The amplifier you have is both a receiver amplifier and transmitter amplifier. The receive side (uplink) says its 70dB gain, but hopefully that is with ALC. You could likely overload usrp receiver easily from that.
The OpenBTS.config has GSM.PowerAttenDB which you can try increasing to reduce power output. your specifications do not give the downlink gain. On Wed, May 9, 2012 at 4:35 PM, Cristian Rougier <crist...@lainfo.com.mx>wrote: > ** > > Hello, Wayne, thank you very much for your answer. > > This is the amplifier and duplexer specs: (i paste this in order to dont > attach the doc). > > AMPLIFIER > > Shenzhen Ledmate Technology Co., Ltd. > PCS Signal Booster > Technical Features: > *Receiving and sending separation,low require for Ant isolation,making it > convenient for installation. > *Mini design with metal cavity filter technology inside. > *Full-duplex&dual-port design,and built-in power supply,making it convenient > for > installation. > *Allowing for continuous gain adjustment 31dB by 1dB step. > *ALC technology used to provide auto amplitude fixing. > *Modules structures,making it convenient for installation,debugging and > maintenance. > LM-P1900-25-A > Item > Frequency Range (Mhz): Downlink :1930-1990MHz Uplink:1850-1910MHz > Downlink :≥65dB > Gain (dB) Uplink :≥70dB > Output Power (dBm) ≥25 dBm > ALC ≥28 dB > Outer-band Spurious <-36dBm ≤-36dBm(9KHz—1GHz) > Spurious emission ≤-30dBm(1GHz—12.5GHz) > Isolation >135dB > Tri-rank intermodulation ≤-40dBc(PO=25dBm/CH/2CH) > band flatness PCS1900≤±5 > Relay Phone PCS > Cover area 1000sq.m > (Without concealment) > Install Methods Lay/ Hanging(Indoor) > Power supply AC220V(Expert AC-DC Convertor)(Facility Power Supply:DC+5V) > Size 200mm(W)×142mm(D)×40mm(H) > Weight Approx. 1.2 kg > Fittings DC+5V/3Apower adapter ; Instruction > High-reliability Comply with GB6993-86 standard > > > > > > DUPLEXER > > *1850～**1910MHz/1930～**1990MHz** **duplexer* > > > > Technical specification > > > > *Serial* > > *Parameters* > > *RX* > > *TX* > > 1 > > Frequency Range > > 1850～1910MHz > > 1930～1990MHz > > 2 > > Insertion Loss > > ≤1.0dB > > ≤1.0dB > > 3 > > Ripple > > ≤0.7dB > > ≤0.7dB > > 4 > > VSWR > > ≤1.3 > > ≤1.3 > > 5 > > Rejection > > ≥65dB@1930～1990MHz > > ≥65dB@1850～1910MHz > > 6 > > Input Power > > 50W CW > > 7 > > Operating Temperature > > -40℃～+70℃ > > 8 > > Surface Finish > > Black Paint > > 9 > > Connectors > > N-Female > > 10 > > RoHS > > Yes > > 11 > > Port Sign > > Port1:ANT ; Port2:RX ; Port3:TX > > > > > > If you please see my last email to the list, were i describe my actual > configuration. > > Thank in advance > > Cristian > > > > > > > > > > > > El 2012-05-09 17:57, wayne roberts escribió: > > You should know the gain of your amplifier. > I would suspect that OpenBTS has USRP output power set to high level for > direct antenna connection. This is probably too much for your amplifier. > Try reducing your USRP output power to minimum level, then slowly increase > it while observing your amplifier output signal on another receiver. Be > careful of signal overload of your receiver too. > > On Wed, May 9, 2012 at 11:44 AM, Cristian Rougier > <crist...@lainfo.com.mx>wrote: > >> Hello, i'm working in a private project with USRP 1 and OpenBTS on PCS >> 1900MHZ. >> >> Currently im working with chinesse (Ledmate.net) 25 dbm amplifier and >> duplexer for pcs 1900, >> this works, but i having problems in some areas, i can't register any >> phones. >> >> Can anybody tell me what is the best amplifiers brand for use in this >> project ?, >> i need to full extend the coverage area. >> >> My current configuration is >> >> >> USRP1+clock tamer > PCS 25dbm amplifier > PCS duplexer > antenna (yagi or >> omni 9dbi) >> >> >> I need any other component? i'm planing to change the amplifier, what is >> the best and >> what better power for full extent coverage and work fine? >> >> I wait your news >> >> Thanks in advance >> >> Regards >> >> Cristian >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> Discuss-gnuradio@gnu.org >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > > -- > > *La Info* > Tecnología y Programación > http://www.lainfo.com.mx > crist...@lainfo.com.mx > *Agréganos en > Facebook<http://www.facebook.com/pages/La-Info-Publicidad-Bluetooth-Marketing-Bluetooth-Marketing-Sms/125635017500475> > * > Tel:(++5255) 8589-1554 / 2452-1030 > Movil: 55-1770-9888 > No imprimir si no es necesario. > Protejamos el Medio Ambiente >
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