ST60 millimeter wave water medium data transmission test report——part1

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ST60 millimeter wave water medium data transmission test report

Document Number	TR_ST60_0001
Keywords	ST60, 60GHz, water medium data transmission, water medium communication
Summary	This test report records the test of ST60's 60GHz high-speed data communication for water medium data transmission, by comparing the data transmission and speed of different media separated by communication modules, including air, pure water, sodium chloride solutions of different concentrations (saturated concentration 26.4%, 1/8 saturated concentration, 3.5‰ concentration of seawater and other salinity), and sediment mixtures of different concentrations. The results show that ST60 can penetrate the water medium and achieve data transmission only when the two communication module shells are pressed tightly together, the gap is very small, and the thickness of the water layer in the middle (including pure water, saturated sodium chloride solution, 3.5‰ sodium chloride solution with salinity equal to seawater, and mud-sand mixture) is extremely low;

Mars4zhu

2022-03-09

Table of contents

2 Test Purpose 1

3 ST60 millimeter wave learning and preliminary trial 1

3.1 Introduction to 60GHz millimeter wave 1

3.2 SK201E data collection and ST60 millimeter wave technology introduction 2

3.3 ST60 is used to test the speed of the computer and the public network 3

3.4 ST60 for peer-to-peer network speed test between computer and Raspberry Pi 4

4 ST60 mmWave Water Media Data Transmission Evaluation Test Procedure 4

5. Build a test device for evaluating data transmission in water medium. 5

6 Test water equipment for different water qualities 7

7 Evaluation Results Summary 8

7.1 Transmission medium: air 8

7.2 Transmission medium: pure water 9

7.3 Transmission medium: sodium chloride solution 10

7.3.1 Saturated sodium chloride solution 10

7.3.2 Sodium chloride solutions of different concentrations 11

7.4 Transmission medium: mud-water mixture 11

7.4.1 Saturated mud-water mixture 11

7.4.2 Mud-water mixtures of different concentrations 12

7.5 Test results summary table 13

8 Conclusion 13

9 Revision History 14

Illustration Index

Figure 31 Results of searching for “millimeter wave screen projection” on the Internet 2

Figure 32 Physical picture of SK201E module 2

Figure 33: Internet speed test of a computer connected directly to the public network and connected via ST60

Figure 34: Internet speed test of the computer connected to the public network through ST60

Figure 35 Point-to-point network speed test between computer and Raspberry Pi 4 via ST60

Figure 36 SK201E module ST60 high-speed communication function block diagram 4

Figure 51 Three sets of liquid container evaluation tools with different thicknesses 5

Figure 52 Three gap thickness configurations between two glass plates (0.9mm, 0.45mm, ~0.1mm) 6

Figure 61: Sodium chloride solutions of different concentrations and their raw materials (salt, purified water)

Figure 62: Prepared mud-water mixtures of different concentrations and their raw materials (mud, pure water) 8

Figure 71 Gap medium: air, spacing: 0.1~10mm, transmission speed is 950Mps 8

Figure 72 Data transmission rate change after staggering and then restoring 9

Figure 73: Medium: pure water, ID card placed on one or both sides of the glass plate, unable to connect, data transmission rate is 0 9

Figure 74: The data transmission rate changes when the medium is pure water, the ID card is placed on the glass plate, and the ID card is removed 10

Figure 75: Medium sodium chloride solution, data transmission rate change when ID card is placed on glass plate and ID card is removed 10

Figure 76: Changes in data transmission rate when a thicker layer of sodium chloride solution is placed on the glass plate.

Figure 75: Data transmission rate change of medium mud-water mixture, ID card placed on glass plate, and ID card removed 12

Figure 75 The medium is a mixture of mud and water, and a piece of paper towel is sandwiched between a glass plate. The data transmission rate is 0 12

Table Index

background

In recent years, with the rapid development and cross-border integration of technology, underwater exploration capabilities have also made great progress. In the past, when facing the complex and changeable underwater environment, there would be certain errors in the positioning, excitation and reception of signals during exploration operations, which would also affect the final exploration results. OBN stands for Ocean Bottom Node, which is an instrument located on the seabed that can independently collect and record signals.

"Seabed nodes" are independent detectors that are free from the constraints of cables and can be flexibly deployed on the seabed, with more accurate positioning and higher quality data collection. The current workflow is mainly: use a water-based robot to deploy the self-powered OBN on the seabed → record signals → recover the OBN → download data → redeploy, and then process and analyze the accumulated data recorded in this cycle. Due to the large amount of data and the inability to use high-speed wireless communications such as Wifi underwater. At present, the most time-consuming and labor-intensive work in this process is to fish the node out of the water, download the data and redeploy it.

Testing purposes

The contactless connector based on ST60's short-range high-speed wireless communication technology can achieve high-speed wireless communication inside and outside the device while the device is completely sealed and waterproof;

By attaching the signal line to the underwater instrument through magnetic absorption and other methods, data can be directly transmitted back to the surface without removing the instrument, which greatly reduces the workload and complexity and improves efficiency. The instrument is fully enclosed, without plugging and unplugging, without loss, and with low maintenance costs; therefore, we applied for the trial of this module to explore the feasibility of ST60 for high-speed data transmission of enclosed underwater instruments.

Study and initial trial of ST60 millimeter wave

Introduction to 60GHz millimeter wave

I did a simple search on the application of millimeter waves. Due to the rapid development of WiFi 6 technology, laboratory tests have been able to achieve 1.2 Gbps or even 2.4 Gbps communication, and in practical scenarios, the speed can reach about 800 Mbps. A few days ago, I also saw that ZTE launched WiFi 7 chips with a speed of 5 Gbps or even 10 Gbps. Therefore, in terms of consumer data transmission, the application gap of 60 GHz millimeter waves is relatively large.

However, in some relatively niche applications, such as wireless screen projection, real-time VR, low-latency data control, etc., millimeter waves have shown their prowess. For example, if you search for "millimeter wave screen projection", you can see some evaluation articles of screen projection devices.

SK201E data collection and ST60 millimeter wave technology introduction

SK201E is a SKLink wireless millimeter wave product launched by Shenzhen Ipsen Technology Co., Ltd. It adopts PCB antenna design and supports full-duplex Gigabit Ethernet through 60GH millimeter wave to achieve Gigabit network air connection. Its interface is RJ45 connector, based on STMicroelectronics' leading ST60A2 millimeter wave transceiver design.

As a simplified version of WIFI wireless transmission, STMicroelectronics' ST60 series contactless connection technology abandons its protocol stack and adopts semiconductor processing technology to achieve ultra-high bandwidth, low power consumption, short-range, point-to-point wireless connection and transmission based on the 60GHz millimeter wave frequency band.

ST60 is used to test the speed of the computer and the public network

Use a Category 5e network cable (CAT5e) to directly connect the computer to the wired network port of the broadband public network, and use speedtest.cn to test the network speed.

Then use two CAT5e network cables to connect the computer and ST60, as well as the ST60 and the wired network port respectively. Then use tape to fix the ST60 to the test box and the glass cover, align the upper and lower ST60s, and use speedtest.cn to test the network speed.

Through preliminary tests, it was found that the network speeds measured by direct connection and connection through ST60 are exactly the same, both of which are the normal download and upload speeds of the installed broadband (claimed to be a Gigabit network, but the actual measurement is 500M, orz) (the upload speed of general home broadband is much lower than the download speed, and the broadband speed is based on the download speed).

ST60 is used for peer-to-peer network speed testing between computers and Raspberry Pi 4

In order to test the function and performance of ST60 in water medium data communication, a Raspberry Pi 4 Gigabit Ethernet port was used to represent the water medium device. A CAT5e network cable was used to directly connect the computer to the Raspberry Pi 4. At this time, the measured network speed was 948Mbps. If the additional overhead of network communication messages is taken into account, it is just close to the full speed of the network card 1Gbps.

Then use two CAT5e network cables to connect the computer and ST60, and ST60 and the wired network port respectively, and use speedtest.cn to test the network speed.

Replace the network cable between the Raspberry Pi 4 and ST60 with a normal 100M network cable, and set the computer network card to 1Gbps and 100Mbps. Tests show that when both are 100Mbps, a connection can be established and stable at the full speed of 100Mbps.

However, when the Raspberry Pi 4 is connected at 100Mbps and the computer is connected at 1Gbps, the two cannot establish a network connection through ST60.