代写ELEC9764、代做 java/c++语言程序

日期：2025-04-19 11:20

ELEC9764 Ground Segment and Satellite Operations

Assignment Term 1, 2025

This assignment is worth 30% of the assessment for ELECF9764.

Satellite visibility and Doppler analysis (13 marks)

Apart from geostationary and geosynchronous orbits with small inclinations, the use of satellites is complicated by the changing visibility of the spacecraft. This means that any ground station is required to determine when satellites will become visible, the azimuth and elevations of the satellite during its visibility period so the ground antenna can be properly oriented, as well as the expected Doppler frequency offsets during the visibility interval so the receiver can be correctly tuned to the satellite carrier frequency.

Two Line Elements (TLEs) are orbital elements that permit the satellite positions and velocities to be propagated from a given time epoch using orbit propagators such as SGP4. The accuracy of the positions and velocities are approximately within 1 km at the epoch and degrade at a rate of about 1 to 2 km per day. TLEs are generated by the US Combined Space Operations Center (CSpOC).

In this assignment, you have been provided with a TLE for the Waratah-Seed-1 6U-cubesat, as well as the location of a ground station at UNSW and a start and end time. Create MATLAB code that uses the MATLAB Satellite Communications Toolbox to calculate various parameters of interest. The commented MATLAB source code forms part of the assignment, as well as the requested plots. The online help for the MATLAB Satellite Communications toolbox will be helpful.

1. Create MATLAB code using the Satellite Communications Toolbox (available in MATLAB version 2023b or later) to determine the ‘satellite visibility intervals’ within 48 hours of the start time of 18 March 2025 00:00:00 UTC. Here a ‘satellite visibility interval’ means a time interval when the satellite is within sight of the ground station and UTC is Universal Coordinated Time.

a) Show the MATLAB code.

b) Produce a table showing the time intervals that the satellite is visible, assuming a minimum elevation angle (also known as the mask angle) of 5 degrees.

c) Select the longest time-interval or longest pass for the remaining parts of the assignment. Note that size of the ‘SampleTime’ parameter for the calculation can affect the result, so don’t select too large a value.

TLE to be used for the assignment

1 60469U 24149B 25076.28646690 .00015184 00000+0 64096-3 0 9992 2 60469 97.4107 154.6858 0003177 68.3922 291.7653 15.23363410 32286

% Ground Station Location at UNSW CORSNET Location % Latitude, Longitude, Altitude

% 33° 55′ 05.5′′ S, 151° 13′ 57.7′′E, 110 m

-4644495, 2549882, -3538981

% This TLE was downloaded from Celestrack.org on 18 March 2025.

% It has an epoch of 076.28646690 days into 2025, so select a date and time of close to this % Start time for the assignment.

18 March 2025, 00:00:00 UTC

WARATAH SEED-

ELEC9764 Assignment, Revision 1

2. For the longest pass, use the MATLAB ‘aer’ function to calculates the azimuth and elevation of the satellite as seen by the ground station as it passes over. Produce plots of azimuth and elevation for the satellite, where azimuth is measured clockwise from north and elevation is measured upwards with 0 degrees at the horizon.

a) Show the MATLAB code

b) Produce plots of the azimuth (degrees) and elevation (degrees) vs time. Sanity check your results.

3. For the longest pass, produce MATLAB code that calculates the range, range-rate and the Doppler frequencies for the satellite using the method given in the lectures. Double check the Doppler calculation with the results returned by the MATLAB ‘dopplershift’ function. Assume that the satellite downlink occurs at frequencies of 2259 MHz and 400.651 MHz, and the uplink occurs at 149.45 MHz.

a) Show both pieces of MATLAB code

b) Produce plots of the range and range-rate, as well as all three Doppler frequency offsets experienced by the 2259MHz, 400.651 MHz and 149.45 MHz carriers over the pass interval from the previous question 2.

4. Suppose the local oscillator inside the S band transceiver has an error of +1 part per million. What will the effect of this be on the carrier frequency generated by the satellite S-band radio? How can the ground station compensate for this effect?

Questions 1, 2, 3 and 4 are worth 4, 4, 4, and 1 mark, respectively.

ELEC9764 Assignment, Revision 1

Link Budget Analysis (12 marks)

The Waratah Seed 1 spacecraft has two radios for communication. The first is a Satlab SRS-4 full- duplex S-band transceiver coupled with an IQ Spacecom S-band patch antenna. The second is an an ISIS TrxVU full-duplex UHF/VHF band radio coupled with an ISIS ANTS deployable antenna. This question uses the results from the previous question.

5. Assume that the UHF transmitter transmits a 10 kHz bandwidth signal with an output power of 27 dBm at 400.651 MHz via a dipole antenna with a gain of 3 dBi.

Produce a plot of the carrier to noise density ratio C/No (dB Hz) at the antenna ground station assuming ground station has an antenna with a gain of 16 dBi and an effective noise temperature of 100 K over the longest pass interval from questions 2 and 3.

6. Assume that the 2259 MHz satellite downlink transmits at a maximum output power of 33 dBm with a bandwidth of 5 MHz using a patch antenna with a gain of 11 dBi.

Produce a plot of the C/No values (dB Hz) at the output of a receiving AWS Ground antenna with a figure of merit (G/T) of 16 dB/K. K over the longest pass interval from questions 2 and 3.

7. The Satlab SRS-4 supports a maximum symbol rate of 5 Mbaud. Use the result from (6) to plot the energy/bit to noise power density ratio Eb/No assuming the maximum baud rate of 5,000,000 symbols/second is used.

Assume that the data is modulated using Binary Phase Shift Keying (BPSK) with no FEC.

According to the Satlab SRS-4 datasheet (Table 9, page 20), the output transmit power from the radio can be varied from 20 dBm to 33 dBm. The radio also supports different modulation types. Given these Eb/No results, what transmission power and modulation type do you recommend be selected for the satellite mission? Give reasons for your answers.

8. Provide reasons why Waratah Seed would have selected two different radios for communication?

Questions 5, 6, 7, and 8 are worth 3, 3, 3, and 3, respectively.

ELEC9764 Assignment, Revision 1

SatNOGS Ground Station for Waratah Seed (5 marks)

The Libre Space Foundation is a non-profit foundation dedicated to developing open-source hardware and software for space applications. One of their projects is the SatNOGS network of ground stations that can be built by any interested party and used to communicate with cubesats.

You have been tasked with creating a low-cost ground station to communicate with Waratah Seed. Using information provided by SatNOGS, design a small ground station that could be used to communicate and download payload data from the spacecraft.

9. Systems engineering starts by considering a set of requirements that then drive the development process. Define a set of requirements that the SatNOGS ground station must satisfy if it is to be useful with the Waratah Seed satellite. Pay particular attention to the RF and communications requirements.

10. Create SatNOGS ground station design that satisfies the requirements defined in (9). The design should be described in tabular form (eg. A table and/or a printable spreadsheet). Your answer should include rows for each component and columns containing descriptions, a reference/URL link for each component, a price or price estimate and any other information you believe to be useful.

Questions 9 and 10 are worth 2 and 3 marks, respectively.

Note

Your assignment is to be submitted as a technical report. The writing style should be clear, effective and conform to that in general use in technical reports. Correct grammar and spelling should be used throughout the report.

Figures and tables should be fully and correctly labelled, e.g., Figure number, title and (if necessary) a reference.

All text, diagrams, ideas or other information which did not originate with you should be clearly identified and the sources properly cited and referenced. The report will be checked for plagiarism.

The final report is due on Moodle by 27 April at 11:59 pm (Sunday night). It is worth 30% of your course grade.

ELEC9764 Assignment, Revision 1