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前言

GNU Radio 中没有实现测量两个模块之间的时间测量模块，本文记录一下通过 python block 制作一个很简单的测时 block。

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一、timestamp_sender 模块

使用 python block 做一个发送端时间戳记录模块，并添加下面的代码：

"""
Embedded Python Blocks:

Each time this file is saved, GRC will instantiate the first class it finds
to get ports and parameters of your block. The arguments to __init__  will
be the parameters. All of them are required to have default values!
"""

import numpy as np
from gnuradio import gr
import time
import numpy as np

class timestamp_sender(gr.sync_block):  # other base classes are basic_block, decim_block, interp_block
    """Embedded Python Block example - a simple multiply const"""

    def __init__(self):  # only default arguments here
        """arguments to this function show up as parameters in GRC"""
        gr.sync_block.__init__(
            self,
            name="timestamp_sender",   # will show up in GRC
            in_sig=None,
            out_sig=[np.float32]
        )
        self.kk = 1;
        
        # if an attribute with the same name as a parameter is found,
        # a callback is registered (properties work, too).

    def work(self, input_items, output_items):
        # Record the current time
        start = np.float32(time.perf_counter())
        
        # Output data and the current timestamp (here using a simple value for demonstration)
        output_items[0][:] = [start for _ in output_items[0]]
        
        if self.kk == 1:
            self.kk = 2;
            print(f"output_items[0][:] = {output_items[0][:]}");
        
        return len(output_items[0])

二、timestamp_receiver 模块

使用 python block 做一个接收端时间戳记录模块，并添加下面的代码：

"""
Embedded Python Blocks:

Each time this file is saved, GRC will instantiate the first class it finds
to get ports and parameters of your block. The arguments to __init__  will
be the parameters. All of them are required to have default values!
"""

import numpy as np
from gnuradio import gr
import numpy as np  # 导入NumPy库
import time

class timestamp_receiver(gr.sync_block):  # other base classes are basic_block, decim_block, interp_block
    """Embedded Python Block example - a simple multiply const"""

    def __init__(self):  # only default arguments here
        """arguments to this function show up as parameters in GRC"""
        gr.sync_block.__init__(
            self,
            name="timestamp_receiver",   # will show up in GRC
            in_sig=[np.float32],
            out_sig=None
        )
        # if an attribute with the same name as a parameter is found,
        # a callback is registered (properties work, too).
        self.kk = 1

    def work(self, input_items, output_items):
        for item in input_items[0]:
            if item == 0:
                continue
            if self.kk == 1:
                self.kk = 2
                end = np.float32(time.perf_counter())
                print(f"input_items[0] = {input_items[0]}")
                print(f"Received at {end}, interval since sent: {(end - item) * 1000000} Microsecond")

        return len(input_items[0])

三、测试

按照下图将 block 进行连接：

采样率 32KHz，延时 320 * 5 = 160000 个采样点，大约 5s 的时间

打印信息：

Generating: '/home/gnep/ofdm_usrp/test.py'

Executing: /usr/bin/python3 -u /home/gnep/ofdm_usrp/test.py

Press Enter to quit: output_items[0][:] = [7809.57 7809.57 7809.57 ... 7809.57 7809.57 7809.57]
item = 7809.56982421875
input_items[0] = [   0.      0.      0.   ... 7809.57 7809.57 7809.57]
Received at 7814.44189453125, interval since sent: 4872070.3125 Microsecond

可以看到打印信息为 4872070.3125 ，大约为 5s 时间

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