Rudy

Came across this article -- have no idea if it has any merit. Can any radio geeks out there add anything?

EMI WORRIES: NEW TIRE PRESSURE MEASURING SYSTEM IS EMI PRONE

As if BPL was not enough for hams to worry about, now comes word of a new vehicle tire pressure monitoring system on luxury cars in Europe and the United States that is far from interference proof. The system operates in the 70 centimeter ham band using a frequency of on 433.92 MHz to communicate between the tires and a monitor receiver mounted in the dashboard.

Recent tests conducted by the Korean Amateur Radio League, found that this system is at the mercy of radio frequency interference ingress. K-A-R-L noted that the system is seriously affected by any amateur station transmitting on or near the frequency at close range. The transmitter does not even have to be mounted in the vehicle for the interference to occurr.

Oh yes. 433.92 MHz is that this same frequency is also under consideration worldwide for remote keyless vehicle entry systems. It is already being used for radio frequency identification tages on some shipping containers now traveling across the globe. (Amateur Radio Victoria via WANSARC News )

radioham

433MHZ is a licensed amauer ham band on a shared basis in some countries being v/uhf it is short range communication on a usual basis but when conditions prevail can be used on long distance communications including satelite down links etc.to use this frequency at the moment ,ie changes to frequency allocations around the world(this band is underused on the ham network worlwide and maybe lost to radio ham allocation in the near future)is stupid .
interference is not the case.legittimate transmissions on frequency not harmonics or out of band carrier is not the case.
a reciever ,that is accepting a transmission on frquency is legitamate if used on a licensed band,albeit in whatever form ie.fm cw data usb whatever.
interference to equipment by rfi is normally strong signal or inadaquate screening on the recieving equipment.
causing blocking and overload in most cases.but to use a specific in use worlwide allocation is irresponsible.or at least very premature.
i will look into this further as it seems illogical to me when there are frequencys allocated for automotive and other uses.
thanks for sharing this,it has not been covered in the rsgb uk jourals as yet or i have missed it.
there is a general dumming dowm of rules and conditions happening in the world at present regarding licensing of radio hams.....geeks! idont think so enthusiasts for radio and mostly communications in general,just like us at e60.net using the internet!to further our interests in all things cars etc.enjoy what you drive enjoy all in this life,it aint long enough
question
anybody seeing the iss go over this week? about 18.30 gmt in uk?

Rudy

radioham, how in the world did I forget about you being here?

Anyway, my only problem now is that I have absolutely no idea what the hell you just wrote!!

If you can find a way to translate all of that into regular old English, that'd be great...if not, we'll just have to wait and see how TPM systems are affected by ham radio signals for ourselves...

EDIT: Click here to go to the Technical Gallery and see an overview of the tire pressure monitoring systems I found in the TIS. It doesn't talk about the specific radio frequencies of the new sensors but it does talk about them in some detail.

zen

The PDF's don't work for me???

Rudy

Anyone else having a problem?

zen, do you have the Acrobat add-in installed in your browser? Do any of the other .pdf files in the Technical Gallery work for you?

dlevi67

.pdf working fine for me - both in Acrobat Reader and using the add-in to IE.

bruce_miranda

Simply wonder why they didn't use the Bluetooth protocol for this. It's designed for extremely short distances and can transfer a lot more information to the car if required.

Rudy

Maybe because BT needs more power to transmit at that frequency? The wheel sensors need to have a power source that won't need to be recharged very often...

radioham

well rudy there you go.
basically simple
why pick a known frequency (433mhz)that is occupied albeit on a secondary usage .that is some users ie military etc have the prime use and hams have to not use transmitters near these frequencys.
also the high risk of overload by ham radio amongst others on this band,using high levels of rf power legal limits can run into kilowatts of rf to the antenna with stacked antenna the gain gan be 10 time from them mostly the antennas are beam (yagi) type so very directional.therefore screening and pass filters would be hard to achieve in the motor industry econimics,leaving us all with problems.
will look for more info from the amateur radio world on this subjact ,hope that helps

BMWSTL

First I've heard of it (I'm an amateur radio operator also). I could find nothing on eHam.net, Radioham, perhaps you'll uncover something.

In the States, any interference that may be caused is the responsibility of the manufacturer of the device. If the amateur station is operating within proscribed technical limits for harmonic supression, grounding, etc., it's up to the consumer to go to the manufacturer for help. It's the responsibility of the manufacturer to work with consumers if they ahve interference issues. That being said, the manufacturers rarely do anything about the issue, and it's often left up to the amateur to try and deal with the situation. Although manufacturers could design their devices to be free from "interference," the cost of manufacture element often gets in the way of sound design.

The flip side is interference an amateur may receive from these devices. Sensitive receiver equipment at 432MHz. could have quite a few issues with these RF producing devices driving around.

Lou