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Application field of dual-frequency chip timing system
Professional sports events: track and field middle and long distance running, race walking, marathon, triathlon, relay race, swimming, bicycle, motorcycle, cross-country skiing, roller skating, kart and many other formal sports events;
Education field: widely used in school sports games, winter long-distance running, sports tests, daily training and tests in sports schools, and timing of high school entrance examinations;
Army and military academies: daily training, assessment and competition, mainly used for: 3000 meters, 5000 meters, 400 meters obstacles, 10 meters × 5 round-trip running, etc.
1. The working principle of dual-frequency chip timing system
Whenever an athlete takes a dual-frequency electronic tag through the timing coil on the runway, the 125K low-frequency activation antenna can immediately activate the dual-frequency electronic tag information. The dual-frequency electronic tag actively sends data to nearby readers in real time, and the reader will read it again. The received card data is uploaded to the connected computer, and the computer obtains the relevant information of the athletes and records the corresponding time when passing, and uses special software to perform a series of processing on the information. The start time of running can be collected by the “timing start” button drawn by the reader and uploaded to the computer back-end system software. The back-end system software corresponds the collected start time and card information with the corresponding athlete information, and counts the competition situation, so as to realize the running status. The purpose of automatic project timing.
The system lays a set of 125K ground-sensing coils at the end for the sports lap counting system.
When the dual-frequency sports timing chip tag carried by the athlete passes the timing carpet, the carpet antenna sends the response signal of the received RFID tag to the reading head connected to it, and the reading head records the current time and the relevant information of the tag to complete the timing. Features. Competition results can be displayed in real time, and referees or training organizers can view, edit, and print the results through the timing system software installed on the computer.
2. Comparison of current technology of dual-frequency chip timing system
current technology:
125kHz/134.2kHz low frequency, 13.56MHz high frequency, 915MHz ultra high frequency, 2.45GHz/5.8GHz microwave.
The frequency of low frequency technology is very low, which means that its carrier frequency is low, and the rate of the data signal modulated on it will be very low. In this way, the system cannot process a large amount of received data at the same time, resulting in weak anti-collision capabilities, and can only read several tags at the same time.
High-frequency technology, such as subway tickets, has a very short range of action, only a few or a dozen centimeters. Because increasing the power makes the distance farther, it will cause a large number of blind spots in the radiation range of the antenna. That is to say, when the tag or card is moved from far and near to the reader, it will not be able to be read after a certain distance.
UHF and microwave technologies are particularly susceptible to environmental influences, and UHF electromagnetic waves propagate approximately in a straight line in the air. Metal objects will obscure the RFID tag placed behind it. Liquid has the ability to “absorb” UHF electromagnetic waves, and the reading performance of UHF RFID tags placed behind the liquid will drop sharply. In addition, the performance of the UHF tag is greatly affected by the material of the article to which it is attached. For common materials such as corrugated boxes, wood, metal, plastic, liquid surface, glass, rubber, etc., different tag antennas need to be developed. Otherwise, the reading distance of the tag may drop from 7 meters to several tens of centimeters, and it cannot be received by the card reader. A variety of different UHF tags will bring great inconvenience to actual use.
It can be seen that there are limitations in the actual use of single-frequency RFID technology. Only in the application scenarios that are most suitable for the technical characteristics of this frequency can a satisfactory effect be achieved.
People can’t help but wonder whether a technology can be developed that takes the advantages of different frequencies while discarding their shortcomings. RFID dual-frequency technology (125K and 2.45G) was born in this way.
Advantages of dual frequency technology:
The 125K low-frequency receiving frequency guarantees a very high data transmission rate and strong anti-collision capabilities, so the system can read multiple chips at the same time.
Because 2.45G microwave is the receiving frequency, and the receiving distance of the card reader, the sensitivity index is easy to do well. Therefore, there is a good reception effect in the entire 2.45G antenna radiation range, and no signal coverage blind zone will be generated.
Dual frequency technology combines the advantages of 125K low frequency and 2.45G microwave technology and abandons their defects. At present, dual-frequency technology is the only technology in the world that can truly realize the timing of chip electronic tags for multiple people at the same time.
3. Timing system hardware introduction
Timing system reader
Timing chip label
Timing carpet/induction coil
1) The dual-frequency motion timing induction coil needs to be connected to the dual-frequency reader to complete the timing function. When the timing induction coil receives the response signal from the dual-frequency timing chip tag, the reading head records the current time and the tag ID number. The timing induction coil can be used in various environments and is waterproof, and can be used for running, cycling, and ice and snow sports; the carpet is quite strong and durable.
2) The ground induction coil contains an independent induction loop (125kHz to activate and wake up the tag) and a receiving loop (2.45G to receive the tag response signal). Sometimes the resonant frequency of the loop will be affected by surrounding metal objects (such as reinforced concrete, water pipes, etc.), thereby affecting the reading distance. For this reason, a special auto-tuning circuit is included in the reading head to minimize this effect.
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