Due to the reserve in income QO-100 I do RX paths ranked before RTL-SDR receiver even TV LTE filter FR13L. He has declared parameters such:
Through loss in the band 5 – 700 MHZ: 0,9 dB
Through loss in the band 700 – 790 MHz: 3,6 dB
Through loss in the band 822 – 2 050 MHz: 60 dB
Separating attenuation band 5 – 40 MHz: 20 dB
Separating attenuation band 40 – 790 MHz: 14 dB
As happened LTE measurement filter using vector analyzer?
The QO-100 is recommended to include a filter in front of the receiver filter GBP, to suppress extremely strong signals, LNB that converts into a higher frequency range than the 739 MHz, wherein the processed signals from the QO-100. These extremely strong signals could shift the operating point of the SDR and thus reduce the sensitivity of the receiving chain.
Measurement LTE filter FR13L Although demonstrated potent inhibition signal 800 to 1300 MHz (-20 to -30 dB), but around 1400 MHz decreases to suppress 0 dB. Followed by a sharp peak around 1800 MHz suppression nearly -50 dB. Higher frequencies are suppressed only -10 dB. Tells more pictures of VNA:
such a filter, such as LTE FR13L can indeed help, but it is not an appropriate solution. If in fact spurious signals fall right in, which filter suppresses insufficiently, get the input SDR receiver.