High-rate DFT-based data manipulator (HDDM) algorithm for effective interference mitigation

Interference can significantly degrade the performance of global navigation satellite system (GNSS) receivers. Therefore, mitigation methods are required to ensure reliable operations. However, as there are different types of interference, robust, multi-purpose mitigation algorithms are needed. This paper describes the most popular state-of-the-art interference mitigation techniques. The high-rate DFT-based data manipulator (HDDM) is proposed as a possible solution to overcome their limitations. This paper presents a hardware implementation of the HDDM algorithm. The hardware HDDM module is integrated in three different receivers equipped with analog radio-frequency (RF) front-ends supporting signals with different dynamic range. The resource utilization and power consumption is evaluated for the three cases. The algorithm is compared to a low-end mass-market receiver and a high-end professional receiver with basic and sophisticated interference mitigation capabilities, respectively. Different type of interference are used to compare the mitigation capabilities of the receivers under test. Results of the HDDM hardware implementation achieve the similar or improved performance to the state of the art. With more complex interferences, like frequency hopping or pulsed, the HDDM shows even better performance.

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Structure of Palladium Single-Crystal Films Prepared by Flash Evaporation onto (001) NaCl Substrates

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100069272 ◽

1970 ◽

Vol 28 ◽

pp. 456-457

Author(s):

L. E. Murr ◽

G. Wong

Keyword(s):

Single Crystal ◽

High Vacuum ◽

Ultra High Vacuum ◽

High Rate ◽

Flash Evaporation ◽

Optimum Load ◽

Single Crystal Films ◽

Crystal Films ◽

A Current

Palladium single-crystal films have been prepared by Matthews in ultra-high vacuum by evaporation onto (001) NaCl substrates cleaved in-situ, and maintained at ∼ 350° C. Murr has also produced large-grained and single-crystal Pd films by high-rate evaporation onto (001) NaCl air-cleaved substrates at 350°C. In the present work, very large (∼ 3cm2), continuous single-crystal films of Pd have been prepared by flash evaporation onto air-cleaved (001) NaCl substrates at temperatures at or below 250°C. Evaporation rates estimated to be ≧ 2000 Å/sec, were obtained by effectively short-circuiting 1 mil tungsten evaporation boats in a self-regulating system which maintained an optimum load current of approximately 90 amperes; corresponding to a current density through the boat of ∼ 4 × 104 amperes/cm2.

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Rapid Freezing of Freeze-Etch Specimens

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s1431927600003275 ◽

1980 ◽

Vol 38 ◽

pp. 752-755

Author(s):

A. Elgsaeter ◽

T. Espevik ◽

G. Kopstad

Keyword(s):

Low Temperature ◽

Metal Surface ◽

Relative Velocity ◽

Thermal Contact ◽

High Rate ◽

Rapid Freezing ◽

Temperature Decrease ◽

Freeze Etching

The importance of a high rate of temperature decrease (“rapid freezing”) when freezing specimens for freeze-etching has long been recognized1. The two basic methods for achieving rapid freezing are: 1) dropping the specimen onto a metal surface at low temperature, 2) bringing the specimen instantaneously into thermal contact with a liquid at low temperature and subsequently maintaining a high relative velocity between the liquid and the specimen. Over the last couple of years the first method has received strong renewed interest, particularily as the result of a series of important studies by Heuser and coworkers 2,3. In this paper we will compare these two freezing methods theoretically and experimentally.

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