Demodulators

FM radio with TDA7000

An FM radio on a single chip requiring only a few simple peripheral components. In particular the ship requires only one simple coil and alignment is very easy. The chip includes an RF input stage, mixer, local oscillator, IF amplifier/limiter, phase demodulator, mute detector and mute switch. The output will directly drive a crystal earpiece or could be used with a TBA820M to form a complete portable radio...

FSK Demodulator/Tone Decoder with RC2211N

A monolithic phase locked loop for data communications. The IC contains a basic phase locked loop for tracking an input signal within the pass band, a quadrature phase detector which provided carrier detector and an FSK voltage comparator which provides FSK demodulation. In the circuit shown, the IC is used as an FSK demodulator such as would be found in the receiver circuit of a modem...

The whole Construction : You can call the transceiver like this as "OZL type". Characteristics of the "OZL type" are as follows. 1. Single conversion super. 2. Using two DBM-s as modulator and converter. 3. Modulator DBM is used as demodulator in receiving time. 4. All amplifiers are used in transmitting and receiving time. 5. Case is second use of my failed or useless machine.(This time I used my useless old 10W 7MHz transmitter.) 6. All decals are done with the "Magic ink". Very simple way! 7. Normal "OZL type" uses 12V DC power from cigar lighter of the car...

When the circuit is energised from a 6V battery, the decade counter CD4017 (IC2), which is configured as a toggle flip-flop, is immediately reset by the power-onreset combination of capacitor C3 and resistor R6. LED1 connected to pin 3 (Q0) of IC2 via resistor R5 glows to indicate the standby condition. In standby condition, data output pin of the integrated infrared receiver/demodulator (SFH505A or TSOP1738) is at a high level (about 5 volts) and transistor T1 is off (reverse biased). The monostable wired around IC1 is inactive in this condition...

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. This rejection is a boon in optical tracking, where the return signal is inevitably buried in 120-Hz ambient light, amplifier offsets, and temperature drifts...

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. This rejection is a boon in optical tracking, where the return signal is inevitably buried in 120-Hz ambient light, amplifier offsets, and temperature drifts. The circuit in Figure 1 is inexpensive, and it operates from 5V dc. The circuit scans eight LED/sensor pairs every 22 msec and stores the result in eight sample/hold (S/H) capacitors for interrogation by a µP-driven ADC. The purpose of the circuit is to determine which sensor is above the line...

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. This rejection is a boon in optical tracking, where the return signal is inevitably buried in 120-Hz ambient light, amplifier offsets, and temperature drifts...

The ADXL series of accelerometers are specified and tested for operation over the range from dc to 1 kHz typically. However, in many applications, such as vibration monitoring, a wider bandwidth is required. The bandwidth of these accelerometers can be increased by decreasing the demodulator capacitance...

When a tachometer is a critical part of overspeed-shutdown circuitry, the response time of conventional demodulators may be too long. The circuit in the block diagram in Figure 1 provides updated speed data. The circuit provides corrections for variations in excitation amplitude and frequency at every excitation half-cycle. The circuit is independent of processors and, therefore, immune to software- and bus-related failures...

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. This rejection is a boon in optical tracking, where the return signal is inevitably buried in 120-Hz ambient light, amplifier offsets, and temperature drifts...

The KD2BD Pacsat Modem is a low cost, high performance 1200 bps BPSK modem designed to interface between a packet radio terminal node controller (TNC) and an amateur satellite ground station, and allows full-duplex access to the 1200 baud "Pacsat" constellation of amateur satellites. The KD2BD Pacsat Modem consists of a 1200 bit per second BPSK demodulator for receiving Pacsat transmissions, and a Bi-Phase Manchester encoder for generating Pacsat uplink signals. The demodulator uses coherent phase detection and correlation decoding techniques that are capable of demodulating BPSK signals well into the noise level. It also includes an Automatic Gain Control (AGC) system to compensate for signal strength variations, and an Automatic Frequency Control (AFC) for tuning the downlink receiver in response to Doppler shift during a satellite pass. The demodulator is very sensitive, and is capable of locking into BPSK signals so weak they are barely audible above the ambient receiver noise...