Vehicle-mounted FM/AM radio set free from interference of switching power supply and anti-interference method thereof

A switching power supply, radio technology, applied in electrical components, transmission systems, etc., can solve the problems of interfering with radio, unable to completely shield low-frequency electromagnetic waves, limited effect, etc., to achieve the effect of simple control circuit

Active Publication Date: 2013-08-14
延锋伟世通(重庆)汽车电子有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] 1. In the radio mode, turn off all switching power supplies as thoroughly as possible, but this is sometimes unrealistic (such as switching power supplies used in display circuits, USB interfaces, etc., generally cannot be turned off at this time);
[0005] 2. Open the distance between the switching power supply and the radio circuit as far as possible when laying out the circuit PCB. For car audio with very limited internal space, the effect of this measure is very limited;
This will not only increase the cost, but also the shielding cover cannot completely shield the low- and medium-frequency electromagnetic waves (switching power supplies usually work at low and medium frequencies between 30KHz and 2MHz), and some electromagnetic interference will interfere with the radio through the conduction of ground wires or power lines;
[0007] 4. Increase the switching frequency to 1.7M or above the highest receiving frequency in the AM (MW) band, but its high-order harmonics are likely to cause serious interference to the FM band, and will form multiple interference frequencies, so it is generally not possible Take; while using a single switching frequency below 1.7MHz, its fundamental wave and harmonics will form one or more interference frequencies in the AM (MW) band that cannot be avoided by conventional methods
Obviously, this method cannot solve the interference of the switching power supply in the machine to the two bands of FM and AM (MW) at the same time.

Method used

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  • Vehicle-mounted FM/AM radio set free from interference of switching power supply and anti-interference method thereof
  • Vehicle-mounted FM/AM radio set free from interference of switching power supply and anti-interference method thereof
  • Vehicle-mounted FM/AM radio set free from interference of switching power supply and anti-interference method thereof

Examples

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Effect test

example 1

[0149] 1. Assuming x=1, y=2, the whole frequency can be divided into 2(y-x)+2=4 segments, the total number of sub-band division points is 2(y-x)+1=3, starting from the first segment High and low switching power supply operating frequencies should be used alternately: fh, fl, fh, fl.

[0150] 2. First calculate the fl and fh of this example:

[0151] According to the inequality: xfl≥FL≥(x-1)fh+25KHz can be deduced:

[0152] fl≥FL means fl≥522KHz;

[0153] According to the inequality: (y+1)fl-25KHz≥FH≥yfh can be deduced:

[0154] That is fl≥551.3KHz, at the same time That is, fh≤814.5KHz

[0155] According to the inequality: fh-y(fh-fl)≥50KHz can be deduced:

[0156] 2fl-fh≥50KHz;

[0157] According to the inequality: x(fh-fl)≥50KHz, it can be deduced:

[0158] fh-fl≥50KHz;

[0159] There are many combinations of fl and fh that fully meet the above requirements, as long as they do not exceed the actual capability of the switching power supply and are all lower than 1M...

example 2

[0166] 1. Assuming x=2, y=3, the whole frequency can be divided into 2(y-x)+2=4 segments, the total number of sub-band division points is 2(y-x)+1=3, starting from the first segment High and low switching power supply operating frequencies should be used alternately: fh, fl, fh, fl.

[0167] 2. First calculate the fl and fh of this example:

[0168] According to the inequality: xfl≥FL≥(x-1)fh+25KHz can be deduced:

[0169] fh≤FL-25KHz or fh≤497KHz, at the same time That is, fl≥261KHz;

[0170] According to the inequality: (y+1)fl-25KHz≥FH≥yfh can be deduced:

[0171] That is fl≥413.5KHz, at the same time That is, fh≤543KHz

[0172] According to the inequality: fh-y(fh-fl)≥50KHz can be deduced:

[0173] 3fl-2fh≥50KHz;

[0174] According to the inequality: x(fh-fl)≥50KHz can be deduced:

[0175] fh-fl≥25KHz;

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Abstract

The invention provides a vehicle-mounted FM / AM radio set free from interference of a switching power supply and an anti-interference method thereof. The anti-interference method comprises the following steps: AM (MW) wave band is subdivided into a plurality of sub frequency band; a microprocessor, and a switching power supply which works at less than 1 MHz and is capable of flexibly switching working frequency are utilized; and two different working frequencies of the switching power supply are alternately adopted. As a result, the inherent advantages of the switching power supply, such as low calorific value and high reliability are maintained, serious fundamental wave interference and harmonic wave interference of the working frequency of the built-in switching power supply to FM / AM (MW) reception circuit are eliminated, and the reception result of the type of radio set is greatly improved.

Description

technical field [0001] The invention relates to the technical field of a radio signal receiving device and its anti-electromagnetic interference, in particular to a vehicle-mounted FM / AM radio capable of avoiding the interference of a switching power supply and an anti-interference method thereof. Background technique [0002] Modern car audio has more and more functions and more and more complex circuits, but its internal space is very limited. In order to reduce the internal temperature, improve the reliability of the audio system and prolong its service life, in addition to using a high-quality radiator with a relatively large thickness and surface area, it is also necessary to use as many high-efficiency circuits as possible to reduce the heat generated by the internal circuit. However, increasing the heat sink will not only be limited by the structural size of the whole machine, but also increase the cost; to reduce the heat generation of the circuit, in addition to usi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04B1/10
Inventor 刘德锋
Owner 延锋伟世通(重庆)汽车电子有限公司
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