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... not Russel! Registered Member #1
Joined: Thu Jan 26 2006, 12:18AM
Location: Tempe, Arizona
Posts: 1052
I'm resurrecting this thread because it is now a featured project. Excellent work, WaveRider! I had nearly forgotten about the awesome work you've done here.
Registered Member #1232
Joined: Wed Jan 16 2008, 10:53PM
Location: Doon tha Toon!
Posts: 881
This is an interesting project and a very good clear write-up of it on here too.
How do you plan to deal with the 180 degree phase ambiguity thing inherent with BPSK? Will you convert it to differential phase shift keying, or add some kind of preamble to the data packets to clarify the ones and zeros in the demodulated data?
Do you have access to a spectrum analyser? It would be interesting to see examples of the PSK carrier spectrum either at the 433MHz or the IF frequency.
Registered Member #2280
Joined: Sun Aug 09 2009, 01:21PM
Location:
Posts: 1
hello sir im Naman Maheshwari a final year student and willing to undertake dis very project of urs as my final year project so please can u send me d complete project description on my email id **link** i'll be really grateful to u
Registered Member #1497
Joined: Thu May 22 2008, 05:24AM
Location: Toronto, Ontario, Canada
Posts: 801
Out of curiosity, is the reverse of your board a solid ground plane? How did you do impedence controlled routing without grounds on either side of the major signal paths (or does it not matter at your power level?).
Registered Member #29
Joined: Fri Feb 03 2006, 09:00AM
Location: Hasselt, Belgium
Posts: 500
Thanks for the comments!
Aonomus: Yes, the back of the board is a solid ground plane, so all lines can be impedance controlled and radiation from the board is minimised.
Also, the phase ambiguity can be easily handled by using differential BPSK.
Note: the sensitivity of the receiver is not quite what I had hoped because the SA639 has a limiter built in which in low SNR (or high interference) situations, "loses" the desired signal and is swamped with noise. I was lucky to get -80dBm sensitivity in the end. The "right" way to do this would be to lose the limiter stage and use a proper AGC so the PLL carrier recovery would have some component of the weak desired signal to lock on to. I may get around to this in a later project....maybe at 2.4GHz.. ALl-in-all I found it an instructive project.
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Low power 433 MHz BPSK data transmission system
