About Digital Demodulation

89601AYAC (Vector Modulation Analysis) adds Digital Demodulation capability to your 89600 Vector Signal Analysis software.

Digital Demodulation performs measurements on digitally modulated signals. Measurements are possible on both continuous and pulsed (burst) carriers (such as TDMA Time Division Multiple Access: A technology for digital transmission of radio signals between, for example, a mobile telephone and a radio base station. In TDMA, the frequency band is split into a number of channels which in turn are stacked into short time units so that several calls can share a single channel without interfering with one another. Networks using TDMA assign 6 timeslots for each frequency channel. TDMA is also the name of a digital technology based on the IS-136 standard. TDMA is the current designation for what was formerly known as D-AMPS.). In addition, it is possible to specify a sync pattern and an offset to look at selected segments of demodulated data.

Digital Demodulation provides various analysis techniques for several standard and non-standard digital modulation formats. Analysis capabilities include several display formats as well as numeric error measurements. Flexible scaling and markers enhance these capabilities.

Among other formats, 89601AYAC provides basic CDMA Code Division Multiple Access: One of several digital wireless transmission methods in which signals are encoded using a specific pseudo-random sequence, or code, to define a communication channel. A receiver, knowing the code, can use it to decode the received signal in the presence of other signals in the channel. This is one of several "spread spectrum" techniques, which allows multiple users to share the same radio frequency spectrum by assigning each active user an unique code. CDMA offers improved spectral efficiency over analog transmission in that it allows for greater frequency reuse. Other characteristics of CDMA systems reduce dropped calls, increase battery life and offer more secure transmission. See also IS-95. modulation analysis. Extended CDMA measurement analysis capabilities such as Wideband CDMA and cdma2000 analysis are available by ordering 89601B7NC.

Digital Demodulation requires no external filters, coherent carriers, or symbol clock timing signals. The VSA allows demodulation of pulsed or continuous carriers. It can lock to the carrier and to a defined symbol rate.

The digital demodulator used in 89600 VSA incorporates advanced technology that does not require external filtering, coherent carrier signals, or symbol-clock timing signals. The VSA has built-in Gaussian, raised-cosine, and user-definable matching filters (with adjustable alpha).

The digital demodulator uses the signal to generate an ideal signal (called I/Q reference or FSK reference). Compare the measured signal to the reference signal to quantify and locate errors in the signal.

Digital Demodulation has built-in filters which may be applied to the measured signal as well as to the reference signal. This allows maximum flexibility in comparing the signal to an ideal signal. Additionally, this allows complete flexibility to probe any analog point in a communication system.

Digital Demodulation can perform I+jQ baseband measurements with hardware that supports a baseband channel configuration (see 89600 VSA Products and Measurement Hardware). IQ baseband measurements can also be performed on data from a file or Keysight's Advanced Design System.