Simple comparison of ATM and IP technology
1. Service quality assurance
Whether for operators or users, QoS is a sign of service credibility. Due to the difference between connection-oriented and connectionless, IP technology and ATM technology are fundamentally different in quality of service (QoS) guarantee. The length of the IP packet is not fixed, and the delay between the information packaging and unpacking in the long and short packets is very different, which introduces a large delay jitter and is not suitable for real-time services. When the number of users increases, the service quality decreases, resulting in unstable service quality. At present, some demonstration real-time applications actually exchange low bandwidth utilization for high quality of service. ATM technology uses fixed-length cells to make the delays of packing and unpacking equivalent, reducing delay jitter, and the small cell length reduces the delay value. In addition, ATM uses flow control technology. Before the connection is established, it can negotiate whether the user's service quality requirements can be guaranteed through signaling. Only after the network is confirmed will it accept the network access to ensure that each virtual circuit provides a different service quality. This is true quality of service (QoS). In order to make up for the defects of IP technology in service quality, TETF proposed such as RSVP (Resource ReservaTIon Protocol) protocol. However, due to IP limitations, the implementation of the protocol is complicated and progress is slow.
2. Protocol simplification
From the perspective of the development process, in the early stage of the development of the IP technology, the transmission technology was not ideal, so techniques such as error correction section by section and feedback retransmission were used, which made the protocol complicated. With the development of optical fiber technology and the improvement of transmission and processing capabilities, these parts have become redundant. However, due to software and hardware investment issues, IP itself has become an obstacle and can only retain these functions. This will inevitably affect the network transmission efficiency. ATM technology makes full use of the development of optical fiber technology, simplifies error control, and does not check the integrity of services at intermediate nodes, greatly simplifying the protocol. ATM flow control and signaling is to obtain the improvement of network utilization rate and the guarantee of service quality with precise control. Although more complicated, it is worth it.
TCP / IP is the basic protocol of the Internet. The IP layer in the TCP / IP protocol framework corresponds to the network layer in the OSI reference model, which completes routing and packet forwarding functions, while TCP corresponds to the transport layer in the OSI reference model. Confirmation of data receipt and error correction from end to end. It can be seen that the IP protocol is essentially a data protocol that does not need to establish a connection in advance, but directly depends on the IP packet header information to determine the packet forwarding path. Technically speaking, it has the following characteristics: First, the distributed structure; second, the end-to-end principle, all value-added functions are completed by the terminal outside the network; third, the IP network can be established on any transmission channel, you can Ensure the interoperability of heterogeneous networks; Fourth, it has a unified addressing system, and the network is highly scalable.
ATM works in a connection-oriented manner. At the beginning of communication, a virtual circuit is first established, and the virtual circuit logo is written into the letterhead. The network sends cells to the destination according to the virtual circuit logo. In order to simplify network control, ATM hands over error control and flow control to the terminal, without the need for link-by-segment link error control and flow control. Can improve processing speed, ensure quality, reduce delay and cell loss rate. ATM combines the advantages of circuit switching and packet switching, that is, ATM has the advantages of statistical multiplexing, flexibility and efficiency, small transmission delay, and good real-time performance. It can carry multiple information media in a single main body network, carry multiple communication services, and can guarantee Qos.
Compared with ATM technology, IP technology has inherent deficiencies in service quality assurance, security, statistical multiplexing, traffic management, and congestion control. When the number of users is relatively small, these problems are not so prominent, and once the number of users increases rapidly, the data traffic on the Internet increases, and the problem comes up. Therefore, in terms of service quality assurance, IP technology is not as good as ATM technology.
Yuhai piezo materials include : hard piezo material, soft piezo material and lead free piezo material
Soft piezo material exhibits: larger piezoelectric constants, higher permittivity, larger dielectric constants, higher dielectric losses, larger electromechanical coupling factors, low mechanical quality factors, a lower coercive field, poor linearity, and is easier to depolarize. The ideal application of soft piezo materials is sensing needs. Yuhai soft pizeo materials are PZT-5, PZT-5H, PSnN-5 and PLiS-51.
Hard piezo material exhibits: smaller piezoelectric constants, lower permittivity, smaller dielectric constants, lower dielectric losses, smaller electromechanical coupling factors, high mechanical quality factors, a higher coercive field, better linearity, and is harder to depolarize. The ideal application of hard piezo materials is high power transducer needs. Yuhai hard pizeo materials are PZT-4, PZT-8, PCrN-4 and PBaS-4.
Yuhai company developped lead free piezo material BaTiO3 and apply for the Chinese Patent in 2011, to meet the needs of environmental protection in today's society.
Piezoelectric Ceramic material
Properties and Classification
General description of material properties
Material Code
Properties
Application
Soft PZT ceramic
PZT-51
Characteristics:
larger piezoelectric constants, higher permittivity, larger dielectric
constants, higher dielectric losses, larger electromechanical coupling
factors, low mechanical quality factors, a lower coercive field, poor
linearity, and is easier to depolarize.
low-power ultrasonic transducers
PZT-52
low-frequency sound transducers
PZT-53
applications with high g coefficient, for example,
PZT-5H
microphones,vibration pickups with preamplifier
PLiS-51
low-frequency vibration measurements
PMgN-51
Hydrophones, transducers in medical diagnostics
PSnN-5
Actuators
Hard PZT ceramic
PZT-41
Characteristics: smaller
piezoelectric constants, lower permittivity, smaller dielectric
constants, lower dielectric losses, smaller electromechanical coupling
factors, high mechanical quality factors, a higher coercive field,
better linearity, and is harder to depolarize.
PZT-42
High-power acoustic applications
PZT-43
Hydroacoustics, sonar technology
PZT-82
piezomotor
PCrN-4
PBaS-4
Lead free Piezo Ceramic
BaTiO3
Characteristics: Low density, low curie temperature, lead free.
Ultrasonic transducers suitable for low-temperature underwater, for example Ultrasonic Transducer in fishfinder
Piezoelectric Material,Piezo Ceramic Element,Piezo Electric Cylinder ,Piezo Sphere
Zibo Yuhai Electronic Ceramic Co., Ltd. , https://www.yhpiezo.com