Hey guys,

for a long time I was looking for a system-on-chip solution of a low power rf receiver, capable of receiving data rates of about 100 - 200 kbps.
Sadly I found out, that all these "finished" solutions consume way to much current. Therefore I decided to develope a kind of similar receiver on my own.

And that's the point where I need your help: my idea is to transmit audio wireless over about 1-3 meters range.
The challenge at this is to have a as low as possible consumption of current on the transmitting and especially the receiving end.
My first idea was to digitalize the audio signal by a comparator (with a triangle wave input), transmiting it via OOK/ASK and then receive it with a "improved" envelope detector (ANT => Full-Wave-Rectifier => Infinite Impedance Detector => Demodulation via Comparator/Schmitt-Trigger + Low Pass). My second choice would be a "classic" and analog transmission via AM. At the receiving end
Operating frequency should be in one of the ISM bands (315/433 .. 915 MHz).

Attached to this post you'll find two pictures - one of a circuit I with OOK modulation scheme and one with classic inf. impedance AM receiver (just an example, resistor values will later be calculated/tested!).
My main questions to all of you are:

• Is it realistic to detect a usable signal with this envisaged "solution" or have you any other suggestions to achieve the lowest power/current consumption possible?
• Can you give me tips at designing the circuit? (Full-Wave-Rect.-Stage/Preamps ..)
• Would you include a SAW bandpass filter after the first unity gain infinite impedance input FET to improve interference rejection (=> higher Q for the tank circuit)?
• Do you have any application examples or other (and better) ideas?

I would be delighted about any suggestions!

Best regards,
Fabian

Fabian,

I likewise am interested in a 910 MHz RF NB FM Analog receiver, but looking for at least 1000 + Feet range in the forest foliage. You indicated your scoured all the finished solutions, power consumption is not my problem, a stand alone "finished solution" is??? What can you share that would fit my project needs from you fast experience of searching?

Thanking you in advance,

 

1000 Feet is a quite big range requirement .. I can only help you with solutions in the range of 1 - 250 meters.
If you still want my help, let me know.