Message-ID: <4F75CB15.4090105@usa.net>
Date: Fri, 30 Mar 2012 17:02:45 +0200
From: Alberto di Bene <dibene@usa.net>
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To: rsgb_lf_group@blacksheep.org
References: <8CEDBB08CDC93E9-6B0-1108@webmail-m065.sysops.aol.com> <4F74A485.8010904@freenet.de> <4F7546E0.3080900@telia.com>
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Z-USANET-MsgId: XID794qcdPcW1968X40
Subject: Re: LF: Dream sampler
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On 3/30/2012 7:38 AM, Johan H. Bodin wrote:
> I am thinking about a front end using something like your old I/Q sampling PIC
> with a preamp and a BPF. Fs should be close to 4*9=36kHz for near-DC IF but not
> too close in order to avoid 1/f noise from the preamp. If the sampling MCU is
> clocked with a precision frequency and connected to a simple serial port, we
> could say goodbye to soundcard jitter and jumps and other unexplainable
> phenomena! Not a "soundCard" really, but a "dreamCard"...
Hi Johan,

   may I suggest you to give a look at the dsPIC from Microchip ?
It has a 12-bit ADC and a couple of DACs on board, together with an instruction set rich of
instructions tailored to DSP processing, like MAC, ring buffer support, etc. etc.

I used it for an SSB generator, using a modified Weaver method, and found it perfectly
adequate for this kind of tasks.  I bet that with a single dsPIC chip, you can digitize
the 8.9 kHz band signals, process them and playback them through the DACs, no PC
whatsoever needed....

73  Alberto  I2PHD


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    On 3/30/2012 7:38 AM, Johan H. Bodin wrote:
    <blockquote cite=3D"mid:4F7546E0.3080900@telia.com" type=3D"cite">
      <pre wrap=3D"">I am thinking about a front end using something like=
 your old I/Q sampling PIC
with a preamp and a BPF. Fs should be close to 4*9=3D36kHz for near-DC IF=
 but not
too close in order to avoid 1/f noise from the preamp. If the sampling MC=
U is
clocked with a precision frequency and connected to a simple serial port,=
 we
could say goodbye to soundcard jitter and jumps and other unexplainable
phenomena! Not a "soundCard" really, but a "dreamCard"...</pre>
    </blockquote>
    <font face=3D"Tahoma">Hi Johan,<br>
      <br>
      =A0=A0 may I suggest you to give a look at the dsPIC from Microchip=
 ?<br>
      It has a 12-bit ADC and a couple of DACs on board, together with
      an instruction set rich of<br>
      instructions tailored to DSP processing, like MAC, ring buffer
      support, etc. etc.<br>
      <br>
      I used it for an SSB generator, using a modified Weaver method,
      and found it perfectly<br>
      adequate for this kind of tasks.=A0 I bet that with a single dsPIC
      chip, you can digitize<br>
      the 8.9 kHz band signals, process them and playback them through
      the DACs, no PC<br>
      whatsoever needed....<br>
      <br>
      73=A0 Alberto=A0 I2PHD<br>
      <br>
    </font>
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