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Author Topic: 433MHz or 315MHz rf?  (Read 18442 times)

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Offline aruna1Topic starter

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433MHz or 315MHz rf?
« on: October 31, 2010, 07:33:44 AM »
hi
following are two rf transmitteres.they are same price but one is 433MHz and other is 315MHz.

http://www.sparkfun.com/commerce/product_info.php?products_id=8946
http://www.sparkfun.com/commerce/product_info.php?products_id=8945

what are the difference between this two except frequency?
and which module should I buy?
thanks
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Offline waltr

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Re: 433MHz or 315MHz rf?
« Reply #1 on: October 31, 2010, 09:05:15 AM »
There is not much difference in performance between the two RF modules. Pick the one that uses a frequency that is legal in your country.

Offline aruna1Topic starter

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Re: 433MHz or 315MHz rf?
« Reply #2 on: October 31, 2010, 12:22:31 PM »
oh i see thank you very much for the info
anyway is there any advantage of one frequency over other if we dont have any legal problem about frequency?
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Offline TrickyNekro

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Re: 433MHz or 315MHz rf?
« Reply #3 on: November 03, 2010, 04:00:59 AM »
They do have a different wave length and that says a lot...

The 433MHz one should behave better on narrow environments, so if your application stays inside then it's better to have that module... On the other hand 315MHz have a longer wavelength and you will get a little bit more range outdoors in an open environment...

Keep in mind that this modules may not have encryption which is vital...
Manchester encryption is an option and quit easy to utilize...

Also the antenna should be different in case you make it and don't buy a pre-made...
λ/4 straight antenna is a good one.... where λ is the wavelength...
λ/2 straight antenna is an option too... but it gets rather long...

To calculate the antenna length the formula is

c = λ*f

Where: c is the speed of light in vacuum space and proximately in the air medium
λ is the wavelength
f is the frequency of the wave hence the frequency of your transmitter

That's it for now... If you want something else... FIRST Google it, then ask ;-)
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Offline chelmi

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Re: 433MHz or 315MHz rf?
« Reply #4 on: November 03, 2010, 09:08:38 AM »
Keep in mind that this modules may not have encryption which is vital...
Manchester encryption is an option and quit easy to utilize...

Encoding, not encryption.

Offline aruna1Topic starter

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Re: 433MHz or 315MHz rf?
« Reply #5 on: November 03, 2010, 10:17:00 AM »
@ TrickyNekro & chelmi

thank you, :)
I have already ordered a 315MHz one
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Offline TrickyNekro

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Re: 433MHz or 315MHz rf?
« Reply #6 on: November 04, 2010, 03:17:01 AM »
Keep in mind that this modules may not have encryption which is vital...
Manchester encryption is an option and quit easy to utilize...

Encoding, not encryption.

Details.... :P
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Offline waltr

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Re: 433MHz or 315MHz rf?
« Reply #7 on: November 04, 2010, 07:04:58 AM »
Google "Manchester Encoding".

Offline blackbeard

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Re: 433MHz or 315MHz rf?
« Reply #8 on: November 04, 2010, 12:30:49 PM »
they are not too different. the real advantage is being able to send 2 way data by having a transmitter at 1 frequency and a receiver on the other.
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