Supplementary answer: Because there are many kinds of wire rod manufacturers, a coil of wire rod has been tampered with in the drawing process, that is, most of the semi-finished products of drawing-in the final drawing process-have been pulled off, that is, the middle and last parts of a coil of wire rod, and the short and thick parts that have not been pulled off in the final drawing are wrapped in the outer insulation layer by the injection molding machine to make the outermost part of the finished cable bundle. The effect of such a complicated processing technology is to show you that the copper core is thick at first, and most of the windings inside are thin. So you must measure the diameter of the copper wire at the beginning and the diameter of the rolled internal copper wire to see if they are consistent.
You can use the mathematics knowledge of middle school to analyze and calculate, that is, volume calculation, the relationship between volume and weight per unit length (for example, one meter long), and the relationship between volume and specific gravity of copper conductor per unit length; The volume and weight of plastic insulation layer, shielding layer and sheath layer per unit length are generally based on the accumulated calculation in the past and the sampling of this batch now. Cut off an insulating layer and measure the weight per unit length. The general length is 10 cm. Accurate calculation, the interception length should be 1 m, which is better, but it is a great waste.
This is too complicated, so it is necessary to set up the equation and list it on a personal computer, so that the computer can solve the equation and calculate it; Or do it yourself on the calculator.
It is strongly recommended that you make your own instrument measurement. I can support you to apply for an invention patent for free without prior economic requirements, and bear legal responsibility for it. You can do it for free, and the specific contact information is provided in the background. In the past two years, I have answered more than 10,000 questions on Baidu Know, and answered more than 260,000 words without repetition. I typed them word by word. This is a very old problem; Before electron tubes appeared, the resistance of wires was measured by Wheaton Bridge. Now, the DC resistance between the two terminals and between the head and the tail is measured with a low resistance meter or four semi-digital voltmeters. After the electron tube appeared, we used the principle of radar to send a very short high-voltage pulse from one end to measure the delay and phase of the echo. As long as one end of the cable is connected to the measuring instrument, we can handle all kinds of armored cables, shielded cables and cables covered with iron grounding layer. There were officially published books during the Cultural Revolution, and even the circuit diagrams were completely open. Now the method of measuring submarine optical cable is similar. Let's send a laser. There are echoes where the impedance does not match, echoes where there are welded joints, and echoes where there are broken lines. Now with advanced semiconductor devices, this kind of cable fault tester is miniaturized, which is not only used by telecom departments, but also by people who do network cables, networks and servers. At least it is used for settlement projects and cost accounting, and returnees are also copying; Of course, there are other extremely ancient and effective methods, so I won't list them one by one. It is suggested to detect the total mass of copper in nuclear reactors. Put an end to what you can't do, and take the lead if you can't learn in this life!
The former has no jobs, but the latter monopolizes resources and power, which is endangering national security! The biggest obstacle is that what can be done is not allowed to be done, and what cannot be done is in the hands of mediocrity. It's not a question of treatment, but there is no post at all, no access to the laboratory and no use of idle ordinary instruments. Everyone has two sides. Overseas Chinese @ # do%...&; Directly affiliated units may have the right to use computers and networks funded by the state for many contract workers to enrich their spare time, and may also assign offices to contract workers. At the same time, people who have been authorized by invention patents and published scientific papers at international academic conferences for many times have no workplace and are banned from using computers and instruments for decades. It depends on who is different from who. It varies from person to person, depending on the specific situation. Is it? What slang and code words do you know? An attacker with a senior professional title was ordered by the leader to drive a limousine and said to the victim, "You can call 1 10 to call the police!" Do you believe I can kill you on the spot? . He is an electronics major, but he can't design single-stage circuits at all. If he buys a multimeter below 100 yuan, he also wants the merchant to give him a large rebate. The paper to improve his professional title was copied from the textbook and asked other teachers to input it into the computer and print it for him. The significance of the 17th National Congress of the Communist Party of China to a harmonious campus is in the military industry, and the slogan is that ignoring quality is a crime. In the education industry, teachers who are unable to design and manufacture teaching equipment and industrial equipment and only transfer formulas from books monopolize the classroom, which is endangering national security and destroying the national foundation! People of this grade own luxury cars and have beaten people who have published papers at international conferences many times. It also shows that you can call 1 10 to call the police. Do you agree? Therefore, we must be broad-minded, persistent and industrialized in order to stand firm in front of developed countries!
Take Fluke's test instruments as an example, each one is tens of thousands of RMB, and each one made in China is several thousand RMB. Domestic accuracy is poor, and normal people don't need it. The principle of this test method is very old. The higher the accuracy, the shorter the length, the harder it is to do and the higher the cost. You can calculate according to the speed of light. The test accuracy of transmitting pulse and receiving resolution in one microsecond is 300 meters (you can calculate it yourself, here is just a fabrication). In fact, to calculate the length of the round trip, it usually needs the transmission accuracy and resolution accuracy of the main frequency of 1G to reach the accuracy of 0.3 meters. Shijiazhuang Semiconductor Research Institute manufactures microwave semiconductor devices, which are not kept secret. It is well known abroad that you can transmit and receive the equipment she produces. The transmitted pulse width should be very narrow, otherwise, like the blind spot of radar, the minimum test length will be too large. All kinds of testing methods in other forests do not directly get the test results, and are not directly readable and authoritative, so it is not easy to be recognized. The vehicle-mounted gas leak detector of the gas company costs several million yuan; Ground penetrating radar for gas companies, water companies, communication companies and municipal buildings, each of which costs several hundred thousand yuan; Infrared photographic equipment is at least several hundred thousand yuan each; The GPS on the street can't be located on high-speed missiles and satellites, and others haven't exported it yet; The precision of deep space exploration and high-energy physical exploration instruments is MINUS 20 power; These are analog instruments, all imported. Now few college students, graduate students and teachers can accurately design and debug the basic circuit of a transistor.
The foundation is so unfathomable, loud diplomas, extreme academic qualifications and terrible professional titles abound. The youth of countless younger generations, the extra-curricular tutoring expenses of various quality training and the amazing investment amount have all become the system integration of foreign scientific and technological literature, foreign system software and foreign hardware platforms. The key depends on the attitude of your leader. Now, regular cable manufacturers have cable length measurement, integration and coding equipment. Look at the absolute value of the length of the imported inkjet head hitting the cable, and compare the length marks of the cable head and tail to know the absolute length of this bundle of cables. If your leader has a behind-the-scenes deal with the enterprise, you will lose your job if you get serious! The solution, first of all, is to place an order with a qualified production enterprise, requiring the production enterprise to be equipped with necessary production equipment, and the measuring instruments you buy are recognized by the industry; For China, the biggest gain is to make the design data, parts purchasing location and debugging methods of self-made measuring instruments with manufacturing costs of several thousand yuan and several hundred yuan public for free, so as to improve the quality of the whole people and strengthen the national strength.
I have no laboratory, no basic equipment, and I am laid off and unemployed. I plan to provide completely open innovative exhibitions of design materials to various science and technology museums in China. Your topic is so good that people can ignore it. This is not high-tech and does not meet the standards.
Its design is very similar to radar; Special police, public security, and special forces like to temporarily blind their opponents with bright bullets, but the amplifier here can't stop because the transmitted signal amplitude is very large (it is not easy to drive nanosecond pulses) and the received echo is very weak. The design skills of the amplifier were made public 50 years ago. Look at the video of China launching manned space flight. The recording often contains "XXX tracking is normal", that is, several domestic radar models. The instruments you need are commercially called cable detectors, cable detectors and cable fault testers. In the past, Fluke Company in the United States asked for 40,000 yuan, but now the low-priced one only needs 1 10,000 yuan. If you search the keyword "American ideal" on the Internet, you can see that this brand can be around 5,000 yuan. As an enterprise, you can only buy imported instruments. For the students who are studying, you should use this instrument with completely open circuit, assembly drawing and waveform test as teaching instruments. This can only be done by people like you, and officials and doctoral supervisors disagree. It is illegal to make them without permission, and you will go to prison, so you should ask them to teach you how to make them. Forty years ago, China often published loose-leaf publications of technological innovation, all of which had official book numbers, and the price was only a few cents to a few cents, all of which were made by industrial and mining enterprises themselves and could be used in practice; Now I have contacted the publishing houses in the north and south of the Yangtze River, and they all refused to publish relevant contents, especially the CDs of teaching videos and word electronic documents, which cost money; To publish books extracted by translation, you should go to the bookstore to find books that are of practical significance to you. I have no culture.
I used the word 1700 to answer your question, but you haven't told me all the detailed specifications of your usual cables.