Re: how about a SoftRock with build in audio processor?
- --- In email@example.com, k5nwa <k5nwa@...> wrote:
>That board was the 'inspiration' but not necessarily the way to go.
> At 06:10 AM 1/1/2008, you wrote:
> >I built the SoftRock RXTX 80/40 over the holidays and have been
> >playing with it using an old laptop for the processing.
> >I started looking for a better audio processor and ran across this
> >He used a USB DAC module for a specific purpose but looking at the
> >board, it occurred to me that it would be easy to modify it (like
> >un-ground the inputs) to build my own USB DAC to use with the SoftRock.
> >Then it dawned on me that it would be even better to go one step
> >further and build the DAC _into_ the SoftRock and get RID of the audio
> >cables and module entirely.
> >Yes, it would require a bit of redesign of the board and soldering a
> >few more SMDs, but they were really much easier to solder than I
> >expected. :)
> >It would raise price a bit, but bandwidth can be optimized and noise
> >level reduced. Seems like a win, all the way around. With a bit more
> >thought, full control of the SoftRock can probably be accomplished via
> >the same USB line.
> >Am I missing a 'downside'?
> >73 de N5bz
> It's doable with a couple of extra components, but be aware that it's
> a 16 bit ADC that you have there
You are right, so, a 24 bit ADC would be a better way to go.
> , it will work but you will loseThat is what I was thinking.
> dynamic range. The "DAC is the output side of the equation, that
> would be used to drive a pair of headphones or the transmitter side
> of a RxTx, the ADC is the source of data to the PC whose pins are now
> grounded, they would connect to the SoftRock outputs.
> If you have the ADC powered by the same power as the SoftRock andThe center hump seems to be from the Local oscillator [at least I can
> physically close with short heavy wires, you will minimize the center
hear it strongly radiated in a nearby receiver], some good shielding
may also be needed. Of course, I don't have the softrock in a case, yet.
> , it may not go completely away because the ADC chip has an inputA USB DAC ADC daughter board for the earlier SoftRocks would also be
> offset, but it may be just a narrow spike instead of that broad
> noise, but even that could eliminated with some circuitry on the
> inputs to compensate for the offsets.
> He provides Eagle drawings, you can get a free limited version of
> eagle to fix the board up, so it looks like this would an interesting
> project, a "USB SoftRock".
> If you build it let us know how it works out, it will be inexpensive
> and handy for a laptop.
possible, Allowing a retrofit of earlier versions.
>It is a beautiful day to be alive, isn't it? [every day]
> www.softrockradio.org www.qrpradio.com
> "Blessed are the cracked, for they shall let in the light."
- On pin 1 (top left of U8) I have 4.9 volts! :(
and on pen seven I have 2.48 volts :)
I am testing things out now and had to pull this thread and info out
of another topic....
Tony does this mean that U8 needs to be replaced?
I see the same things on both sides.
> No RX image rejection results when one of the I / Q signals from theRXTX board is not getting to the stereo soundcard line-in input. The
problem could be on the RXTX board, in the cable or at the soundcard.
Also, if I and Q signal lines are shorted together no image rejection
will be the result.
>output signals were connected to a soundcard when an AC voltage
> There have been a few cases of U8 failing when the RXTX board I / Q
difference existed between the soundcard ground and the ground on the
RXTX board. Please check the DC voltages at pins 1 and 7 of U8 to see
if the two pins are still at about 2.5 volts with reference to circuit >