433MHz

[david miles]

I know there have been a lot of posts re 433MHz Tx/Rx, but I can't find one that answers my question of whether they will work indoors bounce around corners/through 4 1/2 inch brick dividing walls for about 50 feet. Anyone know?

David Miles.

 

[eclectic]

Here at last is a question I can answer authoritatively, from experience.

Sometimes/ possibly / sometimes not.

And that's NOT being facetious.
Just moving the tx/rx a few centimetres can change the whole lot.

You must check for your house, antenna etc. etc.
e.

 

[Dippy]

Quite right.

Depends on the quality of the modules / power / your pcb layout / quality of modulation / your antennae (Tx and Rx) / nearby transmissions / background radio mush.

I've had 433/434 FM (Radiometrix / RF Solutions / LPRS) modules sending simple un-Manchestered 2400baud data through 4 brick walls and much more than 50 feet with home-made helical antennae (on decent ground-planes).

You'll probably find people in NZ have had 'em working 100% through 10 brick walls and 500 metres!

I'm afraid it's time to part with the cash and have a go. All I can say is spend a few extra pennies and get good quality stuff; FM preferably with an RSSI output so you can check it with a READADC.

But first, read the module's Data Sheets as it'll tell you about optimising your setup too.

 

[eclectic]

I'll just add to some of Dippy's comments.

Day of the week and time!

I've got some cheap AM tx/rx modules.
I've had problems between 07.00 - 09.30
on weekdays.
That's when most of the locals open their car doors.

e.

 

[D n T]

Have you considered building a repeater??
Use serial in then depending on the length of thr data, assign variables to each part.
pause for 5 millisecs to be safe
serial out

Just an idea

 

[manuka]

Repeater= GREAT 433 idea, &amp; I covered just this for a Jan. 2006 Silicon Chip article =&gt; <A href='http://www.picaxe.orcon.net.nz/433rpt.jpg ' Target=_Blank>External Web Link</a>. Otherwise highly recommend grabbing a UHF scanner &amp; monitoring the frequency, as co channel 433.92MHz interference increasingly a major issue. Stan

 

[Dippy]

A not-too-cheap repeater seems a little excessive for 50 feet through walls doesn't it?
You've got 3 options:
1. Don't bother.
2. Try a simple Tx/Rx set up.
3. Two tins and a bit of string.

Option 2 seems the best, but no-one can predict the outcome of radio in your specific application. Just make sure you get decent modules and NOT Beijing 20 pence specials.

If there is excessive Co-Ch interference you have to consider option 3 above.

 

[Michael 2727]

Dippy only if you don't own a cat. ~ ;o)

 

[Dippy]

I have 2 cats; Marconi and Eddison.
But they only chase moles so I'm OK.

Edited by - Dippy on 14/08/2006 14:01:02