Voice Shaper is a speech pre-processor for SSB transceivers. It receives the voice signal from the microphone connected to the soundcard, and sends the processed audio back to the soundcard in real time. The following processing functions are implemented in the program:
- bandpass filter;
- 7-band equalizer;
- noise gate;
- RF envelope clipper.
The configuration procedure of the DSP functions is interactive: the program records your voice, then it plays the recording back through the processor and allows you to adjust the settings and immediately hear the effect of your changes. Real-time spectrum and histogram displays provide the insight into the processor operation and make the configuration process even eaier.
Operating system: Windows ME, Windows 2000, Windows XP or Windows 7.
CPU: Pentium 4, 1GHz or higher.
Sound Card: Any sound card with a valid WDM driver.
- Download the Voice Shaper from the Downloads page and install the program.
Input peak meter
Note that the meter is two-sided. The positive and negative peaks are measured separately so that the DC offset in the sound card can be detected, as on the screenshot above. Try to avoid the cards with a significant DC offset.
Use the Software Gain option only if your sound card does not have a Mic pre-amplifier.
The combined frequency response of the bandpass filter and equalizer is shown on the Equalizer page, on a logarithmic frequency scale. The real-time spectrum (dark green line) and the total integrated spectrum (light green shaded area) are overlaid on the chart.
- The bandpass filter cutoff frequencies can be set between 50 and 500 Hz (low) and 1500 and 5700 Hz (high) by dragging the yellow control points on the chart with a mouse.
Filter and equalizer configured for the standard 200-2700 Hz SSB signal
Filter and equalizer configured for the 50-5700 Hz E-SSB signal
The amplitude response of the non-linear part of the processor is shown on the Clipper page, with the histogram of the input envelope magnitudes overlaid on the chart. The red spot indicates the average magnitude. The magnitudes of the output envelope are plotted on the right panel of the chart, on a vertical scale.
- RF envelope clipping is the most efficient way of increasing the average power of the SSB signal without increasing the peak envelope power. Voice Shaper computes the RF envelope analythically, without actually generating RF. The clipping threshold can be adjusted by dragging the green control point. To disable clipping, drag the point all the way to the right. The clipping level, in dB, can be found as the distance between the rightmost bar of the histogram (about -11 dBFS on the chart below) and the clipping threshod (-34.3 dBFS).
RF envelope clipper configured for 23 dB clipping
Compressor configured for the 3.8:1 compression ratio
Noise gate threshold at -52 dbFS
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