Hedging of digital currency contract market maker
Publish: 2021-05-08 17:27:13
1. 1. digital currency contract, also known as futures contract. In short, it's business in the future. A standardized contract uniformly formulated by the exchange to deliver a certain quantity and quality at a specific time and place in the future. The vast majority of users use the margin system of futures contracts, add 10 or even 20 times leverage to leverage big funds, and then use the index fluctuation to buy low and sell high trading contracts, so as to earn double profits< 2. Perpetual contracts are derivatives. From the perspective of trading, it is similar to the traditional futures contract, but there are some differences. First of all, it has no maturity or settlement date. The perpetual swap contract is similar to a margin spot market, so its trading price is close to the underlying reference index price, which is different from the futures contract. Due to the basis, the trading price difference of the futures contract may be significantly different. Secondly, the main mechanism of anchoring spot price is capital cost< At present, rolling spot futures is the main form of perpetual contracts. Rolling contract is a kind of futures contract settled on the same day and automatically extended. Profit and loss are settled on each trading day, and the contract position held by traders will be automatically extended at the end of the trading day. In addition, the cash flow of assets will be exchanged, and the long investors will pay the capital cost to the short investors to compensate the capital cost of the short investors
3. Option contract is a kind of agreement, which can give traders the right to buy or sell assets at a predetermined price before a specific date or on a specific date. Option contracts are trading derivatives that can be based on a wide range of underlying assets, including stocks and cryptocurrencies. These contracts may also come from information such as financial indicators. Generally, option contracts are used to hedge the risk of existing positions and speculative transactions.
3. Option contract is a kind of agreement, which can give traders the right to buy or sell assets at a predetermined price before a specific date or on a specific date. Option contracts are trading derivatives that can be based on a wide range of underlying assets, including stocks and cryptocurrencies. These contracts may also come from information such as financial indicators. Generally, option contracts are used to hedge the risk of existing positions and speculative transactions.
2.
The contract transaction of digital currency is not safe. There are still many loopholes in the digital currency trading platform, for example, the most common are the following six kinds:
1. Denial of service attack
denial of service attack is the most important attack against the digital currency trading platform at present. Through denial of service attack, the attacker makes the trading platform unable to access normally, Because users can not accurately distinguish the degree of attack, it often causes panic asset transfer, which brings some loss
2. Phishing incident
even the best technical measures at present can not make the digital currency trading platform avoid phishing attacks. Some hackers and criminals can confuse digital currency investors by means of fake domain names or fake pages, while ordinary investors can't identify the authenticity, so it's easy to cause asset losses
Many digital currency trading platforms use a single private key to protect the hot wallet. If hackers can access a single private key, they can crack the hot wallet related to the private key. For example, in the attack on yapizon of Seoul stock exchange in 2017, the attackers stole hot wallets from the trading platform twice in a year, resulting in a total loss of nearly 50% of the assets of the trading platform and eventually leading to the bankruptcy of the trading platform Fourth, e to the lack of perfect risk isolation measures, or ineffective supervision on the rights of employees, some employees who have the operation rights of the platform use internal trust to seek unjust wealth for themselves. For example, in 2016, the event of employees stealing bitcoin on shapeshift caused a total loss of US $230000 to the trading platform by stealing and reselling sensitive information to others Fifth, the software vulnerability of digital currency trading platform includes single sign on vulnerability, OAuth protocol vulnerability and so on. At present, all countries have laws requiring banks or other financial institutions to implement information security measures to protect customers' deposits. However, e to the fact that the blockchain field is still in its infancy, there is a lack of such specifications for encrypting digital assets. Therefore, it is not accidental that many trading platforms have a large number of loopholes in the absence of security constraints 6. Transaction malleability the technical supporters of blockchain often think that blockchain transactions are highly secure because they are recorded on records that are said to be unchangeable, but each transaction needs to have a corresponding signature, and the records can be forged temporarily before the final confirmation of the transaction 
extended data:
rules of contract transaction
1. Transaction time
contract transaction is 7 * 24 hours transaction, which will be interrupted only ring the settlement or delivery period of 16:00 (UTC + 8) every Friday. In the last 10 minutes before delivery, the contract can only be closed, not opened
Transaction types are divided into two types, opening and closing. Opening and closing positions are divided into two directions: buying and selling:buying open long (bullish) refers to buying a certain number of contracts when users are bullish and bullish on the index. Carry out "buy open more" operation, match success will increase long position
selling pingo (multi order closing) refers to the selling contract that the user makes up for when he is no longer bullish on the future index, offsets with the current buying contract and exits the market. Carry on "sell flat much" operation, match after success, will rece long position
short selling (bearish) refers to the new sale of a certain number of certain contracts when the user is short or bearish on the index. Carry out the operation of "sell short" and increase the short position after successful matching
buy close (short single close) refers to the buy contract that the user will not be bearish on the future index market and make up for, offset with the current sell contract and exit the market. Carry out "buy short" operation, after matching successfully, short position will be reced
3. Order method
limit order: the user needs to specify the price and quantity of the order. Limit order can be used for opening and closing positions
order at opposite price: if you choose to order at opposite price, you can only enter the order quantity, not the order price. The system will read the latest competitor price at the moment of receiving the entrustment (if the user buys, the competitor price is the selling price of 1); If it is a sell, then the counter price is buy 1 price). Issue a price limit order for this counter price
4. Position
the user owns the position after opening and trading, and the positions in the same direction of the same contract will be merged. In a contract account, there can only be 6 positions at most, that is, multiple positions of current week contract, short positions of current week contract, multiple positions of next week contract, short positions of next week contract, multiple positions of quarterly contract and short positions of quarterly contract
5. Order restriction
the platform will restrict the number of single user's positions in a certain period of contract and the number of single open / close positions, so as to prevent users from manipulating the market
when the number of positions or entrustments of users is too large, the platform has the right to require users to take risk control measures, including but not limited to cancellation of orders, closing positions, etc. The platform has the right to adopt measures including but not limited to limiting the total number of positions, limiting the total number of consignments, limiting the opening of positions, withdrawing orders, forcibly closing positions, etc. for risk control
3. There is no doubt that bitcoin is the best target, and some platform currencies have investment value, such as okb. Don't forget to adopt it
4. Renbtc is based on the BTC anchor currency issued by renprotocol and circulated in Ethereum network. The value of renbtc and real bitcoin is 1:1 anchored
renprotocol has launched the renvm virtual machine on May 27, 2020. Users can deposit the native BTC in the designated renbridge gateway as collateral. Renvm issues the corresponding renbtc in the Ethereum network through the smart contract, which makes the whole distribution process more decentralized
as a person who has been in the coin circle for three years, I am optimistic about the development of ecell coin in the future, because ecell coin is erc20 token (celletf. IO) realized through Ethereum network smart contract, which adopts blockchain technology, all transaction processes on the chain need the approval of each node in the network, and the whole process is transparent and open.
renprotocol has launched the renvm virtual machine on May 27, 2020. Users can deposit the native BTC in the designated renbridge gateway as collateral. Renvm issues the corresponding renbtc in the Ethereum network through the smart contract, which makes the whole distribution process more decentralized
as a person who has been in the coin circle for three years, I am optimistic about the development of ecell coin in the future, because ecell coin is erc20 token (celletf. IO) realized through Ethereum network smart contract, which adopts blockchain technology, all transaction processes on the chain need the approval of each node in the network, and the whole process is transparent and open.
5. Hello, landlord
I'm afraid I can't find the route and station when I take the bus. You can go to the next map and Tencent map.
it's easy to find the place to go and the route on the map with clear route. It's very convenient to find the station and route on the map and type the destination, He also provides a variety of taxi and bus self driving routes to query
nearly a number of cities across the country, as well as the geographical location of banks, hospitals, hotels, parks, etc.
users can use satellite maps and Tencent street view maps to find more accurate locations and targets, and watch high-definition panoramic images of cities covered by the street view map service
I'm afraid I can't find the route and station when I take the bus. You can go to the next map and Tencent map.
it's easy to find the place to go and the route on the map with clear route. It's very convenient to find the station and route on the map and type the destination, He also provides a variety of taxi and bus self driving routes to query
nearly a number of cities across the country, as well as the geographical location of banks, hospitals, hotels, parks, etc.
users can use satellite maps and Tencent street view maps to find more accurate locations and targets, and watch high-definition panoramic images of cities covered by the street view map service
6. Scheme 1: DMR walkie talkie with MCU as the core processor (MSP430F149 + ambe1000)
1. Working principle
when transmitting, the analog voice sent by the microphone is a / D converted by csp1027, the voice is compressed by the vocoder ambe1000, and then it is sent to the MCU MSP430F149 for filling and framing, and then it is sent to cc1101 for molation and emission. When receiving, the code demolated by cc1101 flows through MSP430F149 for frame recovery, and then it is decompressed by vocoder. The data is converted into analog voice signal by D / a through csp1027< The key device is MSP430F149 of TI company, which is a 16 bit ultra-low power, mixed signal microcontroller with von Neumann structure and JTAG (a standard test interface) for simulation and debugging
the power supply voltage of the chip is (1.8 ~ 3.6) V, the power consumption is only 0.1ua in RAM data holding mode, and 250 UA / MIPS (million instructions per second) in active mode. Because this single chip microcomputer uses 16 bit RISC (reced instruction set computer), one clock cycle can execute one instruction, while the traditional single chip microcomputer needs 12 clock cycles to execute one instruction. Operating at 8 MHz crystal frequency, the instruction speed can reach 8 MIPs, and the same instruction speed, 16 bit processor is much more than twice higher than 8-bit processor
overview
the vocoder ambe1000 has been proced in China, and the price is reasonable. The sensitivity of cc1101 is - 116dbm (1.2kbps, 1% packet error rate, working at 433MHz), which is lower than the available sensitivity of domestic walkie talkie - 120dbm, but it is less than - 107dBm according to the EU CE standard. In addition, the power output of RF mole is only 12dbm (16mw), so this scheme is only suitable for short distance communication. Adf7021 can be used as RF mole to improve the sensitivity< In the second scheme, DSP + MCU is used as the core processor of the walkie talkie.
1. Working principle
in the second scheme, MSP430 is used as the central system to complete the data receiving and transmitting control, and the system adopts the SPI synchronous communication mode of USART mole in MSP430. In the receiving process, the FSK data from the RF chip is firstly received. After demolation, MSP430 removes the synchronization domain, tail domain, ID domain and command byte of the data frame. After that, the data is sent to c5402 for de compression processing, and the data is sent to AIC23 for D / a conversion to voice signal. In the sending process, AIC23 performs a / D conversion firstly, and c5402 compresses the data. Then MSP430 fills in the protocol, and adds the header domain, tail domain, ID domain and command byte to form the data frame, and then controls the RF mole to send the data< Key device
TMS320C5402 is a fixed-point DSP chip introced by TI company in 1996. It adopts advanced modified Harvard structure and 8-bus structure, which greatly improves the performance of the processor. Its independent program and data bus allows simultaneous access to program memory and data memory to achieve high-speed parallel operation. For example, three read operations and one write operation can be performed simultaneously in one instruction. The running speed of TMS320C5402 is 40mips and the instruction cycle is 25ns. In addition, it can transfer data between data bus and program bus. Thus, the processor can perform arithmetic operation, logic operation, displacement operation, multiplication and accumulation operation, access program, data storage and other powerful functions in a single cycle
overview
when DSP scheme is adopted, the trouble of selecting voice chip vocoder is avoided, the ability of digital walkie talkie to process voice is improved, the algorithm of voice coding is optimized as far as possible, so that the processing of voice signal of walkie talkie is more universal and expandable. This scheme is based on DSP, through CVSD molation codec, the speech signal has good clarity and naturalness, but the workload of software development is heavy. CC1000 does not support 4FSK molation and demolation, so this scheme is not suitable for DMR and dpmr protocols. In addition, the available sensitivity of CC1000 is - 110dbm, which may be too low for domestic interphone manufacturers< In the third scheme, the dpmr interphone scheme (cmx618 + cmx7141) with single chip microcomputer as the core processor
1. Working principle
when transmitting, the analog voice sent by the microphone is processed by gain adjustment, a / D conversion and compression in cmx618, and then enters cmx7141 baseband processor through SPI (serial peripheral interface), Under the control and management of microcontroller LPC2138, channel coding, dpmr protocol stack packaging, digital filtering and 4FSK molation are carried out inside cmx7141 chip. The voice data after molation and coding are respectively output to the external transmit VCO and voltage controlled temperature compensated reference clock through mod1 / 2 pin of cmx7141 chip. The RF carrier is output to the transmit power amplifier through two-point molation and then output to the antenna
when receiving, cmx7141 demolates the 4FSK demolation signal based on the superheterodyne RF receiving mole under the control and management of the microcontroller LPC2138, unpacks the dpmr, decodes the channel, and finally obtains the speech coding data, which is sent to cmx618 through the SPI serial port for speech decompression and recovery
2. Key device
the speech codec cmx618 is a proct of CML Microelectronics (Singapore) Pte Ltd. the chip consists of audio compression / decompression unit, ralcwi codec, forward error correction codec and other special function moles
ralcwi is a robust and advanced complex waveform insertion technology. Different from other speech coding and decoding technologies, it uses unique signal decomposition and parameter coding methods to ensure better speech quality at higher compression ratio
in the vocoder, the speech quality achieved by ralcwi technology is equivalent to that of the standard vocoder with the coding rate of more than 4kbps
overview
the advantages of this scheme are high flexibility in development, al-mode design of analog and digital, and the same hardware development platform can meet different standards of digital walkie talkie, support a variety of voice vocoders, and high RF receiving sensitivity, up to - 118dbm (when the bit error rate is 1%). The transmitting power is 0.5W, so it is easy to improve< The disadvantage of atb010 is that the cost of software development is high and there are some difficulties in the early stage. Atb010 only supports en301166 standard of dpmr, but does not support DMR.
scheme 4 uses MCU + DSP DMR walkie talkie (MSP430FG4619 + vc5510)
1. Working principle
when transmitting, the analog voice sent by microphone is sampled into digital signal by AD73311, AMBE2000 compresses and encodes the digital voice signal. The digital signal is filled with DMR communication protocol by vc5510 to form frame signal and FM wave shaping of 4FSK. Finally, the MCU performs D / a conversion and sends it to the RF mole for transmission molation to realize transmission
when receiving, MCU sends the demolated data from RF mole for a / D conversion, and then splits the frame by vc5510, and decompresses it by AMBE2000. The data is converted from AD73311 to voice signal< The MCU MSP430FG4619 is the control center of the whole system, and the man-machine interface such as keyboard and display is directly connected with MCU. MCU controls RF mole, including baseband signal sending and receiving, RF frequency point control, channel detection, etc. MCU is also responsible for DMR protocol high-level signaling control, man-machine interface interoperability, etc
in addition, please note that the microcontroller should also complete the ad / DA conversion function of baseband signal< The AMBE2000TM vocoder is an adaptive, high-performance, single-chip speech codec developed by DVSI. It can provide excellent speech quality at low bit rate, and realize real-time, full plex standard setting AMBE speech compression software algorithm
a large number of evaluations show that the vocoder has the ability to provide the same performance as the digital cellular system at normal data rates. AMBE maintains natural speech quality and clarity at 2.4kbps rate. Due to its low complexity, AMBE can be fully integrated into low-cost and low-power chips
overview
the scheme is simple and practical
in software development, the program of microcontroller and digital processor must have a clear concept of DMR protocol layering, and the correct program design is the guarantee of hardware implementation. The selection of vocoder has more room< When transmitting, the voice signal sent by the microphone is sampled by the digital to analog converter AD73311, and the data is compressed by the vocoder. The DSP and arm in OMAP5910 add and control the compressed data to form the 4FSK waveform. The digital to analog converter AIC23 simulates the 4FSK digital waveform and then molates the RF, FM carrier is transmitted by antenna
when receiving, the RF mole demolates the received analog signal, and the analog signal is sent to AIC23 for digital processing. OMAP5910 decodes and frames the received data. The frame signal is decompressed by vocoder, and the data is restored to analog voice signal by AD73311< Key device
OMAP5910 is an embedded al core processor, which integrates high-performance arm925, TMS320C55x DSP core and various widely used interfaces and peripherals. It has strong processing power, low power consumption and high signal price ratio. ARM processor core is used for DMR protocol processing and system control, DSP core is used for real-time digital signal processing
OMAP5910 and its design suite have multiple target application markets, providing multimedia functions, improving human-computer interface and extending battery life
overview
technically speaking, compared with DSP + MCU, the al core processor scheme can rece the volume of the system, rece the complexity of the circuit, make better compatibility with the communication protocol, and have a large upgrade space. The application of vocoder has the choice of domestic chip
the disadvantage is that the workload of software development in the early stage is heavy, and the coordination between arm and DSP should be studied in depth to avoid wasting the resources of processor. In addition, e to the powerful functions of OMAP, the platform can also have more applications, such as adding video, entertainment and other functions< Working principle
when transmitting, the analog voice sent by the microphone is a / D converted by wm8758b and sent to sct3252 for compression processing. After dpmr protocol processing by sct3252, it is sent to the D / a conversion unit of wm8758b for molation into 4FSK signal. After two-point molation, the radio frequency carrier is output to the transmitting power amplifier and sent to the antenna for output
when receiving, wm8758b performs a / D conversion on RF analog signal, sends it to sct3252 for 4FSK demolation, dpmr unpacking, channel decoding, and finally obtains speech coding data. After decoding, the speech data is sent to wm8758b for D / a conversion, and then sent to the bell through external amplification circuit to restore voice< The key device
sct3252 is a voice codec and dpmr stack processing chip proced by Shanghai Shikang company. It has good speech quality and high receiving sensitivity (up to - 126 DBM)
overview
the feature of this scheme is that speech codec and dpmr protocol stack are integrated in sct3252, which greatly reces the workload of control unit MCU. In addition, sct3252 is packaged in lqfp100, which is convenient for welding. The whole scheme is simple and the space for software upgrade is large. This scheme can realize the compatibility of digital and analog, and it is convenient to switch between digital and analog communication
wm8758b only plays the role of analog-to-digital conversion. Manufacturers believe that it is just around the corner to integrate it into sct3252.
1. Working principle
when transmitting, the analog voice sent by the microphone is a / D converted by csp1027, the voice is compressed by the vocoder ambe1000, and then it is sent to the MCU MSP430F149 for filling and framing, and then it is sent to cc1101 for molation and emission. When receiving, the code demolated by cc1101 flows through MSP430F149 for frame recovery, and then it is decompressed by vocoder. The data is converted into analog voice signal by D / a through csp1027< The key device is MSP430F149 of TI company, which is a 16 bit ultra-low power, mixed signal microcontroller with von Neumann structure and JTAG (a standard test interface) for simulation and debugging
the power supply voltage of the chip is (1.8 ~ 3.6) V, the power consumption is only 0.1ua in RAM data holding mode, and 250 UA / MIPS (million instructions per second) in active mode. Because this single chip microcomputer uses 16 bit RISC (reced instruction set computer), one clock cycle can execute one instruction, while the traditional single chip microcomputer needs 12 clock cycles to execute one instruction. Operating at 8 MHz crystal frequency, the instruction speed can reach 8 MIPs, and the same instruction speed, 16 bit processor is much more than twice higher than 8-bit processor
overview
the vocoder ambe1000 has been proced in China, and the price is reasonable. The sensitivity of cc1101 is - 116dbm (1.2kbps, 1% packet error rate, working at 433MHz), which is lower than the available sensitivity of domestic walkie talkie - 120dbm, but it is less than - 107dBm according to the EU CE standard. In addition, the power output of RF mole is only 12dbm (16mw), so this scheme is only suitable for short distance communication. Adf7021 can be used as RF mole to improve the sensitivity< In the second scheme, DSP + MCU is used as the core processor of the walkie talkie.
1. Working principle
in the second scheme, MSP430 is used as the central system to complete the data receiving and transmitting control, and the system adopts the SPI synchronous communication mode of USART mole in MSP430. In the receiving process, the FSK data from the RF chip is firstly received. After demolation, MSP430 removes the synchronization domain, tail domain, ID domain and command byte of the data frame. After that, the data is sent to c5402 for de compression processing, and the data is sent to AIC23 for D / a conversion to voice signal. In the sending process, AIC23 performs a / D conversion firstly, and c5402 compresses the data. Then MSP430 fills in the protocol, and adds the header domain, tail domain, ID domain and command byte to form the data frame, and then controls the RF mole to send the data< Key device
TMS320C5402 is a fixed-point DSP chip introced by TI company in 1996. It adopts advanced modified Harvard structure and 8-bus structure, which greatly improves the performance of the processor. Its independent program and data bus allows simultaneous access to program memory and data memory to achieve high-speed parallel operation. For example, three read operations and one write operation can be performed simultaneously in one instruction. The running speed of TMS320C5402 is 40mips and the instruction cycle is 25ns. In addition, it can transfer data between data bus and program bus. Thus, the processor can perform arithmetic operation, logic operation, displacement operation, multiplication and accumulation operation, access program, data storage and other powerful functions in a single cycle
overview
when DSP scheme is adopted, the trouble of selecting voice chip vocoder is avoided, the ability of digital walkie talkie to process voice is improved, the algorithm of voice coding is optimized as far as possible, so that the processing of voice signal of walkie talkie is more universal and expandable. This scheme is based on DSP, through CVSD molation codec, the speech signal has good clarity and naturalness, but the workload of software development is heavy. CC1000 does not support 4FSK molation and demolation, so this scheme is not suitable for DMR and dpmr protocols. In addition, the available sensitivity of CC1000 is - 110dbm, which may be too low for domestic interphone manufacturers< In the third scheme, the dpmr interphone scheme (cmx618 + cmx7141) with single chip microcomputer as the core processor
1. Working principle
when transmitting, the analog voice sent by the microphone is processed by gain adjustment, a / D conversion and compression in cmx618, and then enters cmx7141 baseband processor through SPI (serial peripheral interface), Under the control and management of microcontroller LPC2138, channel coding, dpmr protocol stack packaging, digital filtering and 4FSK molation are carried out inside cmx7141 chip. The voice data after molation and coding are respectively output to the external transmit VCO and voltage controlled temperature compensated reference clock through mod1 / 2 pin of cmx7141 chip. The RF carrier is output to the transmit power amplifier through two-point molation and then output to the antenna
when receiving, cmx7141 demolates the 4FSK demolation signal based on the superheterodyne RF receiving mole under the control and management of the microcontroller LPC2138, unpacks the dpmr, decodes the channel, and finally obtains the speech coding data, which is sent to cmx618 through the SPI serial port for speech decompression and recovery
2. Key device
the speech codec cmx618 is a proct of CML Microelectronics (Singapore) Pte Ltd. the chip consists of audio compression / decompression unit, ralcwi codec, forward error correction codec and other special function moles
ralcwi is a robust and advanced complex waveform insertion technology. Different from other speech coding and decoding technologies, it uses unique signal decomposition and parameter coding methods to ensure better speech quality at higher compression ratio
in the vocoder, the speech quality achieved by ralcwi technology is equivalent to that of the standard vocoder with the coding rate of more than 4kbps
overview
the advantages of this scheme are high flexibility in development, al-mode design of analog and digital, and the same hardware development platform can meet different standards of digital walkie talkie, support a variety of voice vocoders, and high RF receiving sensitivity, up to - 118dbm (when the bit error rate is 1%). The transmitting power is 0.5W, so it is easy to improve< The disadvantage of atb010 is that the cost of software development is high and there are some difficulties in the early stage. Atb010 only supports en301166 standard of dpmr, but does not support DMR.
scheme 4 uses MCU + DSP DMR walkie talkie (MSP430FG4619 + vc5510)
1. Working principle
when transmitting, the analog voice sent by microphone is sampled into digital signal by AD73311, AMBE2000 compresses and encodes the digital voice signal. The digital signal is filled with DMR communication protocol by vc5510 to form frame signal and FM wave shaping of 4FSK. Finally, the MCU performs D / a conversion and sends it to the RF mole for transmission molation to realize transmission
when receiving, MCU sends the demolated data from RF mole for a / D conversion, and then splits the frame by vc5510, and decompresses it by AMBE2000. The data is converted from AD73311 to voice signal< The MCU MSP430FG4619 is the control center of the whole system, and the man-machine interface such as keyboard and display is directly connected with MCU. MCU controls RF mole, including baseband signal sending and receiving, RF frequency point control, channel detection, etc. MCU is also responsible for DMR protocol high-level signaling control, man-machine interface interoperability, etc
in addition, please note that the microcontroller should also complete the ad / DA conversion function of baseband signal< The AMBE2000TM vocoder is an adaptive, high-performance, single-chip speech codec developed by DVSI. It can provide excellent speech quality at low bit rate, and realize real-time, full plex standard setting AMBE speech compression software algorithm
a large number of evaluations show that the vocoder has the ability to provide the same performance as the digital cellular system at normal data rates. AMBE maintains natural speech quality and clarity at 2.4kbps rate. Due to its low complexity, AMBE can be fully integrated into low-cost and low-power chips
overview
the scheme is simple and practical
in software development, the program of microcontroller and digital processor must have a clear concept of DMR protocol layering, and the correct program design is the guarantee of hardware implementation. The selection of vocoder has more room< When transmitting, the voice signal sent by the microphone is sampled by the digital to analog converter AD73311, and the data is compressed by the vocoder. The DSP and arm in OMAP5910 add and control the compressed data to form the 4FSK waveform. The digital to analog converter AIC23 simulates the 4FSK digital waveform and then molates the RF, FM carrier is transmitted by antenna
when receiving, the RF mole demolates the received analog signal, and the analog signal is sent to AIC23 for digital processing. OMAP5910 decodes and frames the received data. The frame signal is decompressed by vocoder, and the data is restored to analog voice signal by AD73311< Key device
OMAP5910 is an embedded al core processor, which integrates high-performance arm925, TMS320C55x DSP core and various widely used interfaces and peripherals. It has strong processing power, low power consumption and high signal price ratio. ARM processor core is used for DMR protocol processing and system control, DSP core is used for real-time digital signal processing
OMAP5910 and its design suite have multiple target application markets, providing multimedia functions, improving human-computer interface and extending battery life
overview
technically speaking, compared with DSP + MCU, the al core processor scheme can rece the volume of the system, rece the complexity of the circuit, make better compatibility with the communication protocol, and have a large upgrade space. The application of vocoder has the choice of domestic chip
the disadvantage is that the workload of software development in the early stage is heavy, and the coordination between arm and DSP should be studied in depth to avoid wasting the resources of processor. In addition, e to the powerful functions of OMAP, the platform can also have more applications, such as adding video, entertainment and other functions< Working principle
when transmitting, the analog voice sent by the microphone is a / D converted by wm8758b and sent to sct3252 for compression processing. After dpmr protocol processing by sct3252, it is sent to the D / a conversion unit of wm8758b for molation into 4FSK signal. After two-point molation, the radio frequency carrier is output to the transmitting power amplifier and sent to the antenna for output
when receiving, wm8758b performs a / D conversion on RF analog signal, sends it to sct3252 for 4FSK demolation, dpmr unpacking, channel decoding, and finally obtains speech coding data. After decoding, the speech data is sent to wm8758b for D / a conversion, and then sent to the bell through external amplification circuit to restore voice< The key device
sct3252 is a voice codec and dpmr stack processing chip proced by Shanghai Shikang company. It has good speech quality and high receiving sensitivity (up to - 126 DBM)
overview
the feature of this scheme is that speech codec and dpmr protocol stack are integrated in sct3252, which greatly reces the workload of control unit MCU. In addition, sct3252 is packaged in lqfp100, which is convenient for welding. The whole scheme is simple and the space for software upgrade is large. This scheme can realize the compatibility of digital and analog, and it is convenient to switch between digital and analog communication
wm8758b only plays the role of analog-to-digital conversion. Manufacturers believe that it is just around the corner to integrate it into sct3252.
7. IC is the general name of semiconctor components. Including: 1. Integrated circuit (abbreviated as IC); 2. Diodes and triodes; 3. Special electronic components. More broadly speaking, it also involves all electronic components, such as resistance, capacitance, circuit board / PCB board, and many other related procts. General material is molded resin, or pouring two methods of packaging. Material is resin, very hard! Development and transformation of IC instry since the invention of integrated circuit (IC) by Texas Instruments (TI) in 1958, with the development of silicon plane technology, bipolar and MOS integrated circuits have been invented successively in the 1960s, which marks a quantum and qualitative leap in the era of manufacturing electronic complete machines from electron tubes and crystal tubes, It has created an unprecedented emerging instry integrated circuit instry with strong penetration and vigorous vitality. Reviewing the development of integrated circuits, we can see that since the invention of integrated circuits for more than 40 years, & quot; From circuit integration to system integration; This sentence is the best summary of the development process of IC procts from small scale integrated circuit (SSI) to today's ultra large scale integrated circuit (ULSI), that is, the whole development of IC procts has gone through the process from traditional system-on-board to system-on-a-chip. In this historical process, in order to adapt to the development of technology and market demand, the instrial structure of the world IC instry has undergone three changes. The first change: the primary stage of IC instry development led by processing and manufacturing. In the 1970s, the mainstream procts of integrated circuits were microprocessors, memories and standard general logic circuits. During this period, IC manufacturers (IDM) played a major role in the IC market, and IC design only existed as a subsidiary department. At this time, IC design is closely related to semiconctor technology. IC design is mainly manual, CAD system is only used for data processing and graphic programming. IC instry is only in the primary stage of proction oriented. The second change: the rise of foundry company and IC design company. In the 1980s, the mainstream procts of integrated circuits were MPU, MCU and ASIC. At this time, the combination of fabless and foundry has become a new mode of IC instry development. With the wide application and popularization of microprocessors and PCs (especially in communication, instrial control, consumer electronics and other fields), IC instry has begun to enter a customer-oriented stage. On the one hand, the IC with standardized functions has been difficult to meet the system cost and reliability requirements of the whole machine customers. At the same time, the whole machine customers are required to continuously increase the IC integration, improve the confidentiality, rece the chip area, rece the volume of the system, rece the cost, and improve the performance price ratio of the proct, so as to enhance the competitiveness of the proct and obtain more market share and more profits; On the other hand, e to the progress of IC microfabrication technology, software hardware has become possible. In order to improve the speed of the system and simplify the program, all kinds of ASIC with hardware structure, such as gate array, programmable logic device (including FPGA), standard unit, full custom circuit, etc., have been proced, accounting for 12% of the total IC sales in 1982; Thirdly, with the development of EDA tools (electronic design automation tools), PCB design methods are introced into IC design, such as the concept of library, process simulation parameters and their simulation concepts. The design begins to enter the abstract stage, so that the design process can be independent of the proction process. The farsighted manufacturers and entrepreneurs, including venture capital funds (VC), see the market and development prospects of ASIC, and start to set up professional design companies and IC design departments one after another. A kind of fabless or design department without proction line has been set up and developed rapidly. At the same time, it also led to the rise of the standard process line (Foundry). The first foundry factory in the world is Taiwan integrated circuit company founded in 1987. Its founder Zhang Zhongmou is also known as the "father of chip processing". The third change: in the 1990s, with the rise of Internet, the IC instry has stepped into a competition oriented advanced stage. The international competition has changed from the original resource competition and price competition to talent knowledge competition and intensive capital competition. The competition mode of expanding equipment investment with dram as the center has become the past. For example, in 1990, the United States, represented by Intel, actively gave up DRAM market to fight against the threat of Japan's leaping to the top of the world's semiconctor market, vigorously promoted CPU, made major structural adjustments to the semiconctor instry, and regained the dominant position of the world's semiconctor instry. This makes people realize that the growing IC instry system is not concive to the development of the whole IC instry; Score & quot; Talent, talent, talent; Integration & quot; That's the advantage. As a result, it has become a trend for IC instry structure to be highly specialized, and a situation in which the design instry, manufacturing instry, packaging instry and testing instry are independent has been formed. In recent years, the development of global IC instry shows more and more advantages of this structure. For example, Taiwan's IC instry is dominated by small and medium-sized enterprises, which has well formed an instrial structure with high division of labor. Since 1996, affected by the Asian economic crisis, the global semiconctor instry has experienced overproction and declining efficiency, while the IC design instry has achieved sustained growth. Especially in 1996, 1997 and 1998, with DRAM's falling price and MPU's declining for three years, the growth rate of the world's semiconctor instry has been far less than the previous 17%. If we rely on high investment to upgrade technology, pursue large-size silicon wafers and micro processing, rece costs from large-scale proction and promote its growth, it will be difficult to sustain. IC design enterprises are closer to the market and understand the market, and develop high value-added procts through innovation, which directly promotes the upgrading of electronic systems; At the same time, we should make profits from innovation, accumulate capital on the basis of rapid and coordinated development, and drive the renewal and new investment of semiconctor equipment; IC design instry is the core of IC instry; Tap & quot;, It has injected new power and vitality into the growth of the whole IC instry.
8. What is the reason for the shortage of chips? Why is there a shortage of chips<
recently, the topic of chip shortage has been brushing the screen frequently, from TV, smart phone, notebook computer to car
not long ago, Volkswagen confirmed to the media that e to the shortage of chips, it has caused great trouble to the automobile proction. The situation is so serious that it may affect the automobile proction next year. This situation is not particularly common in recent years
in addition to Volkswagen, the prices of MCU, WiFi, Bluetooth and other chips in China are generally rising, and the supply of goods is in short supply, resulting in the phenomenon that money can't be delivered
we should not only ask, what is the reason for this global chip shortage< At present, the main reasons for the global chip shortage are as follows:
the overall recovery of consumer demand. Whether it is automobile, consumer electronics, notebook computers, smart phones and other categories, there has been a rapid recovery. Semiconctor materials all over the world have seen a sharp rise, and most of the foundry factories are out of full load. The current proction lines of TSMC, liandian and gf are facing great pressure. The price rise and the full number of foundry factories have directly increased the proct prices of chip manufacturers. For example, the chip supplier has told all partners that the price of the whole line of procts will rise
the situation of temporary order addition is serious. This year's situation is quite special. There is a big deviation between the market situation and the merchant's expectation, which leads to the serious situation of late customer orders. For example, in order to speed up the hoarding before September 15, China's orders to various chip manufacturers have increased sharply. In order to meet Huawei's supply requirements, the number of orders placed by manufacturers to semiconctor material manufacturers also increased sharply, which eventually led to the early release of the entire proction capacity
smartphone manufacturers expand proction capacity. Next year, as the key year for the comprehensive promotion of 5g smart phones, all mobile phone manufacturers are now ready to do a lot. So far, the expected shipment of Xiaomi will reach 300 million units, the target shipment of glory is 100 million units, and the target shipment of Apple iPhone is 230 million units. The surge of shipment makes the whole market in a state of shortage of parts
the capacity gap of chip foundry is large. In order to expand proction capacity, each generation factory began to invest in new plants. For example, the 5nm proction line invested by TSMC in the United States can greatly increase the 5nm proction capacity of TSMC and meet the needs of more customers. But "far water can't save near fire". The whole cycle from the construction of chip generation plant to output is long, and the 5nm capacity gap is still huge in the short term
conclusion
at present, the global chip shortage problem has covered the whole series of procts from high-end to low-end. According to the current situation, it seems that the shortage is unlikely to be solved in the short term
this kind of chip end pressure will be transferred to the procts, from smart phones to laptops. For consumers, they may have to face higher prices.
recently, the topic of chip shortage has been brushing the screen frequently, from TV, smart phone, notebook computer to car
not long ago, Volkswagen confirmed to the media that e to the shortage of chips, it has caused great trouble to the automobile proction. The situation is so serious that it may affect the automobile proction next year. This situation is not particularly common in recent years
in addition to Volkswagen, the prices of MCU, WiFi, Bluetooth and other chips in China are generally rising, and the supply of goods is in short supply, resulting in the phenomenon that money can't be delivered
we should not only ask, what is the reason for this global chip shortage< At present, the main reasons for the global chip shortage are as follows:
the overall recovery of consumer demand. Whether it is automobile, consumer electronics, notebook computers, smart phones and other categories, there has been a rapid recovery. Semiconctor materials all over the world have seen a sharp rise, and most of the foundry factories are out of full load. The current proction lines of TSMC, liandian and gf are facing great pressure. The price rise and the full number of foundry factories have directly increased the proct prices of chip manufacturers. For example, the chip supplier has told all partners that the price of the whole line of procts will rise
the situation of temporary order addition is serious. This year's situation is quite special. There is a big deviation between the market situation and the merchant's expectation, which leads to the serious situation of late customer orders. For example, in order to speed up the hoarding before September 15, China's orders to various chip manufacturers have increased sharply. In order to meet Huawei's supply requirements, the number of orders placed by manufacturers to semiconctor material manufacturers also increased sharply, which eventually led to the early release of the entire proction capacity
smartphone manufacturers expand proction capacity. Next year, as the key year for the comprehensive promotion of 5g smart phones, all mobile phone manufacturers are now ready to do a lot. So far, the expected shipment of Xiaomi will reach 300 million units, the target shipment of glory is 100 million units, and the target shipment of Apple iPhone is 230 million units. The surge of shipment makes the whole market in a state of shortage of parts
the capacity gap of chip foundry is large. In order to expand proction capacity, each generation factory began to invest in new plants. For example, the 5nm proction line invested by TSMC in the United States can greatly increase the 5nm proction capacity of TSMC and meet the needs of more customers. But "far water can't save near fire". The whole cycle from the construction of chip generation plant to output is long, and the 5nm capacity gap is still huge in the short term
conclusion
at present, the global chip shortage problem has covered the whole series of procts from high-end to low-end. According to the current situation, it seems that the shortage is unlikely to be solved in the short term
this kind of chip end pressure will be transferred to the procts, from smart phones to laptops. For consumers, they may have to face higher prices.
9. Skill original link platform is rechargeable, as long as the actual situation in line with their own words can be recharged, this is OK
10. Now there are a lot of trading platforms in China, such as bitcoin China, okcoin, fire coin, coin deposit, China bitcoin, a lot of them. Are you afraid you can't buy pizza if you have bitcoin?
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