MDNAP - MultiDimensional Network Analysis Program

MDNAP is a comprehensive CAD tool for discrete-domain 1, 2 or 3-dimensional filters and in a limited capacity for continuous-domain filters. Based on the Signal-Flow Graph (SFG) description of the filter, MDNAP is capable of performing frequency-domain and sensitivity analysis for both discrete-domain and continuous-domain filters and spatiotemporal-domain analysis for discrete-domain filters. In addition to a SFG description of the filter, MDNAP offers a means for incorporating fixed-point precision of filter coefficients and node variables.

Frequency-domain Analysis:

• fully symbolic state-space difference equation
• fully symbolic transfer function
• 1, 2 or 3-D frequency response
• rendering of 3-D frequency response as shaded, solid contour volumes (Example: 3D Lowpass with three equi-gain surfaces, 256x256 19k GIF)

Sensitivity Analysis:

• symbolic first-order sensitivity function (of the transfer function w.r.t. any coefficient)
• 1, 2 or 3-D first-order sensitivity (of the frequency response w.r.t. any coefficient)
• rendering of 3-D sensitivity as shaded, solid contour volumes

Spatiotemporal-domain Analysis of discrete-domain filters:

• scheduling information for parallel and sequential implementations
• hardware simulation with control over:
  • quantization methods
  • overflow methods
  • boundary conditions
  • processing orders
• both, delay and advance operators supported

Linear-Trajectory Filter Example:

Linear-trajectory (LT) 3-D filters are capable of being tuned to pass objects moving at a particular velocity in a video sequence. Here is an example of using MDNAP to examine quantization effects in a particular implementation of a LT filter.

Beer cases

One of the critical parameters in filter hardware implementations is data wordlength, which determines the precision and dynamic range of the signals. Choosing a too-short data wordlength can result in filter instability; choosing a too-long data wordlength makes the hardware too expensive.

The input sequence (256x240, 53 frames, MPEG, 499k) was filmed at a local brewery. Note that it contains several objects moving with different velocities.

A filter structure capable of implementing a LT filter was designed, and the coefficients were tuned to pass the diagonally-moving beer cases. In order to investigate the effects of changing wordlength, a simulation (256x240, 53 frames, MPEG, 120k) of a 16-bit hardware implementation of this filter was performed, and the filter was found to perform very well. However, a simulation (256x240, 11 frames, MPEG, 44k) of an 8-bit implementation showed that filter becomes unstable.

See this paper for more details.

MDNAP source is written in C and, to date, has been compiled for SUN SPARCstations, NeXTstations and DOS-based Intel 386-and-up machines. MDNAP is not public software. If you are interested, contact me or Dr. L.T. Bruton.

University of Calgary M-D DSP Group Home Page