Engin Karabulut wrote:
hi all,
I have usrp and tvrx daughterboard,but tvrx sensitivity
is very bad, minimum input signal level is 40 dBuV(equal to-68dBm).
and noise figure is 8-10 dB. even if you have hi gain antenna, weak
signals die in TVRX. then I decided to purchase LNA next to antenna.
LNA that I chose is minicircuit's ZX60-33LN+.
The noise figure is 8-10 dB. However, it is meaningless to say that the
minimum input signal level is -68dBm. Sensitivity numbers only have
meaning if you also specify a modulation system, bandwidth, and error
rate. -68dBm would be very bad for AM radio, but would be perfectly
reasonable for 802.11n.
There's no reason you couldn't receive a signal at -200dBm on any
receiver, as long as the bandwidth was low enough, and you filtered
narrowly enough.
Also, are you sure you are controlling the gain properly?
http://www.minicircuits.com/pdfs/ZX60-33LN+.pdf
If I use this LNA,can I receive weak signals(like -100dBm)?
That LNA has a noise figure around 1 dB. If everything else remained
the same, you could receive a signal which was about 6 or 7dB weaker
than without the LNA.
Matt
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