Eric, Leon & Stan

I saw you were having trouble with Bill's latest software so I just
now downloaded it and updated my system to check it out. It came up
without any problem. I wonder if you have the latest PowerSDR 1.4.4
installed or if you are using a previous version? It seems to be
working fine here without a receiver attached. Remember to select
the "Hardware Oscillator" option under Setup, SoftRock.

-----Original Message-----
From: softrock40@... [mailto:softrock40@...] On Behalf Of Bill Tracey
Sent: Monday, September 19, 2005 8:35 AM
To: softrock40@...
Subject: [softrock40] Fresh Software - 20050917 level

I've posted a few updates to the SoftRock updates for PowerSDR.? Nothing
major, just some bug fixes.? Specifically:

- Fixed problem using an SDR 1000 in fixed freq mode
- Fixed a potential glitch/hang in level calibration with a SoftRock 40
- Fixed smooth panadapter scrolling when in fixed freq mode

To get the new code:

Regards,

Bill (kd5tfd)?

-----Original Message-----
From: softrock40@... [mailto:softrock40@...] On Behalf Of Bill Tracey
Sent: Sunday, September 18, 2005 2:57 PM
To: softrock40@...; softrock40@...
Subject: RE: [softrock40] Re: Interference from PC?

I believe the gunk you see near the center frequency with or w/o hardware
attached is an artifact of the signal processing architecture, and? noise
near DC on the audio input (ie 60 hz hum,. etc)

How the software tuning works is by having a software mixer fed with the
local oscillator to dowconvert the signal of interest.? In the case of the
SoftRock, you have the hardware QSD downconverting and quadrature sampling
a 48 khz swath of RF centered on 7.056 Mhz.? To listen to a signal at 7.060
MHz, the software mixer is set to run with a local oscillator at 4 khz to
mix down the 7.056 Mhz centered signal.? As you tune closer to the center
frequency, the freq of the software local oscillator gets lower and
lower.? Very near the center frequency, the local osc will be in the 100's
of hz,? Mixed with 60 hz (and harmonics) hum this will tend to product
responses at 60Hz (and harmonics)? +/- SoftwareLO? etc -- thereby getting
you the gunk around the center frequency.

I will have to admit that my understanding of this phenomenon is not as
crisp as I would like it to be. As Tony said in a prior post, there's some
hope that some of this can be eliminated with DSP magic.? One approach
would be to record and characterize the noise characteristics with no input
and then try and remove them with DSP magic when fed with a real
signal.? One could do this in either the time domain or frequency domain,
although I'm not sure how one would maintain sync with the noise signal in
the time domain.? My DSP skills are not strong enough (yet) to really know
how feasible such an approach would be.

Another (potentially naive) approach might be to try a different tuning
approach.? If one is interested in a sig at 7.060, I'd think one could take
an FFT of the input signal, zero the FFT bins outside the passband of
interest, shift the spectrum over by 4 khz and then IFFT the result to
recover the signal of interest.? I think this should work, but not having
tried it really can't? say for sure.? Also not too clear in my mind if this
would be better than the software mixing approach currently used as you get
closer to DC.

One thing to be aware of -- in a more complete SDR with a frequency agile
downconverter, you typically don't tune in software down near DC.? For
example, on the SDR 1000, the tuning is always such that you're
approximately 11khz above DC for software tuning.? The reason for this
being approximate is that the DDS tuning is limited to tuning to freqs
where the DDS generates a minimum of spurs.

I will be the first to admit I'm somewhat of a neophyte with DSP.? SDR is
an area rich with opportunities for learning and experimenting, and we've
now got hardware and software accessible to the amateur community to
experiment with.? Hoping folks get in there and do some experimenting and
learning.

Cheers,

Bill (kd5tfd)


At 01:25 PM 9/18/2005, Stan Rife wrote:
>??? Tony, one thing I noticed, when just playing around with the SDR
> software, was the 600 Hz tone that comes from the soundcard (?) at the
> 7.056 freq. after the Fixed HW oscilator is set up per the instructions.
> This is, of course, without the SoftRock hardware installed, as I do not
> even have my kit YET. (boo hoo).
>???? Is this oscilator tone, at that freq., something that will always be
> there? I saw a procedure in the manual that said something about going
> above 7.056, as much as the test oscilator is below 7.056 and adjusting
> for a null. I am not quite clear on all of this. I do have an XG-1, and I
> assume that is what this is refering to.
>
>
>Stan Rife
>W5EWA
>Houston, TX
>K2 S/N 4216
>

The soundcard is one of the most vulnerable spots for letting in
spurious signals.

-----Original Message-----
From: softrock40@... [mailto:softrock40@...] On Behalf Of Bill Tracey
Sent: Sunday, September 18, 2005 2:57 PM
To: softrock40@...; softrock40@...
Subject: RE: [softrock40] Re: Interference from PC?

I believe the gunk you see near the center frequency with or w/o hardware
attached is an artifact of the signal processing architecture, and? noise
near DC on the audio input (ie 60 hz hum,. etc)

How the software tuning works is by having a software mixer fed with the
local oscillator to dowconvert the signal of interest.? In the case of the
SoftRock, you have the hardware QSD downconverting and quadrature sampling
a 48 khz swath of RF centered on 7.056 Mhz.? To listen to a signal at 7.060
MHz, the software mixer is set to run with a local oscillator at 4 khz to
mix down the 7.056 Mhz centered signal.? As you tune closer to the center
frequency, the freq of the software local oscillator gets lower and
lower.? Very near the center frequency, the local osc will be in the 100's
of hz,? Mixed with 60 hz (and harmonics) hum this will tend to product
responses at 60Hz (and harmonics)? +/- SoftwareLO? etc -- thereby getting
you the gunk around the center frequency.

I will have to admit that my understanding of this phenomenon is not as
crisp as I would like it to be. As Tony said in a prior post, there's some
hope that some of this can be eliminated with DSP magic.? One approach
would be to record and characterize the noise characteristics with no input
and then try and remove them with DSP magic when fed with a real
signal.? One could do this in either the time domain or frequency domain,
although I'm not sure how one would maintain sync with the noise signal in
the time domain.? My DSP skills are not strong enough (yet) to really know
how feasible such an approach would be.

Another (potentially naive) approach might be to try a different tuning
approach.? If one is interested in a sig at 7.060, I'd think one could take
an FFT of the input signal, zero the FFT bins outside the passband of
interest, shift the spectrum over by 4 khz and then IFFT the result to
recover the signal of interest.? I think this should work, but not having
tried it really can't? say for sure.? Also not too clear in my mind if this
would be better than the software mixing approach currently used as you get
closer to DC.

One thing to be aware of -- in a more complete SDR with a frequency agile
downconverter, you typically don't tune in software down near DC.? For
example, on the SDR 1000, the tuning is always such that you're
approximately 11khz above DC for software tuning.? The reason for this
being approximate is that the DDS tuning is limited to tuning to freqs
where the DDS generates a minimum of spurs.

I will be the first to admit I'm somewhat of a neophyte with DSP.? SDR is
an area rich with opportunities for learning and experimenting, and we've
now got hardware and software accessible to the amateur community to
experiment with.? Hoping folks get in there and do some experimenting and
learning.

Cheers,

Bill (kd5tfd)


At 01:25 PM 9/18/2005, Stan Rife wrote:
>??? Tony, one thing I noticed, when just playing around with the SDR
> software, was the 600 Hz tone that comes from the soundcard (?) at the
> 7.056 freq. after the Fixed HW oscilator is set up per the instructions.
> This is, of course, without the SoftRock hardware installed, as I do not
> even have my kit YET. (boo hoo).
>???? Is this oscilator tone, at that freq., something that will always be
> there? I saw a procedure in the manual that said something about going
> above 7.056, as much as the test oscilator is below 7.056 and adjusting
> for a null. I am not quite clear on all of this. I do have an XG-1, and I
> assume that is what this is refering to.
>
>
>Stan Rife
>W5EWA
>Houston, TX
>K2 S/N 4216
>

Tony, one thing I noticed, when just playing around with the SDR software, was the 600 Hz tone that comes from the soundcard (?) at the 7.056 freq. after the Fixed HW oscilator is set up per the instructions. This is, of course, without the SoftRock hardware installed, as I do not even have my kit YET. (boo hoo).
Is this oscilator tone, at that freq., something that will always be there? I saw a procedure in the manual that said something about going above 7.056, as much as the test oscilator is below 7.056 and adjusting for a null. I am not quite clear on all of this. I do have an XG-1, and I assume that is what this is refering to.


Stan Rife
W5EWA
Houston, TX
K2 S/N 4216

-----Original Message-----
From: softrock40@... [mailto:softrock40@...] On Behalf Of Jim Sheldon
Sent: Sunday, September 18, 2005 11:47 AM
To: softrock40@...
Subject: RE: [softrock40] Re: Interference from PC?

I have my softrock 40 running.? It's plugged into an external USB hub for
power, and hooked up to my B & W broadband folded dipole.? I can find no
birdies within it's limited tuning range - 7.030 to 7.080 as specified in
the AMQRP info.? It is extremely sensitive, and copies signals within that
range as well as my K2 does, and that's saying something.? The K2 has by far
the best receiver of any rig I've ever owned.

All this talk about computer birdies and pc noise is pretty much unfounded.
There is NO noise apparent with the scope on the DC voltage line coming from
the USB port.

The computer is a Dell Dimension 8100, Pentium IV @ 1.4GHz and even with the
covers off, I still cannot find any birds attributable to the computer.?

I AM using just the bare-bones, unsupported SoundBlaster PCI sound card
that's built into the Dell's motherboard.? It performs adequately for the
Soft Rock 40, but I would presume to say that if one had an SDR-1000, this
card would definitely be struggling.? My sampling rate is only 48 KHz, and
it still does very well.?

Maybe this will allay some of the fears I see expressed here on the
reflector.?

What the heck do you expect for $23 bucks a full blown SDR-1000?? Jeez,
lighten up and experiment with the thing! It works as advertised, and maybe
even better considering the low end sound card I'm using.

Jim - W0EB

Tony, one thing I noticed, when just playing around with the SDR software, was the 600 Hz tone that comes from the soundcard (?) at the 7.056 freq. after the Fixed HW oscilator is set up per the instructions. This is, of course, without the SoftRock hardware installed, as I do not even have my kit YET. (boo hoo).
Is this oscilator tone, at that freq., something that will always be there? I saw a procedure in the manual that said something about going above 7.056, as much as the test oscilator is below 7.056 and adjusting for a null. I am not quite clear on all of this. I do have an XG-1, and I assume that is what this is refering to.

Stan Rife
W5EWA
Houston, TX
K2 S/N 4216

-----Original Message-----
From: softrock40@...
[mailto:softrock40@...] On Behalf Of kb9yig
Sent: Saturday, September 17, 2005 9:28 PM
To: softrock40@...
Subject: [softrock40] Re: Interference from PC?

Hi Rein,

I have built about 25 of the v4.0 SoftRock40 receivers and find
the PC
noise does not cause much of a problem. When the receiver is
calibrated to S9, (-73 dBM, 50 uV RMS), the baseline is around -135
dBm with 10-15 dB spikes riding on the baseline every 1 kHz or so. Also at the LO frequency, around 7.054-7.056 MHz there is a large
broad spike associated with the LO and the fact that the soundcard
contributes lots of noise near zero frequency.
I will be quite interested in the experience of SoftRock40
builders as
they finish their kits. If I can help with problems in getting the
little receive running, I would be happy to do so.

73,
Tony KB9YIG

--- In softrock40@..., "observer35" <rein0zn@i...> wrote:
> Hi all,
>
> Just new to the group.
>
> Does anybody experience interference from the PC on 40 meters?
>
> What about noise and garbage on the 5 V USB line?
>
> 73 Rein W6/PA0ZN
>
>



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-----Original Message-----
From: softrock40@... [mailto:softrock40@...] On Behalf Of KY1K
Sent: Sunday, September 18, 2005 11:26 AM
To: softrock40@...
Subject: Re: [softrock40] Re: Interference from PC?

I'm brand spankin' new to the group so didn't see the original thread.

Expecting a sensitive receiver to operate just inches away from a
wideband noise source is optimistic (IMHO). For best results, it
needs shielding just like any other receiver and or transmitter does.

Computer noise might not show up as clean carriers or be identifiable
by tuning across the band. It appears as an elevated noise floor most
of the time, which sounds like background noise. I'm sure many people
have interference from their own computers and most don't even
realize it's there because it sounds rather like normal atmospheric noise.

For absolute best results, shield it. For casual listening on a
crowded band, don't worry about it and run it as supplied.

My softrock-40 is going on LF when I get it and it will be located
away from the computer and shielded. Switching supplies, florescent
lamps and computer interference is pretty severe at 190 kHz and I
want to have good reception. I'm even considering magnetic shielding
due to the nature of the interference at these frequencies.

Regards,

Art





>The supply from the USB connector is 5V. Are you using a separate power
>supply?


--
No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.0.344 / Virus Database: 267.11.1/104 - Release Date: 9/16/2005

-----Original Message-----
From: softrock40@... [mailto:softrock40@...] On Behalf Of kb9yig
Sent: Saturday, September 17, 2005 9:28 PM
To: softrock40@...
Subject: [softrock40] Re: Interference from PC?

Hi Rein,

I have built about 25 of the v4.0 SoftRock40 receivers and find the PC
noise does not cause much of a problem.? When the receiver is
calibrated to S9, (-73 dBM, 50 uV RMS), the baseline is around -135
dBm with 10-15 dB spikes riding on the baseline every 1 kHz or so.?
Also at the LO frequency, around 7.054-7.056 MHz there is a large
broad spike associated with the LO and the fact that the soundcard
contributes lots of noise near zero frequency.?

I will be quite interested in the experience of SoftRock40 builders as
they finish their kits.? If I can help with problems in getting the
little receive running, I would be happy to do so.

73,
Tony KB9YIG

--- In softrock40@..., "observer35" wrote:
> Hi all,
>
> Just new to the group.
>
> Does anybody experience interference from the PC on 40 meters?
>
> What about noise and garbage on the 5 V USB line?
>
> 73 Rein W6/PA0ZN
>
>

I'm brand spankin' new to the group so didn't see the original thread.

Expecting a sensitive receiver to operate just inches away from a
wideband noise source is optimistic (IMHO). For best results, it
needs shielding just like any other receiver and or transmitter does.

Computer noise might not show up as clean carriers or be identifiable
by tuning across the band. It appears as an elevated noise floor most
of the time, which sounds like background noise. I'm sure many people
have interference from their own computers and most don't even
realize it's there because it sounds rather like normal atmospheric noise.

For absolute best results, shield it. For casual listening on a
crowded band, don't worry about it and run it as supplied.

My softrock-40 is going on LF when I get it and it will be located
away from the computer and shielded. Switching supplies, florescent
lamps and computer interference is pretty severe at 190 kHz and I
want to have good reception. I'm even considering magnetic shielding
due to the nature of the interference at these frequencies.

Regards,

Art

The supply from the USB connector is 5V. Are you using a separate power
supply?

--
No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.0.344 / Virus Database: 267.11.1/104 - Release Date: 9/16/2005






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