# Characterization of a COTS-Based RF Receiver for Cubesat Applications +
## 5 Test Results
### Measure of the Sensitivity Range, Output Power and IF  
In this subsection, the results of the board-level functional tests regarding the sensitivity range, the output power and the IF are reported.  
Figure 8 shows the general scheme of the test setup adopted for the functional tests. Figure 9 shows a photograph of the implemented test setup.  
Figure 6: The low-pass filter S\({}_{21}\) parameter: (a) simulation result; (b) result measured with the network analyzer.  
Figure 7: Simulated and tested S\({}_{11}\) parameters of the low-pass filter.  
The test setup is constituted by the device under test (the RF receiver), a power source, a spectrum analyzer, a local oscillator, a bench power supply and a host Personal Computer (PC) with a control program.  
The receiver test required the generation of a test signal delivered at the RF input port and the reading the 390 MHz output signal at the IF port. The test signal was generated, exploiting a commercial Software-Defined Radio (SDR) as a power source [26], which was configured to generate a Continuous Wave (CW) signal at 2050 MHz frequency, which is within the receiver input frequency range. The output signal was acquired at the IF port by means of a spectrum analyzer [27], which has provided information on frequency, power level, and noise floor.  
Regarding the local oscillator, although a COTS Phased-Locked Loop (PLL) was implemented directly on the receiver board, in the first test phase the 1660 MHz LO signal was delivered externally to the mixer LO input using the evaluation board of the same PLL. The signal was brought to the receiver exploiting a debug LO input, which was made through an RF test point. The PLL evaluation board was power-supplied with a unique 5 V voltage and was configured using a dedicated software provided  
Figure 8: General scheme adopted for the board-level functional tests executed for the RF receiver.  
Figure 9: Photograph of the test setup really implemented for the board-level tests executed for the RF receiver.  
by the manufacturer [28] along with the board. An integer-N configuration was set configuring a 0 dBm power level signal, carefully measured on the spectrum analyzer. The PLL configuration was executed with the same host PC, connected to the evaluation board through a USB A-B cable and an interface board.  
The receiver board was power supplied with a 30 V-5 A two-channel bench power supply [29], adjusted to deliver the 5 and 3.3 V voltages. The 5 V voltage was used to supply both the receiver and the PLL evaluation board while the 3.3 V voltage was delivered to the receiver board to power supply some auxiliary functions of the AGC amplifiers. The 5 V and 3.3 V voltages were brought to the receiver by means of dedicated test points directly implemented on the board.  
The test was executed in two steps: in the former, the input power level was finely adjusted to generate CW signals from -115 dBm to -70 dBm with a 2.5 dB step; in the latter, the CW signal was applied at the receiver RF input and measured the IF output with the spectrum analyzer. Tuning of the input power level was obtained by combining the SDR gain control (performed by the control program) with the use of one or two 30 or 60 dB external coaxial attenuators. The correct tuning was carefully checked, connecting the SDR directly on the spectrum analyzer input through a coaxial cable and measuring the power level. For each input power level, the IF output signal was measured.  
Figure 10 shows a graph that reports the output power level (vertical axis) as a function of the input power level (horizontal axis).  
The graph shows that, for input power levels from -115 to -70 dBm, the output power level is within the -1+1 dBm range. Moreover, for each input power level delivered at 2050 MHz, the IF output signal appeared at 390 MHz frequency on the spectrum analyzer.  
These results prove that the system-level requirements regarding the sensitivity range, output power, and the value of the IF have been fulfilled.