This is a read-only archive of an earlier blog posting. Reasons for the
change are at http://blog.sensicomm.com.
The permanent version of this post - with comments (if any) - is at
http://sensicomm.blogspot.com/2009/08/915mhz-signal-with-100mhz-ad.html
915MHz signal with a 100MHz A/D
I've been using a Radiotronix DP-1205
RF transceiver that operates in the 915MHz unlicensed ISM band. The
power level, operating frequency, FM deviation, etc., are set using
the SPI serial interface. So I decided to see if my MHZ100Q A/D PCB
could see the signal. I bypassed the antialiasing filter and
associated buffer, and then coupled the transceiver signal to the
input.
It Works! The signal is low amplitude (less than
10% of full scale), and there are a lot of spurs 20dB down or so,
but the carrier is clearly visible. The 902 to 928 MHz band is
being undersampled at 100 MHZ so it shows up at 2 to 28 MHz in the
digitized signal (in full compliance with Nyquist's rules).
The A/D is only spec'ed to 550 MHz, so I wouldn't trust the
signal and distortion levels, but it's definitely a usable
signal.
More details on the MHZ100Q
project site at Source Forge.Comments on blogspot.com
To make or view comments, see the original post at
http://sensicomm.blogspot.com/2009/08/915mhz-signal-with-100mhz-ad.html