|Discontinued Audio Filters
The Timewave DSP-59+ uses digital signal processing technology to provide optimum filters for random noise reduction, heterodyne elimination, highpass filtering, lowpass filtering, and bandpass filtering. Digital Signal Processing (DSP) technology provides superior performance in reducing QRM and QRN.
The noise reduction functions of the DSP-59+ operate by examining a characteristic of signals and noise called correlation, and dynamically filtering out the undesired noise. The degree of correlation is relative. Random noise such as white noise or static is uncorrelated. Speech is moderately correlated. Heterodynes and pure tones are highly correlated. The DSP-59+ measures correlation and automatically filters out noise that is outside its correlation thresholds. The amount of noise reduction varies according to the correlation characteristics of the noise. Typical noise reduction ranges from 5 dB to 20 dB for random noise and up to 50 dB for heterodynes.
SSB signals often have a high signal-to-noise ratio but have interference from other signals that overlap the desired signal. The steep skirts of the highpass and lowpass filters allow the interference to be eliminated with minimal impact on the desired signal. The 30 selectable highpass and lowpass filters also allow enhanced filtering for other modes such as SSTV, wideshift RTTY or facsimile. Highpass filters range from 200 to 1600 Hz and lowpass filters range from 1700 to 3400 Hz.
Narrow band signals like CW and RTTY require bandpass filters with steep skirts and linear phase response. Linear phase response maximizes the usable signaling rate for a given bandwidth and minimizes ringing often heard on other types of extremely sharp filters. The filter skirts on the 195 CW filters are so steep that a signal literally falls off the edge of the passband as you tune through a CW signal. Bandwidths range from 25 Hz to 600 Hz, and center frequencies from 400 to 1000 Hz. The narrow filters are useful for trying to dig out extremely weak signals from the noise and QRM. The wider filters allow easy tuning and listening to multiple CW signals simultaneously. The selectable bandwidths of the 2210 Hz and optional data bandpass filters allow selection of the optimum bandwidth for 170 Hz and 200 Hz shift data signals of various baud rates.
The DSP-59+ requires a power source of 12 to 16 VDC at 1 amp. The center pin of the power connector is positive (+). 7.6 x 1.9 x 8.5 inches. 2 lb.
Copyright 2008-2010, Universal Radio, Inc.