Tektronix, Inc.

Tektronix International Sales Gmbh

Nec Corporation

Koichi Yoshihara

Yoneo Akita

Kenichi Miyake

A half-symbol constellation display for readily providing better observability of signal distortions in a modulated signal representing symbols of information uses a sample clock derived from a symbol clock for the modulated signal, the sample clock having the same period as the symbol clock but being shifted one-half period in phase with respect to the symbol clock. Quadrature component signals of the modulated signal are sampled using the sample clock to produce sample pairs, referred to as pseudo-symbols, that are symmetric about a symbol sample point. The pseudo-symbols form a plurality of clusters when displayed on a quadrature coordinate plane, with the diameter of each cluster being determined by the outer pseudo-symbols for the corresponding symbols. The circumferences of such clusters for an ideal modulated signal may be displayed as a template to make it easier to recognize the shift of the pseudo-symbols from the ideal locations due to distortions in the modulated signal.

Half-symbol constellation display

A receiverreceives a wireless signal of, for example, an RFID system that conducts communication with a wireless signal based on reflection modulation. A demodulation blockdemodulates the received signal obtained at the receiverwith orthogonal demodulation. A display blockprovides signal points derived from the orthogonal demodulation onto an orthogonal coordinate display to display characteristics of the reflection modulation concerning an RF tag that conducts the reflection modulation of the wireless signal. The display of the signal points may have vector display or at least numerical values indicating magnitudes of the vectors. The processed results may be stored and signal points based on the stored results may be displayed on the orthogonal coordinate to compare sets of the characteristics of the reflection modulations on the display.

Apparatus and methods for displaying signal characteristics

Carrier frequency detection for an N-ary modulated signal is achieved by digitizing the N-ary modulated signal, frequency shifting the digitized N-ary modulated signal to prevent aliasing, raising the frequency-shifted signal to the Npower, transforming the raised signal to frequency domain data and determining an initial maximum frequency peak, iteratively fine shifting the frequency of the N-ary modulated signal around the initial maximum frequency peak and repeating the raising, transforming and determining steps to obtain a plurality of maximum frequency peaks, and calculating the carrier frequency from the maximum frequency peaks and the total related frequency shift.

Carrier frequency detection for N-ary phase modulated signal

A first test signal from a test signal source is provided to a spectrum analyzer to produce first measurement data. The test signal source is expressed by a first transfer function G(w) and the spectrum analyzer is expressed by second transfer function F(w). A second test signal is provided to the spectrum analyzer to produce second measurement data where the second test signal is derived from the first test signal by shifting the frequency by a known increment. From the first and second measurement data, the components are the same on G(w) but different on F(w). The G(w) components are cancelled by calculation using the first and second measurement data and then the second transfer function F(w) is evaluated independently of G(w).

Independent measurement of complicated transfer functions

A photolithographic mask for use in the fabrication of semiconductor integrated circuit devices, comprising a transparent substrate having a major surface, and a metallic film formed on the major surface of the transparent substrate and impermeable to ultraviolet rays having wavelengths within a predetermined range, wherein the metallic film is doped with sulfur ions to provide a reduced angle of contact between the surface of the film and a body of pure water to achieve an increased degree of adaptability of the photomask to cleaning with pure water when the photomask is put to repeated use over a prolonged period of time.

Growing community of inventors

Tokyo, Japan

Koichi Yoshihara