DSP-599zx Audio Noise Reduction Filter
March 6, 1997
6-5
HF Packet
HF packet modems are usually centered at 1700 Hz or 2210 Hz, depending
upon the modem manufacturer. Kantronics’ Kam+ is factory set to 1700 Hz
center frequency and 200 Hz frequency shift. AEA’s PK-232 is factory set
to 2210 Hz center frequency and 200 Hz frequency shift.
CLOVER
CLOVER is a DSP-based mode and theoretically should not benefit from
additional filtering. However, Timewave DSP users report some benefit
from using a 500 to 600 Hz bandwidth filter.
SSTV and WeFAX
These two modes use individual fixed bandpass filters specifically designed
for the each mode. Pressing
[Tone]
has no effect on the SSTV and WeFAX
filters.
RTTY FSK Test Signals
Press
[Tone]
while in a non burst Data mode at 75 baud or less activates a
sync nul (diddle) test tone. The sync nul test tone may sound different than
what you may be used to. It has been padded with extra stop bits to equalize
the mark and space energies. It functions identical to what most consider
“normal.”
If the baud rate is 100 baud or higher, pressing
[Tone]
activates a space
mark reference calibration tone that toggles at the specified baud rate. It is
not a standard ASCII character.
Pressing
[Shift+Tone]
while in the Data RTTY mode at 75 baud or less in-
serts an “RYRY” audio FSK test signal into the receive channel. The
“RYRY” test signal center frequency, frequency shift, and baud rate is de-
termined by the RTTY parameter settings. The level of marker tone is ad-
justable relative to the processed receive signal. If the baud rate is 100 baud
or higher, nothing happens when
[Shift+Tone]
is pressed.
Wideband Data Operating Hint
The DSP-599zx can simulate almost any filter necessary for wideband data
signals. If you know the upper and lower audio frequency limits of the sig-
nal you are using, simply set the Highpass and Lowpass filters to pass
those frequencies. The linear phase response and steep skirts of DSP-
599zx will help reject QRM and improve S/N ratio. If you don't know the
frequency limits, tune in a strong signal with the Highpass and Lowpass
filters set to 300 Hz and 2.7 kHz. Then tighten up the filters until the copy
from the signal begins to degrade. Then back off the filters until the copy
is acceptable. Store these highpass and lowpass settings in a memory loca-
tion or record them so that you can use them when you operate that mode
again. You will have optimum QRM rejection and the best signal-to-noise
ratio.
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 ...
