Timewave DSP-599zx Noise Filter

  • Hyper-speed DSP Processor with 80 KB Ram
  • Field upgradeable design keeps you up to date
  • LCD display for Visible Memory™ and Calibrated Filters™
  • Wideband filter for AM and FM (VHF & UHF)
  • Continuous filter tuning up to 5,000 Hz using optical encoders
  • Voice, Lowpass, Highpass, from 200 Hz - 5,000 Hz
  • CW and Data filters 10 Hz to 600 Hz wide
  • Binaural CW (Version 5 firmware only)
  • CW Spotlight (Version 5 firmware only)
  • PC-Radio Interface & filter for PSK-31 (Version 5 firmware only)
  • Audio Test Instrument Generator & Millivoltmeter
  • Manual notch Heterodyne Eliminator

Timewave's Digital Signal Processing (DSP) technology provides superior performance in reducing QRM and QRN. No other technology can do what our DSP can!

The DSP-599zx is part of the latest generation of Timewave DSP filters incorporating the newest high speed CPU. The extra power gives the user unparalleled features and field upgradeability for the future. The new LCD display, push buttons, and Visible Memory let you see the exact settings of the filter. The optical encoders give the operator continuous tuning of the filters.

Noise Reduction

The noise reduction functions of the DSP-599xz 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-599zx 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.

Data and 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 are so steep that signals literally fall off the edge of the passband as you tune through them. Bandwidths range from 10 Hz to 600 Hz, and center frequencies from 200 Hz to 2150 Hz. Narrow filters are useful for trying to dig extremely weak signals out of the noise and QRM. The wider filters allow for easy tuning and listening to multiple CW signals simultaneously.

The Data filters support RTTY, AMTOR, PacTOR, G-TOR, HF Packet, SSTV, WeFAX, SITOR and Clover. In addition to regular filtering, the DSP-599zx offers two other RTTY functions. The RTTY Remodulator mode detects and regenerates the mark and space tones going to your Multi-Mode Controller (KAM, PK-232, MFJ-1278, Etc.), giving it the benefits of a DSP front-end. The RTTY Modem mode provides a complete RTTY Terminal Unit when used in conjunction with a PC and appropriate software.

Test Instruments

An added benefit of the powerful DSP processor and LCD display in the DSP-599zx is a Test Instrument Mode. This mode is designed to provide the audio test instruments necessary for normal maintenance and setup of audio circuits in radio equipment installations. A low distortion Sine wave Generator and an Audio Millivoltmeter cover the frequency range from 20 Hz to 10 kHZ. The millivoltmeter measures true rms, peak, dBV, and dBm as low as 1 mv. The sine wave generator is calibrated in the same units. The sine wave generator and audio millivoltmeter operate simultaneously for gain and frequency response measurements.

(Version 4 firmware only!) Another feature enhanced by the millivoltmeter is the CTCSS or "PL" tone encoder/decoder with the tone frequency autodetect. Millivoltmeter measurements allow relative frequency deviation measurements of a received signal's CTCSS tone. A CTCSS squelch output can switch a tape recorder or other device. A Two-Tone audio generator is provided for SSB linearity testing.


The DSP-599zx is compatible with all amateur radio transceivers and receivers. Simply connect the DSP-599zx between the radio and an external speaker or headphones. Connect 12-16 VDC to the DSP-599zx and turn it on!

ALL Timewave DSP Filter models SIMULTANEOUSLY Reduce Noise, Kill Heterodynes and QRM!

Timewave DSP-599zx Specifications

Audio Input A & B

Audio Output A & B

Impedance 20K ohms or 25 Ohms, jumper selectable Output power 1.0 watts into 8 ohms at 13.8 VDC, both output channels A&B operating.
1.5 watts into 4 ohms at 13.8 VDC, both output channels A&B operating.
Signal range for full output 10 mV to 1 volt, front panel programmable
Line output level 0 dB, referenced to input level. Not controlled by gain control

Automatic Gain Control (AGC)

Voice 36 dB
CW & Data Modes 18 dB

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 ms max
Variable Noise Reduction Noise reduction aggressiveness front panel adjustable
Heterodyne Eliminator (Multiple Automatic Notch) Entire freq. range of selected bandpass filter Up to 50 dB, varies with noise characteristics Adaptive 5 ms max
Heterodyne Eliminator (Manual Notch) Entire freq. range of selected bandpass filter Up to 50 dB, varies with noise characteristics Adaptive Manual

Voice Filters

Function Frequency range Attenuation Type Delay
Highpass Corner freq. = 100 to 1000 Hz., 10 Hz. steps. 60 dB at 180 Hz. outside the passband FIR Linear phase 21 ms max
Lowpass Corner freq. = 1000 to 5000 Hz. 10 Hz. steps 60 dB at 180 Hz. outside the passband FIR Linear phase

CW Filters

Function Frequency range Attenuation Type Delay
CW Filters Bandwidth = 5 Hz to 600 Hz, 5 Hz steps. 55 dB at 60 Hz. outside the passband FIR Linear phase BW less than 20 Hz = 58 ms max. BW greater than 20 Hz = 34 ms max
Center freq. = 200 to 2150 Hz., 5 Hz. steps.
CW Marker Tone Sine wave at center freq. of selected CW filter.

Data Filters

Function Frequency range Attenuation Type Delay
RTTY, AMTOR, PacTOR, G-TOR, & HF-Packet Bandwidth = 60 Hz. to 600 Hz.
Center freq. = 2210 Hz. plus option of 1700(default), 1360, 1300, 1530 or 2125 Hz.
40 dB at 60 H. outside the passband FIR Linear phase 30 ms max
SSTV 1100-1300 Hz. & 1500-2300 Hz. 50 dB at 75 Hz. outside the passband Composite FIR Linear phase 21 ms max
WeFAX 1500-2300 Hz. 55 dB at 75 Hz. outside the passband FIR Linear phase 21 ms max
CLOVER 2000-2500 Hz. 55 dB at 75 Hz. outside the passband FIR Linear phase 21 ms max
FSK Marker Tones 1) Sync-Nul character (Diddle) of selected data filter at selected baud rate
2) RY string (RTTY only)

RTTY Modem

Shifts 170, 200, 425, 850 Hz
Data Rates 45, 50, 57, 75 Baud
Input Audio from receiver
Output Open collector FSK and variable level AFSK
Transmit Data Polarity Normal or Reverse
I/O Receive data, Transmit data, PTT (RS-232 compatible)

Signal Processing

A-D/D-A Converter 16 bit linear, sigma-delta conversion, dual channel
Signal Processor 16 bit, 27ns Analog Devices ADSP-2181 with 80 KB of memory

Test Instrument

Audio Generator Single Sine wave adjustable 20 Hz to 10 kHZ
Two-tone fixed 700 Hz and 1900 Hz.
Audio Millivoltmeter True RMS from 1mV to 2000 mV, 20 Hz-10 kHz
CTCSS Encoder/Decoder Decodes and displays CTCSS "PL" tones from 67.0 Hz to 254.1 Hz (Version 5 firmware only)
CTCSS Squelch Open collector output pulls low when selected CTCSS tone is present. (Version 5 firmware only)


Six Memories All configuration setups can be stored and recalled (except volume control setting)


2X16 alphanumeric characters, dot matrix, yellow-green backlit LCD


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 2.53 lb. (1.15 Kg.)


12-16 VDC @ 1A, Fuse 1.6A, 5 mm x 20 mm

Note: RTTY, AMTOR, PacTOR, G-TOR, and HF Packet data filter bandwidths are specified at -3 dB points to comply with traditional data filter specification methods. All other filter bandwidths are specified to comply with conventional DSP FIR filter parametric descriptions.

Amateur Products

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