DSP-599zx Audio Noise Reduction Filter
March 6, 1997
1-11
Data Mode
The Data Mode digitally processes data signals including several versions of
RTTY, AMTOR, SITOR, PacTOR, G-TOR, CLOVER HF packet, SSTV
and WeFAX. Independently selectable processing techniques include noise
reduction, tunable bandpass filtering and automatic gain control, and a spe-
cial RTTY modem and RTTY remodulator.
Bandpass Filters
The DSP-599zx has both fixed and tunable bandpass filters for the data
mode. Narrow band data signals like RTTY require a bandpass filter with
steep skirts, linear phase response, and matched amplitude response. Linear
phase response maximizes the usable signaling rate for a given bandwidth
and minimizes ringing often heard on extremely sharp filters. The matched
amplitude response tailors the filter to match the selected modulation type
and baud rate to minimize noise and interfering signals.
The DSP-599zx also has fixed frequency matched bandpass filters centered
at 2210 Hz as well as lower frequencies for European standards and 1600-
1800 Hz HF packet. The selectable bandwidths of the bandpass filters pro-
vide optimum filtering for 170 Hz and 200 Hz frequency shift data signals
of various baud rates. Within setup, you can select between European or
American standards as your default.
The DSP-599zx has individual linear phase fixed bandpass filters with steep
skirts for SSTV, WeFAX and CLOVER. Since the bandwidths for these
modes are fixed, the filters are primarily QRM filters for adjacent channel
signals rather than noise reduction filters for eliminating random noise. The
SSTV filter is a dual passband filter with one passband centered on the
SSTV sync pulse at 1200 Hz, and the other passband around the varying FM
picture tones from 1500-2300 Hz. WeFAX is similar to SSTV but has no
separate sync pulse so the filter bandpass covers 1500-2300 Hz. The CLO-
VER filter has a 500 Hz bandwidth with a center frequency of 2250 Hz.
Function
6
Shift
5
AGC
3
Bypass
Data
DSP-599zx
CW
Voice
Mode
1
Random
4
Tone
2
599-029
Setup
Test
Rcl/
Store
Spkr/
Chan
High Pass
Center Freq
Time
Summary of Contents for DSP-599zx
Page 1: ...DSP 599zx Audio Noise Reduction Filter Operating Manual March 6 1997 TECHNOLOGY INC ...
Page 56: ...4 Voice Mode 4 8 March 6 1997 ...
Page 62: ...5 CW Mode 5 6 March 6 1997 ...
Page 92: ...8 Troubleshooting 8 4 March 6 1997 ...
Page 96: ...Appendix B Glossary A 4 March 6 1997 ...
Page 98: ...Appendix C Product Warranty A 6 March 6 1997 ...
Page 100: ...Appendix D Electromagnetic Interference A 8 March 6 1997 ...
Page 102: ...Appendix E Schematic Diagrams A 10 March 6 1997 ...
Page 103: ...DSP 599zx Audio Noise Reduction Filter March 6 1997 A 11 ...
Page 104: ...Appendix E Schematic Diagrams A 12 March 6 1997 ...
Page 105: ...DSP 599zx Audio Noise Reduction Filter March 6 1997 A 13 ...
Page 106: ...Appendix E Schematic Diagrams A 14 March 6 1997 ...
