AM images on LF and MF range

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Sasan
Posts: 124
Joined: Sat Jun 27, 2015 1:15 am
Location: Berlin

AM images on LF and MF range

Post by Sasan » Sun Jan 24, 2016 11:04 am

Hi
I knew about FM images on UHF (380-440)
Today I was playing with SDRPlay and I heard some commercial stations on 18KHZ, 155KHZ, 276KHZ, etc
I knew that these can't be real and found out that these are in fact, images.
Has anyone else noticed this behaviour before? Can it be overcome?

Thanks
Last edited by Sasan on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
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DF2HF, NM9A, EP2C

DaveB
Posts: 142
Joined: Sun Feb 01, 2015 6:04 pm

Re: AM images on LF and MF range

Post by DaveB » Mon Jan 25, 2016 11:26 pm

A good quality low pass filter with a suitable cut-off is the only way to get rid of these 'images'. It might comfort you to know that the much more expensive SDRs requires filters to remove break through from strong stations.
Last edited by DaveB on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
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jackb
Posts: 2
Joined: Thu Apr 28, 2016 3:34 am

Re: AM images on LF and MF range

Post by jackb » Thu Apr 28, 2016 3:56 am

I had the same problem with the RSP and a fairly high end receiver that I have. A Google search brought me to this forum topic. I found a very complete discussion (including how to set up the filter) at this: http://www.dxing.com/tnotes/tnote06.pdf
Last edited by jackb on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
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