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Re: [Openbts-discuss] USRP/OpenBTS Extending Range/Coverage Help
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From: Kurtis H. <khe...@cs...> - 2013-07-22 16:52:51
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Oh this is one daughterboard? My understanding is that there's a lot of crosstalk on the board with one daughterboard, that's going to limit your coverage a lot. Also may explain why the duplexer does so little. On Mon, Jul 22, 2013 at 9:49 AM, Derek Wells <der...@gm...> wrote: > 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 >> >> > |
