I experienced building a softrock for 40m months ago, very interesting (and
cheap :-))
Anyway I don't think a softrock-style SDR would fit the requirements, it is
by far too simple to compete with a "real" radio in my humble opinion. In
addition to this, performance requirements then move from the radio
front-end to the audio card, which is not exactly what I mean when I think
of a receiver...
Cheers
D.
----- Original Message -----
From: "Johan H. Bodin" <[email protected]>
To: <[email protected]>
Sent: Monday, April 26, 2010 9:37 PM
Subject: Re: LF: Probably not a new question...
Yes, or building a simple "SoftRock style" direct conversion front end
and feed the audio to the soundcard for further processing by Winrad or
similar software capable of processing I/Q audio. What you need is some
kind of preselection filer, a quadrature mixer (half-complex mixer,
"Tayloe mixer") and a pair of good audio preamps. The front end LO can
be as simple as an XTAL oscillator followed by a 74HC74 that divides the
XTAL frequency by 4 and produces the two 0/90 degree clocks needed by
the mixer. A 74HC4052 analog switch works quite well as mixer on LF,
this one can be clocked by the 'HC74 mentioned above or any other 2-bit
synchronous binary counter clocked by fLO*4. The tuning is done in the
software.
You can find some ideas at
http://yu1lm.qrpradio.com
or look at Gerald Youngblood's QEX article series "A Software Defined
Radio for the masses"
http://www.flex-radio.com/News.aspx?topic=publications
73 de Johan SM6LKM
Graham skrev 2010-04-26 20:55:
You may be better building a LF convertor ?
G ..
*From:* Daniele Tincani <mailto:[email protected]>
*Sent:* Monday, April 26, 2010 6:23 PM
*To:* [email protected] <mailto:[email protected]>
*Subject:* LF: Probably not a new question...
Hi LF,
among the so-called "communications receivers" (0.1-30MHz, all modes,
well-known brands, etc.) in the "< 300 euros" price range (used, of
course :-)), which models have good characteristics at LF frequencies?
Any recommended models (in the same price range) outside of the "comms
receivers" class?
Many thanks for your feedbacks.
Cheers
D.
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