Urgent problem infotainment system - Mazda CX3 Forum
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post #1 of 12 Old 05-13-2017, 07:53 PM Thread Starter
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Urgent problem infotainment system

Hi
I have a problem with the infotainment system of my 2016 CX-3.

There is a radio frequency carrier at about 145.600Mhz (exact freq appears to be 145.598.200Mhz) that appears to come from the amplifier/entertainment system.

With the 15A fuse (audio 2) removed from the cars fuse box the problem goes, (In this mode the infotainment system powers up but there is no audio).

Using a portable radio I can walk around the car with severe pickup. I can still pick the frequency from about 3 to 4 meters away. I have also tried another CX-3 with the same results

The main problem is that the Radio Amateur frequency band for 2mts covers 144.000 Mhz to 146.000 Mhz, the radio repeater that covers most of Somerset transmits on 145.600 Mhz. The interfering frequency from the mazda is right on top of this and completely wipes out all reception from the transmitter (using in car amateur radio equipment). Adjacent channels either side of this frequency are completely clear of the interference.

I am not sure if cars are subject to EMC regulations or not? How ever the main problem remains, that I cannot receive the relay transmitter on 145.600Mhz because of the cars interference. I have discussed this with our Mazda dealer but they dont seem to be aware of any problems (I am due to take the car up in a weeks time to demonstrate the problem).

I would appreciate any information or if any one has any suggestions.

Regards

Zeta

Last edited by Zeta; 05-14-2017 at 02:04 PM.
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post #2 of 12 Old 05-15-2017, 03:22 PM
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I'm surprised the government allows commercial and amateur broadcasts on the same frequency band. I don't know what the UK equivalent is to the FCC in the USA, but maybe worth reporting the problem to them.

Edit: Reading your post again, are you saying the interfering RF you're picking up is not commercial traffic, but something being radiated by the car? I would have guessed that CE testing would have found that problem as radiated and conducted emissions are usually tested, but I suppose the question then becomes, "What is included in the pass/fail criteria for their required tests?"

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post #3 of 12 Old 05-15-2017, 06:54 PM Thread Starter
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Thanks for your reply.
The RF is being radiated by the car and is interfering with the reception of the radio station on 145.600Mhz. So using a radio receiver in the car or a portable radio in or around the car, the RF interfering frequency from the car is enough to block the received station.

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Zeta
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post #4 of 12 Old 05-16-2017, 02:08 AM
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Does it need to be using any particular feature of the infotainment system?

I don't have a CX-3 yet, but the local dealer is getting used to me coming by to measure things on them. I could bring my HT and see if the US model does the same thing as what you have observed.

alan
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post #5 of 12 Old 05-16-2017, 04:17 AM
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Also, does your car have the advanced keyless entry system? My understanding is that the keyfob is just an RFID tag and the car needs to create that field to detect the keyfob for all of the function it performs. I wonder if that might be what's causing the interference. I can't imagine what other need there'd be for the car to be emitting any sort of RF except for maybe if you have wifi function on the infotainment system in your country, but that's not running at that frequency band...

Still... odd that anything would be running on the precise frequency in use by other consumer radio equipment.

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post #6 of 12 Old 05-16-2017, 06:57 AM
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Look at page 8-32 and 8-24 in the UK manual.
It describes the Electromagnetic Compatibility.

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post #7 of 12 Old 05-16-2017, 07:30 PM Thread Starter
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Hi
Couldnt find any reference to emc in my handbook. Also I don't have 8.32 and 8.34 in the hand book.

The only way (as stated earlier) was to remove the 15a audio2 fuse..this stops the problem, its what ever the 15A audio 2 fuse supply's that generates the rf carrier.

All functions where turned on or off in the infotainment menu but the problem still remains.

As far as I am aware the wireless, rf keyless entry etc do not cause a problem.

KE7RUJ ...be interesting if you get the same results..73

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post #8 of 12 Old 05-16-2017, 08:30 PM
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Originally Posted by Zeta View Post
Hi
Couldnt find any reference to emc in my handbook. Also I don't have 8.32 and 8.34 in the hand book.

The only way (as stated earlier) was to remove the 15a audio2 fuse..this stops the problem, its what ever the 15A audio 2 fuse supply's that generates the rf carrier.

All functions where turned on or off in the infotainment menu but the problem still remains.

As far as I am aware the wireless, rf keyless entry etc do not cause a problem.

KE7RUJ ...be interesting if you get the same results..73
My mistake, it should read 8-20 and 8-21 (at least in the manual i've downloaded from mazda.co.uk).

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Last edited by santa; 05-16-2017 at 08:33 PM.
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post #9 of 12 Old 05-20-2017, 04:30 PM Thread Starter
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Saturday 20th May
Update.
Just been to dealer to demonstrate the problem and he is going to get in touch with Mazda as this is an unusual problem.
I checked another CX-3 and CX-5 and can confirm that these have the same problem.
I suppose it's down to EMC emission now?.
As a backup I will be contacting the RSGB (radio society of Great Britain) who have a EMC committee for advice.

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post #10 of 12 Old 05-21-2017, 03:02 AM
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I'm at a loss for what it could be if you've definitely been able to rule out NFC and RFID. Those devices can operate in that frequency range. WiFi and Bluetooth are both very far away from that frequency. GPS is one-way communication, AFAIK. I suppose there is the iActive-sense cruise system maybe on equipped vehicles. And the lane departure, blind-spot monitoring, or rear cross traffic alert, or parking assist systems. All of those will radiate some emissions, but I have no idea what frequency band those run at.

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