Signal modulation mode identification and parameter estimation device (Question D) [Undergraduate Group]
1. Task
Design and produce a device (hereinafter referred to as the device) that can identify the modulation mode and estimate the parameters of the signal generator output signal uM. The device can not only display the results of modulation mode identification and parameter estimation, but also output the demodulated signal uo for waveform observation with an oscilloscope. The system block diagram consisting of the device and measuring instruments is shown in Figure 1.
2. Requirements
1. basic requirements
The output uM of the signal generator may be AM, FM or continuous carrier (CW) signals. The peak-to-peak value of the carrier voltage is 100mV and the carrier frequency fc is 2MHz. For the estimation range and error requirements of uM related parameters, see the description of this question (1) ~(3), the requirements for the demodulated signal uo are shown in (4) of this question.
- (1) It is known that uM is an AM signal (a double-sideband amplitude modulation signal containing a carrier frequency component), and its sinusoidal modulation signal frequency F =1kHz. Estimate and display the amplitude modulation coefficient ma of the AM signal; output the demodulated signal uo for waveform observation with an oscilloscope.
- (2) It is known that uM is an FM signal, and its sinusoidal modulation signal frequency F=5kHz. Estimate and display the frequency modulation coefficient mf and maximum frequency deviation fmax of the FM wave; output the demodulated signal uo for waveform observation with an oscilloscope.
- (3) Under the condition that the uM modulation method is unknown, the device can independently identify and display the uM modulation method.
- (4) When uM is an AM wave or FM wave, its sinusoidal modulation signal frequency F is one of 1kHz, 2kHz, 3kHz, 4kHz, and 5kHz. Based on the basic requirement (3), the device can estimate and display the relevant parameters of uM and output the demodulated signal uo. The specific requirements are: if uM is identified as an AM signal, estimate and display its sinusoidal modulation signal frequency F and amplitude modulation coefficient ma, and output the demodulated signal uo for the oscilloscope to observe the waveform; if uM is identified as an FM signal, estimate and display its sinusoidal modulation signal frequency F. Frequency modulation coefficient mf, maximum frequency deviation fmax, and output demodulation signal uo for waveform observation by the oscilloscope; if uM is recognized as a CW signal, the character "CW" will be displayed.
2. play part
uM can be binary amplitude keying (2ASK), phase shift keying (2PSK) or frequency shift keying (2FSK) signals. All three transmit binary non-return to zero (NRZ) codes, and the code rate Rc can be 6kbps, 8kbps, One of 10kbps; uM carrier voltage peak-to-peak value is 100mV, carrier frequency fc is 2MHz. The device is required to be able to independently identify and display the uM keying method, and have the following functions:
- (1) If uM identification is displayed as a 2ASK signal, estimate and display the binary code rate Rc of uM transmission, and display the binary code sequence waveform of the demodulation output on the oscilloscope.
- (2) If the uM identification is displayed as a 2FSK signal, estimate and display the binary code rate Rc of uM transmission, the frequency shift keying coefficient h of uM, and display the demodulated output binary code sequence waveform on the oscilloscope.
- (3) If uM identification is displayed as a 2PSK signal, estimate and display the binary code rate Rc of uM transmission, and display the binary code sequence waveform of the demodulation output on the oscilloscope.
- (4) Others.
3. Description
*(1) The carrier wave of uM in this question is a sine wave. The signal type of uM and its parameter estimation range include: AM (amplitude modulation coefficient: 0.3<ma<1), FM (frequency modulation coefficient: 1≤mf≤5) CW, 2ASK , 2PSK, 2FSK (frequency shift keying coefficient: 2≤h≤5) signal, frequency shift keying coefficient c1 c0 chff R = −, where fc1 and fc0 are the carrier frequency values of the 2FSK signal to send binary codes 1 and 0 respectively.
- (2) The uM parameter value specified in this question (such as carrier frequency, modulation signal frequency, etc.) refers to the parameter setting value of the output signal uM of the participating team's own signal generator. The modulator within the signal generator generates uM.
- (3) Parameter estimation error requirements of the device: The absolute value of the error between the ma estimated value and its signal generator setting value is ≤ 0.1; the absolute value of the error between the mf estimated value and its signal generator setting value is ≤ 0.3; the F estimated value and its signal generator setting value The absolute value of the value error is ≤50Hz; the absolute value of the error between the estimated value of fmax and its signal generator setting value is ≤300Hz.
- (4) The demodulated signal output must be a single port output. When observing the demodulated signal uo with an oscilloscope, uo should have no obvious waveform distortion, and the peak-to-peak voltage should not be less than 1V.
- (5) Team members must be proficient in setting and operating the parameters of the output signal (including AM, FM, CW, 2ASK, 2PSK, 2FSK signals) of their own signal generator (function generator). The participating teams are required to bring their own signal generator to participate in the competition area test and national retest. During the test of the work, they should skillfully set the relevant parameters of the signal uM by themselves according to the specific requirements of the test experts.
- (6) In each test, after the participating teams complete the settings of uM parameters by themselves, they press the "start button" of the device to identify the modulation method, estimate and display the uM parameters. After pressing the "start button" for 10 seconds, they still cannot When the result is displayed, the test ends and no points are awarded. Before setting the uM parameters each time, the keyboard is allowed to be operated once; from the time the uM parameters are set to the time the device displays the results, except for pressing the "start button", any other operations on the device are prohibited, otherwise it will be considered a violation.
4. Scoring Criteria
Open source reference for excellent works (source: Lichuang Open Source Platform)
- Jialichuang : https://lceda.cn/
- LiChuang open source platform : https://oshwhub.com/
- Identification and parameters of signal modulation method for Question D of the National Open Source 2023 Electronic Competition
- 2023 Electronic Competition Question D Signal Modulation Mode Identification and Parameter Estimation Device Hardware
