One guy asked an advice for his poor minus minus GSM coverage. I gave the councel to buy the https://www.ebay.com/itm/1955217324...rUT92Aw8NkPMcRTDVjJHtMOcqizQ4_b98aWLIR5f2RjlA
And then I started to calculate and probably got a swine in the sack. So, the input data: Max Gain 72 dB (producer given); 5 dB Nyquist Noise Figure (producer given). In the first approximation, signal is diminishing proportionally to distance in square. Thus, if the good phone have weak but still satisfactory signal at -120 dBm (phone maker given) and absolute unsatisfactory at -127...-130 dBm (phone maker given), then 72 dB=60+6+6=100x2x2=4000x or sqrt(4000)=60x. What?! Distance have 60-folded?? Never! Dont believe in no way.
Okay, probably there is poridge between voltage decibels and power decibels. Therefore shall take the screen calulator from www.rfwireless-world.com/calculators/Antenna-Range-Calculator.html. Shall put-in that <antenna amplification factor> 72 dB, the <transmitter power> +33 dB for 800 MHz or (better) +30 dB for 1800 MHz and get... 1.5 million kilometers. Nonsens!!!
Okay, bit validate. Antenna sensitivity 0.5 dB, 30 dBm transmitter and get 420 km by rfwireless. Never!!!. Okay, sometimes GSM transmitters have rather small power like +8 dBm or even +4 dBm only. Am not sure what is the typical power at our towers, but let take the least, 4 dBm, and then distance is ... 21 km. What the f..... Nothing works like it should. What the mistake I am getting into having so absurd output??
Second question - what means practically the 5 dB Noise figure? Should it be added to input dBm or to output dBm? Anyway, my marine radiostation hace 0.15 dB Noise factor thus I guess the 5 dB is rather much. However for transistor indeed 5 dB is rather reasonable figure. So, how I may decide from this Noise figure the distance after what no signal will be received in-spite it exist in the air?
And then I started to calculate and probably got a swine in the sack. So, the input data: Max Gain 72 dB (producer given); 5 dB Nyquist Noise Figure (producer given). In the first approximation, signal is diminishing proportionally to distance in square. Thus, if the good phone have weak but still satisfactory signal at -120 dBm (phone maker given) and absolute unsatisfactory at -127...-130 dBm (phone maker given), then 72 dB=60+6+6=100x2x2=4000x or sqrt(4000)=60x. What?! Distance have 60-folded?? Never! Dont believe in no way.
Okay, probably there is poridge between voltage decibels and power decibels. Therefore shall take the screen calulator from www.rfwireless-world.com/calculators/Antenna-Range-Calculator.html. Shall put-in that <antenna amplification factor> 72 dB, the <transmitter power> +33 dB for 800 MHz or (better) +30 dB for 1800 MHz and get... 1.5 million kilometers. Nonsens!!!
Okay, bit validate. Antenna sensitivity 0.5 dB, 30 dBm transmitter and get 420 km by rfwireless. Never!!!. Okay, sometimes GSM transmitters have rather small power like +8 dBm or even +4 dBm only. Am not sure what is the typical power at our towers, but let take the least, 4 dBm, and then distance is ... 21 km. What the f..... Nothing works like it should. What the mistake I am getting into having so absurd output??
Second question - what means practically the 5 dB Noise figure? Should it be added to input dBm or to output dBm? Anyway, my marine radiostation hace 0.15 dB Noise factor thus I guess the 5 dB is rather much. However for transistor indeed 5 dB is rather reasonable figure. So, how I may decide from this Noise figure the distance after what no signal will be received in-spite it exist in the air?
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