A quadrature bandpass modulator IC facilitates monolithic digital-radio-receiver design by allowing straightforward “complex A/D conversion” of an image-reject mixer’s I and Q outputs. Quadrature bandpass modulators provide superior performance over pairs of real bandpass modulators in the conversion of complex input signals, using complex filtering embedded in loops to efficiently realize asym...

Flexibility and choice -The DAB signal is essentially a highly flexible over-air 'data-pipe' that can broadcast a wide range of service types, from purely audio-based to multimedia. Typically, each multiplex can broadcast five or more high-quality audio services plus a number of extra services. The multiplex can be dynamically reconfigured to introduce additional services, temporary or permanen...

The air/ground voice communication between air traffic controller and aircraft does not provide any means of automatic speaker identification and is therefore susceptible to call sign confusion and originator ambiguity. In the near future the analogue VHF radio will not disappear from avionic communications. With an add-on to the analogue radio it is possible to automatically detect the origina...

Critical to the design of a digital impulse radio (IR) receiver is the ability of the analog-to-digital converter (ADC) to efficiently sample and digitize the received signal at the signal Nyquist rate of several gigahertz. Since designing a single ADC to operate at such frequencies is not practical, channelized receivers that efficiently sample at a fraction of the signal Nyquist rate are pres...

High speed Digital Subscriber Line (DSL) systems transmit signals that overlap in spectrum with the bands used for radio communications. AM broadcast stations and radio amateur transmitters result into electromagnetic interference impairing the DSL-receiver. For Discrete Multitone (DMT) systems, windowing, in combination with Radio Frequency Interference (RFI) cancellation has been proposed to ...

This paper discusses results of the recent experiments, which intention was to test security in accessing e-mail servers and radio relay systems within the amateur radio digital infrastructure. There are many opportunities in available safety measures, which support the integrity of user's and system administrator's credentials. This work suggests various methods which aim is to bridge the gap ...

The Single European Sky Air Traffic Management (ATM) research programme SESAR has identified continued growth in demand for aircraft communications as air traffic increases and communications become more network centric. Alongside existing systems such as VHF Data Link Mode 2, new systems such as the L-band Digital Aeronautical Communication System (LDACS) and the Aeronautical Mobile Airport Co...

"his paper presents a model for channels with memory and applies that model to the process of speciflmg error performance in a digital communications system. A partitioned Markov chain with a single error state is described, based on the well-known Fritchman model, and then applied to error parameters used in perfomance allocation, including bit error rate, error-second rate, block error rate, ...

The precise time available from the atomic clocks orbiting the earth in GPS satellites is used in many systems where time synchronization is important. The satellite clocks are monitored and adjusted by ground based control telemetry to within one microsecond of Universal Time. A number of commercial GPS receivers have the ability to provide a time synchronised output, typically one pulse per s...

To achieve the performance required of the latest generation of wireless access, DOCSIS, and a plethora of other radio applications, direct RF-sampling technology holds the promise of increased flexibility and higher performance. Direct RF-sampling provides the flexibility by moving much of the RF signal processing into the digital domain, thereby eliminating much of the analog signal processin...