Discontinued Product

DSP-59+ Noise Filter

Simultaneously reduces noise, kills heterodynes and filters QRM!

Reduce noise and interference
- Adaptive noise filter for Voice and CW
Eliminate heterodynes
- Automatic multiple tone noise filter
Sharp Speech, CW and Data filters
- 555 Linear phase FIR filters
- 25 Hz. - 600 Hz. adjustable bandwidth for CW & Data
- 200Hz. - 3.4 kHz. adjustable Lowpass & Highpass
- RTTY, AMTOR, PACTOR, HF-Packet and G-TOR
Built-in Self-Test & Audio Generator


The 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.
No other technology can do what DSP can!


New Version 3 Features

Remodulator for RTTY Variable noise reduction New noise reduction algorithm
Improved data filters SSTV, WEFAX filters and more!

NOISE REDUCTION

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.

HIGHPASS/LOWPASS FILTERS

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.

BANDPASS FILTERS

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.

INSTALLATION

The DSP-59+ is compatible with all amateur radio transceivers and receivers. Simply connect the DSP-59+ between the radio and its speaker or headphones. Connect 12-16 VDC to the DSP-59+ and turn it on!



MODEL DSP-59+ SPECIFICATIONS

AUDIO INPUT

Impedance 2K ohms or 22 Ohms, jumper selectable

AUDIO OUTPUT

Output power 1.6 watts into 8 ohms at 13.8 VDC, 2.5 watts into 4 ohms at 13.8 VDC
Line output level -6 dB, referenced to input level, into 10K ohms. Not controlled by gain control
Distortion less than 1% at rated output

NOISE REDUCTION FILTERS

Function Frequency range Attenuation Type Delay
Random Noise Reduction entire freq. range of
selected bandpass filter
Up to 20 dB, varies
with noise characteristics.
Adaptive 5 msec max
Tone Noise Reduction
(multiple automatic notch)
entire freq. range of
selected bandpass filter
Up to 50 dB, varies with
Adaptive noise characteristics
Adaptive 5 msec max

VOICE FILTERS

Function Frequency range Attenuation Type Delay
Highpass Corner freq. = 200 to 1600 Hz.,
100 Hz. steps.
60 dB at 180 Hz.
outside the passband
FIR Linear
phase
18 msec max
for any
Lowpass Corner freq. = 1700 to 3400 Hz.
100 Hz. steps
60 dB at 180 Hz.
outside the passband
FIR Linear
phase
combination of
highpass and lowpass
Note: The Random Noise Reduction, Tone Notch and voice Highpass / Lowpass filters can operate simultaneously.

CW FILTERS

Function Frequency range Attenuation Type Delay
CW Filters Bandwidth = 25 Hz to 600 Hz,
15 steps.
60 dB at 50 Hz.
outside the passband
FIR Linear
phase
30 msec max
Center freq. = 400 to 1000 Hz.,
50 Hz. steps.
Optional Collins
KWM-2 &
S-Line
Bandwidth = 25 Hz to 600 Hz
Center freq. = 1350, 1500, 1750 Hz.
55 dB at 75 Hz.
outside the passband.
FIR Linear
phase
18 msec max
CW Marker Tone Sine wave at center freq. of selected CW filter.
Sine wave distortion less than 1%
Note: The CW Bandpass filter and Random Nois Reduction can operate simultaneously

DATA FILTERS

Function Frequency range Attenuation Type Delay
RTTY,
AMTOR,
PACTOR,
G-TOR,
& HF-Packet
Bandwidth = 100 Hz. to 600 Hz.
Center freq. = 221-0 Hz. plus option
of 1700(default), 1360, 1300, 1530 or
2125 Hz.
40 dB at 60 H.
outside the passband
FIR linera
phase
18 msec max
SSTV 1100-1300 Hz. & 1500-2300 Hz. 50 dB at 75 Hz.
outside the passband
Composite FIR
Linear phase
18 msec max
WEFAX 1500-2300 Hz. 55 dB at 75 Hz.
outside the passband
FIR
Linear phase
18 msec max
CLOVER 2000-2500 Hz. 55 dB at 75 Hz.
outside the passband
FIR
Linear phase
18 msec max
FSK Marker Tone Sine waves at mark-space freq. of selected data filter(170 or 200 Hz. shift).
Sine wave distortion less than 1%
Note: RTTY, AMTOR, and PACTOR (100-350 Hz.) filters have a notch at the center frequency.
All Data filters and Random Noise Reduction can operate simultaneously

CONTROLS

Front Panel
Volume / power On-Off Bandpass center freq. adjust
Bypass switch Bandpass bandwidth adjust
AGC switch Lowpass roll-off freq. adjust
Random Noise Reduction switch Highpass roll-off freq. adjust
Tone Noise Reduction switch Marker Tone switch
Bandpass / Highpass / Lowpass switch RTTY Remodulator switch
Rear Panel
Audio Input Phono jack - RCA style
Speaker Audio Output Phono jack - RCA style
Line Audio Output Phono jack - RCA style
PTT Input Phono jack - RCA style
Power In 5.5 mm / 2.1 mm power
jack (center positive)

SIGNAL PROCESSING

A-D/D-A Converter 16 bit linear, sigma-delta conversion
Signal Processor 16 bit, 77ns Analog Devices ADSP-2105

TEST MODE

Self-test Self-test for circuitry, switches, and PTT input. User initiated from front panel.
Test tones Single or two-tone. Sine wave at the center freq. of each highpass and lowpass filter.
Sine wave distortion less than 1%.

DIMENSIONS

Size 7.6 in. wide x 8.5 in. deep x 1.9 in. high (193 mm wide x 216 mm deep x 48 mm high)
Weight 2.0 lb. (0.9 Kg.)

POWER

12-16 VDC @ 1A

Amateur Products

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