Re: Motorola home control

[nobody@xxxxxxxxxxxx (Dave Houston)]

You have to look for the first non-noise pulse. Some protocols are easier
than others, using a lead-in pulse that also functions to set the AGC in the
receiver. The NEC protocol used by X-10 is one of the easiest as it has a
long lead-in but lots of others also have easily distinguishable lead-ins.

Noise pulses tend to be shorter than most data pulses so even protocols
without a lead-in are fairly easy to handle. And, as you can see from my
screenshots, the AGC quickly separates the wheat from the chaff, giving you
a fairly clear signal.

Also, the specific RF receiver I mentioned has a linear output which can be
used with an ADC input as an RSSI indicator. The RSSI of random noise will
be low in comparison to a signal (as long as the signal is stronger than the
random noise. You can use it as a rough Carrier Detect indicator.

The screenshots are a bit misleading in that the RF receiver has automatic
threshold control which tries to make mountains out of molehills. See...

     http://www.mbx-usa.com/rf-noise.htm

It's actually pretty easy to separate signal and noise as long as the signal
is stronger than the noise.

But, how easy also depends on the specific protocol. I have seen some with
no lead-in and short data pulse/spaces.

What language do you use with the AVRs? You can probably find example code
somewhere as this is a frequent application.

BTW, I'm just across the river from cinci - about halfway to CVG.

"jibberjabber" <none@xxxxxxxxx> wrote:

>Thanks, Dave.
>I've interfaced AVRs to LINX serial radio modules, but never ASK/OOK.  If
>there is constant radio noise, and therefore constant data coming in, how do
>you pick out the real data in the stream?
>jj, cinci
>
>
>"Dave Houston" <nobody@xxxxxxxxxxxx> wrote in message
>news:42b57ce5.82022622@xxxxxxxxxxxxxxxx
>>I have no idea what protocol they use nor whether they use FSK or ASK but
>> most similar devices use ASK/OOK because it's simplest and lowest cost.
>>
>> You can buy a 418MHz ASK receiver from Mouser - PN 509-RCR-418-RP FOR
>> $4.26.
>>
>> The data output will be in the audio range so you can record it as a .WAV
>> file using a soundcard line-in (It's IMPORTANT that you use line-in.) and
>> view it in almost any Wave editor.
>>
>> I have illustrated this at...
>>
>>     http://www.mbx-usa.com/learn.htm
>>
>> The RF section is about half-way down the page.
>>
>> For any final 'server' device, you'll need to interface the RF receiver
>> with
>> something that can decode the data output. Unless you have experience in
>> programming microcontrollers, you'll be better off buying their 'server'.
>>
>> "jibberjabber" <none@xxxxxxxxx> wrote:
>>
>>>Motorola is expanding there home automation products:
>>>http://broadband.motorola.com/consumers/home_monitoring.asp
>>>
>>>The spec sheet says the wireless sensors run at 418 mhz.  Anyone know what
>>>it takes to interface with them (type of radio needed, protocol)?...I'd
>>>really rather not have to buy their "server".
>>>
>>>jj
>>>
>>
>