roccoschili Page 673
Page 673
The Doppler frequency shift system is based on the received signal frequency, compared with the frequency of the satellite transmitter in theory, to see whether the frequency has become higher or lower, and the amount of change, and then calculate the key data.Of course, the transmission frequency of the Sextant-1 transmitter itself changes slightly according to a certain law, and the receiving end needs to know the change law of the satellite’s transmission frequency.
If there is no problem in grasping the change law of launch frequency, precise time + orbital parameters + frequency shift, the three parameters can locate the ship.
When a navigation satellite is launched into the sky, the orbit will always have some errors from the original estimated orbit.The prerequisite for the satellite navigation system to provide accurate positioning is to first grasp the accurate orbital parameters of the satellite.From 110 minutes after launch, the four ground tracking stations took the first position measurement of the satellite. 24 hours later, the satellite orbit passed over China again, and the four satellite ground tracking stations were able to conduct two more rounds of measurements.
If only tracking stations could be built in the Soviet Union and East Germany, the time it takes to calibrate satellites could be cut in half.
The tracking station records the orbital data of the satellites and transmits them to the computing center together with the time corrections.Based on the data sent by each tracking station, the calculation center calculates the position of each satellite at the beginning of even-numbered minutes in the next 16 hours, and sends it to the injection station after encoding, and injects data into the satellite, washes out the original old data of the satellite, and corrects it. Time-Location Correlation.
It was a very troublesome thing. Tang Hua and Qian Xuesen returned to Beijing from Pingyao, and many days later, the computing center and tracking station were still busy.Anyway, Sextant-1 is a test star. Although the satellite launched into the sky is fully functional, the orbit is normal, and all equipment self-tests are also normal, but the first purpose is testing.
"Minister Tang, Sextant-1 can be used for positioning today!"
"What?" Tang Hua looked at the calendar. Today is July 7, and it's only been 3 days since the launch.
"Well, the ground terminal of the Chongqing ship received a positioning signal when the satellite passed over the area," Wang Xiji said, "then the ground terminal calculated a coordinate. The Chongqing ship is cooperating with the test, and he knows the coordinates of the ship. Comparing the two coordinates, the difference is not too much."
Tang Hua: "Not too much difference, how much difference?"
"One thousand nine hundred meters."
Tang Hua: ...
"Then at the same time, a ground terminal on the shore of Dalian also started a positioning test and calculated a coordinate with an error of 1330 meters. The data measured by the General Staff Force in Inner Mongolia had a relatively large error of 3700 meters. "
Tang Hua: "The test point in Inner Mongolia, I guess it may be that the altitude correction is not correct. The ground end of Dalian and the Chongqing ship are both near sea level, which means that there is no altitude error. The errors of these two may come from the Measurement errors in satellite orbital parameters."
Wang Xiji: "Then our ground tracking station will continue to track, measure and make corrections."
……
houston.
Sextant-1 is sending radio signals all the time in the sky, not only China can receive the signal, but also the United States.
"Boss, Chinese satellites are using two frequency bands at the same time," a technician reported, "The first frequency band is 155 plus or minus 5 MHz, which was also written in the manual when the Canton Fair China released the ground terminal; the second The first frequency band is 410 plus or minus 10 megahertz, and the Chinese have never announced it, but satellites have been radiating energy in this frequency band."
Hugh Dryden listened to the technician's report, and turned his head to Richard Kershner: "The frequency band setting is the same as that of the meridian meter, isn't it?"
Richard Kershner is the director of the satellite laboratory at Johns Hopkins University and the designer of the meridian system. He shared his hands, "We have come up with the Chinese, a low-frequency radio wave with relatively high positioning accuracy. Low, used to meet the needs of commercial users; a high-frequency radio wave, with high positioning accuracy, used to serve the military.”
Dryden: "But the Chinese have covered the frequency bands of the meridian system on both frequency bands, which will affect the future use of the meridian system."
Kershner: "Maybe... maybe it will affect it. But we have only manufactured three test satellites for the Meridian satellite, and we still have time to modify the satellites that are officially in operation, so that the working frequency band of the constellation is staggered from that of the Chinese. Boss, This is not a bad thing, but bodes well for our project's success."
Dryden: "What does it mean to have a good chance of success?"
"China's constellation is in polar orbit, and there are also four ground tracking stations and injection stations. The working mode is the same as that of the meridian, and even the working frequency band uses a number similar to that of the meridian," Kershner grinned, showing two rows of white teeth, "This shows that so far, our technology development route is correct."
Dryden looked at the guy with no self-respect in front of him, and was speechless for a moment.
"Odford of Martin Marietta is my friend. We have known each other for a long time," Kershner said. "His greatest achievement is to follow the technological development route of Chinese missiles. On the road of TV guidance After three years of research, the total contract awarded to Martin Marietta by the Navy and Air Force each year exceeds 5000 million US dollars, all of which are for the purchase of TV-guided air-to-surface missiles and TV-guided bombs..."
……
Moscow.
When the Long March-2 launched the Sextant-1 satellite, the Prime Minister and Nehru were negotiating border conflicts.
The satellite navigation system is used by both Chinese and Soviet armies, and it is very promising. Soviet newspapers and TV also reported a lot. This put a lot of pressure on Nehru, and his subconscious distrust of the Soviet Union became more serious. .
"Mr. Nehru, during the time I was in Moscow, your country sent an additional [-]th Artillery Division [-]th Brigade and two infantry battalions to Assam," the Prime Minister said to Nehru seriously, "In addition, our border residents have reported that your country's garrison in Itanagar - these garrisons have already crossed the border into southern Tibet, and have moved northward in the past ten days, and one of them has been stationed in Ziruo. "
Nehru shook his head: "Mr. Prime Minister, we have never been able to reach an agreement on whether southern Tibet should belong to India or China. Moreover, you have been avoiding discussing the ownership of sovereignty in southern Tibet."
Prime Minister: "It's not avoiding, but I don't want to emphasize. If there is anything I want to avoid, it is to try to avoid a war or bloody conflict between China and India. I and the government I represent sincerely hope that China and India will Territorial disputes can be put aside for a while, and our next generation can solve this troublesome problem."
"To avoid war or bloodshed between China and India, you should still ask your country to withdraw its troops from the direction of Tawang and Pasika, so that the power of our two sides there can be restored to the state it was in 1958."
"If time can be turned back, then we can do too much. For example, let our power there go back to the state of 1951, or 1950?" The Prime Minister replied, "We can't just go back one year. That’s not enough for everyone.”
……
Khrushchev was also very anxious about the negotiations between China and India.
Now the Soviet Union is implementing industrial assistance to India that is larger than 156 key projects, and it is also systematic.
Pull China into their own camp and provide industrial assistance. After a five-year plan, China's industry looks decent, and it has formed a complement to the Soviet Union. This has greatly improved the Soviet Union's Cold War situation, economy, and technology.
With this successful experience first, wouldn’t it be more comfortable for the Soviet Union to draw the second most populous country in the world to its side, form an alliance or a younger brother relationship, and then provide assistance to start up the industry?
Anyway, Khrushchev thought so. In 1955, after Khrushchev replaced Malenkov as the leading man in the Soviet Union, the Soviet Union's attitude towards India changed from cold to hot.In order to support India's five-year plan (1956-1960), the Soviet Union provided India with US$10.2 billion in aid, all of which was used for construction, rather than taking a considerable part of it to fight against US aggression and aid Korea like China.
It's 1959...India has not yet shown its true colors of letting the USSR down.In the 60s, the Soviet Union discovered that India’s executive power was less than [-]% of China’s. The same investment in India would not be able to build the industries that should be built. Only then did the Soviet Union realize that not all countries can build like China.
But it is not yet the time. In Khrushchev's eyes, India is still a potential stock.So Khrushchev is of course anxious about the possible quarrel or even fight between China and India.
Or, ignore China and India, let them fight and fight, and then...?
Sometimes another idea flashed through Khrushchev's mind.
No then, plan no.
Only if China and India fight each other for several years, can the Soviet Union continue to benefit from it—and the premise is that Khrushchev learns Stalin's set of international tactics.
If there is no Stalin's level of intrigue, the result of the matter is: India will definitely be beaten very painful by China, but India will not admit defeat. It is a big country and has almost unlimited human lives to maintain the so-called "shameful conflict".China has been restrained, but there is a high probability that India will vent its anger on the Soviet Union, and its relationship with the Soviet Union will turn from hot to cold.
The Soviet Union's situation in the Indian Ocean is not easy to open, at least the more than 10 billion US dollars of aid it has invested in is for nothing.Even if you want to stumbling China, you should find a rogue small country instead of using India to do it.
……
Khrushchev was trying to find a way to help India, while Eisenhower had already begun to help India.
On July 7, a 7-ton Greek freighter docked in Kolkata.
People in suits and leather shoes got off the boat, but when they were still walking on the trestle, these people were so hot that they took off their suits and carried them in their hands.
"Mr. Dale Foss, hello." An Indian on the pier came up to greet several guests.
The leader who got off the boat said softly, "Virgil, talk this way."
A group of people left the freighter and walked to a remote place.
"The 'Marathon' carried small arms and ammunition, the heaviest being a 120mm mortar, but they were all tightly packed, and you can unload them now," Dale Foss handed the list to Virgil, referring to Looking at the "Marathon" behind him, he said.
"Mr. Secretary of State said that the aid also includes tanks and artillery." Virgil is now wearing civilian clothes, but he is actually an intelligence officer of the Indian Army's General Staff.
"That was taken by another ro-ro vessel, the MSC Express, which arrived in Calcutta 48 hours later," Dale Foss said. Well-organized, the tanks must be at night when they get off the ro-ro ship, and if you still haven’t finished transferring the cargo of the ‘Mediterranean Express’ by four o’clock in the morning, then you have to stop operations and wait for the next day to get dark.”