John Mulcahy
REW Author
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- Joined
- Apr 3, 2017
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- 7,289
V5.20 beta 2 has now been posted. There are quite a few changes, I'll summarise the main ones.
Signal generator
The signal generator has had something of a makeover. A signal waveform preview panel has been added, there is a new set of multitone test signals and there are new AES17 MD and DFD presets for the dual tone signals. Here is how it looks now:
The generator also has some new options for the RMS level setting, adding dBu, dBV and volts. For those to make sense the output level needs to be calibrated, either by measuring it and telling REW the result (using the Calibrate level button) or, if the conversion from dBFS to volts is know, typing the full scale rms voltage figure into the box below the Calibrate level button. Before doing those make sure to set the View preference for how the rms level of a full scale sine wave (whose peaks reach digital full scale) is represented. AES set that as 0 dBFS, the alternative is a more mathematically-biased option of -3 dBFS.
RTA
The RTA has also had some attention. The Y axis options for the RTA now include dBu, dBV, dBW, volts and watts. The dBW and watts choices assume a reference resistance (typically 8 ohms) which is specified in the graph controls panel. The rms levels panel reflects the axis choice, and a display of the peak sample value has been added. As with the signal generator, REW needs to be told how dBFS relates to volts using the Calibrate level button or by typing the full scale rms input voltage into the box next to the button.
The RTA now allows FFT lengths up to 1M, the update rate is of course slower for increased lengths so if the update interval for the chosen length and overlap is more than 1 second a percentage progress appears on the record button. The Save button has been split into 3, with separate buttons to save either the current trace, peak trace or both. There are also two new Dolph-Chebyshev window options, with side lobes either 150 dB down or 200 dB down.
The RTA distortion ratios can be displayed as either percentages or dB and when playing a dual tone or multitone signal the distortion results have been expanded to include Total Distortion + Noise. The THD distortion figures now include an A weighted dynamic range figure, typically used when applying a - 60 dBFS sine wave as input.
Impulse graph
The way the inter-sample behaviour of the impulse response is generated has changed. It used to be a simple Hermite interpolation, but now uses band limited oversampling to produce a result that shows the same shape regardless of fractional sample offsets in the sample positions. A side effect of that has been to enable more accurate determination of the value for the IR peak when it lies between samples, improved precision for the estimated IR Delay and more precise acoustic timing reference delay estimates.
Buttons have been added in the Impulse graph controls to set t=0 at the cursor position (also activated by Alt+z when the control is visible) or at the IR start (also activated by Alt+y when the control panel is visible). There is a button in the All SPL graph controls to set t=0 at the IR start for all the currently selected measurements. There is also an option to normalise the step response to the IR peak value rather than the step response peak value.
Measurement
The behaviour while capturing the noise floor before a sweep measurement has been changed. REW used to play a 1 Hz sine at -150 dBFS, then stop the generator and start it again to play the measurement sweep. Now it plays 1 lsb dither while capturing the noise, then the sweep starts without having to stop and start the generator. That should help ensure digital inputs are active and locked to the generator before the sweep starts and prevent issues with audio drivers due to rapid stopping/restarting of the audio lines.
2M and 4M sweep options have been added, useful for improving signal to noise on high sample rate measurements.
Level checks when measuring and elsewhere now use Pink PN instead of random pink noise for faster and more accurate level readings.
Other changes
There are a number of further changes in this version:
Bug fixes
Signal generator
The signal generator has had something of a makeover. A signal waveform preview panel has been added, there is a new set of multitone test signals and there are new AES17 MD and DFD presets for the dual tone signals. Here is how it looks now:
The generator also has some new options for the RMS level setting, adding dBu, dBV and volts. For those to make sense the output level needs to be calibrated, either by measuring it and telling REW the result (using the Calibrate level button) or, if the conversion from dBFS to volts is know, typing the full scale rms voltage figure into the box below the Calibrate level button. Before doing those make sure to set the View preference for how the rms level of a full scale sine wave (whose peaks reach digital full scale) is represented. AES set that as 0 dBFS, the alternative is a more mathematically-biased option of -3 dBFS.
RTA
The RTA has also had some attention. The Y axis options for the RTA now include dBu, dBV, dBW, volts and watts. The dBW and watts choices assume a reference resistance (typically 8 ohms) which is specified in the graph controls panel. The rms levels panel reflects the axis choice, and a display of the peak sample value has been added. As with the signal generator, REW needs to be told how dBFS relates to volts using the Calibrate level button or by typing the full scale rms input voltage into the box next to the button.
The RTA now allows FFT lengths up to 1M, the update rate is of course slower for increased lengths so if the update interval for the chosen length and overlap is more than 1 second a percentage progress appears on the record button. The Save button has been split into 3, with separate buttons to save either the current trace, peak trace or both. There are also two new Dolph-Chebyshev window options, with side lobes either 150 dB down or 200 dB down.
The RTA distortion ratios can be displayed as either percentages or dB and when playing a dual tone or multitone signal the distortion results have been expanded to include Total Distortion + Noise. The THD distortion figures now include an A weighted dynamic range figure, typically used when applying a - 60 dBFS sine wave as input.
Impulse graph
The way the inter-sample behaviour of the impulse response is generated has changed. It used to be a simple Hermite interpolation, but now uses band limited oversampling to produce a result that shows the same shape regardless of fractional sample offsets in the sample positions. A side effect of that has been to enable more accurate determination of the value for the IR peak when it lies between samples, improved precision for the estimated IR Delay and more precise acoustic timing reference delay estimates.
Buttons have been added in the Impulse graph controls to set t=0 at the cursor position (also activated by Alt+z when the control is visible) or at the IR start (also activated by Alt+y when the control panel is visible). There is a button in the All SPL graph controls to set t=0 at the IR start for all the currently selected measurements. There is also an option to normalise the step response to the IR peak value rather than the step response peak value.
Measurement
The behaviour while capturing the noise floor before a sweep measurement has been changed. REW used to play a 1 Hz sine at -150 dBFS, then stop the generator and start it again to play the measurement sweep. Now it plays 1 lsb dither while capturing the noise, then the sweep starts without having to stop and start the generator. That should help ensure digital inputs are active and locked to the generator before the sweep starts and prevent issues with audio drivers due to rapid stopping/restarting of the audio lines.
2M and 4M sweep options have been added, useful for improving signal to noise on high sample rate measurements.
Level checks when measuring and elsewhere now use Pink PN instead of random pink noise for faster and more accurate level readings.
Other changes
There are a number of further changes in this version:
- The decay, waterfall and spectrogram plots now generate automatically when the graph is selected
- The All SPL trace arithmetic Merge operation uses the window settings of the B (low frequency) trace rather than the A trace, to better match the normal use case where B is the near field measurement
- There are more decimal places shown on the window reference time as it gets closer to zero
- The impulse response can be exported with EQ filters applied
- There is a new Analysis option for setting t=0 to use either the IR peak, the start of the IR (based on it first exceeding 10% of the peak level) or the estimated IR delay
- When importing impulse responses the feature that rotated the peak to the middle of the data if it was found very close to the start of the data has been disabled
- An all-zeroes check has been added for imported audio files
- The choice of sub or main speaker for levels check in SCSettings is remembered for the next startup
- Rendering of scope traces has been improved
- The legend panel right click menu is now available in all graphs, not just overlays
- A warning is shown if the timing reference peak level is high
- The span of the level meters in the Soundcard preferences has been increased to 100 dB
- Heading text has been removed from the TS parameters results panel to reduce the height of the window
- A View preference has been added for the font size used for the graph axes in graph image captures
- The ASIO sample rate is re-applied after reloading the ASIO driver
- REW now requires a Java 8 JRE, Java 7 is no longer supported
Bug fixes
- Bug fix: FDW phase correction for win ref time offset from zero was inverted
- Bug fix: Generating a min phase measurement did not take account of any frequency dependent window applied
- Bug fix: Mouse wheel zoom did not maintain aspect ratio when zooming out
- Bug fix: Input name disappeared from RTA window title when settings were changed
