Digital Function Generator for NeXTSTEP Real Time Sine Generator -Demo Version 1.4, June 1994 Copyright 1993-1994, DIGITAL RECORDINGS, All Rights Reserved Topics covered ** Installation Instructions **....................................................... General Information ............................................................................ Use of DFG in Teaching and Research .................................... Software Specifications / Parameters............................................. DFG Modules......................................................................................... How to use the DFG_P Module .................................................... Variables and Buttons used in the Software................................... General Information about Digital Recordings ............................. Software for NeXTSTEP developed at Digital Recordings ...... Your Satisfaction and Your Suggestions...................................... More Information.................................................................................. Warning: Please decrease Volume on NeXTSTEP Computer (or on external amplifier) to avoid damage to speakers or your hearing ! ** Installation Instructions ** 7 Copy DFG_RT file to the directory of choice (eg. Apps ). 7 Read this Help file for further information about DFG and how to use it. General Information DFG_RT module was written for real-time synthesis of the sinusoidal (pure tone) signal. Signals are generated in real time and do not require the DSP processor (which is not available in some NeXTSTEP computers). Therefore this software will run on all NeXTSTEP computers equipped in D/A converters. Signal is generated in RAM and for this reason no hard disk space is required for operation of the DFG_RT program. This program works very nicely with Digital Oscilloscope and Spectrum Analyzer (both applications come with NeXT) and any recording / editing software. Playback and recording/analysis of the signal could be done simultaneously since DSP chip is not used and main processor is used only 2->3% during signal production. The Digital Function Generator (DFG) software has been developed under NeXTSTEP Release 3.2 by DIGITAL RECORDINGS - Advanced R & D, Halifax, Nova Scotia, Canada. It works on Motorola and Intel - based NeXTSTEP computers with NeXTSTEP-supported D/A converters. Soon it will be also available for Sun and HP computers running NeXTSTEP. The DFG / NeXT combination is a powerful tool for generating arbitrary sounds of arbitrary complexity and ultimate quality. Since DFG does not use DSP resources (Motorola 56001 chip) and since it uses only 2-3% of the CPU time, it can run simultaneously with such applications as the Digital Oscilloscope and Spectrum Analyzer (both applications come with NeXT). Therefore, the single DFG/NeXT combination can be used to perform sophisticated tests and experiments, since it can synthesize and analyze signals at the same time. The DFG is an ideal signal source for many applications in the field of acoustics, psychoacoustics, physics, architecture, audiology, electronics, electroacoustics, vibration measurements and transducer testing. Use of DFG in Teaching and Research In the past DFG software has been used successfully in various research and projects and in the teaching of various courses related to acoustics, psychoacoustics, hearing aids, instrumentation, electronics, audiology and speech pathology. In particular, the Principles of Digital Audio module, illustrated by this demo, has been used to generate pure tones and white noise, to illustrate concepts of signal amplitude, frequency, phase, interference, coherence, incoherence, signal ramping, beats and virtual pitch. Also, it has been used to demonstrate quantization, dithering, aliasing / hard clipping / harmonic/ intermodulation distortions, etc. Students generated signals according to parameters input through the Graphical User Interface and listened to these signals via headphones or an amplifier with a set of speakers. The A/D64x Interface from Singular Solutions was used to input the generated signal back to the NeXT computer, so the signal could then be displayed on the Oscilloscope and Spectrum Analyzer. The same interface was used to digitally transfer generated test signals to a DAT (Digital Audio Tape) recorder. These recordings were used in various experiments conducted in electronic and acoustical labs. The quality of signals generated with DFG is higher than the quality of signals available on most test CDs. Also, DFG can generate a much wider variety of test signals than are available on CDs. This proved to be very helpful in both teaching and research. Teachers' and students' satisfaction with DFG has been very high. Concepts which have often been difficult or even impossible to demonstrate with standard equipment, can now be easily demonstrated, both acoustically and visually, with the DFG/NeXT/A/D64x combination. This dramatically increased the speed of learning and the level of understanding. Users' remarks about DFG Software : We have been using the DFG software on a NeXT computer both for doing research and for teaching. DFG has proved to be an excellent companion to courses on acoustics and psychoacoustics. Teachers in our department have used the software for generating stimuli to demonstrate hearing phenomena to students in our classes. In addition, DFG's user-friendly visual interface has enabled our students to have 'hands-on" experience of acoustics and digital signal processing concepts without having to spend a lot of time learning about digital sound synthesis. In my research, I have used the DFG modules to generate stimuli for running psychoacoustics and auditory pattern perception experiments. Dr. Valter Ciocca Dept. of Speech & Hearing Sciences University of Hong Kong, Hong Kong The five modules of Digital Function Generator are excellent sound sources for digital synthesis on the NeXT workstation. For the generation of pure tones in arbitrary and/or complex situations these programs are fast, efficient and easy to use. I have used them extensively in combination with such standard NeXT sound programs as Paul Lansky's cmix and realtime and SoundWorks from Metaresearch. As a composer, I feel my suite of NeXT software tools greatly enhanced with them not only in contributing to my composing, but in what I have learned about tone generation and architecture through analysis of their results. The interfaces of the five DFG modules are also among the best I have seen among all NeXTSTEP software I have auditioned. I found tech support from Digital Recordings to be fast, efficient and thorough. I recommend Digital Function Generator highly to any composer seriously working in a NeXTSTEP environment. Charles Dvorak, composer Pacific Palisades, California, USA Digital Function Generator software is available for over one year in the Sound Engineering Dept. of the Technical University of Gdansk. It has been widely used in the following laboratories: o Laboratory of Principles of Digital Technology, o Laboratory of Psychophysiology of Hearing, o Laboratory of Musical Acoustics, o Laboratory of Sound Synthesis Methods. I found this software exceptionally flexible. It was conceived in such a way that it is possible to use it to both: to demonstrate principles of digitally generated sound and to replace many standalone devices used as a standard equipment of sound engineering laboratories. The first mentioned feature is particularly useful in the Laboratory of Principles of Digital Technology. The DFG is the first commercially available tool for the demonstration and explaining the dither effect and its influence on the quality of low-bit quantized audio. Using this feature students may observe the dependence of subjective quality of generated waves on the dither presence and parameters. The capability of producing almost any wave using additive synthesis module is widely exploited in the Laboratory of Psychophysiology of Hearing. The software is applied to demonstration of the bits perception, the masking effect, the threshold of hearing, the threshold of nonlinear distortion perception, the dynamic scale of hearing sense and many others. Hitherto, I was compelled to use 5 or 6 heavy and expensive standalone devices. Now, I have direct access to all such functions and I feel not constrained by the necessity to reconfigure the hardware layout during the experiments. The sound synthesis is also the basic tool used to the Laboratory of Sound Synthesis Methods. Once again the flexibility of the software is applicable to the generation of diversified signal patterns. The exceptional quality of the NeXT audio channel being clever exploited by the software allows for producing sound patterns having very high resolution. Consequently, the NeXT work-station provided with the DFG software is becoming step by step the main device in our laboratories. Presently, we use this platform for almost every subjective or objective testing in the domain of pure tones or synthetic waves. Bozena Kostek, Ph.D., P. Eng. Sound Engineering Dept., Faculty of Electronics Technical University of Gdansk, Gdansk, Poland Software Specifications / Parameters Stereo output - different waveforms can be synthesized in two independent channels. Frequency adjustable continuously from 0 to 20,000 Hz. Frequency stability +/- 0.0001 Hz (accuracy of the quartz clock). Amplitude adjustable continuously from -140 to 0 dB or from 0 to 32,767. Phase adjustable continuously from 0 to 360 degrees. S/N ratio = 95 dB (with dither). No harmonic and no intermodulation distortion. DFG does not use DSP resources (Motorola DSP 56001 processor), therefore the DFG, Digital Oscilloscope and Spectrum Analyzer can run simultaneously. The simultaneous playback of sound by DFG and the recording of this sound via microphone input or the stereo A/D interface (from Singular Solutions, Ariel or MetaResearch) allows for very flexible testing and experimental procedures. Generated sounds are written to standard stereo, linear 16-bit soundfiles (*.snd). These files can be used in other sound applications such as sound editors. Complex sounds can be saved for fast retrieval and playback. Available Signals: sine wave, square wave, triangular wave, sawtooth wave, pulse, white noise, AM, FM and AFM modulation, frequency sweep, amplitude sweep, amplitude plus frequency sweep, additive synthesis, etc. DFG Modules The Digital Function Generator software consists of five modules: Principles of Digital Audio - for generating pure tones and white noise, to illustrate concepts of signal amplitude, frequency, phase, interference, coherence, incoherence, signal ramping, additive synthesis, beats, virtual pitch as well as to demonstrate quantization, dithering, aliasing / hard clipping / harmonic / intermodulation distortions, etc. Modulation (AM, FM, AFM) - for generating amplitude modulated tones (AM), frequency modulated tones (FM) and amplitude plus frequency modulated tones (AFM). Additive Synthesis - for generating complex sounds synthesized from their Fourier components. Amplitude, Frequency and Phase of each stereo component is adjustable continuously. Sweep Generator (AS, FS & AFS) - for generating linear, logarithmic, up or down types of amplitude sweeps (AS), frequency sweeps (FS) and amplitude plus frequency sweeps (AFS). Function Generator - for generating waves such as sine, square, triangular, sawtooth, pulse and to generate white noise. How to use the DFG_RT Module Warning: Please decrease Volume on NeXTSTEP Computer (or on external amplifier) to avoid damage to speakers or your hearing ! DFG software is intuitive to use and was designed with ergonomics in mind. However, we recommend that you read the following instructions before using the software. 7 To start the application, double click on DFG_RT icon. 7 Press "Play" button to produce signal. This will play signal for 100 sec. 7 You can change any parameters on the DFG_RT screen to change parameters in real time. 7 Press "Stop" button to stop signal or wait for 100 sec and signal will be turned "OFF". 7 More than one DFG_RT panel can be opened at the same time. One panel can produce one signal while the other is producing another signal. This is useful during demonstrations. Variables and Buttons Used in the Software The following is a short description of variables and buttons used in the software : The L channel / L+R/ R channel switch allows signal to be synthesized in L, R or both channels at once. This could be changed in real time during playback. Frequency is any integer number from 1 to 20,000 and represents the frequency of the signal in Hz. Please avoid loud levels when listening through the built-in speaker, since it can cause damage to it. Practical range for this speaker is from 100 Hz to 15,000 Hz. For best results use headphones or an external amplifier and speakers. Frequency could be changed in real time during playback by using provided buttons or by direct number entry in the window. This method is more reliable than slider. Please note - in DFG_RTdemo version frequency is limited to 200 Hz to 2000 Hz. Dither is added to all signals to eliminate the harmonic and intermodulation distortion generated in typical generators. Amplitude of signal is adjusted to maximum to provide S/N = 95 dB (with good D/A converters). General Information about Digital Recordings and our products Digital Recordings is a small High-Tech company formed in 1985. Our company is primarily involved in the following Services / Consulting / Research areas : o Advanced Research and Development in Acoustics o Digital & Analog Sound Recording and Editing o Digital Signal and Sound Processing (DSP & DSdP) o Audio / Acoustical Consulting & Systems Design o Computerized Data Acquisition & Systems Design o Software and Hardware Development for NeXTSTEP (we are Registered NeXTSTEP Developer) Inventions / New Techniques / Novel Products / Scientific Contributions : o DCC High-Precision Time of Flight Method o Ultrasonic Computerized Tomography Scanner o Tomographic Thermal-Wave Scanner o DSA (Digital Speech Aid) for stutterers o DFG (Digital Function Generator) Software o New theory on the origins of Life We consider NeXTSTEP to be the best operating system on the market today. Its features and object-oriented development environment lead the industry. This is why we decided to develop software and hardware products for the NeXTSTEP computers. Currently we are working on many new products for NeXTSTEP in the area of sound and DSP. Below is a short description of our commercial software product for NeXTSTEP. Our most recent research project is in the area of speech disorders. We have developed a new, revolutionary electronic device called DSA (Digital Speech Aid) for elimination of stuttering. DSA works similarly to the Hearing Aid and is in the process of being patented internationally. Software for NeXTSTEP developed at Digital Recordings Digital Function Generator (DFG) Product availability: shipping now The Digital Function Generator (DFG) software has been developed under NeXTSTEP Release 3.2. It runs under system 2.0 and 3.2 on all types and configurations of NeXTSTEP computers. The DFG/NeXT combination is a powerful tool for generating arbitrary, stereo 16-bit sounds of arbitrary complexity and ultimate quality. DFG consists of 5 modules. The Principles of Digital Audio module allows synthesis of pure tones and white noise and it can be used to illustrate concepts of signal amplitude, frequency, phase, interference, coherence, incoherence, signal ramping, additive synthesis, beats, virtual pitch, quantization, dithering, aliasing / hard clipping / harmonic / intermodulation distortions, etc. The Modulation panel allows synthesis of Amplitude, Frequency or Amplitude and Frequency Modulated tones. The Additive Synthesis module allows synthesis of complex sounds from their Fourier components. The Sweep Generator module is for producing arbitrary amplitude, frequency or amplitude and frequency sweeps. The Function Generator module can be used to synthesize sine, square, triangular, sawtooth, pulse and white noise signals. Since DFG does not use DSP resources (Motorola 56001 chip) and since it uses only 2-3% of the CPU time, it can run simultaneously with such applications as the Digital Oscilloscope and Spectrum Analyzer (both applications come with NeXT). Therefore, the single DFG/NeXT combination can be used to perform sophisticated tests and experiments, since it can synthesize and analyze signals at the same time. DFG is an ideal signal source for research and teaching in the fields of acoustics, psychoacoustics, physics, architecture, audiology, electronics, electroacoustics, vibration measurements and transducer testing. Academic discounts are available. A free demo version of this software can be provided. Digital Function Generator - Extended Product availability: June 1994 The Digital Function Generator -Extended (DFG_EX) software is being developed under NeXTSTEP Release 3.2. It runs under system 2.0 and 3.2 on all types and configurations of NeXTSTEP computers. DFG_EX is a DFG-enhancing set of software modules for construction and playback of arbitrary,stereo 16-bit sounds. Since DFG_EX does not use DSP resources, it can run simultaneously with such applications as the Digital Oscilloscope and Spectrum Analyzer. The current version of the DFG_EX software consists of 4 modules: o Sound Sequencer - for construction and playback of arbitrary sound sequences o File Editor / Mixer - for precise editing and mixing of sound files o Sound Presenter - for simultaneous and convenient playback of many sound files o An enhanced version of DFG Noise Generator, for generating noise with uniform, triangular, and gaussian PDF (Probability Density Function). DFG_EX is an ideal signal source for many teaching and research applications in the fields of acoustics, psychoacoustics, physics, audiology, electronics, electroacoustics, audio and vibration measurements. Academic discounts are available. Digital Psychoacoustic Laboratory Product availability: September 1994 The Digital Psychoacoustic Laboratory (DPL) software is being developed under NeXTSTEP Release 3.2. It runs under system 2.0 and 3.2 on all types and configurations of NeXTSTEP computers. DPL is a DFG-enhancing set of software modules for performing experiments related to psychoacoustics. It includes various presentation panels for automatic testing of subject's responses. Soundfiles produced by DFG (Digital Function Generator), DFG_EX (Digital Function Generator-Extended) or other sound generating applications are stored in a "Sound Box" folder, from which they can be retrieved in sequence or in random order by the DPL software. Subject's responses are recorded in a data file for later analysis. DPL is an ideal tool for teaching and research in the fields of acoustics, audio, psychoacoustics, neurology, audiology and speech pathology. Academic discounts are available. Digital Audiometer Product availability: December 1994 Digital Audiometer, software plus hardware, enables investigations of threshold of hearing in the frequency range from 20 Hz to 20,000 Hz, with frequency resolution of 1Hz and amplitude resolution of 1dB. All standard tests are available. Moreover, some special hearing evaluation procedures were implemented, which are seldom applied in practice today due to technical problems. Various non-standard tests are available for investigation of DLs (Difference Limens), temporal resolution, etc. Digital Audiometer allows for an easy assessment of intensity, frequency and temporal resolving capabilities of the normal and impaired auditory systems. Calibration of the audiometer is not required due to the stability of the digital circuitry. This new audiometer allows for a more accurate evaluation of hearing loss, auditory problems and capabilities. It is particularly important for the new generation of more advanced Digital and semi-Digital Hearing Aids. Digital Audiometer is being developed under NeXTSTEP Release 3.2 in collaboration with the Sound Engineering Department of the Technical University of Gdansk, Gdansk, Poland. It runs under system 2.0 and 3.2 on all types and configurations of NeXTSTEP computers. Academic discounts are available. Digital Sound Restoration Laboratory Product availability: December 1994 Digital Sound Restoration Laboratory (DSR-Lab) is a NEXTSTEP 3.2 application designed for digital restoration of sound from old records or magnetic tapes. An artificial intelligence learning algorithm, based on neural networks, is used for the detection and elimination of scratches and similar types of impulse noise. Another artificial intelligence learning algorithm, implementing the Wiener adaptive filtering procedures, is used for noise suppression. The neural network approach, used in the DSR-Lab, brings a "human touch" to the recognition of clicks and noise, because the training process is based on a human perception. This in turn leads to an obvious supremacy of the DSR-Lab algorithms over other methods that exist today for the detection of impulse sounds and noise in the old recordings. Also, the processing speed achieved with the DSR-Lab algorithms is much higher than with other algorithms. The DSR-Lab application is being developed under NeXTSTEP Release 3.2 in collaboration with Sound Engineering Department of the Technical University of Gdansk, Gdansk, Poland. Academic discounts are available. ASCII File Filter Product availability: shipping now The ASCII_Filter program was written for filtering out of the non-ASCII characters from ASCII files. Transmission errors, wrongly entered characters, etc., are only a few reasons for non-ASCII characters making their ways into ASCII files. Tasks such as Kermit file transfer, transfer of files from one application to another and compiling corrupted source code often results in errors when such corrupted files are involved. Since standard editors will not display some of these characters, detecting them becomes not an easy task. Second application of the ASCII_Filter program is a conversion of ASCII files and non-ASCII files between different platforms. The following conversions are currently possible: DOS->Mac, DOS->UNIX, UNIX->Mac and Mac->UNIX. Third application of the ASCII_Filter program is an exchange of arbitrary characters (decimal value 0->255) in the ASCII or non-ASCII file into arbitrary characters (decimal value 0->255). ASCII_Filter displays also the number of characters of given type and the total number of characters in the input file. TOP SECRET Product availability: June 1994 TOP_SECRET software is being developed to protect privacy of communication between people doing research and classified work. NeXTmail and other types of communication software can be used with encrypted files. TOP_SECRET can be also used for encryption of confidential files on the hard disk in order to protect them from unauthorized access. TOP_SECRET works on all types of files. Level of protection is adjustable. For increased security one can use several different keys in order to "open" a file. Each key could be in hands of a different person. Loss of one or several keys will not jeopardize security of protected files. Keys and algorithms could be changed and modified in order to customize TOP_SECRET for a particular application and level of security. TOP_SECRET is based on the latest algorithms in the Chaos Theory. For all practical purposes probability of unauthorized decoding of encrypted information is equal to 0. Academic discounts are available. Your Feedback on DFG_RT We hope that you will find this program useful. It provides at low cost very high quality real-time generator, which could be used in teaching and reasearch in the fields of physics, acoustics, electronics, audio engineering, mechanics etc. We are looking forward to your feedback regarding the use and improvements of this program. All suggestions regarding the DFG_RT software and its use will be greatly appreciated. Please feel free to use and to distribute DFG_RTdemo software to other NeXTSTEP users. More Information For more information about the DFG_RT software and other products and how to order them please contact: DIGITAL RECORDINGS - Advanced R & D 5959 Spring Garden Road, Suite 1103 Halifax, Nova Scotia B3H - 1Y5, Canada Tel. / Fax. (902) 429-9622 E-mail : mmieszko@ac.dal.ca