Why don't dual horn radar detectors interfere with themselves?

blackmapp

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I'm hoping this isn't a stupid question, or isn't something that has already been discussed, however I was thinking about this and couldn't find an answer, so I decided to post the question to the people who are far more knowledgeable than me about this to hopefully get an answer. Why don't radar detectors that have a front and rear horn interfere with itself like can be possible if you run two (or more) radar detectors side by side?

From testing that I've seen for the R7, Max360, Max360c, V1, V1G2, RL360c, DP360, and possibly any others I may have missed, these detectors have a front and rear horn, in order to give you arrows, but they seem to perform well (some better than others and each has their own pros and cons, so this isn't about a specific brand, but rather just generically the front/rear horn RD's that give you arrows), however if you run two RD's next to each other, you can get issues where perhaps one or both detectors go to sleep, range can be drastically be reduced, they can false to each other, etc.

If I had to guess, I would assume that the hardware/software as well as horn placement and design of these detectors is what prevents the kinds of issues you can see if you run two detectors at the same time. Maybe it's just as simple as the horns are facing in opposite directions whereas when you have two detectors that are next to each other the horns for those detectors are both facing the same way and the interference that leaks from the detectors' horns is on the same plane and is what is actually causing the problem.

Hopefully all of this makes sense, but if anyone has any questions or needs additional information from me, please let me know.
 

Noddy

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OK, let me have a try!
I would say it's a matter of factory tuning and that since each horn picks up exactly the same signal, it makes no difference weather a detector has 1, 2 or 3 horns it will not react to it's own innate frequency. A bit like a bsm filter for the detector.
 

odiddy

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Take a look at this:


If you look at the images, you will notice there is a “switch” or “mux” that only lets the front or rear antenna be “seen” in the downstream signal chain path (it shares the same

so it’s not two individual detectors glued together..it’s more like checking for presence of a signal via 1 horn at a time then swapping to the other horn and checking for it.
 

oversteer325

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Do they typically share a local oscillator? That’s where the interference comes from right? If there’s only one there’s nothing to cause interference.
 

odiddy

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Do they typically share a local oscillator? That’s where the interference comes from right? If there’s only one there’s nothing to cause interference.
I’m not 100% sure of the different architectures.

you could technically tune it out with a band pass filter, but to keep component cost down (from duplication of those blocks) it would make sense to go this path for a consumer product.

you may get a very very slight edge by having them both run in “real-time”

if you wanted a detector with great off axis, I wonder if you could put a left horn and right horn (technically on axis at that point)

the way dual horn detectors know if it’s a “side signal” today is by comparing the signal intensity of the front vs. back. If they are close, they opt to call it a side signal.
Post automatically merged:

Wait, if someone implements this… that means we could get a detector with arrow precision like this

for example, if you find a signal that is equally strong from the front and right, call it front right quadrant..

1627171050599.gif
 
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Noddy

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Take a look at this:


If you look at the images, you will notice there is a “switch” or “mux” that only lets the front or rear antenna be “seen” in the downstream signal chain path (it shares the same

so it’s not two individual detectors glued together..it’s more like checking for presence of a signal via 1 horn at a time then swapping to the other horn and checking for it.
This is a different mechanism to how one rd interferes with another rd, right?
 

sdrawkcaB

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OK, let me have a try!
I would say it's a matter of factory tuning and that since each horn picks up exactly the same signal, it makes no difference weather a detector has 1, 2 or 3 horns it will not react to it's own innate frequency. A bit like a bsm filter for the detector.

Not exactly. For windshield mount detector with both horns inside the same unit, each horn operates at different timing than the other. On detectors like the Valentine One Gen. 2, the scan cycle occurs once for the front horn, then once for the rear horn. Only one horn is being scanned at a time.

On remote mount detectors with separate front and rear mounted antennas, it has to be handled differently. Each antenna is operating and scanning constantly, and in theory it is possible to have one antenna detect the other. This can be mitigated though through both hardware and firmware design. On the hardware side of things, the circuitry can be designed to limit emitted interference traveling back up and out the horn. In the firmware side of things the detector can be programmed to do repeat checks when it encounters a signal. Additional checks help it know if it was a signal from an actual threat (speed enforcement RADAR) or if it was just an incidental spurious emission caused by another emitter such as another nearby RADAR detector horn also performing a scan.

A good quality detector will implement both of these approaches; hardware and firmware.
 

blackmapp

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@Noddy @odiddy @oversteer325 @sdrawkcaB thank you all for your replies, they were all helpful!

Take a look at this:


If you look at the images, you will notice there is a “switch” or “mux” that only lets the front or rear antenna be “seen” in the downstream signal chain path (it shares the same

so it’s not two individual detectors glued together..it’s more like checking for presence of a signal via 1 horn at a time then swapping to the other horn and checking for it.
Thank you! I'll admit that had you not helped to explain what the information was in the patent drawings for the V1 G2, I would have been lost, but your additional explanation with the link was very helpful to navigate through the patent drawings.
I’m not 100% sure of the different architectures.

you could technically tune it out with a band pass filter, but to keep component cost down (from duplication of those blocks) it would make sense to go this path for a consumer product.

you may get a very very slight edge by having them both run in “real-time”

if you wanted a detector with great off axis, I wonder if you could put a left horn and right horn (technically on axis at that point)

the way dual horn detectors know if it’s a “side signal” today is by comparing the signal intensity of the front vs. back. If they are close, they opt to call it a side signal.
Post automatically merged:

Wait, if someone implements this… that means we could get a detector with arrow precision like this

for example, if you find a signal that is equally strong from the front and right, call it front right quadrant..

View attachment 184568

I think this would be a really interesting idea to have four horns in order to get something like in your example, but I think the reasons that it hasn't been done is probably a few different issues. I'm thinking the first reason would be cost, since I think at a minimum a 4 horn windshield mount would be ~$1000.

In a windshield mount, another issue that I think would also come up would be the side horns wouldn't have great left or right detection/sensitivity since how the detectors are mounted on the windshield, the A-pillar could end up interfering with those horns, so on top of being more expensive, I could also potentially see the left & right horns, not actually working as well as the front and rear horns and also cause some accuracy/arrow issues as well related to this.

In a remote mount, it wouldn't have the potential issue of interference from the A-pillar because you're mounting outside of your vehicle, but there would be some difficulty in finding a place to mount on the side of a vehicle, especially on vehicles that sit lower to the ground since you don't have bumpers on the side, with for lack of a better term, a "pocket" to mount the horns in, so in addition to the costs of the additional horns themselves, I could also see additional labor costs or fragility issues if it has to be mounted externally, or some other issues similarly related to being on the side of the vehicle.

Also, I could see a hardware limitation as well where the actual hardware only can support two radar horns and it isn't worth the cost to the manufacturer to be able to add 2 additional horns for the sides because most people wouldn't opt for 4 horns when front and rear would be less expensive and I think it'd be cool to have 4 horns to get front, rear, left and right information, I honestly probably would still only go with a detector that only had front & rear horns as I couldn't afford/justify a 4 horn detector.

The main reason though, is at least from what I understand, police can't actually get your speed, at least not in a way that is accurate & would hold up in court if they are perpendicular to traffic, so, while it would be really interesting to be able to get more accurate information on location with 2 additional horns, since the police can't get your speed if they're perpendicular to traffic, it isn't as important as front/rear horns to give you arrows to be able to tell if the police are in front of you or behind you.

Not exactly. For windshield mount detector with both horns inside the same unit, each horn operates at different timing than the other. On detectors like the Valentine One Gen. 2, the scan cycle occurs once for the front horn, then once for the rear horn. Only one horn is being scanned at a time.

On remote mount detectors with separate front and rear mounted antennas, it has to be handled differently. Each antenna is operating and scanning constantly, and in theory it is possible to have one antenna detect the other. This can be mitigated though through both hardware and firmware design. On the hardware side of things, the circuitry can be designed to limit emitted interference traveling back up and out the horn. In the firmware side of things the detector can be programmed to do repeat checks when it encounters a signal. Additional checks help it know if it was a signal from an actual threat (speed enforcement RADAR) or if it was just an incidental spurious emission caused by another emitter such as another nearby RADAR detector horn also performing a scan.

A good quality detector will implement both of these approaches; hardware and firmware.

Thank you for this explanation and I didn't realize that a windshield mount would operate differently then a remote mount, but that makes a lot of sense as you don't have the same space constraints in a remote mount that you do in a windshield mount so you can do things a little differently.

Do you think that perhaps the reason the K40 remote mounts don't perform well is in part because the hardware and/or firmware isn't as well implemented and the front and rear antennas are interfering with each other? I'm guessing this isn't the main issue since the K40 single antenna detectors also have performance problems, but your explanation regarding how remote detectors handle front and rear antennas differently makes sense, I was wondering if you thought this could also be part of why the K40 remote mount with front/rear antennas are not great performers.
 

sdrawkcaB

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Do you think that perhaps the reason the K40 remote mounts don't perform well is in part because the hardware and/or firmware isn't as well implemented and the front and rear antennas are interfering with each other? I'm guessing this isn't the main issue since the K40 single antenna detectors also have performance problems, but your explanation regarding how remote detectors handle front and rear antennas differently makes sense, I was wondering if you thought this could also be part of why the K40 remote mount with front/rear antennas are not great performers.

No. I think it has more to do with the fact that K40 are using cheaper hardware in their remote mount systems. They are made by Attowave, but share the same components as the Uniden DFR5 platform, which is a pretty basic near-entry-level detector.

The best remote mount systems out right now in terms of sensitivity and performance are going to be the Escort Max Ci (Using the M7 and M3R+ antennas), the Radenso RC-M, and the ALP NetRadar (using the same Attowave platform as the Uniden R1/R3). The current K40 products aren't even in the same league as the other ones I've mentioned.
 

blackmapp

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No. I think it has more to do with the fact that K40 are using cheaper hardware in their remote mount systems. They are made by Attowave, but share the same components as the Uniden DFR5 platform, which is a pretty basic near-entry-level detector.

The best remote mount systems out right now in terms of sensitivity and performance are going to be the Escort Max Ci (Using the M7 and M3R+ antennas), the Radenso RC-M, and the ALP NetRadar (using the same Attowave platform as the Uniden R1/R3). The current K40 products aren't even in the same league as the other ones I've mentioned.
That makes a lot more sense and thank you for the information!
 

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