Low power RF solution 1

[berty1971]

I'm fairy new to eng-tips so not sure if this is the best forum.
But can anyone recomend the best tecnology to go for a short range short burst RF data link, we were looking at an RF PIC system 433MHz but this would seem to be unsupported, A customer has suggested zigbee but we wonder if this is overkill.

Bert.

 

[Comcokid]

For simple wireless design applications, there are several things that affect how you approach the project.
1) What is the volume? Unless you are making more than around 10K units, it's probably best to buy someone’s pre-made module. This is because of the time to design and agency approval issues.
2) What is the range needed? Through what kind of obstacles? How big a space do you have for your antenna? These issues affect “link margin” which determine how much power you must transmit and sensitive your receiver will need to be.
3) How reliable does the link have to be? Does it matter if a few transmissions are missed? In other words, if your wireless link closes the loop in a process system, the link must be robust, reliable under all conditions, probably will require receipt acknowledgements, and contain error correction. If the data is for a less critical use, then a missed data packet will probably not be important and latency may not be an issue. This issue will also influence the best type of modulation to use and the networking
4) Does the application require battery power? Battery operated data links cannot be ON all the time. This then requires synchronizing the ends of data link and what kind of networking layer you may need to consider.
5) How much data are you communicating in each burst? A few bytes? A few Kbytes? Zigbee/802.15.4 are good for a few tens of bytes. If you are trying to do digital audio or video, then you’re looking at something more like wireless LAN or Bluetooth.

Within Engineering tips, there is also an Antenna and Propagation Engineering Forum and a Microwave and Electromagnetic Engineering Forum.

 

[itsmoked]

Comcokid; really nice synopsis there, excellent actually.


berty1971; Several times I have been able to solve short range RF problems, circumventing the whole miserable bureaucracy of regulations by using IR com links. So you should consider if this would be viable too.

 

[killabyte]

by far eng-tips is the best forum one ever find. kind people.

few kbps?
ask, ook modulation up to 300 m open ground

try this:

laipac.com
abacomtech.com

just plug and play.

id like to know what are you doing to help you

best

killa

 

[nbucska]

stable or mobile stations ? If they stay in place, with
collimator lenses 300m shouldn't be difficult with LED
-- i.e. without laser . I suggest a carrier of a few
tenthousand Hz-s.

With IR you need error correction/detection.
What about weather if outdoors ?


<nbucska@pc33peripherals.com> omit 33 Use subj: ENG-TIPS
Plesae read FAQ240-1032

 

[itsmoked]

It could even be non-fixed but remains in the same room. Wall reflections work well. As for the carrier frequency the ONLY way to go is use the standard frequency!! It's like 25kHz or so (I forget) but all the TV controls on the planet run the same freq. All the driver chips and receiver chips are based around that frequency and work very well. Check them out.

 

[killabyte]

nbucksa: how do you drive a led to achieve such distance?

do you use few leds in paralell?

what kind of driver and receiver you know?

regards

killa

 

[nbucska]

itsmoked: The "300 m open ground " specs makes
the wall reflection questionable...

Killa:
You can use e.g. QED234-ND IR LED from <DIGIKEY.COM>
which can take max. 200mA at 50% duty cycle

Radio Shack has a 38 kHz ir receiver, but it is too slow
for your need.

The circuit: TX: LTC6900 silicon oscillator with some
buffer and LED

RX: photo detector , narrow band AC amplifier,
amplitude detector.


<nbucska@pc33peripherals.com> omit 33 Use subj: ENG-TIPS
Plesae read FAQ240-1032

 

[itsmoked]

I guess I'm confused... The OP NEVER mentioned 300m anything... Why are we talkining about 300m?

 

[nbucska]

Right, itsmoked... killabyte supplied a spec which
I assumed to be valid. Just confusion.

berty:
Could you please specify your need?

Killa:

If you are working on a similar project, why don'y you
start a new thread?


<nbucska@pc33peripherals.com> omit 33 Use subj: ENG-TIPS
Plesae read FAQ240-1032

 

[killabyte]

im working on a similar project but ivent needed further help.

just if anyone of you know about electric or electronic low pressura gas propane valve or regulator?

regards