Corrections to 'Decision Methods and Realization of 2-D Digital Filters Using Minimum Number of Delay Elements'

1981 ◽  
Vol 28 (3) ◽  
pp. 262-263 ◽  
Author(s):  
S. Chakrabarti ◽  
S. Mitra
Keyword(s):  
Digital Filters ◽  
Decision Methods ◽  
Minimum Number ◽  
Delay Elements

scholarly journals DIRECT SYNTHESIS OF LADDER WAVE DIGITAL FILTERS WITH TUNABLE PARAMETERS

2017 ◽  
Vol 20 (1) ◽  
pp. 1-18
Author(s):  
S.A. Samad
Keyword(s):  
Transfer Function ◽  
Digital Filters ◽  
Direct Method ◽  
Direct Synthesis ◽  
Infinite Impulse Response ◽  
Iir Filter ◽  
Minimum Number ◽  
Wave Digital Filters ◽  
Domain Transfer ◽  
Bandstop Filters

This paper proposes a method for the synthesis of ladder wave digital filters (WDFs) directly from the digital domain. This method avoids the need for the synthesis of analog reference filters conventionally required in WDF design. This direct method allows for the determination of the WDF coefficients from the digital domain transfer function. This is similar to conventional infinite impulse response (IIR) filter coefficient determination but the WDF will give a more efficient realization. Due to the WDFs power complementary properties, a first-order ladder WDF can simultaneously realize both lowpass and highpass responses using the same structure, while a second-order WDF can realize both the bandpass and bandstop responses simultaneously. By appropriately choosing the WDF adaptor configuration and structure, tunable parameters can be determined from the digital domain transfer function that controls the 3dB cut-off frequency of the lowpass and highpass filters, and the centre frequency and 3-dB bandwidth of the bandpass and bandstop filters. This results in the WDFs requiring a minimum number of multipliers for realization.

Information capacity and bandwidth limitations in the SEM

1989 ◽  
Vol 47 ◽  
pp. 84-85
Author(s):  
D. C. Joy ◽  
R. D. Bunn
Keyword(s):  
Signal To Noise Ratio ◽  
Critical Dimension ◽  
Information Capacity ◽  
Acquisition Time ◽  
Signal To Noise ◽  
Sem Image ◽  
Probe Size ◽  
Minimum Number ◽  
Noise Ratio ◽  
Signal Channel

The information available from an SEM image is limited both by the inherent signal to noise ratio that characterizes the image and as a result of the transformations that it may undergo as it is passed through the amplifying circuits of the instrument. In applications such as Critical Dimension Metrology it is necessary to be able to quantify these limitations in order to be able to assess the likely precision of any measurement made with the microscope.The information capacity of an SEM signal, defined as the minimum number of bits needed to encode the output signal, depends on the signal to noise ratio of the image - which in turn depends on the probe size and source brightness and acquisition time per pixel - and on the efficiency of the specimen in producing the signal that is being observed. A detailed analysis of the secondary electron case shows that the information capacity C (bits/pixel) of the SEM signal channel could be written as :

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