, depending on how much of your time you devote to AOA detection.

In both of my examples I envision a clip on / add on directional antenna array, probably clipped to the bottom of the detector and itself roughly the same size as the original detector. This add on would contain a set of antennas and the associated LNA's/LOs/Mixers, specific configuration depending on the techniques used.

In a passive scanned phased array you would have an array of 4 (or more) antennas which you control the feed phase of each, say using a digital controlled phase shifter in each feed line. Once queued from the main detection and identification systems you could rapidly "scan" the phase control, steering the beam, for each adjacent set of 2 antennas. This would mimic a physically spun antenna by establish direction based on the peak signal strength.

Off the top of my head I am not familiar enough with commercially available phase shift modules to say if this would be fiscally viable. I suspect there are several different paths to success here, but it would take a little research to determine the most cost effective way forward. My own experience with this hardware has never been based on trying to produce a piece of consumer electronics, it has always been more along the lines of "these are our performance specifications, tell me how much it will cost me", so having a custom built, one of a kind, solution, with the associated NRE, is just part and parcel of getting it done.

And the simplest way would be using a pseudo Doppler system. Use the same basic receiver and long range detection antennas that has been demonstrated to date. Detect and identify a signal of interest. Stare at the threat signal, switch to a different antenna input, use a pseudo Doppler based system to detect direction of arrival.

And again a caveat, I know this technique works and I have applied it myself as needed. However I have never done it trying to cover 3 different microwave bands in a single antenna module, indeed I have never done it above about 3 GHz. I am not aware of any limitations that would prevent its applications at such short wavelengths as Ka band, but that does not mean there are not any.

And I just thought of a third possibility. Maybe something like a multiple beam parallel plate stripline microwave lens array. I have no real idea if it could be done in a size that would be applicable, but I suspect it might be doable. I have seen that application at lower frequencies, and scaling it in my head ... maybe. If you are not familiar with what I mean look at how the directional antenna array of something like the AN/SLQ-32 ESM system works.

OK, this might all be pipe dream (or Scotch dream) stuff, but it is fun to brain storm.

T!
It actually doesn't have to be that complicated. Since you're detecting on a flat plane as your target (the radar gun) is going to be ground level (and overpasses count as ground level) you only need a single row of feedhorns, each covering 10 degrees, overlapping slightly and pointed in different directions, to get the required coverage. This would mean ten 10-degree feedhorns to cover 90 degrees. You could do a 360 degree feedhorn setup, using analyzing software to detect signal strength, to get the true direction. The side feedhorns could be single 90 degree horns covering either side because to the side, you just need to know it's there. You could also do three 30 degree or a single 90 degree feedhorn to the rear, because you're rapidly going away from whoever might be behind you and it's highly unlikely that anyone would clock you from the rear that you hadn't already picked up scatter from up when they were in front of you. When the radar gun is to one side you can be going 500MPH and the radar gun will clock your speed at 0ish MPH because your distance to the gun isn't changing it sees your speed near 0MPH. If you really wanted to get spendy, you could have two rows of feedhorns with the eleven 10-degree feedhorns on the top row staggered in relation to the bottom row, for a more detailed detection on where the gun is. And that's where you get the fighter jet threat display that shows where the cop is and how far away he is. The feedhorns wouldn't even need to be that large for this either, since you really don't want a huge amount of range with this much detailed information. If you can't register a cop and get slowed down with a one mile warning, there's something wrong with you, and this kind of detailed information would tell you if the cop was on the same road you're on or clocking a cross street you're approaching.
 

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It actually doesn't have to be that complicated. Since you're detecting on a flat plane as your target (the radar gun) is going to be ground level (and overpasses count as ground level) you only need a single row of feedhorns, each covering 10 degrees, overlapping slightly and pointed in different directions, to get the required coverage. This would mean ten 10-degree feedhorns to cover 90 degrees. You could do a 360 degree feedhorn setup, using analyzing software to detect signal strength, to get the true direction. The side feedhorns could be single 90 degree horns covering either side because to the side, you just need to know it's there. You could also do three 30 degree or a single 90 degree feedhorn to the rear, because you're rapidly going away from whoever might be behind you and it's highly unlikely that anyone would clock you from the rear that you hadn't already picked up scatter from up when they were in front of you. When the radar gun is to one side you can be going 500MPH and the radar gun will clock your speed at 0ish MPH because your distance to the gun isn't changing it sees your speed near 0MPH. If you really wanted to get spendy, you could have two rows of feedhorns with the eleven 10-degree feedhorns on the top row staggered in relation to the bottom row, for a more detailed detection on where the gun is. And that's where you get the fighter jet threat display that shows where the cop is and how far away he is. The feedhorns wouldn't even need to be that large for this either, since you really don't want a huge amount of range with this much detailed information. If you can't register a cop and get slowed down with a one mile warning, there's something wrong with you, and this kind of detailed information would tell you if the cop was on the same road you're on or clocking a cross street you're approaching.
One mile detection range won't cut it for the I/O encounter even with fine directional information. This is an interesting idea. You'd have a large device with so many horns. Very interesting and there's a way to apply some economy of scale in this in processing and parts of the receiver.

Let's see how Theia changes things. At some point people may ask what kind of performance can be had for $3K or 5 or even $10K. Radenso deserves credit for driving such a conversation. We have lots of folks in this country who can afford it. Well, we do now. Hopefully we'll have more but that'll take leadership. I'm always encouraged to see things like wages, home ownership and labor participation rates increase. They certainly had been prior to Covid.
 
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