Fwd: Tuesday Tech Net

[Jeff Scaparra]

I am partial to the peaberry design that doesn't require a sound card.
Other than that they are very similar.

http://ae9rb.com/

Jeff - N6SDR

On Mon, Jun 8, 2015 at 11:23 PM, Dave <dave at wb6dhw.com> wrote:

>    A simple SDR(crystal osc  and a 74hc74 plus FST bus switch + 2 opamps)
> like a softrock and one of the free SDR programs should do it. If the
> signal is not very weak, you might get by with connecting an antenna to one
> of the inputs of your sound card.  They have a recording option plus DSP
> processing.
>
> Dave - WB6DHW
> <http://wb6dhw.com>
>
>
> On 6/8/2015 9:05 PM, Nan and Sandy Sanders wrote:
>
>>
>>  From Hal WB3KDU
>>>
>>>
>>>
>>> Tuesday Tech*Net   8PM AMRAD repeater (21/81) and Echolink.
>>> ======================================================
>>>
>>> Built in 1927 SAQ is VLF station operating on 17.2Khz generating its
>>> signal with a
>>> mechanical Alexandrian generator.  AMRAD members have been DXing SAQ for
>>> a number of years and some have been the repent of its special QSL which
>>> can
>>> only be obtained by copying accurately most of its transmission.  SAQ
>>> operates
>>> twice a year, Christmas Eve and the first Sunday of July which is
>>> rapidly approaching.
>>>
>>> There are practical problems to receiving SAQ.  First you need a
>>> receiver that
>>> covers 17.2Khz with adequate sensitivity.   Next, there is a large
>>> amount of
>>> noise to contend with - simple radio static, weather and man-made.  This
>>> requires a very narrow filter, usually around 50hz to limit the noise.
>>> If the signal
>>> strength is not strong (this happens from time to time) you may be
>>> unable to
>>> hear the transmission or you may discern it but be unable to copy it
>>> because
>>> it is so weak.
>>>
>>> Attempts have been made to record and digitally process the signal
>>> attempting
>>> to apply DSP techniques to recover the station's audio.  This hasn't
>>> proved
>>> successful in the past due to various technical issues. However, it
>>> might be worth
>>> trying this route if the signal is too weak to copy by ear.
>>>
>>> It also might be possible to have several stations record whatever audio
>>> they can
>>> and then combine a number of recordings made by receiver in different
>>> parts
>>> of the country.  This could be done processing just the audio. A more
>>> ambitious
>>> idea is to record the RF baseband and combine and process it. It would
>>> require phase
>>> references to be recorded along with the signal.  It would involve some
>>> tricky DSP code too.
>>>
>>> http://en.wikipedia.org/wiki/Varberg_Radio_Station
>>>
>>> Besides SAQ we will have our usual exchange on digital modes and SDR.
>>>
>>> Should we sponsor a "Learn Verilog" project of some kind?  This is one
>>> of the popular languages for programming an FPGA.
>>>
>>> Last week we had a couple of station check in so attendance on the net,
>>> while still small is definitely up.
>>>
>>> ======================================================
>>> Tech*Net meets Tuesday 8PM on the AMRAD repeater (21/81) and
>>> via Echolink on the W4CIA conference point.  WB5MMD is conference
>>> coordinator and net control.
>>>
>>>
>> _______________________________________________
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>> https://lists.amrad.org/mailman/listinfo/tacos
>>
>
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