Downconverters Supply The Ability To Show Performance

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Published: 15th January 2013
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A downconverter is important for any electronics project in need of a shift in the primary, or carrier frequency. Downconverters are used in a range of common electronic equipment, including television receivers, radio receivers, and cable converter boxes.

Due to the characteristics of the waves that move at particular frequencies, a variety of frequencies are used in many different types of communication equipment. Take an FM radio for instance. Radios are designed to broadcast frequencies which are then listened to by humans. The uppermost range of frequency is 30 kilohertz, which individuals with great hearing can hear; however, the majority of systems broadcast at 20 kilohertz or lower. But the issue is that the frequency really doesn't broadcast efficiently. Test it by yelling as loud as you're able. You won't reach a mile. To broadcast successfully, FM transmitters have the audio frequency "ride" on a carrier frequency of around 100 MHz. With this frequency, audio can be transmitted all throughout a complete metropolitan area. To place the audio frequency on the carrier frequency, an upconverter is used. To accomplish this going in the opposite direction, a receiver relies on a downconverter.

An FM receiver basically uses two downconverters. There's an intermediate frequency that is somewhere between the carrier and audio frequencies, and it is employed for processing like filtering and amplification. A general IF for any FM radio is 10 MHz. At 10 megahertz, reasonably low-cost, small components can handle the processing that is more complicated at an audio frequency.

Standard downconverters utilize both a filter plus a mixer. As an example, an FM carrier frequency of 100 MHz feeds a mixer that also receives a 90 MHz signal from a tuning generator. The two frequencies of 10 megahertz and 110 megahertz are then grouped together by way of the mixer. A filter blocks the higher frequencies and permits only the 10 MHz intermediate frequency to pass.

Mixers have the ability to be both passive or active, with the latter meaning it requires DC power. They are chosen by a number of factors, starting with frequency bandwidth. The range of frequencies need to be handled by every port. The carrier port will need to handle the complete FM band. The narrow range of frequency that borders 10 megahertz merely must be managed by the intermediate frequency port. The conversion efficiency, which is the way the loss of power occurs from input to output, is how the downconverters are rated. Impedance matches between the antenna and port, also referred to as return loss, needs to be had by the carrier port. Excessive return loss can result in standing waves that can burn out the antenna circuitry. To help remedy radiations out of the system and to stop noise in the circuit, it is necessary that the filter has ample rejection of higher frequencies. The limit is regulated by the FCC with regards to a variety of products.

The price for the top performing downconverters can run into prices that are many thousands of dollars. However, emerging technology has made it possible for for low-cost parts in the range of hundreds of dollars. These components are ideal for putting together a demonstration unit to fabricate a proof of concept system. This permits engineers to produce a unit they can use to uncover any unexpected problems prior to manufacture. It also gives them a unit to demonstrate functionality to managers and investors.
In order to allow a genuine signal to become decimated into a lower sampling rate so that lower speed processors can process it, you might need a digital downconverter. Additional particulars on Windfreak Technologies Products are available on the organization's web page, http://www.windfreaktech.com/.

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