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<blockquote data-quote="s-band" data-source="post: 976413" data-attributes="member: 407744">Unless I've lost the plot (quite possible), I understood that the Airspy only has the R820T2 as a front end without an extra LNA. The LNA control in the software operates on the R820The main advantage of the Airspy is that it has a better ADC (12 vs 7.5 bits) giving a better instantaneous dynamic range and resolution.Assuming:LNA NF = 1dB, Gain 15dBCable Loss NF = 10dB Gain =-10dBRX (Airspy or RTL) NF = 5dBUsing HP/Agilent Appcad <a href="http://www.hp.woodshot.com" target="_blank">AppCAD</a>LNA1 &gt; Filter &gt; LNA2 &gt; 3dB atten for stability &gt; LNA3 &gt; Cable &gt; RX gives NF of 1.22dB (NF without atten 1.21dB )LNA1 &gt; Filter &gt; LNA2 &gt; Cable &gt; RX gives 1.41dB NFLNA1 &gt; Filter &gt; LNA2 &gt; Cable &gt; LNA 3 &gt; RX gives 1.28dB NFFor satellite you really need to play with the whole budget including the antenna. Try plugging some of the figures into this calculator: <a href="http://www.satsig.net/noise.htm" target="_blank">Noise temperature, Noise Figure and Noise Factor</a>All theory though! I haven't tried an RTL dongle with L band JAERO although the performance on C band (where the NF is determined 99.9% by LNB ) was the same using an Airspy or RTL</blockquote>

[QUOTE="s-band, post: 976413, member: 407744"] Unless I've lost the plot (quite possible), I understood that the Airspy only has the R820T2 as a front end without an extra LNA. The LNA control in the software operates on the R820 The main advantage of the Airspy is that it has a better ADC (12 vs 7.5 bits) giving a better instantaneous dynamic range and resolution. Assuming: LNA NF = 1dB, Gain 15dB Cable Loss NF = 10dB Gain =-10dB RX (Airspy or RTL) NF = 5dB Using HP/Agilent Appcad [URL='http://www.hp.woodshot.com']AppCAD[/URL] LNA1 > Filter > LNA2 > 3dB atten for stability > LNA3 > Cable > RX gives NF of [B]1.22dB[/B] (NF without atten 1.21dB ) LNA1 > Filter > LNA2 > Cable > RX gives [B]1.41dB[/B] NF LNA1 > Filter > LNA2 > Cable > LNA 3 > RX gives [B]1.28dB[/B] NF For satellite you really need to play with the whole budget including the antenna. Try plugging some of the figures into this calculator: [URL='http://www.satsig.net/noise.htm']Noise temperature, Noise Figure and Noise Factor[/URL] All theory though! I haven't tried an RTL dongle with L band JAERO although the performance on C band (where the NF is determined 99.9% by LNB ) was the same using an Airspy or RTL [/QUOTE]

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