## 1 Introduction
Over 1990s, Dr. [PERSON] proposed the concept of software radio [12], which has a reconfigurable software and hardware architecture. The device's communication frequency, transmission power, modulation method, coding system, etc. can be adjusted through software configuration, effectively improved the openness and flexibility of the communication system. With the development and maturity of software radio technology, software radio-based architecture is also used by more scholars in the field of SOP positioning [13; 14; 15; 16; 17]. \begin{table}
\begin{tabular}{c c c} \hline
**Signal** & **Frequency** & **Bandwidth** \\ \hline WiFi & 2.4 GHz/5 GHz & 20 MHz/40 MHz/80 MHz \\ Bluetooth & 2.4 GHz & 1 MHz \\ ZigBee & 2.4 GHz & 2 MHz \\ DVB-T & 40–200 MHz & 8 MHz \\ GMS & 900, 1800 MHz & 200 kHz \\ Iridium & 1620 MHz & 41.67 kHz \\ \hline \end{tabular}
\end{table} 
Table 1: List of common SOP. At present, the usual SOP positioning system architecture is shown in the Figure 2. In order to complete signal perception and access, dedicated receivers need to equipped for each type of signal [18; 19]. The equipped receiver will increase along with the types of signals, which leads to a series of problems: (1) since the lack of available signal information, all receivers need continue working to ensure the perception of all types signals, even if only no signal exist, which causes high power consumption, and hardware and energy resources waste; (2) different signals in the same frequency band (such as WiFi, ZigBee, Bluetooth, etc. in the ISM band) still need multiple devices to complete the signal perception, which does not make full utilization of hardware resources. With this as the backdrop, this paper designs a new signal perception unit of the SOP positioning system to achieve efficient SOP perception. The relationship between the perception unit and the SOP positioning system is shown in Figure 3. The task of SOP perception is completely performed by the perception unit. When the perception unit recognizes the existence of signal, it notifies the perception controller to flexibly configure the USRP equipment for target SOP and activity the corresponding receiver to start signal access. Otherwise, the receivers are in a standby state to decrease useless energy consumption. The flexibly configuration of USRP means each one can be used for all types of SOP, so we can develop a SOP positioning system with less USRP than  
Figure 1: Schematic flow charts of three common detection methods. (**a**) Schematic flow chart of coherent detection; (**b**) schematic flow chart of energy detection; (**c**) schematic flow chart of cyclostationary feature detection. Figure 2: Structure diagram of traditional SOP positioning system. fixed configuration system in Figure 2. It improves the system integration and resource utilization efficiency. The remaining part is to completes signal capture, tracking and demodulation and produce pseudorange, carrier phase observables, time synchronization and signal strength, etc. The positioning engine calculates the positioning result according to the signal information obtained. The advantages of the new SOP perception architecture are as follows: (1) it can monitor hundreds of MHz bandwidth at the same time, which is related to the bandwidth of the USRP device (in this article, B210 can monitor 50 M bandwidth). Combined with time-sharing frequency hopping technique, signal perception can be implemented in a wider frequency band, but it will reduce the real-time performance of perception; (2) it can identify multiple types of signals in the same frequency band at one time. A typical example of this situation is the ISM frequency band; (3) there is no need for multiple receivers, which can save hardware resources and reduce energy consumption. The new SOP perception architecture can be extended to other SOP and realize almost all frequency domain SOP perception.