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Demodulator Circuits
Last Updated on:
Friday, March 12, 2010 12:07 PM |
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Links to electronic circuits,
electronic schematics, designs for engineers, hobbyists, students & inventors:
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Ber Meter is Easy to Build - 03/02/00 EDN-Design Ideas / (added 1/06) A
bit-error-rate (BER) tester is a basic tool for digital-communications measurements.
Although many commercial BER testers are available, you can easily design and build an
inexpensive version. The scheme in Figure 1 has performance similar to that of a
commercial tester but requires you to perform a manual calculation based on displayed
data. The tester displays received bits and received erroneous bits, and you must
calculate BER data using a handheld calculator, for example.... |
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Circuit Yields Accurate Absolute Values - (07/05/01 EDN-Design Ideas / (added
1/05) 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 for logarithmic
amplifiers, or simply as a demonstration of the wonders of.... |
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Clock Recovery Scheme Suits Low Snr Systems - 06/05/00 EDN-Design Ideas / (added
7/03) 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).... |
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Demodulator Schematic/Design - The demodulator block diagram below has three major
sections that were implemented in this iteration of the design, the mixer, the filter,
and the phase shift network (added 7/03) |
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Experimental 1 kHz Synchronous Demodulator - This circuit employs a synchronous
demodulator to separate a 1 KHz signal from noise and measures the 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....(added 6/07) |
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Inverted Bipolar Transistor Doubles as a Signal Clamp - 11/09/00 EDN-Design Ideas
/ (added 7/03) A number of circuits, such as level detectors and AM demodulators,
benefit from a rectifier with a low offset voltage.... |
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Novel Method Detects Lock in Costas Loops - 06/22/00 EDN-Design Ideas / (added
7/03) 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,... |
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Self Modifying Code Extends Addressing Mode - 12/17/98 EDN-Design Ideas / (added
(07/05) 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,.... |
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Simple Ber Meter is Easy to Build - 03/02/00 EDN-Design Ideas / (added 1/06) A
bit-error-rate (BER) tester is a basic tool for digital-communications
measurements. Although many commercial BER testers are available, you can easily
design and build an inexpensive version. The scheme in Figure 1 has performance
similar to that of a commercial tester but requires .... |
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Single Sideband Demodulator Covers the Hf Band #1 - (07/20/00 EDN-Design Ideas
/ (added 7/03) The circuit in Figure 1 complements a previous Design Idea (
Reference 1 ). The modulator used a phasing network to split a low-frequency
(audio) signal into in-phase and quadrature (orthogonal) components. The phasing
network has an advantage over... |
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Spread Spectrum Method Identifies Audio Path - 04/13/00 EDN-Design Ideas /
(added 8/04) 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... |
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