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Re: [Openbts-discuss] USRP/OpenBTS Extending Range/Coverage Help
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From: Derek W. <der...@gm...> - 2013-07-22 16:49:15
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John, Can you discern whether you are uplink or downlink limited? That is, is your range limitation due to a transmitter problem or a receiver problem? And furthermore, is it the on phone end (unlikely) or the USRP end of the up or downlink? It sound like you are working off of one daughterboard, is that correct? -99 dBm sounds pretty low at 15 meters with a Yagi (like Kurtis said). Consider using the "noise" and "power" commands from the CLI and providing some numbers back to the forum. And because I've done it before with other systems...check each RF connection and cable to make sure you have a male pin mated with a female socket at every connection, and not two female sockets...it happens. Derek On Sat, Jul 20, 2013 at 1:37 AM, Kurtis Heimerl <khe...@cs...>wrote: > There's something wrong with your USRP, you should certainly get more than > 15 meters with a USRP1 and a 12db Yagi. > > > On Sat, Jul 20, 2013 at 1:20 PM, john wake <dag...@ho...>wrote: > >> Hello guys, >> >> We are having trouble extending the range of our USRP1 which is running >> OpenBTS I really hope someone can help our current setup is as follows >> >> RX = Antenna -> Duplexer -> LNA -> USRP >> TX = Same antenna -> Same duplexer -> Power Amplifier -> Fullband >> Transmit Filter -> USRP >> >> When we try running the USRP with just the antenna we get a range of >> around max 10-15 meters the phone showing -99dBM when we add the power amp >> the range increases by a few meters however when we also add the LNA so we >> have both the LNA + power amp connected at the same time >> this is when the range decreases to around 5 meters. >> >> We would be happy if we were able to cover 1/2 mile or anything near this >> range we do have a temporary license to transmit in our frequency however >> this expires in 2 months. >> >> There has been quite a bit spent on equipment so far trying to extend the >> range with no luck it seems the USRP is made only to work at a very short >> range so any help on how to do this would be very much appreciated. >> >> Also would adding a bandpass filter to the RX side make any difference? >> >> The spec of equipment we are using is as follows >> >> 900 Mhz 12 dBi Yagi antenna >> >> Frequency（MHz）824~960MHz >> Length:55cm >> SWR ≤≤1.5 >> Input Impedance-Ω: 50 >> Horizontal Beamwidth -° :54/48/40/36/30 >> Vertical Beamwidth -° :48/40/36/32/30 >> Maximum Power -W :100 >> Bandwidth-MHz :154/154/154/140/120 >> >> Duplexer >> >> 30 W GSM Duplexer TX RX >> Pass Band 925 - 960 MHz 880 - 915 MHz >> Insertion Loss 1.0 dB 1.0 dB >> Passband Ripple 0.2 dB 0.2 dB >> Rejection 50 dB @ 80-850 MHz 50 dB @ 80-800 MHz >> 50 dB @ 1-3 GHz 50dB @ 1-3 GHz >> Return Loss minimum 20 dB >> Impedance 50 Ohms >> Coupling Port -30 dB (+/- 1.5 dB) >> Power 30 W average RF poewr >> >> >> LNA >> >> Parameter Unit Minimum Typical Maximum >> Frequency Range MHz 850 950 >> Small Signal Gain dB 40 41 >> Output Power Pout @ Pin = 0dBm dBm +40 >> Saturated Power Psat @ Pin = +5dBm dBm +42 >> IP3 dBm +50 >> Reverse Isolation dB -75 >> Efficiency at Pout = +40dBm % 38 >> VSWR Input 1.4:1 >> DC Power Supply V +12 >> >> Power Amp >> >> 775-950 Mhz >> 40 dB gain >> +18 dBm >> >> Filter >> >> Passband: 925-960 MHz >> Passband Insertion Loss: 1.5 dB maximum >> Rejection: >> DC-915 MHz 80 dB minimum >> 1000-2880 MHz 60 dB minimum >> Passband Return Loss: 15 dB minimum >> Maximum Power Handling: >> CW 10 watts >> Peak Instantaneous 40 watts >> Intermodulation Products: -110 dBm maximum >> with two +34 dBm carriers >> >> >> >> >> ------------------------------------------------------------------------------ >> See everything from the browser to the database with AppDynamics >> Get end-to-end visibility with application monitoring from AppDynamics >> Isolate bottlenecks and diagnose root cause in seconds. >> Start your free trial of AppDynamics Pro today! >> >> http://pubads.g.doubleclick.net/gampad/clk?id=48808831&iu=/4140/ostg.clktrk >> _______________________________________________ >> Openbts-discuss mailing list >> Ope...@li... >> https://lists.sourceforge.net/lists/listinfo/openbts-discuss >> >> > > > ------------------------------------------------------------------------------ > See everything from the browser to the database with AppDynamics > Get end-to-end visibility with application monitoring from AppDynamics > Isolate bottlenecks and diagnose root cause in seconds. > Start your free trial of AppDynamics Pro today! > http://pubads.g.doubleclick.net/gampad/clk?id=48808831&iu=/4140/ostg.clktrk > _______________________________________________ > Openbts-discuss mailing list > Ope...@li... > https://lists.sourceforge.net/lists/listinfo/openbts-discuss > > |
