Below is the main schematic of the RX + Xtall V9. 0 SDR. The schematic has been partitioned into separate stages, each of which is covered in a separate page of build instructions in this web site. You can click on each shaded area and view the corresponding stage builders` notes. This receiver is patterned on the classic `direct conversion` receiv
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er, in that it mixes incoming RF down to audio frequencies by beating the RF against a Local oscillator such that the mixer products are in the audio frequency range. Unlike the traditional DC receiver, the SDR does not "tune" the local oscillator`s frequency to beat up against a desired RF signal. Instead, the local oscillator generates a fixed, "center frequency. The beauty of an SDR design is that the operator can, in one display, "see" all activity within the design bandwidth and immediately "click" on any interesting signal within that spectrum. This version (9. 0) of the Softrock SDR receiver has a programmable local oscillator (U4 in the schematic below), permitting the operator to select any desired center frequency. Frequency selection is done in a SDR program on the PC, and implemented via a USB connection and control circuit (U2 in the schematic below). The local oscillator is the Silabs Si570, of which there are two versions: LVDS - which requires U5, a high-speed, differential receiver that translates LVDS levels, with a typical differential input threshold of 100 mV, to LVTTL signal levels While it would be tempting to use that frequency progammability to directly tune the oscillator to a specific desired frequency, the SDR design for Version 9. 0 follows the SDR paradigm of providing a "chunk" of spectrum that is simultaneously detected and presented for processing in the PC. To accomplish this, the SDR...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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