satelit receiver

communication model: a two-way transmission channel is established between sending SMTP and receiving SMTP for users' mail requests. The receiving SMTP can be the final receiver or intermediate transmitter. The SMTP command is sent by the sending SMTP and received by the receiving SMTP, while the response is sent by the opposite side. Once the transfer channel is established, the SMTP sender sends the MAIL command to specify the mail sender. If the S

Currently, TCP/IP communication protocol and its standard socket application programming interface (API) are widely used in network transmission applications ). The TCP/IP transport layer has two parallel protocols: TCP and UDP. TCP (Transport Control Protocol) is connection-oriented and provides high-reliability services. User Data Protocol (UDP) is connectionless and provides efficient services. In practical engineering applications, the selection of reliability and efficiency depends on the a

calculate. The formula is as follows: (where the Devrtt is the meaning of deviation RTT)SRTT= Srtt+ α(rtt–s RTT)devrtt= (1-β) *devrtt+β* (| Rtt-srtt |) Rto=µ*srtt +∂*devrtt(among them: under Linux, α= 0.125,β= 0.25,μ= 1,∂= 4--This is the algorithm "good tuning parameters", nobody knows why, it just Works ... The final algorithm is used in today's TCP protocol (the source code for Linux in: Tcp_rtt_estimator).TCP Sliding windowTo illustrate, if you do not understand the TCP sliding window, you

，Receiver会将数据在内存中积累到一定程度的时候才会写入到WAL或者说写入到磁盘中。但是如果还没有积累到一定程度，Receiver崩溃了咋办？5. InputDStream的真正产生是在：Driver端产生的。Receiver不断的接收数据，Receiver为了保证安全性，他会不断的通过容错的方式进行处理(把数据写进磁盘，写进内存同时有副本的方式，或者说WAL)，StreamingContext: First get data, second generation job.6. 假设数据崩溃的话，如何处理？A) driver-side data recovery: Directly driver checkpoint fi

each time, and waits for the receiver's acknowledgement signal;3> the sender receives an ACK signal from the receiving party, explaining that the packet is properly received and has the meaning of sending the next packet;4> the sender receives a NAK signal from the receiving party and interprets the request to resend the same packet;The 5> sender receives the CAN signal from the receiving party and interprets it as a request to stop the transmission unconditionally;6> the sender to complete the

+∂*devrtt(among them: under Linux, α= 0.125,β= 0.25,μ= 1,∂= 4--This is the algorithm "good tuning parameters", nobody knows why, it just Works ... The final algorithm is used in today's TCP protocol (the source code for Linux in: Tcp_rtt_estimator).TCP Sliding windowTo illustrate, if you do not understand the TCP sliding window, you are not aware of the TCP protocol. As we all know,TCP must solve the problem of reliable transmission and packet Chaos , so TCP must know the actual network data pr

protocol identifies the application process on the source and target side by using "port". The port number can use any number from 0 to 65535. When a service request is received, the operating system dynamically assigns a port number to the client's application. On the server side, each service serves the user on a "well known port" (Well-know).Serial Number field: 32 bits. Used to identify a stream of data bytes sent from the TCP source to the TCP destination, which represents the first data b

+∂*devrtt(among them: under Linux, α= 0.125,β= 0.25,μ= 1,∂= 4--This is the algorithm "good tuning parameters", nobody knows why, it just Works ... The final algorithm is used in today's TCP protocol (the source code for Linux in: Tcp_rtt_estimator).TCP Sliding windowTo illustrate, if you do not understand the TCP sliding window, you are not aware of the TCP protocol. As we all know,TCP must solve the problem of reliable transmission and packet Chaos , so TCP must know the actual network data pr

Encapsulates a request as an object, allowing you to parameterize the customer with different requests, queue requests or log requests, and support actions that can be undone Structure diagram of the command pattern The composition of the command pattern As you can see from the structure diagram of the command pattern, it involves five roles, namely:(1), Customer role (client): Creates a specific command object and sets the recipient of the Command object.

Solve the problem of "sticking packets" for TCP network transmission Author: Yang Xiaoping Wang shengkai Source: http://www.ciw.com.cn/ Currently, TCP/IP communication protocol and its standard socket application programming interface (API) are widely used in network transmission applications ). The TCP/IP transport layer has two parallel protocols: TCP and UDP. TCP (transport control protocol) is connection-oriented and provides high-reliability services. User Data protocol (UDP) is connectionl

, then load the system, and then start the computer properly. But who will complete these processes? How to complete?We cannot allow customers who use computers to do this work. The main board is the main board. How can customers contact the main board? In reality, the button is connected to the motherboard using a connection line, so when the customer presses the button, it is equivalent to sending a command to the motherboard, let the motherboard to complete the subsequent work.In addition, fr

was executed.The command allows the requesting party and the party receiving the request to evolve independently, with the following advantages:(1) The command mode makes it easy to add new commands to the system.(2) Allow the party receiving the request to decide whether to veto the request.(3) It is easier to design a command queue.(4) The revocation and recovery of the request can be easily achieved.(5) If required, it is easier to log commands into the logs.The following is a schematic syst

. For example, when the consultation is received: only the RSS server will send the inquiry (message) to the user. The user cannot consult (send) the message to the RSS server. This is the most common case of a message channel.If you want to implement Qm_a-->qm_b and qm_b-->qm_a, then you need to establish two channels between queue management.Type of message Channel definition:The message channel contains both ends of the channel.The message Channel definition is just one end of the channel.

payload, an information header and request information, or a response message. The information payload is a description of the packet attribute, which is used to represent the sender and receiver of the message, and the request information or the response information is the main content of the message. The information payload includes two properties:Version number: Used to indicate the version used by the communication, you must ensure that both sid

the repeater amplification, the signal-to-noise ratio of the signal is still good, basically will not affect the system. Take the wireless repeater as an example: according to the equipment working conditions, to reach the repeater signal intensity is greater than -80dbm, the Gaussian ambient noise level is -113dbm, when the signal-to-noise ratio is (s/n) in=33db, the repeater's noise coefficient is 5dB, then amplified signal signal-to-noise ratio (s/n) output= 33-5=28DB, it satisfies the requ

Tags: sip kamailio gdbTo kamailio/opensips single-step debugging, you need to understand the structure and operation of its code, kamailio/opensips using reactor and Proactor combined IO network model, using the main process is responsible for monitoring the network, When a connection is generated or the first packet arrives, the file is described character to the worker process through a pipe, and the worker process is responsible for the data fetching, business processing, data sending, etc. o

SeeAndroidBroadcast is divided into two different types:Normal broadcast Normal broadcasts) "and" Ordered broadcast Ordered broadcasts)". Normal broadcast is completely asynchronous and can be received by all receivers at the same time logically. The message transmission efficiency is relatively high, but the disadvantage is: the receiver cannot pass the processing result to the next receiver, and cannot te

internal data classes (ReceiverRecord and BroadcastRecord) and three data sets of the LocalBroadcastManager class. Private static final class ReceiverRecord {// record the current intent to filter the final IntentFilter filter; // record the current broadcast receiver final BroadcastReceiver receiver; // whether the current broadcast receiver is broadcasting boo

characteristics of the network, and is responsible for transmitting 0 and 1 electrical signals. 3. Link Layer 3.1 Definition 0 and 1 alone have no meaning. You must specify the interpretation method: How many electric signals are counted in a group? What is the significance of each signal bit? This is the function of "link layer". It is above the "entity layer" and determines the grouping method of 0 and 1. 3.2 Ethernet protocol In the early days, each company had its own electric signal groupi

, theTCP header has a field called Window, also called Advertised-window, this field is the receiver tells the sender how many buffers can receive data . The sender can then send the data based on the processing power of the receiving end, without causing the receiver to process it. To illustrate the sliding window, we need to look at some of the data structures of the TCP buffers:, we can see: The