spectrum and chromecast

With the rapid development of communication service and the surge of traffic, the future mobile communication system should not only have large system capacity, but also can support the effective transmission of voice, data, image, multimedia and other services. The third generation mobile communication system combines high speed mobile access and internet-based protocol services to provide users with more economical and richer wireless communication services while increasing the wireless freque

) variables. The spatial domain is the coordinate system spanned by f (x, y) . The spectral components of the spectrum system in the four corners of the spectrum graph are obtained by 0. The discrete Fourier inverse transformation is given by the following formula:So that R and I represent the real and required parts of F respectively, then the Fourier spectrum,

channel, so the interference between the signal waveforms can be greatly eliminated. In the OFDM system, the carriers of subchannels are orthogonal to each other, and their spectrum overlaps with each other. This not only reduces the mutual interference between subcarriers, but also improves the spectrum utilization. OFDM is a Multi-Car • rierModulation, MCM) Multi-carrier modulation technology. In some do

frequency w is divided into n parts, and the range of the entire digital frequency w covers the analog frequency range from the 0-2PI*FS. The FS here is the sampling frequency . And we usually only care about the spectrum in 0-pi, because according to Naikost law, only the signal within the F=FS/2 range is the valid signal that is sampled. So, in the range of W, the resulting spectrum is definitely about N

Guo Bin, Professor of the Department of television engineering, Beijing Broadcasting Institute 2) Two-Dimensional DCT MPEG adopts the discrete cosine transform (DCT-discrete cosine) proposed by Ahmed N. et al. in 1974.Transform compression algorithm to reduce the space redundancy of video signals (spatial)Redundancy ). Because static images and prediction error signals have very high spatial redundancy, the most widely used frequency domain decomposition technology to reduce spatial redundancy i

, which in the past two years has launched several rounds of tenders for td-lte equipment, and has opened a network of experiments in more than 10 cities in China. But even so, the 4G license plate guessing mystery or in the river of suspense tapered, the industry in addition to several operators and 4G standard back and forth to do radish and pit collocation, still did not give a convincing answer. The doubts about the Spectrum layout format October

China's LTE commercialization is approaching, and the industry's attention to the subsequent evolution of LTE has reached a new peak. Compared with 3G, LTE significantly improves the spectrum efficiency. However, the industry has not stopped. A few years ago, 3GPP began to research and develop the LTE-Advanced standard, and a series of technologies that can effectively improve the performance of existing LTE Networks emerged. Among them, the two most

decompose the time domain signal into the sum of the sinusoidal signal or cosine function superposition of different frequencies. In continuous case, the original signal is required to satisfy the absolute integrable condition in one cycle. In discrete cases, the Fourier transform must exist. Gonzalez Fourier transforms have many excellent properties. such as linearity, symmetry (which can be used in the Fourier transform of the computed signal);Time-shift: The time shift of function in time do

discrete signal is a continuous pulse, because the Fourier series coefficient of the discrete signal is cyclical, but continuous is not of this nature ); At last, continuous signals can only move the spectrum to a finite band, while discrete signals will continue to shift (however, in fact, the spectrum is 2 π, 4 π, 6 π, and so on, which is the same as 0, therefore, the low frequency is an even number of t

1: What are the characteristics of TDD technology? L Time Division Duplex (TDD): distinguishes uplink and downlink based on different time slots P advantages N when the upstream and downstream services are asymmetrical, different quantities of time slots can be flexibly allocated to the upstream and downstream operations, resulting in high spectrum efficiency. N uplink and downlink use the same frequency carrier, which facilitates the introduction of

Frequency-hopping spread spectrum; FHSS receives signals transmitted by narrow-frequency carriers of a specific type at both ends of synchronization and at the same time, for a non-specific receiver, the hop signal generated by FHSS is also called pulse noise. FHSS signals can be specially designed to avoid noise or non-repetitive channels of one-to-one channels, and these frequency hopping signals must comply with fcc requirements, the maximum interv

About DCT ......... MPEG adopts the Discrete Cosine Transform (DCT-Discrete Cosine Transform) compression algorithm proposed by Ahmed (a giant mathematician) in 1970s to reduce the spatial redundancy of video signals.DCT converts motion compensation errors or original image information blocks into coefficients that represent different frequency components. There are two advantages: first, signals usually focus most of their energy on a small range of frequency domains. In this way, desc

between 1.25MHz and 28 MHz instead of fixed. Main test parameters of Power Amplifier For general power amplifiers, focus on the following test parameters: (1) power gain, reflecting the amplifier's signal amplification capability; (2) 1 dB compression point, reflecting the linearity of the amplifier, that is, the amplifier's ability to enlarge large signals; (3) maximum output power. In fact, the first two indicators can reflect the maximum output power available for the amplifier. They are tes

highest signal strength nearby and send and receive data through this AP to maintain uninterrupted network connections. This is called wireless roaming. 2. Most WLAN devices use the Spread Spectrum Technology. The Spread Spectrum Technology was originally a broadband wireless communication technology used in the military communication field. The Spread Spectrum

, correlation analysis, and other mathematical processing on the signal. Figure 6.4-1 The signal after the periodic extension is different from the real signal. The following shows the error caused by this processing from the mathematical point of view. Cosine SignalX (t)The time-domain distribution is infinitely long (-∞, ∞), When the rectangular window function is usedW (t)Returns the truncation signal when it is multiplied.XT (t) = x (t) W (t). Returns the

"Hahahaha, Yi Laozi ?! How can I compete with Mr. Min, who is famous for dancing ?! How can he compete with me ?!" In the flame, the moon King said with great contempt. He did not know, but he really looked down on the hero spectrum, and also looked down on yibu. The hero of the world, wenwupu, also known as "Heaven and Man", has a total of two pieces of money and Wu. Here, the "biography of the martial arts" is specially recorded as the talents of th

, and some of the audio plus filters such as improve the tone (such as biquadfilternode), change the monotony, some audio segmentation, For example, the sound source in the channel segmentation to get the sound of the left and right channels (Channelsplitternode), some of the audio data spectrum analysis is used in this article (Analysernode). Audio API in the browserUnified PrefixThe processing of audio in JavaScript requires first instantiating

user is serialized/transformed into multiple low-rate bitstreams, and each bitstream is sent using one subcarrier. OFDM does not use a band-pass filter to separate subcarriers, but uses the Fast Fourier Transform (FFT) to select waveforms that can maintain orthogonal even if they are overlapped. OFDM is a high-speed transmission technology in wireless environments. The frequency response curves of wireless channels are mostly non-flat, and the main idea of OFDM technology is to divide a given c

130 degrees, but only a central view of the 6~7度 in a small area to more clearly see the details of the object.In addition, the eye resolution ability and lighting environment has a great relationship, in the night when the lighting conditions are poor, the ability of the eyes to resolve greatly reduced, the minimum resolution angle of up to 1 degrees.There are about 100 different colors that people can tell. This single-wavelength shade is very vivid and is known as a solid color. Most of the

1, why the Fourier transform, what is the physical meaning of it?Fourier transform is a very important algorithm in the field of digital signal processing. To know the meaning of Fourier transform algorithm, we must first understand the meaning of Fourier principle. Fourier principle shows that any continuous measurement of the timing or signal, can be expressed as a different frequency sine wave signal infinite superposition. The Fourier transform algorithm based on this principle is used to ca