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ed190's questions

Martin Hope
ed190
Asked: 2025-04-03 16:26:26 +0800 CST
  • 5

我创建了一个 Python 块，它接受五个用户输入，并根据这些条目生成一个 .txt 文件，其中包含第 1 列中的时间戳和第 2 列中的多普勒频移数据。

前两个输入是两行元素，第三个输入是 CubeSat 的频率，第四个输入是时间戳，最后一个输入指定存储 .txt 文件的文件目标，类似于“文件接收器”块。

例如，在 GNU Radio 的默认“文件接收器”块中，单击三个点会打开一个窗口来浏览并选择最终文件目标。但是，我无法在我的代码中复制此行为。

此外，单击“执行流程图”时，是否可以在整个流程图启动之前运行该块？

例如：步骤 1.条目 1：“1 49263U 21088D 24308.92471420 .00079255 00000+0 26750-2 0 9998”

条目 2：“2 49263 97.4796 14.7363 0010511 313.1417 46.8944 15.30328253170926”

条目 3：437.250e6

条目 4：1730713098

条目 5：---单击三个点打开文件浏览器保存文件---

步骤2.单击“执行流程图”---在主流程图之前运行python块---

import scipy.constants
import skyfield.api
from skyfield.api import wgs84, EarthSatellite
import numpy as np
import datetime
from tkinter import filedialog
import tkinter as tk
from gnuradio import gr

class DopplerBlock(gr.sync_block):
  
    
    def __init__(self, tle_line1='', tle_line2='', frequency=0, timestamp=0):
        gr.sync_block.__init__(
            self,
            name='Doppler Shift Generator',
            in_sig=None,
            out_sig=None
        )
        
        self.tle_line1 = tle_line1
        self.tle_line2 = tle_line2
        self.frequency = frequency
        self.timestamp = timestamp  # User-provided timestamp
        self.ts = skyfield.api.load.timescale()
        self.groundstation = wgs84.latlon(53.1111, 8.8583, 0)  # ESTEC ground station
        self.output_file_path = self.get_file_path()

    def get_file_path(self):
        """Opens a file dialog to let the user choose a file."""
        root = tk.Tk()
        root.withdraw()  # Hide the root window
        file_path = filedialog.asksaveasfilename(title="Select file to save data")
        return file_path if file_path else None

    def compute_doppler(self):
        if not self.tle_line1 or not self.tle_line2:
            raise RuntimeError("Both TLE lines must be provided.")
        
        satellite = EarthSatellite(self.tle_line1, self.tle_line2, 'satellite', self.ts)
        
        unix_epoch = datetime.datetime(1970, 1, 1, tzinfo=datetime.timezone.utc)
        t0 = unix_epoch + datetime.timedelta(seconds=self.timestamp)
        t0 = self.ts.from_datetime(t0)

        # Generate time steps
        duration_s = 25 * 60  # 25 minutes in seconds
        time_steps = np.arange(0, duration_s, 0.1)  # Every 0.1 sec
        t = t0 + time_steps / (24 * 3600)  # Convert seconds to fractional days
        
        # Compute Doppler shift
        topocentric = satellite.at(t).observe(self.groundstation)
        _, _, range_rate = topocentric.apparent().velocity.km_per_s
        range_rate *= 1e3  # Convert to m/s

        doppler_shift = -range_rate / scipy.constants.c * self.frequency

        # Save to file if path is provided
        if self.output_file_path:
            with open(self.output_file_path, 'w') as output_file:
                for time, shift in zip(time_steps, doppler_shift):
                    output_file.write(f'{self.timestamp + time}\t{shift}\n')

    def work(self, input_items, output_items):
        """This block does not process streaming signals, so work does nothing."""
        return 0
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