Re: [Openbts-discuss] USRP/OpenBTS Extending Range/Coverage Help

[Gullik W. <gul...@co...>]

I concur,

Range is at least 200 m, limited by TX power. I have made a few folded 
dipoles for the TX side, this compresses the radiation
diagram vertically, to give less range up or down and more gain in the 
horizontal plane.

Combined with a single RX dipole, and careful adjustment of RXGain, in 
excess of 200 m is easily done.

Gullik

On 07/23/2013 12:28 PM, Ralph A. Schmid, dk5ras wrote:
>
> Believe me, this crosstalk problem is nothing but a rumor from someone 
> who did not understand the difference between crosstalk when using one 
> frequency vs. using two frequencies. In fact I cover 200 m with a 
> standard WBX and two directly attached small antennae without any 
> problems when using GSM1800 with its large uplink/downlink spacing. At 
> a demonstration a few weeks ago it was no problem to cover three 
> floors of a conference center with only a few mW of output power.
>
> The OP must have some error in his setup, maybe mixing up 
> downlink/uplink or input/output. Or some bad cable, bent connector 
> pin, whatever.
>
>
> Ralph.
>
> *From:*Kurtis Heimerl [mailto:khe...@cs...]
> *Sent:* Monday, July 22, 2013 6:52 PM
> *To:* Derek Wells
> *Cc:* ope...@li...
> *Subject:* Re: [Openbts-discuss] USRP/OpenBTS Extending Range/Coverage 
> Help
>
> 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... 
> <mailto: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... <mailto: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... 
> <mailto: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-?: 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
>
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