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# image frequency in fm recievers

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#### abishek

##### Member level 1
image frequency

if a certain fm receiver is tuned to say 90.6 mhz....at what frequency does it detect the image frequency???

also what happens if a gadget at home operates at a frequency of that of a radio station(local)

image freq

The image frequency is twice the IF frequency away from the desired station. I suspect that FM receivers use low side LO so the image is lower than the desired signal.

As far as reception goes, the RF amplifier has selectivity from tuned circuits and broadcast stations are high power so there is a low probability that any signals on the image frequency will interfere with the broadcast reception.

### abishek

Points: 2
recievers of fm

see basic comunication books.

Some FM receivers use a high-side local oscillator, some use low side.

If you have a high-LO receiver and a low-lo receiver turned on near each other you can get feedback if you tune them to each other.

image frequency in fm

where fi is image freq , fs: is signal freq and, if: is the intermediate frequency which will vary depend on fm(10.7mhz) or am(455khz) receiver.
double spotting will occur for the calculated image freq.
for any other details refer electronic communication by kennedy.

fm reciever image frequency

it all depens on the if frequency the image will be at the double freq. of the if freq.

fm image lo

Incorrect, it can be fi=fs+2if or fi=fs-2if depending on if the local oscillator is above or below the frequency you want to receive.

calculate fm image frequency

Image would be at 2*IF away from RF

how to calculate image frequency in fm

The IF frequency for FM is 10.7 MHz. Therefore, the image is 21.4 MHz away from the station. Therefore, for FM radio, which only has a range of 88 MHz - 108 MHz (20 MHz), the image is not within the FM receiver tuning range. So, you can't get an image unless you have a general receiver.

image frequency double if

The front end filtering in FM receivers is never perfect.
The image frequency can fall on aircraft frequencys above 108MHz or on low-VHF frequencys somtimes used by taxi's and other mobile radio users.

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