[Freedombox-discuss] Amateur radio and block converters

Jack Wilborn jkwilborn at gmail.com
Mon May 28 03:12:07 UTC 2012

Hi, Maybe I can help with this.  I didn't watch the video, mainly because I
pay per byte of data so movies are almost out.  A block converter, whether
up or down or inverted, works by mixing with the signal or an IF
(intermediate frequency) another frequency, which produces the IF +
frequency, IF - Frequency and IF * frequency and multiples of the
combinations.  By making an amplifies for the selected +, - or multiple
where the amplification is selective in frequency you can end up with a new
frequency with all the attributes of the original.  In fact most radios do
just that by using a lower IF and then whatever the demodulator needed to
recover the information on the transmission.  By making the the range of
the frequency very wide along with the IF amplification, you can move a
block of transmissions up or down in frequency.  This in done in satellites
when a group of up-link transmissions are 'translated' to a different and
then the 'band' is flipped over so the higher going in are now the lower
going out.  This is usually called a 'transverse' type device.

Most home dish receivers do this with what is know as a LNA or LNB for Low
Noise Amplifier or Low Noise Block.  Here the whole group of channels are
moved in frequency to facilitate the receiver the ability to tune the
correct channel.

It's a common practice for most radio or communications equipment to use
this technique so they don't have to deal with the high frequencies
involved in the original transmission frequencies.

This is a simplified example,but I hope it answers your question.

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