On 03/31/2010 03:59 AM, Li Mei-Wen wrote: > Hi: > > Please tell me, how much the TVRX receiver sensitivity? > > Thanks in advance. > > The "sensitivity" of a receiver depends on a few factors, so it's hard to give a meaningful answer.
The tuner module (MT4937) has a noise figure of about 8-10dB, which will be the dominant contributor to sensitivity. But the "sensitivity" depends heavily on what type of signal you're trying to detect/demodulate, etc. In FM radio, for example, "sensitivity" is often quoted in terms of the minimum signal level (usually in microvolts) that is required to produce an audio output signal that is of acceptable quality, or that has a certain minimum SNR (Signal-to-Noise Ratio). Some types of signals are more "noise robust" than others. Standard AM signals, for example, are notoriously non-robust, so they require less-noisy signals (more power received at the input of the receiver) to produce equivalently-acceptable audio output. Narrowband digital modulation schemes with built-in forward-error-correction are much more noise tolerant, and so can operate acceptably well with smaller signals available at the antenna input. You should be able to use the quoted noise figure of the MT4937 (used on the TVRX) of 8-10dB to work out the sensitivity levels for your application. If an 8-10dB noise figure produces unacceptable results in your application, then placing a low-noise-amplifier (less than 2dB noise figure) ahead of the TVRX will vastly improve your results. -- Marcus Leech Principal Investigator Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org
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