Group items tagged

In traditional short-haul microwave transmission (that is, line-of-sight microwave transmissions operating in the 18 GHz and 23 GHz radio bands),RF design engineers typically are concerned with signal aspects such as fade margins, signal reflections, multipath signals, and so forth. Like an accountant seeking to balance a financial spreadsheet, an RF design engineer normally creates an RF budget table, expressed in decibels (dB), in order to establish a wireless design. Aspects like transmit power and antenna gain are registered in the assets (or plus) column, and free space attenuation, antenna alignment, and atmospheric losses are noted in the liabilities (or minus) column. The goal is to achieve a positive net signal strength adequate to support the wireless path(s) called for in the design.

The race to create tiny wireless sensors that could monitor anything from pressure in the eyes and brain to the stability of bridges appears to be heating up. Earlier this month, IEEE Spectrum reported on two approaches to creating an almost-indefinitely-running sensor using piezoelectric systems to convert tiny vibrations into power. Now, another team from the University of Michigan has created an alternative approach that uses solar power to keep the sensor running autonomously for many years.

Having the lowest system power allows customers to achieve their design objectives, whether it be for longer battery life, higher product performance or lower system cost. The Si100x/1x wireless MCU family features the industry’s lowest active mode current consumption, which saves power when the application is running. It also has the industry’s lowest current consumption sleep modes that save power when the device is sleeping, which is typically the majority of time in most battery powered applications.

In addition to voice connectivity, digital cellular wireless networks such as GSM and its enhancement, GSM-EDGE, can now provide increased data speeds up to a (theoretical) limit of 384ﾠKbps. Third generation mobile networks, such as CDMA2000 and WCDMA or UMTS (Universal Mobile Telecommunications Standards) and TD-SCDMA (China only) are currently being deployed worldwide. These systems offer services such as video streaming, Internet browsing and, by using a technique called High Speed Packet Access (HSPA), they can in theory deliver downlink speeds up to 14,4 Mbps.

With the consumer demand for richer content and its resultant , increasing high data bandwidth continuing to drive communications systems, coding for error control has become extraordinarily important. One way to improve the bit error rate (BER), while maintaining high data reliability, is to use an error correction technique like the Viterbi algorithm. Originally conceived by Andrew Viterbi as an error-correction scheme for noisy digital communication, the Viterbi algorithm provides an efficient method for forward error correction (FEC) that improves channel reliability. Today, it is used in many digital communications systems in applications as diverse as CDMA and GSM digital cellular, dial-up modems, satellite, deep-space communications and 802.11 wireless LANs. It is also commonly used in speech recognition, keyword spotting and computational linguistics.