diff --git a/README.md b/README.md index 5ec0dc0..42884c5 100644 --- a/README.md +++ b/README.md @@ -262,7 +262,7 @@ Please refer to our [paper][paper] for more details. To sniff the uplink traffic, LTESniffer requires USRP X310 with 2 daughterboards. There are two reasons for this. First, sniffing the uplink traffic requires precise time synchronization between uplink and downlink subframes, which can be simply achieved by using two daughterboards with the same clock source from a single motherboard of USRP X310. Second, the "srsran_rf_set_rx_freq" function used by LTESniffer seems to only support the USRP X310 with 2 daughterboards for simultaneous reception of signals at two different frequencies. --> **Q:** Is it mandatory to use GPSDO with the USRP in order to run LTESniffer? \ -**A:** GPSDO is useful for more stable synchronization. However, for downlink sniffing mode, LTESniffer still can synchronize with the LTE signal to decode the packets without GPSDO. For uplink sniffing mode, GPSDO is only required when using 2 USRP B-series, as it is the time and clock reference sources for synchrozation between uplink and downlink channels. Another uplink SDR option, using a single USRP X310, does not require GPSDO. +**A:** GPSDO is useful for more stable synchronization. However, for downlink sniffing mode, LTESniffer still can synchronize with the LTE signal to decode the packets without GPSDO. For uplink sniffing mode, GPSDO is only required when using 2 USRP B-series, as it is the time and clock reference sources for synchronization between uplink and downlink channels. Another uplink SDR option, using a single USRP X310, does not require GPSDO. **Q:** For downlink traffic, can I use a cheaper SDR? \ **A:** Technically, any SDRs supported by srsRAN library such as Blade RF can be used to run LTESniffer in the downlink sniffing mode. However, we only tested the downlink sniffing function of LTESniffer with USRP B210 and X310.