pam4 modulation

Abstract: As more and more wireless devices enter people's lives, a large number of multimedia services also emerge. As multimedia transmission services require a certain amount of bandwidth, the bandwidth of traditional wireless networks also shows some shortcomings in expanding multimedia services. The emergence of OFDM modulation technology solves the bandwidth requirements of users to a certain extent. In addition, the OFDM

Transferred from: http://baike.baidu.com/link?url= KEOJCOEXYDZUH8N7BNUGEDUTAGLDGDI7ESJUSZESPUREBK0NI6SFMTPWGIRED-H-L3ZZ7CY6QSHXVHHILK7BCQ the speed at which a microcontroller or computer communicates at the serial port. Refers to the signal is modulated after the change in the unit time, that is, the number of times the carrier parameter changes in the unit time, such as 240 characters per second, and each character format contains 10 bits (a starting bit, 1 stop bit, 8 data bits), the baud rate

Figure 8-4-3 of the voltage controlled oscillator, this characteristic describes the oscillation frequency ω U of the voltage controlled oscillator. Take ω 0 Center, UC with input signal voltage (T) changes. The expression for this feature is (8-4-6) When UC (T) The oscillation frequency ω U of the voltage controlled oscillator varies with time It also changes with time. The phase-locked loop enters the "Frequency traction" and automatically tracks and captures the frequency of the input signa

This article mainly discusses the technical advantages of the wireless LAN Standard IEEE802.11g. Data Transmission Based on OFDM technology With the wide application of wireless LAN technology, users have higher and higher requirements on data transmission rates. However, in the indoor environment, the complex electromagnetic environment, the multi-pass effect, frequency selective fading, and other interference sources make it more difficult to achieve high-speed data transmission in wireless c

there are tags nearby. RFID is usually called a near-pairing system for communication at a very close distance. The range of near-pairing systems is usually 0 to 1 cm. This means that the tag is appended to the reader or pressed to the reader. The advantage of this close distance is that the label battery plant can produce a lot of energy. This energy is sufficient to support tag communication without the need for Built-in power. Near-matching is also conducive to highly confidential occasions.

Spectrum utilization, supporting high speed multimedia services, system capacity, multipath channel interference and other factors are the main starting points for the majority of fixed broadband wireless access devices to select CDMA (Code Division multiplex) or OFDM (Orthogonal Frequency Division multiplexing) as the key technology for point to Point (PMP). And these two technologies have their own strengths in these areas, so the equipment business needs to weigh the pros and cons of the actu

------------------------------------------------------------------------------- Chorus reverbParameter value range descriptionMod. freq0.8hz0.1-20Hz Modulation SpeedMod. depth40 % 0-100% modulation depthMod. dly1.3ms0-24ms delay time before initiation of modulationRev. time2.4s0.3-30s reverb timeHigh ratio0.70.1-1 high-frequency attenuation rateDiffusion70-10 reverb DiffusionDelay Time between ini. dly30ms

the data is represented by binary or more discrete level values. Therefore, the communication channel maximum transmission rate and channel bandwidth have a clear relationship, so people can use "bandwidth" to replace the "rate." For example, people often use the network's "high data rate" to express the "high bandwidth" of the network. So "bandwidth" and "rate" are almost synonymous in the discussion of network technology. ------------------------------------------------------ bit rate. Baud

attenuation rateDiffusion60-10 reverb DiffusionThe delay time between INI. dly12.0ms0.1-200.0ms and early reflection.Cut-off frequency of lpf4.0khz1.0khz-16108khz.thru low-pass filterCut-off frequency of hpfthruthru, 32hz-8khz high-pass filter Reverb vocal used for voice and chorus reverbParameter value range descriptionRev. time1.9s0.3-30.0s reverb timeHigh ratio0.50.1-1.0 high-frequency attenuation rateDiffusion60-10 reverb DiffusionDelay Time between INI. dly16ms0.1-200.0ms direct and earl

amplifier. This product is specially designed to support GSM/edge pam and 3G/3.5g pa. Because the space of the circuit board in the mobile phone is very precious, the designer no longer needs to use two independent step-down converters. FAN5904 supports 3G wireless standards from WCDMA to HSUPA +, as well as the world's popular CDMA 200 1x EV-DO. In addition, the device supports China's 3G standard TD-SCDMA and HSUPA for TD-SCDMA signal modulation fo

downlink data transmission rate of WCDMA network, Is 3GPP in the R5 protocol in order to meet the requirements of the data business asymmetry, it can be in the construction of the WCDMA network structure on the basis of greatly improve the user downlink data Service rate (theoretical maximum can reach 14.4Mbps), This technology is an important technique to improve the downlink capacity and data service rate in WCDMA network construction. (Computer science) 1, HSDPA technology and its new featu

. When the upper type is not equal to zero, the phase of the PLL is not locked, and the frequency of the input signal and the output signal are different, and U C (t) changes with time. As shown in Fig. 8-4-3, the voltage-controlled oscillator is characterized by the oscillation frequency of the voltage-controlled oscillator ωu is centered on the ω0 and varies with the input signal voltage u C (t). The expression for this attribute is (8-4-6) that when u C (t) changes with time, the oscillation

is also my first experience with microcontrollers),I was a little surprised so analogwrite didn ' t actually output a voltage, but a PWM (pulse-width modulated) sig Nal.After all, the ATmega had a a-d (analog to digital) converter along with Arduino ' sanalogread.The complementaryanalogwrite function is there, but no d-a (digital to analog) converter on the AVR chip itself.Fortunately, there is an easy-to-convert a PWM signal to a analog voltage.Need to implement a simple single-pole low pass f

capabilities of the host machine to complete the GPS function. It is expected that GPS receivers of similar architectures will gradually become mainstream in the market due to their low overall cost. The architecture is a two-step sub-frequency super-external receiver, and the output is a digital Second Intermediate Frequency Signal Stream. In addition to the RF input filter, an intermediate frequency output filter, and a phase-locked loop filter, the filter must be set up on the chip. The MAX2

user communicates with a PSTN user, the IAD user accesses the IP bearer network through the WIMAX wireless link, which is controlled by the media gateway controller Huawei SOFT3000) and sends the media stream to the integrated media gateway Huawei UMG8900 ), UMG8900 and PSTN Programmable switch Huawei CC08) have a direct circuit to complete communication. When IAD users perform voice communication, they are controlled by the media gateway controller Huawei SOFT3000) and communicate through the

HSDPA (High speed downlink packet access) is used to realize high speed downlink data service of WCDMA network, which can make the downlink data rate reach 8~10mbps, which is regarded as the main solution of the 3G era. The data rate can reach 20Mbps in the HSDPA system with multiple and multiple out (MIMO) technology. The emergence of HSDPA has aroused great concern of the industry. As the following evolution technology of WCDMA system, many key technologies in HSDPA are similar to CDMA20001XEV

The earliest modem can be traced back to the one launched by att in 1958. Data phone number , Used to connect a terminal device to a remote host. . The technical standard of this modem is called bell103, which uses Simple Frequency Modulation Technology ( Frequency Shift Keying Only BPS of transmission speed is provided. CCITT issued a similar technical standard V.21 according to bell103.Since then, the development of

of the lower frequency, demodulation, channel decoding, multiplexing, decompression, Video coding and audio DAC, and sends the analog video/audio output signal to the TV set, thus realizes the interactive video/data information service. At present, the most influential digital broadcasting standards are DVB,DSS and large Alliance DTV, which DVB for satellite broadcasting, cable television and terrestrial broadcasting in different forms are divided into dvb-s,dvb-c and DVB-T. This scheme uses s

In the field of electronic communication,Baud Rate (Baudrate) that isModulation rateIndicates the unit time after the signal is modulated.PorterNumber, that is, the number of times the carrier parameter changes within the unit time. It is a measure of the symbolic transmission rate. Generally, the unit is "Porter per second" (BPS, 1 port transfers 1 Symbol per second (may contain multiple bits ). The rate of the analog line signal, also known as the modulati