R7 with attenuated rear horn for Mazda CX-5

[SixPackABS]

MAZDA CX5 owners are unfortunate to have BSM falsing being picked up by the R7 rear horn. The only work around I had just to be able to use the R7 was to have an R7/R3 combo. R7 with K band disabled and the R3 with Ka band disabled. So far I was not having falsing issues being triggered by one of the RD,,,,,,, I cannot say the same if there was no interference issue. As we all know there will be. I would have run my set-up permanently this way. I really don't like running the second RD, (R3). Until heaven sent a possible problem solver.
@hiddencam suggested a very nice idea. Attenuating the rear horn of the R7 to decrease/eliminate the BSM falsing from the CX5.

If the rear BSM issue is the only reason you're doing this risky practise, why not just control the physical attenuation of the rear antenna by using a product like a (piece of) stick-on tuned frequency absorber. 65 bucks for a 12"x12" piece and you'd have enough for 12 R7s. You could recoup your cost by selling 1"x1" pieces for 6 bucks to other forum members experiencing your issue of too sensitive rear horn. That way, interference is fully eliminated. You'd get 20db attenuation, tuned only to K-band radar and not Ka band. The R7 is about -124dB in Hwy mode (a few dBs more sensitive than the R3 in the below chart), so that would bring it to -104dB in Hwy mode, and % reductions in Advanced mode much closer to what you're looking for.

A month after,,,,, here it is.

Initial Result.
K band 50%/ K fliter on/ K wide/ MRCD off. ( same setting pre attenuation mod)
After I powered it on the bsm falsing started. Just an initial beep , since the quite ride is on you would not hear anything. Bummer. Decided to take a ride downtown. As soon as the car started moving the falsing stopped. Stopping at a traffic light didn't trigger any falsing. As soon as I am parked falsing will start very briefly then quite ride kicks in. Very big difference from pre attenuation mod. Very much quite. Would keep this set-up if it holds up.

I need to run this tomorrow morning where in it much busier downtown.


6 WEEKS AFTER USING THIS MOD.

I have added 2 more layers a total of 4 layers of MAST on the rear horn.
Covered the left side of the rear horn close to the LED screen with 3 layers of MAST.
BSM filtering is superb, equall or greater than the RPM.

Final Look now.

 

[Elcid2015]

I would be interested to see if it affected the Ka band sensitivity at all

 

[InsipidMonkey]

Can you post a view from the rear? Did you cover the rear horn?

Post automatically merged: Jun 4, 2019

I would be interested to see if it affected the Ka band sensitivity at all

According to the chart @hiddencam posted, rear Ka band sensitivity would be attenuated by ~5-10 dB.

 

[SixPackABS]

Edited. Front pic on first post.

 

[Elcid2015]

Can you post a view from the rear? Did you cover the rear horn?

Post automatically merged: Jun 4, 2019

According to the chart @hiddencam posted, rear Ka band sensitivity would be attenuated by ~5-10 dB.

Thanks for pointing out the chart. Its interesting though, the chart is only for attenuation via reflectivity.

 

[InsipidMonkey]

Thanks for pointing out the chart. Its interesting though, the chart is only for attenuation via reflectivity.

Based on the thickness of the material (~1mm), and the fact it's mostly silicone, I suspect losses due to absorption are negligible.

 

[hiddencam]

Glad you're testing this out! You really wrapped the tail end of your R7 with a lot of that stuff haha. Awesome that it's significantly better now; that's a big win!

 

[SixPackABS]

@hiddencam
initial test is encouraging. Tomorrows heavy traffic will be the real test. Thanks for the idea.

 

[crabu2]

It looks like you're building an R3 by killing the rear horn. Maybe you're better off with just running the R3, unless there's something on the R7 you need?

 

[SixPackABS]

@hiddencam
The result has been consistent so far. I will get the rear falsing if parked for a longer period of time. Once moving I have not experienced any rear falsing.
Added another layer at exactly the rear horn itself. No layers added to the side. I will test this new set-up in my afternoon ride.

@crabu2
This set-up is for Mazda CX5 users experiencing rear horn K band falsing caused by the cars BSM. By attenuating the rear horns K band sensitivity this will make it usable on the CX5's. For me I don't really nead the K band rear detection that much. What matters most is the Ka band arrows. I used to have the R7 and R3 combo. Attenuating the rear horn for K band detection gives me a single RD set-up instead of 2 RD set-up

 

[SixPackABS]

Result is really great. Falsing only when you are in a standstill or at the traffic stop. Just one beep and quite ride kicks in.This really solves the problem.
The only issue that I have noticed that might be a problem are these small squares partially peeling off. If I were to keep these things semi permanent what would be the best glue/ silicon to use?

 

[InsipidMonkey]

Result is really great. Falsing only when you are in a standstill or at the traffic stop. Just one beep and quite ride kicks in.This really solves the problem.
The only issue that I have noticed that might be a problem are these small squares partially peeling off. If I were to keep these things semi permanent what would be the best glue/ silicon to use?

I like @hiddencam's idea in the other thread to open up the case and just apply a square over the rear horn. Much cleaner, and no risk of it falling off.

 

[SixPackABS]

@InsipidMonkey
I am too chicken for that, lol.

 

[InsipidMonkey]

Additionally, I wonder if a layer of the 11 GHz material over both horns could minimize Spectre-detectability, without compromising K/Ka band performance?

 

[fishing66]

I wish Uniden would add the ability to mute K band on the rear horn as is seen on the V1.....

 

[UnidenSupport]

Very interesting, but have you tried aluminum foil?

 

[Kennyc56]

Very interesting, but have you tried aluminum foil?

Really? Tin foil again?!!! Is there any damn thing that tin foil can't fix?

Post automatically merged: Jun 6, 2019

I would be interested to see if it affected the Ka band sensitivity at all

I was wondering the same thing. looks like some testing is in order!

 

[SixPackABS]

Very interesting, but have you tried aluminum foil?

The Mast affects the K band more.
"You'd get 20db attenuation, tuned only to K-band radar and not Ka band. The R7 is about -124dB in Hwy mode (a few dBs more sensitive than the R3 in the below chart), so that would bring it to -104dB in Hwy mode, and % reductions in Advanced mode much closer to what you're looking for. "

The tinfoil will affect the K band and the Ka band as well. Which is not what I want. If Uniden will be able to allow the firmware to shut down the rear K band ,,,,,,, it would be heaven.

 

[Blizzard]

if you are willing to disable the bsm system all together check this post out. not sure what the odds are of really screwing something up are though.

Help me pick a new SUV to replace my Miata

@Vortex If you really want to go out on a limb, and can wait another year: Chinese auto manufacturer Zotye coming to America | Car News | Auto123 Don't do it man. I've ridden in Chinese vehicles. I've used Chinese "Machine Tools". China is good for cheap doohickeys and some electronics but...

www.rdforum.org

 

[uhoh]

I'm having the same exact issue in my '19 RDX (Acura changed the BSM freq, so K Block does not work).

I may try @hiddencam's solution and see how it works for me.

What do we think the odds are of Uniden adding an update for K band segmentation or independent horn sensitivity attenuation?

Edit: Does anyone know if there is a tamper evident sticker inside the R7? I'd like to try the cleaner install option, but not at the risk of voiding the warranty.