The development of radar began in the 1980s. The earliest radar companies in the world were: vega (pulse radar) and saab (FM radar).
Vega is a low-end radar. Technically, it is a pulse radar. The emission principle is relatively simple, namely: sending a high-frequency pulse (6.3GHZ), the microwave is reflected back after encountering the medium, the microwave propagation speed is the speed of light, and the temperature is irrelevant to the calculation of the propagation time to calculate the distance; but, due to If it depends on time to calculate the value, it needs to be accurate to tens of ps (1ps = 10^-12s), that is, it is equivalent to dividing one second into 10^12 (10 12th power) shares.
L = T (propagation time) * C (light speed) / 2 (formula 1)
Introduced: â–³L = â–³t * C (light speed) (Equation 2)
Where ------C=3*10^5Km = 3*10^8m=3*10^11mm
â–³t = â–³L/ C (formula 3)
We assume that the measurement accuracy is 5mm, then: Δt=5/(3*10^11)=16.666 ps
At present, the most accurate record time is 50ps, and the chip price is generally 200~500 yuan. Calculated with time 50ps, the measurement error: ΔL = Δt * C = 15mm.
In other words, if the pulse radar only processes data with time, the highest precision is 15mm.
The Vega radar had been produced as early as the 1980s, and the high-precision time recording chip was only available in 2002. Therefore, most of the early-pulse radars used the time-expanded method to accurately record the time, plus multiple measurements to obtain the average The way. Regardless of how the development time is used and the average delivery value is obtained, the final accuracy must reach 5 to 10 mm, all of which are somewhat unrealistic.
As early as 2005, Vega radar occupied 80 to 85% of the domestic market, mainly due to its massive publicity in China, and no corresponding domestic radar products. Since 2004, pulse radars have appeared in 3 to 5 countries in succession. Manufacturers, vega radar market is being replaced by domestic radar manufacturers. Saab entered the domestic market in 1999, which is 6-7 years later than vega. After entering the domestic market, saab has been positioned in the high-end products sector, and is only targeting the petroleum and chemical industries. At present, radars used in domestic oil and chemical industry before 2002 were basically saab radar. Saab radar prices are very expensive, ordinary radar prices in the 3 to 40,000, slightly higher precision radar (FM radar) prices in the 8-10 million yuan. The principle of FM radar is to send continuous signals (eg, signal bands from 6 to 7 GZH, 8 to 9 GZH, etc.), perform FFT changes on the received continuous signals, and perform phase-locked tracking on the signals to calculate the time difference between the two signals. Frequency modulated continuous-wave radar (FMCW) can obtain high accuracy, and its accuracy mainly depends on the temperature drift (temperature compensation of the crystal oscillator) and the FFT calculation speed of the chip. The use of warm-up crystal oscillator can generally achieve an accuracy of ±1mm.
At present FMCW radar has already had this kind of technology in China in 2001. As FMCW radar needs to be tested and tested in many aspects, such as EMC certification test and temperature test. Until the end of 2003, domestic FM continuous wave radar was formally launched. The basic processing of frequency modulated continuous wave radar is similar. Since domestic FM radars began to be developed after 2000, the speed of selecting chips and the selection of special devices are all superior to SAAB, and can be achieved within ±1mm through simple temperature compensation. Waveguides are measured with an accuracy of ±0.3mm. If you use a faster CPU and build some devices, it is easy to achieve ±0.1mm accuracy.
At present, radar level gauges are gradually replacing the foreign radar market as the domestic manufacturers’ technological strength continues to grow.
In terms of pulse radar, except for the fact that some manufacturers do not have professional technicians to assist in processing conditions, they are comparable to vega radars.
FMCW radar has so far been our only domestic one. Except for on-site installation and radar shell design, we still need to learn from the experience of foreign manufacturers; in terms of various performance parameters, working conditions, our Radar products are all stronger than SAAB; based on the advantages of foreign radars, we have adopted military technology to produce FM radars with independent property rights. We will provide customers with the highest quality service.