Download Receive Sensitivity Characterization of the PolySat Satellite

4.6.4 Forward Gain of LNA ............................................................................................................................... 35
4.6.5 Reverse Gain of LNA ................................................................................................................................. 37
4.6.5 1 dB Compression Point............................................................................................................................ 37
4.6.6 Noise Figure of LNA ................................................................................................................................. 39
4.7 HP8566A SPECTRUM ANALYZER ...................................................................................................................... 41
4.8 FARADAY CAGE................................................................................................................................................. 43
4.8.1 Screen Rooms ............................................................................................................................................ 44
4.8.2 Custom Faraday Cage .............................................................................................................................. 48
4.8.3 Construction .............................................................................................................................................. 49
4.8.4 Features .................................................................................................................................................... 51
4.8.5 Attenuation Performance of Faraday Cage .............................................................................................. 54
4.9 OTHER CONSIDERATIONS .................................................................................................................................. 55
4.9.1 RF Leakage ............................................................................................................................................... 55
4.9.2 Yaesu Radio RF Output Power ................................................................................................................. 56
4.10 SENSITIVITY MEASUREMENT SETUP CHARACTERIZATION .............................................................................. 56
4.11 TEST SETUP – MEASURING SENSITIVITY OF THE POLYSAT COMM SYSTEM ................................................... 59
CHAPTER 5.
SENSITIVITY TESTING ............................................................................................................ 64
5.1 POLYSAT SATELLITE COMM SYSTEM .............................................................................................................. 64
5.1.1 Overview of COMM Setup ........................................................................................................................ 64
5.1.2 CC1000 UHF Transceiver ........................................................................................................................ 65
5.1.3 Receive Sensitivity versus Frequency Separation and Data Rate ............................................................. 66
5.1.4 RSSI Output ............................................................................................................................................... 68
5.4.3 CDH Revision 4 ........................................................................................................................................ 69
5.4.4 CDH Revision 5 ........................................................................................................................................ 69
5.2 COMM SENSITIVITY TESTING ....................................................................................................................... 70
5.2.1 Overview of Testing................................................................................................................................... 70
5.2.2 CDH Testing – Measuring the Receive Sensitivity .................................................................................... 71
5.2.3 CDH Rev 4 – Measured Sensitivity Testing .............................................................................................. 71
5.2.4 CDH Rev 5 – Measured Sensitivity Testing .............................................................................................. 72
5.2.5 CP5 CDH Flight Candidate ...................................................................................................................... 74
5.2.7 Yaesu FT-847 Transceiver ........................................................................................................................ 75
CHAPTER 6.
ADDITIONAL TESTING ............................................................................................................ 78
6.1 RECEIVER NOISE FLOOR COMPARISON .............................................................................................................. 78
6.1.1 Receive Line of CC1000 – Noise Floor at RX/TX Frequency ................................................................... 82
6.1.2 Receive Line of CC1000 – Broadband Noise Floor .................................................................................. 85
6.1.3 Receive Line of CC1000 – Noise Floor over 70 CM Amateur Band ......................................................... 88
6.1.4 Receive Line of CC1000 – Noise Floor Characteristics ........................................................................... 89
6.2 TESTING FOR REDUCED COMM SENSITIVITY FROM SWITCHING NOISE ............................................................ 90
6.2.1 Switching Noise from DC-DC Converters ................................................................................................ 90
6.2.2 Switching Noise from I2C Bus ................................................................................................................... 92
6.3 ADDITIONAL ISSUES RELATING TO INCONSISTENT UPLINK ............................................................................... 93
6.3.1 Observations from CP3 and CP4 .............................................................................................................. 93
6.3.2 Observations from Sensitivity Testing ....................................................................................................... 93
6.3.3 Long Duration Communication Test ......................................................................................................... 95
CHAPTER 7.
RESULTS OF SENSITIVITY TESTING................................................................................... 98
7.1 COMPARISON OF COMM SENSITIVITY .............................................................................................................. 98
7.1.1 Overall COMM Performance.................................................................................................................... 98
7.1.2 CC1000 Performance................................................................................................................................ 98
7.1.3 PolySat COMM Performance Compared to Future Replacement Transceiver ........................................ 99
7.2 RECOMMENDATIONS FOR IMPROVING UPLINK AND FUTURE POLYSAT COMM ............................................ 99
7.2.1 Improved Layout of CDH Rev 5 .............................................................................................................. 100
7.2.2 COMM Software Testing......................................................................................................................... 100
7.2.2 Temperature Controlled Crystal Oscillator ............................................................................................ 100
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