Re: how about a SoftRock with build in audio processor?
- --- In firstname.lastname@example.org, k5nwa <k5nwa@...> wrote:
> At 12:41 PM 1/1/2008, you wrote:
> >That board was the 'inspiration' but not necessarily the way to go.
> >You are right, so, a 24 bit ADC would be a better way to go.
> >The center hump seems to be from the Local oscillator [at least I can
> >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,
> During late winter (I need to recover from expenses and build up my
> slush fund), around March I will be doing a group buy of several
> components. One of the devices will be a fairly good quality 24 bit
> A/D and D/A chip that will be less than $6, that chip and a PIC
> 18F2550 will make a very nice 24 bit USB sound board for little
> money. Right now I can't recall the name of the manufacturer but I
> have it down "somewhere".
>I tried a different laptop which seems to have a much better 'sound
> Unplug the SoftRock and power it off, you will still see the hump,
> it's due to the A/D in your sound card not reading 0 when it's
> getting 0V for an input, a FFT of a small DC voltage will give you a
> large signal at 0Hz. some of it is due to ground loops. The QSD
> detector is deaf to it's LO frequency which produces a steady DC
> output due to the signal being capacitively coupled in it's output
> and amplifiers.
card'. Almost no 'hump' in the middle, and YES, you are [of course]
right, it MUST be deaf to its own LO.
I will be looking forward to March'ing together.
> 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 >