Clock Recovery Scheme Suits Low-SNR Systems - 06/05/00 EDN-Design Ideas A clock-recovery architecture can operate with NRZ digital signals, even at low SNRs. A clock-recovery subsystem is based on a PLL comprising a phase comparator, a loop filter, and a voltage-controlled oscillator (VCO) __ Circuit Design by Luis Miguel Brugarolas, SIRE, Madrid, Spain
Demodulator Makes Low Cost Optical Tracker - 06/18/98 EDN-Design Ideas (Several circuits here, scroll to find this one.) Demodulator makes low-cost optical trackerSteven Sarns, Kesta Technology Inc, Wheat Ridge, CO A project required building a synchronous-demodulator circuit to track a line drawn on paper. The beauty of the synchronous-modulator/demodulator approach is its inherent noise rejection. The method rejects nearly all out-of-band noise, whether from internal drift or external illumination. __ Circuit Design by Steven Sarns, Kesta Technology Inc, Wheat Ridge, CO
Experimental 1 kHz Synchronous Demodulator - This circuit employs a synchronous demodulator to separate a 1 KHz signal from noise and measuresthe amplitude of the 1 kHz signals once a second at about 60 microvolts per count then sends the measurements via an RS-232 interface for further processing or display. An LED on the board also lights when the measured signal exceeds a preset threshold __ Designed by Dick Cappels
Inverted Bipolar Transistor Doubles as a Signal Clamp - 06/07/01 EDN-Design Ideas A number of circuits, such as level detectors and AM demodulators, benefit from a rectifier with a low offset voltage. Silicon diodes have an offset of approximately 0.6V and do not work well in low-level circuitry. A Schottky diode is a bit better__ Circuit Design by Art Hogrefe, Puma Instrumentation, State College, PA
Novel Idea Implements Low-Cost Keyboard - 3-Apr-03 EDN-Design Ideas Many applications that use a microcontroller also use a keyboard. If your application uses a relatively powerful microcontroller, you can use several free I/O pins or an unused input with an ADC to effect an easy keyboard connection. But, if the microcontroller in your system has too few free I/O pins and no on-chip ADC, you can be in trouble__ Circuit Design by Jean-Jacques Thevenin, Thomson Plasma, Moirans, France
Novel method Detects lock in Costas loops - 06/22/00 EDN-Design Ideas In the well-established lock-detection scheme for conventional PLLs, the VCO or VCXO local oscillator splits the output into 0 and 90° signals(Figure 1). The incoming IF signal mixes with the 0 and 90° signals to perform phase locking and lock detection, respectively. This method gives unambiguous results even under noisy conditions. __ Circuit Design by MR Raghavendra, ISRO Satellite Centre, Bangalore, India
Self-modifying code extends addressing Mode - 12/17/98 EDN-Design Ideas As just about any assembly-language programmer knows, self-modifying code (SMC) is usually undesirable, unintentional, and destructive. However, the SMC routine in Listing 1 is extremely useful to extend the indexed, 16-bit offset addressing mode of the venerable HC05 µC from 8 bits, or 256 locations, to the full 13-bit (8-kbyte) memory address space that the µC’s architecture supports. This routine is very useful for error tables, text messages tables, or any array manipulation for a large number of elements. Circuit Design Paul Sofianos, Motorola Inc, Tempe, AZ
Simple Circuit BER meter is easy to build - 03/02/00 EDN-Design Ideas General filters are bandpass filters that usually employ bridging couplings between nonadjacent interstage couplings (Reference 1]. This class of filters also includes bridging coupling across filter input and output ports. The implementation of input-to-output bridging already exists for a one-pole filter (Reference 2]. For a two-pole filter, dielectric resonators help achieve input-to-output bridging coupling (Reference 3]__ Circuit Design by Luis Miguel Brugarolas, Sire Sistemas y Redes Telmaticas, Tres Cantos, Madrid, Spain
Single-sideband Demodulator covers the HF band - 10/26/00 EDN-Design Ideas The circuit in Figure 1 complements a previous Design Idea(SSB modulator covers HF band EDN , Sept 30, 1999, pg 122]. The modulator employs a phasing. __ Circuit Design by Israel Schleicher, Bakersfield, CA
Spread Spectrum Method Identifies Audio Path - 04/13/00 EDN-Design Ideas An unusual method of audio spread spectrum can identify the audio path that's currently in use through a consumer-electronic device. The design in Figure 1a uses an injected audio spread-spectrum tag signal because a listener does not notice the low__ Circuit Design by Bob Dougherty, Nielsen Media Research
Yield Accurate Absolute Values - 07/05/01 EDN-Design Ideas The circuit in Figure 1 delivers the absolute value of the input signal with an accuracy better than 10 ppm of the full-scale range. The circuit has low zero-crossing error. You can use it as an asynchronous demodulator, as a source__ Circuit Design by Marco Pisani, Istituto di Metrologia G Colonnetti, Turin, Italy |