Search results
Results from the WOW.Com Content Network
In digital communications, chirp spread spectrum (CSS) is a spread spectrum technique that uses wideband linear frequency modulated chirp pulses to encode information. [1] A chirp is a sinusoidal signal whose frequency increases or decreases over time (often with a polynomial expression for the relationship between time and frequency).
A chirp is a signal in which the frequency increases (up-chirp) or decreases (down-chirp) with time. In some sources, the term chirp is used interchangeably with sweep signal. [1] It is commonly applied to sonar, radar, and laser systems, and to other applications, such as in spread-spectrum communications (see chirp spread spectrum). This ...
The spectrum is of particular interest when pulses are subject to signal processing. For example, when a chirp pulse is compressed by its matched filter, the resulting waveform contains not only a main narrow pulse but, also, a variety of unwanted artifacts many of which are directly attributable to features in the chirp's spectral characteristics.
Moreover, for a given noise power spectral density (PSD), spread-spectrum systems require the same amount of energy per bit before spreading as narrowband systems and therefore the same amount of power if the bitrate before spreading is the same, but since the signal power is spread over a large bandwidth, the signal PSD is much lower — often ...
IEEE 802.15.4c was approved in 2008 and was published in January 2009. This defines a PHY amendment that adds new RF spectrum specifications to address the Chinese regulatory changes which have opened the 314-316 MHz, 430-434 MHz, and 779-787 MHz bands for Wireless PAN use within China.
DASH7, a low latency, bi-directional firmware standard that operates over multiple LPWAN radio technologies including LoRa. Wize is an open and royalty-free standard for LPWAN derived from the European Standard Wireless Mbus. [3] Chirp spread spectrum (CSS) based devices. Sigfox, UNB-based technology and French company. [4]
Frequency-hopping spread spectrum (FHSS) is a method of transmitting radio signals by rapidly changing the carrier frequency among many frequencies occupying a large spectral band. The changes are controlled by a code known to both transmitter and receiver .
Resistance of spread-spectrum system against narrowband interference. In a spread-spectrum system, the process gain (or "processing gain") is the ratio of the spread (or RF) bandwidth to the unspread (or baseband) bandwidth. Research suggests that it is one of the important factors in making decisions over the performance of system in jamming ...