Hi Marcus, -10dBm corresponds to 100µW. With an input impedance of 100Ohms, since Pmax rms= (Vmax rms)^2 / R, --> Vmax rms= 0.1 volt
So, if I am right the maximum theoretical voltage at the input of the ADC, if 0 dB gain is set in the transceiver (XCVR2450 in my case) and noise figure of all components were 0 dB, is 0.1 volt However the gain of the transceiver is set to increase this [0 - 0.1] volt range to [0 - 1] volt range at the input of the ADC. Is it right ? Regarding the value of the ADC SNR (72.4dB), why is it important if it doesn´t depend on the input range? (SNR= 6.02*N + 1.76) There is something I miss......grr ! Many thanks. Jorge. On 24 October 2010 19:57, Marcus D. Leech <mle...@ripnet.com> wrote: > On 10/24/2010 01:07 PM, Jorge Miguel wrote: > > Hello, > > > > I am trying to find out the minimum/maximun input power of the ADC > > LTC2284. > > I know that the maximum input voltage is 1 Volt, 0.707Vrms, but what > > is the input impedance? so that I can calculate the maximum input > > power as: > > > > minimum input power (SNR ADC) = Maximun input power > > ( [(0.707)/(2^14))^2]/Rin) + 72.4 dB = Maximun input power > > > > Am I right? > > > > Many thanks, > > Jorge > > > > > I believe that it's a 100ohm balanced input. > > But the daughtercards all take a 50-ohm input, and convert to a balanced > output just before the > A/D. > > With the exception of the Basic_RX and LFRX, the maximum input power for > any of the other > daughtercards is below -10dBm. > > The BASIC_RX and LFRX have a maximum input power of about +10dBm. > > > > > -- > Principal Investigator > Shirleys Bay Radio Astronomy Consortium > http://www.sbrac.org > > >
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