A simple comparison of the two rangescopes shows that the combined rangefinder uses a horizontal long tube as the reference length, and sets the objective lens group at both ends, and the optical axis of the objective lens group is perpendicular to the ranging baseline, and the image about the target is generated separately during ranging. The image formed in the eyepiece on one side is only the top half, and the other side has only the bottom half. Due to the existence of the ranging baseline, the image on the right side is biased to the right relative to the image on the left. By rotating the polarizer, the upper and lower images coincide. By measuring the angle at which the polarizer rotates, the distance to the target can be calculated.

The stereo rangefinder is similar to the conjunctive rangefinder, except that after the target is imaged in the eyepiece, the rangefinder observes the image of the same target at both ends of the rangefinder in the left and right eyepieces at the same time, and the person senses the target through visual senses. In this case, by moving the cursor in the eyepiece back and forth, the distance data is read directly when the operator feels that the target coincides with the cursor.

The reason why the error of the stereo rangefinder is smaller than that of the conjunctive rangefinder is that its ranging is based on the distance measured by the rangefinder's parallax and directly derives the distance data, while the conjunctive rangefinder is through the image of the upper and lower parts, as long as the image is not completely aligned (and this is very difficult), the error will be amplified in the conversion of angle to distance.

Therefore, when the line of sight angle is small at a long distance, the accuracy of the stereo rangefinder will be better than that of the conjunctive type. Moreover, the stereo rangefinder also has the ability to measure the range of irregularly shaped targets, so the stereo rangefinder is often used for calibration and air defense.

Although the accuracy of long-distance ranging is not high, compared with stereo rangefinders, it has less operating pressure on personnel. And it's faster to get a close target distance. The accuracy is also high. So while long-range accuracy is at a disadvantage for stereo rangefinders. However, it is still useful to plot the track of your own fleet when sailing. Because the target at this time is a friendly ship and a fixed navigation beacon in a close formation, and a fast data rate is required at this time, and at the same time, it may be necessary to quickly change the ranging target, and the accuracy requirements are low. Therefore, the combined rangefinder is generally suitable for this kind of scenario.

Of course, whether it is a conjunctive rangefinder or a stereo rangefinder, it is an optical rangefinder, which has relatively high requirements for optical glass and grinding mirror technology, and not all countries can do it. It also has relatively high technical requirements for the personnel used, and the reaction speed is relatively slow, which is not suitable for artillery combat within one or two kilometers.

For tank crews. There is an urgent need for a faster and more accurate rangefinder, and it is clear that neither the conjunctive rangefinder nor the stereo rangefinder can meet this demand. The only thing that can meet this need is a laser rangefinder. Whether it is reaction speed or accuracy, the laser rangefinder can completely explode the above two traditional optical rangefinders. The only problem was that the backward technology at that time restricted the size and power of the laser, and the early first-generation laser rangefinder still had some damage to the human eye.

Of course, for the urgent Red Army armored troops, all this was not a problem, with sufficient financial investment, the publication of the armored laser rangefinder was born in the first half of 1944, the first batch of equipment to the T-54 tank. This led directly to a sharp increase in the combat effectiveness of the T-54, in conjunction with the D-10T and the new 100-mm smoothbore gun. It was finally possible to accurately snipe German tanks at long distances.

Of course, only a few heavy tanks of the T-54 and the original IS series can enjoy the treatment of installing laser rangefinders. This batch of tanks was also only equipped with the Guards, after all, the cost of the first-generation laser rangefinder was quite high, and it was not something that the cheap T-34 and T-35 could enjoy.

However, the Red Army did not stop improving the fire control of the T-34 and T-35, although it was impossible to install expensive laser rangefinders on them, but at the suggestion of Li Xiaofeng, the Red Army armored troops began to popularize rangefinder machine guns on low-grade tanks. The so-called rangefinder machine gun is actually a heavy machine gun mounted coaxially with a tank gun, and at a distance of about 1,500 meters, the ballistic characteristics of the machine gun are basically the same as those of the tank gun.

The specific method of use is: when the artillery commander discovers the enemy, immediately carry out the range, and then bind the gauge of the rangefinder machine gun according to the measured distance, and then immediately shoot a short burst. After that, observe the impact point of the tracer bullet of the rangefinder machine gun, and if it hits the target, immediately fire it with the tank gun. Otherwise, it means that the ranging is wrong, and the shooting is carried out again according to the impact point of the rangefinder machine gun until it hits the target.

To be honest, the performance of the range-finding machine gun is limited, but it is only a method of "coping" in the early stage of the development of fire control equipment, and it has a limited effect on improving the hit rate of long-distance shooting, especially for shooting long-distance moving targets, and the operation is relatively cumbersome, especially in the field of ranging there is no essential improvement.

However, in 1943, this was already a very high solution, at least the majority of Red Army tankmen still welcomed it. Soon in July and August 1943, a project to equip the T-34 and T-35 with rangefinder machine guns began in full swing.

From October 1943, the German tank crews suddenly found that the long-distance combat capability of the Red Army tankmen had skyrocketed, not only the "rare" T-54 long-distance artillery battles had become very fierce, but even the T-34 and T-35 with the vast "reptile system" had also begun to expand the combat distance, making the German tank crews and anti-tank artillery miserable.

With this out of the way for now, let's go back to the previous topic - navigation. The realization of lasers made it possible to realize laser gyroscopes, but with the basis of the Soviet Union in this field at that time, it was still very difficult to quickly get a laser gyroscope for publication. Li Xiaofeng soon discovered that the first-generation laser gyroscope could only be manufactured in small quantities in the laboratory, not to mention the volume and accuracy, and the cost was categorically unacceptable. In desperation, a certain immortal could only cheat and purchased a batch of laser gyroscope equipment at the level of the 60s of the 20th century for the use of the Red Army's long-range aviation. Of course, the number is relatively limited, and basically each bomber regiment can be divided into two or four units.

However, this is not a big problem, for the carpet bombing of large aircraft groups in those years, it is not necessary for every bomber to be equipped with laser gyroscopes, and two navigators equipped with laser gyroscopes in one formation can solve the problem. The rest of the planes will just fly along.

From September 1943. The Germans were clearly surprised. It was clear that they had taken effective measures to interfere with the radio navigation equipment of the Red Army, but the Soviet heavy bombers were always able to find the exact targets for bombing. Even in the dark of night, cities with strict lighting control would still be found by Red Army bombers and blown into flames.

The Germans were always puzzled by how the Red Army could accurately navigate and locate the country, and they tried every effort to crack the secret, but under the strict defense of the KGB, no breakthrough was made.

It's not just the Germans who are puzzled. Even the allies Britain and the United States are scratching their heads, and they are also facing navigation problems when they also carry out strategic bombing of Germany, even if Great Britain is closer to Germany, but after the Germans have taken strict countermeasures, the navigation problem is still imminent. As a result, Britain and the United States had to upgrade their radio navigation systems again and again. And they also wanted to know how the Red Army managed to pinpoint and circumvent interference. Especially the latter, their interest is not ordinarily large.

Of course, it was impossible for the Soviet Union to reveal the secret of the laser to Britain and the United States, and it was easy to lead for almost 20 years, and it was naturally impossible for the Soviet Union to give away its superiority in this field. In order to confuse Britain and the United States, the KGB spread a lot of false information. And deliberately misled Britain and the United States.

For example, the claim that the Soviet Union had created extremely high-precision mechanical gyroscopes lured Britain and the United States to invest a lot of valuable money in this field. For example, the Soviet Union claimed to have invented a completely new radio navigation system. This system completely avoided interference from the German army. This also caused Britain and the United States to spend a lot of effort to spy on the secrets of the Red Army's so-called new radio navigation system, thus exposing a large number of hidden spies and bribed renegade traitors.

Britain and the United States spent a lot of energy and money trying to figure out the secrets of Soviet navigation, but in the end, both extremely high-precision mechanical gyroscopes and so-called new radio navigation systems proved to be nothing. So much so that Britain and the United States finally concluded that the only reason why the Red Army was able to navigate accurately was that it had trained a group of extremely high-quality navigators, and this group of cattle allowed the Red Army to avoid the interference of the German army.

It wasn't until 20 years later, when the Americans created laser gyroscopes, that there was a conjecture: Could it be that the Soviets had discovered the mystery of lasers back then?

At first, the proud Americans dismissed this as nonsense, believing that it was simply impossible to create a laser gyroscope for publication in the 1940s at the theoretical and industrial level of the USSR. Until 1965, the year when Li Xiaofeng retreated, a large number of super secrets in World War II were declassified, among which the laser gyroscope was impressively listed. At that time, the Americans realized that they were too far behind the Soviet Union in this field, and when they first began to use laser gyroscopes, the Soviet Union was already widely using second-generation fiber optic gyroscopes.

Of course, Li Xiaofeng did not put all the eggs into the laser gyroscope, although the navigation of the inertial device has strong anti-interference ability (unable to interfere), but the inertial device has a cumulative error, when the range is long enough, the deviation will be bigger and bigger. Relying on inertial navigation alone will not meet military needs.

There must be other means to assist inertial navigation for more accurate navigation. To this end, Li Xiaofeng ordered the relevant institutions of the KGB to carry out the research and development of a new radio navigation system, which is also known as the TACAN system, the full name of which is Tactical Air Navigation System, which is later called the TACAN system.

The TACAN system is a short-range polar coordinate radio navigation system. Historically, it was the US imperialists who began research and development in the late 40s and put it into use in 1952. The principle is that 30 pairs of interrogation pulses (pulses emitted in pairs) are emitted from the aircraft every second at 12 microsecond intervals.

After receiving the interrogation pulse pair, the surface station emits the same interval of answer pulse pairs. The aircraft compares the time of receiving the answer pulse pair with the time of the interrogation pulse pair to obtain the time of the pulse wave propagating in space, so as to obtain the distance from the aircraft to the ground platform.

This completes the ranging work, which is not enough, it must also be able to be sideways. In the lateral operation, the ground station emits nine amplitude-modulated pulse signals in the form of heart-shaped lobes. This AM envelope consists of a 15 Hz azimuth signal from a rotating heart pattern and a 135 Hz azimuth signal from the rotation of nine lobes (the phases of these two signals are related to the spatial bearing of the ground station relative to the aircraft).

I won't go into detail about the specific principle, anyway, by comparing the above two pulse signals and applying the flap removal technology. The aircraft can get a more accurate orientation information. This enables positioning. Combined with inertial navigation equipment, accurate positioning information can naturally be obtained.

This set of Tacan system was developed from 1944 to 1949, and it was basically able to meet the navigation requirements within 500 kilometers, which was very practical for the front-line aviation of the Red Army.

Of course, Li Xiaofeng was still not satisfied, and after that, he tried his best to promote the Red Army's research on satellite navigation. From 1950, when it was predicted, until 1965, when the first experimental GLONASS in the Soviet Union was launched, $20 billion was burned in 15 years. This huge amount of money made the political It's an unusually painful situation, but who made Li Xiaofeng insist strongly?

Of course, in the future, the political . The government will find that the $20 billion spent is really worth it, not only solving the problem of the precise positioning of the Red Army at one time, but also making a big profit in the civilian market, creating no less than $2 trillion in economic value in the next half century.

That's it for now, let's get back to the battlefield. Look at the situation on the Soviet and German sides at the beginning of April. Let's start from north to south, in East Prussia. The standoff remains a stalemate. Although the German army did not have the ability to cross the Great Wall of steel built by the Jews, the Jews did not have the power to counterattack, and the national strength was limited, especially the human resources were too precious, and they did not have many mobile troops, and the precious armored divisions were more responsible for the role of mobile anti-tank batteries, they were firefighters, and once they found the breakthrough point of the German army, they immediately moved to extinguish the fire.

And this unique tactic also left a design idea that was contrary to the mainstream of the time for the future Jewish use of armored forces. The Jews wanted an anti-tank platform with strong armor and good maneuverability. From the very beginning, the Jewish armoured forces were based on defense, which was completely different from the offensive of their good friends, the Red Army. This also led to the fact that the advanced tanks of the Red Army did not fully meet the needs of the Jews.

In the 1960s, the Jews developed the distinctive Merkava tank, which had a front-mounted engine and gearbox, and was a true outlier to the super-heavy tank built with extensive use of inclined armor. It is not suitable for real armored warfare, and it is easy to be paralyzed in the face of an evenly matched opponent, but fortunately, the Jews had a certain battlefield advantage at that time, and were able to control the battlefield to recover the paralyzed merkava and then repair it, but the merkava based on defense was still good to use as a mobile turret.

The northern front was a stalemate for both sides, and the real complication was the central and southern fronts, where the German army was at a total disadvantage and passive with the crushing defeat of the Second Battle of Bryansk on the central front, which stretched from Minsk to Mozyr, and basically lost the ability to maintain the front. If it were not for the fact that the Red Army had previously carried out continuous operations with relatively high consumption and was unable to continue to pursue the victory, it would not have been a big problem to drive the German army to the border line between Belarus and East Poland.

The situation of the Germans on the southern front was only slightly better, and the capture of Kyiv was a political boost for the Germans, at least in Germany, and Hitler's personal popularity reached its peak.

But we all know that Kyiv was not captured by the Germans, but abandoned by the Red Army on its own initiative. The reason why the Red Army abandoned Kyiv was actually for the sake of a counteroffensive, and with the return of the Ukrainian Second Front to the north of Kiev, the time was basically ripe for the Ukrainian First Front and the Second Ukrainian Front to regain Kyiv and encircle and annihilate the Manstein cluster and the German 17th Army.

For the Red Army, it was basically a matter of time before the operation was carried out, as soon as the supplies were in place, as soon as the Ukrainian Second Front had completed its rest, it would be possible to give the Germans a little color. Note that the two fronts of the Red Army in the Kiev direction concentrated the huge forces of about 8 armies, while the Germans against them had only four armies, and the difference in strength between the two sides was almost a multiple!

If we take into account the fact that the Voronezh Front and the 3rd Ukrainian Front are already ready for battle, in the future the forces of the Red Army will swell to at least 12 army groups. And the Germans will not be able to make up many people even if they squeeze Hungary, Romania and Italy cannon fodder again, so to speak, once the battle for Kyiv breaks out, the Germans will face a raging storm!

This storm will sweep through Ukraine, driving the Germans all the way to eastern Poland and threatening Romania. Let's put it this way, the situation of the Germans is really a pill!

Of course, Hitler could not admit defeat, and the Führer always believed that the winner of this war could only be him and Germany. Especially when the Führer found the key fortress and fortress tactics to turn the tide of the war, he believed that passivity was only temporary, and after the fortressed Kiev and other large and medium-sized cities consumed the vital force of the Bolshevik devil, the great Germany would win the victory in one go.

However, at that time, there were not many people who were optimistic about the Führer's tactics, such as Manstein, who was dismissive of this so-called fortress and fortress tactic...... (To be continued.) )

PS: Bow and thank you for a piece of snow 1, frankregill, the king of horsemen and comrade Juventus!