On 5/23/06, Peter Martinez [EMAIL PROTECTED] wrote:
Sami: Please could you try an experiment with this crud
I have performed all kinds of tests with SDR-1000, but unfortunately
haven't really documented the results. Now, in response to your
request, I looked at my old files and quickly put up
From G3PLX:
From what Ahti says, there is not a 1/f problem with the current SDR1000,
which is what I found with the earlier version, but the oscillator radiation
effect may or may not still be there.
In the last topic I raised, concerning 24 bit soundcards, I speculated that
the 'ideal' ADC
Sami Aintila wrote:
Peter,
I am seeing all kinds of nasty crud around DC, and so are many other
SDR-1000 users. On some systems - maybe with some sound cards - maybe
with better grounding - the problem is not very prominent. But for
optimal (receiver) performance it's always safer to operate at
Peter Martinez wrote:
...poor (or missing) DC coupling...really is not a problem...
As a generalization, I believe this is untrue.
73
Frank
AB2KT
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At 02:05 AM 5/22/2006, Peter Martinez wrote:
From G3PLX:
Jim's point about poor (or missing) DC coupling probably crossed with my
answer to Frank. It really is not a problem. Jim mentioned clock noise
again, and I have to say I haven't studied this at all, but my understanding
is that it is a
Alberto I2PHD wrote:
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Well, the reflector didn't like my HTML formatted message with an embedded
picture. This is the price we must pay for
the existence of a bunch of idiots that send out spam and viruses...so I repeat
here my message in plain text, with a
From G3PLX:
Alberto:
Thanks for your input! The peak in the centre of the spectrum plot you
showed at http://sundry.i2phd.com/zeropeak.gif is certainly the small DC
offset of the ADC's in the Delta 44. The Zero-IF software would remove this
of course. It can be done automatically, it doesn't
From G3PLX:
The software that comes with the SDR1000 uses an 11.025kHz intermediate
frequency. I understand the reasons for doing it this way, but even before
the SDR1000 appeared I was doing software radio with an I.F. of zero. By
this I mean that the sine and cosine RF oscillators were set
The DSP software is already capable of 0 Hz IF, and has been since its
earliest version. IIRC the 11025 Hz IF is primarily a consequence of the
frequency response of typical soundcards, which start rolling off
somewhere in the vicinity of 200-300 Hz.
73
Frank
AB2KT
Peter Martinez wrote:
From
Another reason for using IF higher than 0 Hz is the high inherent
noise level of typical transistors and opamps at low frequencies (so
called 1/f-noise). This and the leakage of the VFO signals made me to
move away from the zero-IF in my early switching (and Tayloe) mixer
experiments.
Typo correction: ... article in QEX...
Ahti OH2RZ
On 21/05/06, Ahti Aintila [EMAIL PROTECTED] wrote:
Another reason for using IF higher than 0 Hz is the high inherent
noise level of typical transistors and opamps at low frequencies (so
called 1/f-noise). This and the leakage of the VFO
From G3PLX:
I just checked my two soundcards for the low-frequency roll-off. My new
Firebox is 2.4dB down at 1.8Hz and the MP3+ is 1.5dB down at 1.2Hz. And that
was done quickly by linking line-out to line-in, so it includes the LF
roll-off of the transmit side too. I am quite certain the
Peter,
You are right about the 22 kHz image in transmission. That is why I am
reluctant to transmit without checking (and adjusting) the attenuation
on the used frequency.
With the preamplifier board the leakage of the sampling signal still
can be detected by my other receivers. In practice it
At 09:41 AM 5/21/2006, Peter Martinez wrote:
From G3PLX:
The software that comes with the SDR1000 uses an 11.025kHz intermediate
frequency. I understand the reasons for doing it this way, but even before
the SDR1000 appeared I was doing software radio with an I.F. of zero. By
this I mean that
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