Matrix user forums

Hi,

I was wondering if anybody had come across these modules before:

http://www.ebay.co.uk/itm/300595165811? ... 1439.l2649

I would like to use one for a car alarm as my car doesn't have one and it got broken into last week .

Thanks
Acestu

Hi
How you want to use this sensor? DO you have any plan? Like are you going to measure the distance of the coming object to your car? or you are planning anything else?

To start with, you should go through Martin's nice thread specifically for this sensor..
http://www.matrixmultimedia.com/mmforum ... 4&start=25
You can find my posted code in 2nd page where temperature effect and timing effects are considered to make the result more accurate. After getting full idea from you, I can share my program which I used to measure fuel level in Diesel Generator Fuel tank using this sensor. In that program, I need to modify couple of things..

Hi Enamul,

I know that the better car alarms use ultrasonic transducers to measure any changes inside the car, I believe that they work similarly to an echo sounder.

If I could just make a simple micro controller circuit to control the module then I could build on this to make a simple car alarm.


Thanks
Acestu

Hi Enamul,

I have just had a look at Johns post, I think if it was used in an alarm when the car is locked and the alarm is on then the UT measurement is always going to be the same but if an intruder breaks a window or enters the car then the measurement changes and the alarm goes off. So i suppose the UT measurement would have to be monitored once the alarm was set and an output switched if there were any noticeable differences in the measurement.

Does this make sense ?

Thanks
Acestu

Actually ultra sound sensor is not appropriate for this purpose rather PIR sensor is more useful for the application you looking for. PIR sensor when enabled radiate IR beam if any object come inside the beam it triggers alarm. If you interested I can give you link for pir sensors which is cheap. If you buy 2/3 you can easily cover whole car from intruder.

Hi Enamul,

I wanted to steer clear of PIR because sunlight can cause false alarms, I fit domestic and commercial alarms and we do not use a single PIR sensor because of false alarms, in order to combat this we use either a "Quad" which has 4 PIR elements in it, or a "Dualtech Sensor" which is a combination of microwave and PIR. What are your thoughts on this Enamul ?


Thanks
Acestu

Hi Stuart,
What about setting both transmitter and receiver at a slight outwards angle. Then US sound waves will bounce around the car at a few angles.
Make a note of the distance reading with no one in the car.
Then get in the car and note the distance reading again.
You will then have a set point to work to.
When I started this thread:
http://www.matrixmultimedia.com/mmforum ... 26&t=10694
I had only just started playing with those sensors, and found them to be very good with consistent results.

There are a few different flowcharts by different forum users based around this sensor, So you should not have any problems with driving sensor.

Martin

Hi Stuart
I am not quite sure without checking inside car whether US sensor can smoothly got some signal back while no one is inside the car as it depends the position and orientation of the sensor. I think we can start doing some R&D and you post some video results I can hopefully guide you to finalize the position of sensor or may be sensors..

Hi Enamul, Martin,

This is a quote from Thatcham the car alarm manufacturers that are Insurance approved in this country,

"A Thatcham approved car alarm will have an ultrasonic or microwave sensor to protect the interior and it is important to choose a microwave sensor if you have a soft top car, all other category1 Thatcham approved car alarms can be used for hard top cars."

So I guess it is either microwave or Ultrasound and I don't think there are any microwave modules available.

I don't know how they calibrate the ultrasonic alarms because I have fitted them to my own cars in the past and the sensors are just placed on the windscreen pillars on each side and the alarm seems to work ok, so wether they sell the alarms for a particular car and work out the readings before hand I don't know.

Thanks
Acestu

Hi All,

I have just seen these:

http://www.ebay.co.uk/itm/Wireless-Dopp ... 4aaa847f6b


What do you think about these ?

Thanks
Acestu

That's great! I think it would be a nice sensor.I have ordered one for me to have some fun
Also asked for detailed datasheet from supplier to make sure we can use that. So please wait till tomorrow.

Hi Enamul,

I have ordered one of the microwave sensors too, I was thinking about the ultrasonic in the car as well, would i be right in thinking that the distance measured would not matter and it would only matter if it changed ?

Thanks
Acestu

Good. I hope I will get some info about the sensor soon.

About US sensor, yes; it measures distance and we can decide if suddenly distance of object changes. But I was actually thinking where to put the sensor and which surface you will use to get the reflected signal back so that if anyone inside the car can be easily detected without false detection. If you have any planning about sensor position you can post video link or any nice schematic which will help me to plan.

Hi Enamul,

I have seen these type of sensors that sit on the dashboard,

http://www.neewer.com/Car-Alarm-Security-308.html


and here is the fitting instructions for the roof mounting type:

http://www.abacuscaralarms.co.uk/images/GT613.pdf

EDIT: This PDF shows the microwave unit fitted:

http://xenocide.info/ITR/resources/7908 ... Manual.pdf

Thanks
Acestu

Hi Enamul,Martin,

If you have a look at the bottom of this page there is info and circuits for the microwave unit:

http://www.ebay.co.uk/itm/Doppler-Radar ... 3366671b71


EDIT: you might find this interesting too:

http://news.jpnelson.com/post/376234680 ... -hb100-and

thanks
Stuart

Great findings....
It will be useful

Hi Enamul,

Here is the PDF for that microwave module that we are buying:

http://www.evselectro.com/image/data/da ... oppler.pdf

Thanks
Acestu

Hi

Thanks for the pdf..but i have got the manual from the supplier which is very useful for us. Here it is..

Hi Enamul,

What do you make of the manual ?

I think it has loosely been translated from Chinese LOL !



thanks
Acestu

What do you make of the manual ?
I think it has loosely been translated from Chinese LOL !

The Chinese supplier send me doc copy and I just made pdf...might be pdf converter made to Chinese

Hi Enamul,

Never mind, as long as you understand it lol


Thanks
Stuart

He is my thoughts on Microwave verses ultrasonic:

Microwaves can travel through glass, so if not set right people out side of the car or a cat jumping on the car in the right place could set the alarm off. its minim range is 3 meters which is nearly 10 Feet.
I'm not saying outright it won't work since I have not tried it, I don't know.

Ultrasonic does not travel though glass, since bounced around inside the car, less chances of false alarms.
Before deciding maybe best weighing up pro's and con's so you know which is time best spent on first.
In the end both types have their different uses, but in different applications.

Martin

Before deciding maybe best weighing up pro's and con's so you know which is time best spent on first.
In the end both types have their different uses, but in different applications.

Yes, you are 100% right and that's the reason why I am interested to buy to find application.

I have just ordered the microwave version, as I'm sure it will be handy for various useful applications.
So I will get to play like you two
Thanks for the link Stuart. £5.19 is a very good price.