[Linrad] Re: Using Linrad and SDR-IQ for AM Radio

[Eastzone <gmail.com; eastzonexp@xxxxxxxxxxxxxxxx>]

Thanks a lot, Leif!

It is caused by the bad environment where I put the SDR-IQ and the
antenna. When I move it to an open space, even a 20cm wire will give
satisfactory receiving quality without any additional adjustment on
Linrad :)

Eastzone

On 1月31日, 上午8时28分, Leif Asbrink <l...@xxxxxxxxxx> wrote:
> Hi Eastzone,
>
> > Maybe it is a question that not closely related to Linrad.
>
> Yes, surely it is:-)
>
> > I want to use SDR-IQ to listen to local AM Radio stations, since SDR-
> > IQ's highest capturing BW is 40MHz and not suitable for FM stations.
>
> It could be possible to use it for FM with a suitable converter.
> I actually do not know whether the FM detector in its current
> state would be any good. There will be a wideband FM mode
> some day....
>
>
>
>
>
> > I've made a GND line to the outer surface of SDR-IQ's coaxial jack,
> > and inserted a 3-m long line into the center of that jack.
>
> > Next, I launch Linrad and go into AM mode. I switch the SDR-IQ's
> > central frequency to the frequency of local station. No matter how I
> > adjust the filter, only noises (like sounds of wind) come out of my
> > loudspeakers, although I do see some meaningful patterns on the
> > waterfall.
>
> > Here are some snapshots
>
> >http://farm4.static.flickr.com/3116/3240318798_b2a0074911_o.jpg
> >http://farm4.static.flickr.com/3089/3240318780_445276e521_o.jpg
>
> > Do I need any special configuration on Linrad? I just used the default
> > configurations of AM mode and 8kHz output sampling frequency.
>
> To start with you need an antenna that picks up the local
> radio waves rather than the interference created by your
> computer;-)
>
> With the 3 m wire you might find that AM stations on HF
> can win over the computer noise and produce some detected
> AM.
>
> Setting 8 kHz for the D/A limits the bandwidth to 4 kHz
> and for a local AM station I would expect you would like
> to have more bandwidth than that.
>
> In case you have good Internet it might be a good idea to
> download This filehttp://sm5bsz.com/linuxdsp/usage/kari/530-930khz.wav 
> and read about it here:http://www.sm5bsz.com/linuxdsp/usage/kari/kari.htm
>
> In that file you can listen to plenty of local and lot
> so local AM stations and try out what the different
> parameters of Linrad do to the detected AM output.
>
> With a reasonable antenna you should se the typical symmetric
> waterfall diagrams of AM stations (see e.g. kari.htm)
> Then I hope you will find out what to do with Linrad
> reasonably fast. Please give me feedback on anything
> that you find hard to understand and that I might change
> to make it easier for others.
>
> 73
>
> Leif / SM5BSZ- 隐藏被引用文字 -
>
> - 显示引用的文字 -
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