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'[EE] Wireless communication...'
2000\05\28@170308 by Jilles Oldenbeuving

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Hi...


For prototypeing purposes we bought a couple of 4 pins 'complete AM radio
transmitters' from R.F. Solutions. Also bought
a couple of matching receivers ofcourse (433 MHz). (http://www.rfsolutions.com).
My problem with them is this: when supplying Vcc (5V) and GND to the
transmitter and connecting a function generator
at the data in, of 2 kHz, 50 % dutycycle (coupled AC or DC) i can't see
anything at the receiving end. I can't measure
if the transmitter is actually oscilating at 433 MHz becouse the fastest
scopes we have is a Philips 200 Mhz scope...

Also the datasheets and the technical support are far beneath appropiate, in
my opinion.

The units were places 20 cm apart and had just a wire of 15 cm as an
antenna. Anybody couped with the same problem?
Anyone have experience with these modules (i mean the AM-RT4-433 transmitter
and the AM-HRR-433 receiver, of RF Solutions)

Jilles

2000\05\28@174746 by Jim P

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     "  ...Philips 200 Mhz scope...  "

... should still see something as that is usually the
"3 dB point" for the scope's bandwidth ... I once trouble
shot a Tektronix 454 (150 MHz scope) trigger circuit using
just a 10 MHz bandwidth Tek portable - the trigger circuit
incorporated a tunnel diode that excited a 'tank' circuit that
resonated at several hundred MHz ... the indication was only
a small 'blip' when the tunnel diode was working as seen on
the low bandwidth scope.

Take a look at the xmtr with the Philips scope -  433 MHz
is just over an octave higher frequency - and the scope
should show enough to give a yea/nay indication.

Watch out for the the scope probe though - they often have a
much lower cutoff freq than the scope itself. You may have to
rig a short piece of coax and if the scope has a built-in 50 Ohm
termination switch it it to then couple the xmtr output directly
into the scope.

Zero dBm is about .223 V RMS (.6 V Pk-Pk) less any rolloff
in amplitude the scope shows at 433 MHz.

Jim P

{Original Message removed}

2000\05\28@180453 by Jilles Oldenbeuving

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{Quote hidden}

Hmmm, you're right i guess. But the scope is a digital one. Even when i
measure a
voltage that goes from 0V to 5V it takes approx. 3 seconds to adjust the
screen. What
one will see is this:

0V -----------------------------

('bout 1 sec later:)


5V       .                 .
0V -----  -------------  ------------

again, 1 sec later:


5V   --    ---      ---
0V --   ---    ----   ----

and, finaly after about 3 seconds:


5V -----------


I think this has to do with how the A/D converter works within the scope...
If i measure a point were
i *suspect* to be 433 MHz all i see is something like 3/4 Vcc, wich could be
the avarage voltage?
I want to say that i mustn't have to measure these 'ready to go'-modules! I
mean, they have to work, don't they?
The only thing i could find on the website of RF Solutions was a ****3****
page datasheet. And after asking some
application information, they reffered to book! That application information
had to be in the datasheet in my humble opinion...
(frustrated, you guessed it right :)

Did anyone get these modules to work? I'm interested in how they did it.

Jilles

2000\05\29@233441 by Ian Hynes

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If you've got a UHF capable sig-generator around the lab somewhere,
maybe try heterodyning the the Tx's output down into the scope's
range?
Just a thought.

Ian

Jilles Oldenbeuving wrote:
>
>  .... i can't see
> anything at the receiving end. I can't measure
> if the transmitter is actually oscilating at 433 MHz becouse the fastest
> scopes we have is a Philips 200 Mhz scope...
>
>
> Jilles

--

2000\05\30@012206 by Jilles Oldenbeuving

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Hmmm... I might try that today.... still, i think it just had to work... :)


Regards,

Jilles Oldenbeuving
spam_OUTjillesTakeThisOuTspamrendo.dekooi.nl


>If you've got a UHF capable sig-generator around the lab somewhere,
>maybe try heterodyning the the Tx's output down into the scope's
>range?
>Just a thought.
>
>Ian
>

2000\05\30@022130 by Vasile Surducan

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> Jilles Oldenbeuving wrote:
> >
> >  .... i can't see
> > anything at the receiving end. I can't measure
> > if the transmitter is actually oscilating at 433 MHz becouse the fastest
> > scopes we have is a Philips 200 Mhz scope...

 One poor man method is to modulate the transmitter with low
frequency (let say 1KHz ) and to detect a proportional DC signal
near antenna using a Schottky diode and a 1MHz bandwith
oscilloscope...
*********************************************
Surducan Vasile, engineer
mail: .....vasileKILLspamspam@spam@l30.itim-cj.ro
URL: http://www.geocities.com/vsurducan
*********************************************

2000\05\30@024239 by markwillcox56

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<x-flowed>Jilles
  How much power out is your xmtr?


{Quote hidden}

________________________________________________________________________
Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com

</x-flowed>

2000\05\31@011636 by Robert Rolf

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Or use a cable TV convertor to do the same thing. The video detector
should show you the modulation.  North American cable channel 59 is
433.25Mhz. You'll also see a nice herringbone pattern on a TV screen
from a stable carrier. (sortta like 'sound' in video when the fine
tuning is off).

Ian Hynes wrote:
{Quote hidden}

2000\05\31@014226 by David Huisman

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I suggest that a known working TX/RX pair is a simple, low cost way of
determining that the RF is functional.
Especially if the receiver has RSSI facility and you can monitor the signal
on your scope.

Regards
David Huisman
Orbit Communications
http://www.orbitcoms.com
NSW
Australia

2000\05\31@234315 by Ian Hynes

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If you've got a UHF capable sig-generator around the lab somewhere,
maybe try heterodyning the the Tx's output down into the scope's
range?
Just a thought.

Ian

Jilles Oldenbeuving wrote:
>
>  .... i can't see
> anything at the receiving end. I can't measure
> if the transmitter is actually oscilating at 433 MHz becouse the fastest
> scopes we have is a Philips 200 Mhz scope...
>
>
> Jilles

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