|
Hi All,
Question. Does Power SDR software provide a "Variable Beat or Carrier Oscillator"? Perhaps 2 ?
What is the freq range of that oscillator ( up to 48 or 96 kHz ? )
73 Rein W6/PA0ZN
KD5NWA wrote:
toggle quoted message
Show quoted text
It would only let me see 6.5 KHz on one side.
I'm going to try putting two crystals in parallel, and try to pull
them so I can get at least 10 KHz on either side of the IF, the
crystals are cheap enough. I'll get the ones that are close to the
center of the IF and pull them down. I'll also buy one that is
68.8KHz lower than the 4X IF frequency, just in case.
At 01:58 PM 9/28/2005, Tony Parks wrote:
Cecil,
The crystal that is 17 kHz low would work well if you are meaning the
crystal is 68 kHz low at its fundamental frequency. Seventeen kHz low even
at its fundamental frequency would still probably be ok.
----- Original Message -----
From: "KD5NWA" <KD5NWA@...>
To: <k4oah@...>
Cc: <softrock40@...>
Sent: Wednesday, September 28, 2005 1:51 PM
Subject: [softrock40] Re: [QRP-L] (no subject)
We are in the process of backing up and punting instead. I've been
advised to move the crystal frequency of SR-40 by 12KHz on the low or
on the high side, to get away from some of the noise in the center of
the receivers band.
Not an easy job due to lack of crystals at those high frequencies, I
found one 17 KHz low, too low for my taste. I'll be checking for
something closer later when I get a break.
Any guesses as to how low could I pull a 35.328 MHz crystal? 48KHz lower?
I kept the names of the interested parties, and will keep you posted.
Cecil Bayona
KD5NWA
www.qrpradio.com
'Never argue with an idiot. They drag you down to their level then
beat you with experience.'
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The radio is simplicity itself, and it receives a band of signals that is 48KHz wide, it has only one oscillator, the rest is faked by the computer. The radio has two signals it puts out, I and Q that are sampled by a sound card taking samples of both channels at a rate of 48KHz, after the computer reads those two signals it figures out the rest in it's program. The SR-40 has a oscillator that is used in creating a quadrature phased clock at the center of the band that you are interested in. This clock is used to extract the I and Q signals in the frequency range of interest, the detectors, injection of carrier, filtering , etc all the typical added on hardware of a radio is handled by the software in the PC. This makes the radio hardware very simple, "Elegance through simplicity" as I like to say of simple designs that do the job well. The main Osc. is crystal controlled and divided by 4 to generate clocks in Quadrature to "detect" the signals in the frequency range of interest. Some of us are trying to find the appropriate crystals so we can move the frequency of the receiver to our area of interest. In my case I want on to be able to look at the IF frequency range of Kenwood HF radios, that frequency is 8.830MHz, I need some crystals a little higher or lower than 4 times that frequency (around 35.3 MHz), not an easy task if you are not willing to spend a lot of money on the crystal. At 03:20 PM 9/28/2005, you wrote: Hi All,
Question. Does Power SDR software provide a "Variable Beat or Carrier
Oscillator"? Perhaps 2 ?
What is the freq range of that oscillator ( up to 48 or 96 kHz ? )
73 Rein W6/PA0ZN
KD5NWA wrote:
It would only let me see 6.5 KHz on one side.
I'm going to try putting two crystals in parallel, and try to pull
them so I can get at least 10 KHz on either side of the IF, the
crystals are cheap enough. I'll get the ones that are close to the
center of the IF and pull them down. I'll also buy one that is
68.8KHz lower than the 4X IF frequency, just in case.
At 01:58 PM 9/28/2005, Tony Parks wrote:
Cecil,
The crystal that is 17 kHz low would work well if you are meaning the
crystal is 68 kHz low at its fundamental frequency. Seventeen kHz low even
at its fundamental frequency would still probably be ok.
----- Original Message ----- Cecil Bayona KD5NWA www.qrpradio.com 'Never argue with an idiot. They drag you down to their level then beat you with experience.'
|
If you shift the desired signal up or down in freq you would need to shift it back
to its natural audio freq spectrum
IF = 8330 kHz center of pass band
Suppose SSB signl .3 - 2 kHz
output IF filter 8330.3 - 8332 kHz depending on tuning front end IF BW > 2 kHz
softrock board xtal 8352 kHz or 8318 kHz
output from board I and Q : 11.7 kHz - 10.0 kHz USB -> LSB
In order to copy the I/O signal it needs to be shifted back to .3 to 2 kHz by "mixing"
My question was what is the freq. range of this "mixing" process in the powerSDR software,.
the computer
The same case can be made for the use of a softrock crystal of 8318 kHz In that case there would be
no side band switch.
73 Rein W6/PA0ZN
KD5NWA wrote:
toggle quoted message
Show quoted text
The radio is simplicity itself, and it receives a band of signals
that is 48KHz wide, it has only one oscillator, the rest is faked by
the computer. The radio has two signals it puts out, I and Q that
are sampled by a sound card taking samples of both channels at a rate
of 48KHz, after the computer reads those two signals it figures out
the rest in it's program.
The SR-40 has a oscillator that is used in creating a quadrature
phased clock at the center of the band that you are interested in.
This clock is used to extract the I and Q signals in the frequency
range of interest, the detectors, injection of carrier, filtering ,
etc all the typical added on hardware of a radio is handled by the
software in the PC. This makes the radio hardware very simple,
"Elegance through simplicity" as I like to say of simple designs that
do the job well.
The main Osc. is crystal controlled and divided by 4 to generate
clocks in Quadrature to "detect" the signals in the frequency range
of interest. Some of us are trying to find the appropriate crystals
so we can move the frequency of the receiver to our area of interest.
In my case I want on to be able to look at the IF frequency range of
Kenwood HF radios, that frequency is 8.830MHz, I need some crystals a
little higher or lower than 4 times that frequency (around 35.3 MHz),
not an easy task if you are not willing to spend a lot of money on the crystal.
At 03:20 PM 9/28/2005, you wrote:
Hi All,
Question. Does Power SDR software provide a "Variable Beat or Carrier
Oscillator"? Perhaps 2 ?
What is the freq range of that oscillator ( up to 48 or 96 kHz ? )
73 Rein W6/PA0ZN
KD5NWA wrote:
It would only let me see 6.5 KHz on one side.
I'm going to try putting two crystals in parallel, and try to pull
them so I can get at least 10 KHz on either side of the IF, the
crystals are cheap enough. I'll get the ones that are close to the
center of the IF and pull them down. I'll also buy one that is
68.8KHz lower than the 4X IF frequency, just in case.
At 01:58 PM 9/28/2005, Tony Parks wrote:
Cecil,
The crystal that is 17 kHz low would work well if you are meaning the
crystal is 68 kHz low at its fundamental frequency. Seventeen kHz low even
at its fundamental frequency would still probably be ok.
----- Original Message ----- Cecil Bayona
KD5NWA
www.qrpradio.com
'Never argue with an idiot. They drag you down to their level then
beat you with experience.'
------------------------------------------------------------------------
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* Visit your group "softrock40
<>" on the web.
* To unsubscribe from this group, send an email to:
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|
I have,,, 'SomeWhere' a really good description of the Weaver ssb method. How, if at all, does that method compare with the softrock? (ok,,, I haven't seen that document in at least 6 years, but will find it before spring.)
|
The audio out of the I and Q signals have a 24KHz bandwidth, but their relationship tell the PC if the signal is above or below the quadrature clock. Those two signals together represent a 48 KHz swath of radio signals. Not each having 24KHz of the spectrum, but together they have 48KHz.
The PC is able to "put" a phoney carrier anywhere in that 48KHz space so that the signal is demodulated correctly into audio.
But whether you have a crystal that is low or one that is high, it makes no difference as long as the signal is in the band-pass, you still need USB and LSB demodulation. That crystal just sets the center of the frequency range that you are looking at.
It's kind like looking at book but you have a piece of cardboard with a rectangle cut in it, as you move that piece of cardboard you see different parts of the book. A word may be on the right side of the rectangle but when you move the cardboard its on the left side now, but the letters don't reverse do they? The signals just move their position in the frequency spectrum as you move the crystal frequency, you still need USB and LSB decoders.
Somebody else feel free to try to explain how it works. There are plenty of people on this list that are more knowledgeable than I am.
toggle quoted message
Show quoted text
If you shift the desired signal up or down in freq you would need to
shift it back
to its natural audio freq spectrum
IF = 8330 kHz center of pass band
Suppose SSB signl .3 - 2 kHz
output IF filter 8330.3 - 8332 kHz depending on tuning
front end IF BW > 2 kHz
softrock board xtal 8352 kHz or 8318 kHz
output from board I and Q : 11.7 kHz - 10.0 kHz USB -> LSB
In order to copy the I/O signal it needs to be shifted back to .3 to
2 kHz by "mixing"
My question was what is the freq. range of this "mixing" process in
the powerSDR software,.
the computer
The same case can be made for the use of a softrock crystal of 8318
kHz In that case there would be
no side band switch.
73 Rein W6/PA0ZN
KD5NWA wrote:
The radio is simplicity itself, and it receives a band of signals
that is 48KHz wide, it has only one oscillator, the rest is faked by
the computer. The radio has two signals it puts out, I and Q that
are sampled by a sound card taking samples of both channels at a rate
of 48KHz, after the computer reads those two signals it figures out
the rest in it's program.
The SR-40 has a oscillator that is used in creating a quadrature
phased clock at the center of the band that you are interested in.
This clock is used to extract the I and Q signals in the frequency
range of interest, the detectors, injection of carrier, filtering ,
etc all the typical added on hardware of a radio is handled by the
software in the PC. This makes the radio hardware very simple,
"Elegance through simplicity" as I like to say of simple designs that
do the job well.
The main Osc. is crystal controlled and divided by 4 to generate
clocks in Quadrature to "detect" the signals in the frequency range
of interest. Some of us are trying to find the appropriate crystals
so we can move the frequency of the receiver to our area of interest.
In my case I want on to be able to look at the IF frequency range of
Kenwood HF radios, that frequency is 8.830MHz, I need some crystals a
little higher or lower than 4 times that frequency (around 35.3 MHz),
not an easy task if you are not willing to spend a lot of money on the
crystal.
At 03:20 PM 9/28/2005, you wrote:
>Hi All,
>
>Question. Does Power SDR software provide a "Variable Beat or Carrier
>Oscillator"? Perhaps 2 ?
>What is the freq range of that oscillator ( up to 48 or 96 kHz ? )
>
>73 Rein W6/PA0ZN
>
>KD5NWA wrote:
>
> > It would only let me see 6.5 KHz on one side.
> >
> > I'm going to try putting two crystals in parallel, and try to pull
> > them so I can get at least 10 KHz on either side of the IF, the > > > crystals are cheap enough. I'll get the ones that are close to the
> > center of the IF and pull them down. I'll also buy one that is
> > 68.8KHz lower than the 4X IF frequency, just in case.
> >
> > At 01:58 PM 9/28/2005, Tony Parks wrote:
> > >Cecil,
> > >
> > >The crystal that is 17 kHz low would work well if you are meaning the
> > >crystal is 68 kHz low at its fundamental frequency. Seventeen kHz
> > low even
> > >at its fundamental frequency would still probably be ok.
> > >
> > >
> > >----- Original Message -----
Cecil Bayona
KD5NWA
www.qrpradio.com
'Never argue with an idiot. They drag you down to their level then
beat you with experience.'
------------------------------------------------------------------------
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* Visit your group "softrock40
<>" on the web.
* To unsubscribe from this group, send an email to:
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<mailto:softrock40-unsubscribe@...?subject=Unsubscribe>
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--
Cecil
KD5NWA
<www.qrpradio.com>
I fail to see why doing the same thing over and over and getting the same results every time is insanity: I've almost proved it isn't; only a few more tests now and I'm sure results will differ this time ...
|
The PC is able to "put" a phoney carrier anywhere in that 48KHz space
so that the signal is demodulated correctly into audio.
This is the answer I wanted to know for the POwerSDR sotfware. Thanks.
kd5nwa wrote:
toggle quoted message
Show quoted text
The audio out of the I and Q signals have a 24KHz bandwidth, but
their relationship tell the PC if the signal is above or below the
quadrature clock. Those two signals together represent a 48 KHz swath
of radio signals. Not each having 24KHz of the spectrum, but together
they have 48KHz.
The PC is able to "put" a phoney carrier anywhere in that 48KHz space
so that the signal is demodulated correctly into audio.
But whether you have a crystal that is low or one that is high, it
makes no difference as long as the signal is in the band-pass, you
still need USB and LSB demodulation. That crystal just sets the
center of the frequency range that you are looking at.
It's kind like looking at book but you have a piece of cardboard with
a rectangle cut in it, as you move that piece of cardboard you see
different parts of the book. A word may be on the right side of the
rectangle but when you move the cardboard its on the left side now,
but the letters don't reverse do they? The signals just move their
position in the frequency spectrum as you move the crystal frequency,
you still need USB and LSB decoders.
Somebody else feel free to try to explain how it works. There are
plenty of people on this list that are more knowledgeable than I am.
If you shift the desired signal up or down in freq you would need to
shift it back
to its natural audio freq spectrum
IF = 8330 kHz center of pass band
Suppose SSB signl .3 - 2 kHz
output IF filter 8330.3 - 8332 kHz depending on tuning
front end IF BW > 2 kHz
softrock board xtal 8352 kHz or 8318 kHz
output from board I and Q : 11.7 kHz - 10.0 kHz USB -> LSB
In order to copy the I/O signal it needs to be shifted back to .3 to
2 kHz by "mixing"
My question was what is the freq. range of this "mixing" process in
the powerSDR software,.
the computer
The same case can be made for the use of a softrock crystal of 8318
kHz In that case there would be
no side band switch.
73 Rein W6/PA0ZN
KD5NWA wrote:
The radio is simplicity itself, and it receives a band of signals
that is 48KHz wide, it has only one oscillator, the rest is faked by
the computer. The radio has two signals it puts out, I and Q that
are sampled by a sound card taking samples of both channels at a rate
of 48KHz, after the computer reads those two signals it figures out
the rest in it's program.
The SR-40 has a oscillator that is used in creating a quadrature
phased clock at the center of the band that you are interested in.
This clock is used to extract the I and Q signals in the frequency
range of interest, the detectors, injection of carrier, filtering ,
etc all the typical added on hardware of a radio is handled by the
software in the PC. This makes the radio hardware very simple,
"Elegance through simplicity" as I like to say of simple designs that
do the job well.
The main Osc. is crystal controlled and divided by 4 to generate
clocks in Quadrature to "detect" the signals in the frequency range
of interest. Some of us are trying to find the appropriate crystals
so we can move the frequency of the receiver to our area of interest.
In my case I want on to be able to look at the IF frequency range of
Kenwood HF radios, that frequency is 8.830MHz, I need some crystals a
little higher or lower than 4 times that frequency (around 35.3 MHz),
not an easy task if you are not willing to spend a lot of money on the
crystal.
At 03:20 PM 9/28/2005, you wrote:
>Hi All,
>
>Question. Does Power SDR software provide a "Variable Beat or Carrier
>Oscillator"? Perhaps 2 ?
>What is the freq range of that oscillator ( up to 48 or 96 kHz ? )
>
>73 Rein W6/PA0ZN
>
>KD5NWA wrote:
>
> > It would only let me see 6.5 KHz on one side.
> >
> > I'm going to try putting two crystals in parallel, and try to pull
> > them so I can get at least 10 KHz on either side of the IF, the > > > crystals are cheap enough. I'll get the ones that are close to the
> > center of the IF and pull them down. I'll also buy one that is
> > 68.8KHz lower than the 4X IF frequency, just in case.
> >
> > At 01:58 PM 9/28/2005, Tony Parks wrote:
> > >Cecil,
> > >
> > >The crystal that is 17 kHz low would work well if you are
meaning the
> > >crystal is 68 kHz low at its fundamental frequency.
Seventeen kHz
> > low even
> > >at its fundamental frequency would still probably be ok.
> > >
> > >
> > >----- Original Message -----
Cecil Bayona
KD5NWA
www.qrpradio.com
'Never argue with an idiot. They drag you down to their level then
beat you with experience.'
------------------------------------------------------------------------
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Cecil
KD5NWA
<www.qrpradio.com>
I fail to see why doing the same thing over and over and getting the
same results every time is insanity: I've almost proved it isn't;
only a few more tests now and I'm sure results will differ this time
...
SPONSORED LINKS
Shortwave receivers <> Ham radio <>
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OK, now I'm really confused...........
One question..........
If I fire up my softrock-40 on my computer that has the ability to sample at 48 Khz (with the center frequency at 7056 KHz)....
Will I be able to listen to a cw station on 7056 Khz (down 10 KHz)?
Will I be able to listen to a cw station on 7046 KHz (down 20 Khz)?
Will I be able to listen to a cw station on 7066 KHz (up 10 Khz)?
Will I be able to listen to a cw station on 7076 KHz (up 20 Khz)
I thought only a 96 Khz bandwidth card would give a 48 KHz spectral display....
Thanks,
Art
toggle quoted message
Show quoted text
At 07:35 PM 9/28/2005, you wrote: The audio out of the I and Q signals have a 24KHz bandwidth, but
their relationship tell the PC if the signal is above or below the
quadrature clock. Those two signals together represent a 48 KHz swath
of radio signals. Not each having 24KHz of the spectrum, but together
they have 48KHz.
The PC is able to "put" a phoney carrier anywhere in that 48KHz space
so that the signal is demodulated correctly into audio.
But whether you have a crystal that is low or one that is high, it
makes no difference as long as the signal is in the band-pass, you
still need USB and LSB demodulation. That crystal just sets the
center of the frequency range that you are looking at.
It's kind like looking at book but you have a piece of cardboard with
a rectangle cut in it, as you move that piece of cardboard you see
different parts of the book. A word may be on the right side of the
rectangle but when you move the cardboard its on the left side now,
but the letters don't reverse do they? The signals just move their
position in the frequency spectrum as you move the crystal frequency,
you still need USB and LSB decoders.
Somebody else feel free to try to explain how it works. There are
plenty of people on this list that are more knowledgeable than I am.
If you shift the desired signal up or down in freq you would need to
shift it back
to its natural audio freq spectrum
IF = 8330 kHz center of pass band
Suppose SSB signl .3 - 2 kHz
output IF filter 8330.3 - 8332 kHz depending on tuning
front end IF BW > 2 kHz
softrock board xtal 8352 kHz or 8318 kHz
output from board I and Q : 11.7 kHz - 10.0 kHz
USB -> LSB
In order to copy the I/O signal it needs to be shifted back to .3 to
2 kHz by "mixing"
My question was what is the freq. range of this "mixing" process in
the powerSDR software,.
the computer
The same case can be made for the use of a softrock crystal of 8318
kHz In that case there would be
no side band switch.
73 Rein W6/PA0ZN
KD5NWA wrote:
The radio is simplicity itself, and it receives a band of signals
that is 48KHz wide, it has only one oscillator, the rest is faked by
the computer. The radio has two signals it puts out, I and Q that
are sampled by a sound card taking samples of both channels at a rate
of 48KHz, after the computer reads those two signals it figures out
the rest in it's program.
The SR-40 has a oscillator that is used in creating a quadrature
phased clock at the center of the band that you are interested in.
This clock is used to extract the I and Q signals in the frequency
range of interest, the detectors, injection of carrier, filtering ,
etc all the typical added on hardware of a radio is handled by the
software in the PC. This makes the radio hardware very simple,
"Elegance through simplicity" as I like to say of simple designs that
do the job well.
The main Osc. is crystal controlled and divided by 4 to generate
clocks in Quadrature to "detect" the signals in the frequency range
of interest. Some of us are trying to find the appropriate crystals
so we can move the frequency of the receiver to our area of interest.
In my case I want on to be able to look at the IF frequency range of
Kenwood HF radios, that frequency is 8.830MHz, I need some crystals a
little higher or lower than 4 times that frequency (around 35.3 MHz),
not an easy task if you are not willing to spend a lot of money on the
crystal.
At 03:20 PM 9/28/2005, you wrote:
>Hi All,
>
>Question. Does Power SDR software provide a "Variable Beat or Carrier
>Oscillator"? Perhaps 2 ?
>What is the freq range of that oscillator ( up to 48 or 96 kHz ? )
>
>73 Rein W6/PA0ZN
>
>KD5NWA wrote:
>
> > It would only let me see 6.5 KHz on one side.
> >
> > I'm going to try putting two crystals in parallel, and try to pull
> > them so I can get at least 10 KHz on either side of the IF, the > > > crystals are cheap enough. I'll get the ones that are close to the
> > center of the IF and pull them down. I'll also buy one that is
> > 68.8KHz lower than the 4X IF frequency, just in case.
> >
> > At 01:58 PM 9/28/2005, Tony Parks wrote:
> > >Cecil,
> > >
> > >The crystal that is 17 kHz low would work well if you are meaning the
> > >crystal is 68 kHz low at its fundamental frequency. Seventeen kHz
> > low even
> > >at its fundamental frequency would still probably be ok.
> > >
> > >
> > >----- Original Message -----
Cecil Bayona
KD5NWA
www.qrpradio.com
'Never argue with an idiot. They drag you down to their level then
beat you with experience.'
------------------------------------------------------------------------
YAHOO! GROUPS LINKS
* Visit your group "softrock40
<>" on the web.
* To unsubscribe from this group, send an email to:
softrock40-unsubscribe@...
<mailto:softrock40-unsubscribe@...?subject=Unsubscribe>
* Your use of Yahoo! Groups is subject to the Yahoo! Terms of
Service <>.
------------------------------------------------------------------------
Yahoo! Groups Links
--
Cecil
KD5NWA
<www.qrpradio.com>
I fail to see why doing the same thing over and over and getting the
same results every time is insanity: I've almost proved it isn't;
only a few more tests now and I'm sure results will differ this time
...
Yahoo! Groups Links
--
No virus found in this incoming message.
Checked by AVG Anti-Virus.
Version: 7.0.344 / Virus Database: 267.11.8/113 - Release Date: 9/27/2005
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Checked by AVG Anti-Virus.
Version: 7.0.344 / Virus Database: 267.11.8/113 - Release Date: 9/27/2005
|
Hi Art,
Yes to all for questions below. Both I and Q channels are being individually sampled at 48 kHz which provides for the 48 kHz of bandwidth.
73,
Tony KB9YIG
toggle quoted message
Show quoted text
----- Original Message ----- From: "KY1K" <ky1k@...> To: <softrock40@...> Sent: Wednesday, September 28, 2005 7:37 PM Subject: Re: [softrock40] carrirer oscillator OK, now I'm really confused...........
One question..........
If I fire up my softrock-40 on my computer that has the ability to
sample at 48 Khz (with the center frequency at 7056 KHz)....
Will I be able to listen to a cw station on 7056 Khz (down 10 KHz)?
Will I be able to listen to a cw station on 7046 KHz (down 20 Khz)?
Will I be able to listen to a cw station on 7066 KHz (up 10 Khz)?
Will I be able to listen to a cw station on 7076 KHz (up 20 Khz)
I thought only a 96 Khz bandwidth card would give a 48 KHz spectral display....
Thanks,
Art
At 07:35 PM 9/28/2005, you wrote:
The audio out of the I and Q signals have a 24KHz bandwidth, but
their relationship tell the PC if the signal is above or below the
quadrature clock. Those two signals together represent a 48 KHz swath
of radio signals. Not each having 24KHz of the spectrum, but together
they have 48KHz.
The PC is able to "put" a phoney carrier anywhere in that 48KHz space
so that the signal is demodulated correctly into audio.
But whether you have a crystal that is low or one that is high, it
makes no difference as long as the signal is in the band-pass, you
still need USB and LSB demodulation. That crystal just sets the
center of the frequency range that you are looking at.
It's kind like looking at book but you have a piece of cardboard with
a rectangle cut in it, as you move that piece of cardboard you see
different parts of the book. A word may be on the right side of the
rectangle but when you move the cardboard its on the left side now,
but the letters don't reverse do they? The signals just move their
position in the frequency spectrum as you move the crystal frequency,
you still need USB and LSB decoders.
Somebody else feel free to try to explain how it works. There are
plenty of people on this list that are more knowledgeable than I am.
If you shift the desired signal up or down in freq you would need to
shift it back
to its natural audio freq spectrum
IF = 8330 kHz center of pass band
Suppose SSB signl .3 - 2 kHz
output IF filter 8330.3 - 8332 kHz depending on tuning
front end IF BW > 2 kHz
softrock board xtal 8352 kHz or 8318 kHz
output from board I and Q : 11.7 kHz - 10.0 kHz
USB -> LSB
In order to copy the I/O signal it needs to be shifted back to .3 to
2 kHz by "mixing"
My question was what is the freq. range of this "mixing" process in
the powerSDR software,.
the computer
The same case can be made for the use of a softrock crystal of 8318
kHz In that case there would be
no side band switch.
73 Rein W6/PA0ZN
KD5NWA wrote:
The radio is simplicity itself, and it receives a band of signals
that is 48KHz wide, it has only one oscillator, the rest is faked by
the computer. The radio has two signals it puts out, I and Q that
are sampled by a sound card taking samples of both channels at a rate
of 48KHz, after the computer reads those two signals it figures out
the rest in it's program.
The SR-40 has a oscillator that is used in creating a quadrature
phased clock at the center of the band that you are interested in.
This clock is used to extract the I and Q signals in the frequency
range of interest, the detectors, injection of carrier, filtering ,
etc all the typical added on hardware of a radio is handled by the
software in the PC. This makes the radio hardware very simple,
"Elegance through simplicity" as I like to say of simple designs that
do the job well.
The main Osc. is crystal controlled and divided by 4 to generate
clocks in Quadrature to "detect" the signals in the frequency range
of interest. Some of us are trying to find the appropriate crystals
so we can move the frequency of the receiver to our area of interest.
In my case I want on to be able to look at the IF frequency range of
Kenwood HF radios, that frequency is 8.830MHz, I need some crystals a
little higher or lower than 4 times that frequency (around 35.3 MHz),
not an easy task if you are not willing to spend a lot of money on the
crystal.
At 03:20 PM 9/28/2005, you wrote:
>Hi All,
>
>Question. Does Power SDR software provide a "Variable Beat or
Carrier
>Oscillator"? Perhaps 2 ?
>What is the freq range of that oscillator ( up to 48 or 96 kHz ? )
>
>73 Rein W6/PA0ZN
>
>KD5NWA wrote:
>
> > It would only let me see 6.5 KHz on one side.
> >
> > I'm going to try putting two crystals in parallel, and try to
pull
> > them so I can get at least 10 KHz on either side of the IF, the > > > crystals are cheap enough. I'll get the ones that are close to
the
> > center of the IF and pull them down. I'll also buy one that is
> > 68.8KHz lower than the 4X IF frequency, just in case.
> >
> > At 01:58 PM 9/28/2005, Tony Parks wrote:
> > >Cecil,
> > >
> > >The crystal that is 17 kHz low would work well if you are meaning the
> > >crystal is 68 kHz low at its fundamental frequency. Seventeen
kHz
> > low even
> > >at its fundamental frequency would still probably be ok.
> > >
> > >
> > >----- Original Message -----
Cecil Bayona
KD5NWA
www.qrpradio.com
'Never argue with an idiot. They drag you down to their level then
beat you with experience.'
> ------------------------------------------------------------------------
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Cecil
KD5NWA
<www.qrpradio.com>
I fail to see why doing the same thing over and over and getting the
same results every time is insanity: I've almost proved it isn't;
only a few more tests now and I'm sure results will differ this time
...
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WOW, thanks Tony.
It's good news for me. I have been designing a crystal oscillator coupled to a divide by N counter. I had assumed no more than 24 Khz (12 KHz on each side of the center frequency).
It turns out that a simple divide by N counter and a crystal oscillator can enable LF operation from 200 KHz down to DC without phase noise and without spurs, except for the phase noise associated with the quartz crystal itself, which is pretty minimal. And, it's cheap and simple to build too.
So, I hope to fire my softrock-40 up on LF soon after testing the stock unit on 40 M.
Regards,
Art
toggle quoted message
Show quoted text
At 09:10 PM 9/28/2005, you wrote: Hi Art,
Yes to all for questions below. Both I and Q channels are being
individually sampled at 48 kHz which provides for the 48 kHz of bandwidth.
73,
Tony KB9YIG
----- Original Message -----
From: "KY1K" <ky1k@...>
To: <softrock40@...>
Sent: Wednesday, September 28, 2005 7:37 PM
Subject: Re: [softrock40] carrirer oscillator
OK, now I'm really confused...........
One question..........
If I fire up my softrock-40 on my computer that has the ability to
sample at 48 Khz (with the center frequency at 7056 KHz)....
Will I be able to listen to a cw station on 7056 Khz (down 10 KHz)?
Will I be able to listen to a cw station on 7046 KHz (down 20 Khz)?
Will I be able to listen to a cw station on 7066 KHz (up 10 Khz)?
Will I be able to listen to a cw station on 7076 KHz (up 20 Khz)
I thought only a 96 Khz bandwidth card would give a 48 KHz spectral
display....
Thanks,
Art
At 07:35 PM 9/28/2005, you wrote:
The audio out of the I and Q signals have a 24KHz bandwidth, but
their relationship tell the PC if the signal is above or below the
quadrature clock. Those two signals together represent a 48 KHz swath
of radio signals. Not each having 24KHz of the spectrum, but together
they have 48KHz.
The PC is able to "put" a phoney carrier anywhere in that 48KHz space
so that the signal is demodulated correctly into audio.
But whether you have a crystal that is low or one that is high, it
makes no difference as long as the signal is in the band-pass, you
still need USB and LSB demodulation. That crystal just sets the
center of the frequency range that you are looking at.
It's kind like looking at book but you have a piece of cardboard with
a rectangle cut in it, as you move that piece of cardboard you see
different parts of the book. A word may be on the right side of the
rectangle but when you move the cardboard its on the left side now,
but the letters don't reverse do they? The signals just move their
position in the frequency spectrum as you move the crystal frequency,
you still need USB and LSB decoders.
Somebody else feel free to try to explain how it works. There are
plenty of people on this list that are more knowledgeable than I am.
If you shift the desired signal up or down in freq you would need to
shift it back
to its natural audio freq spectrum
IF = 8330 kHz center of pass band
Suppose SSB signl .3 - 2 kHz
output IF filter 8330.3 - 8332 kHz depending on tuning
front end IF BW > 2 kHz
softrock board xtal 8352 kHz or 8318 kHz
output from board I and Q : 11.7 kHz - 10.0 kHz
USB -> LSB
In order to copy the I/O signal it needs to be shifted back to .3
to
2 kHz by "mixing"
My question was what is the freq. range of this "mixing" process in
the powerSDR software,.
the computer
The same case can be made for the use of a softrock crystal of
8318
kHz In that case there would be
no side band switch.
73 Rein W6/PA0ZN
KD5NWA wrote:
The radio is simplicity itself, and it receives a band of signals
that is 48KHz wide, it has only one oscillator, the rest is faked by
the computer. The radio has two signals it puts out, I and Q that
are sampled by a sound card taking samples of both channels at a rate
of 48KHz, after the computer reads those two signals it figures out
the rest in it's program.
The SR-40 has a oscillator that is used in creating a quadrature
phased clock at the center of the band that you are interested in.
This clock is used to extract the I and Q signals in the frequency
range of interest, the detectors, injection of carrier, filtering ,
etc all the typical added on hardware of a radio is handled by the
software in the PC. This makes the radio hardware very simple,
"Elegance through simplicity" as I like to say of simple designs that
do the job well.
The main Osc. is crystal controlled and divided by 4 to generate
clocks in Quadrature to "detect" the signals in the frequency range
of interest. Some of us are trying to find the appropriate crystals
so we can move the frequency of the receiver to our area of interest.
In my case I want on to be able to look at the IF frequency range of
Kenwood HF radios, that frequency is 8.830MHz, I need some crystals a
little higher or lower than 4 times that frequency (around 35.3 MHz),
not an easy task if you are not willing to spend a lot of money on
the
crystal.
At 03:20 PM 9/28/2005, you wrote:
>Hi All,
>
>Question. Does Power SDR software provide a "Variable Beat or
Carrier
>Oscillator"? Perhaps 2 ?
>What is the freq range of that oscillator ( up to 48 or 96 kHz ? )
>
>73 Rein W6/PA0ZN
>
>KD5NWA wrote:
>
> > It would only let me see 6.5 KHz on one side.
> >
> > I'm going to try putting two crystals in parallel, and try to
pull
> > them so I can get at least 10 KHz on either side of the IF, the > > > crystals are cheap enough. I'll get the ones that are close to
the
> > center of the IF and pull them down. I'll also buy one that is
> > 68.8KHz lower than the 4X IF frequency, just in case.
> >
> > At 01:58 PM 9/28/2005, Tony Parks wrote:
> > >Cecil,
> > >
> > >The crystal that is 17 kHz low would work well if you are meaning the
> > >crystal is 68 kHz low at its fundamental frequency. Seventeen
kHz
> > low even
> > >at its fundamental frequency would still probably be ok.
> > >
> > >
> > >----- Original Message -----
Cecil Bayona
KD5NWA
www.qrpradio.com
'Never argue with an idiot. They drag you down to their level then
beat you with experience.'
>
------------------------------------------------------------------------
YAHOO! GROUPS LINKS
* Visit your group "softrock40
<>" on the web.
* To unsubscribe from this group, send an email to:
softrock40-unsubscribe@...
<mailto:softrock40-unsubscribe@...?subject=Unsubscribe>
* Your use of Yahoo! Groups is subject to the Yahoo! Terms of
Service <>.
>
------------------------------------------------------------------------
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--
Cecil
KD5NWA
<www.qrpradio.com>
I fail to see why doing the same thing over and over and getting the
same results every time is insanity: I've almost proved it isn't;
only a few more tests now and I'm sure results will differ this time
...
Yahoo! Groups Links
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Checked by AVG Anti-Virus.
Version: 7.0.344 / Virus Database: 267.11.8/113 - Release Date: 9/27/2005
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Normally yes, to sample 48KHz signals you need 96KHz sampling rate, but the I and Q are quadrature signals and are only at 24 KHz each.
7036KHz 20 KHz signal
7046KHz 10 KHz signal
7056KHz 0 KHz Signal
7066KHz 10 KHz Signal
7076KHz 20 KHz Signal
Normally you can see that a signal at 7036 and 7076 each give a 20KHz signal so you have a image problem. But because the signals are in quadrature, one signal lags the other if your below the sampling signal, and it leads if it's above the sampling frequency. The computer program looks at both signals and figures where each signal is in frequency so it can tell the lower image from the upper image.
But because each signal is only 24 KHz then 48KHz sampling does fine with each of I and Q signals.
If you sampled at 96 KHz and the integrating capacitor was not too big then you would be able to look a a 96 KHz band of signals, 48KHz below the quadrature clock and 48KHz above. You would need to modify the integrating capacitor and analog filters to allow a 48 KHz signal without attenuation.
Now a lot of sound cards can sample at 96Khz but that doesn't mean that their amplifiers are capable of passing a 48KHz signal faithfully, you need to be careful in picking your audio card.
Around 7056 you end up with a lot of garbage, because any hum and harmonics show up in that area, and if your signals are not well balanced you can end up picking some of the clock signals making it look like there is a carrier there. Good shielding and elimination of ground loops can help.
Hope that helps.
toggle quoted message
Show quoted text
OK, now I'm really confused...........
One question..........
If I fire up my softrock-40 on my computer that has the ability to
sample at 48 Khz (with the center frequency at 7056 KHz)....
Will I be able to listen to a cw station on 7056 Khz (down 10 KHz)?
Will I be able to listen to a cw station on 7046 KHz (down 20 Khz)?
Will I be able to listen to a cw station on 7066 KHz (up 10 Khz)?
Will I be able to listen to a cw station on 7076 KHz (up 20 Khz)
I thought only a 96 Khz bandwidth card would give a 48 KHz spectral display....
Thanks,
Art
At 07:35 PM 9/28/2005, you wrote:
--
Cecil
KD5NWA
<www.qrpradio.com>
I fail to see why doing the same thing over and over and getting the same results every time is insanity: I've almost proved it isn't; only a few more tests now and I'm sure results will differ this time ...
|
--- In softrock40@..., KY1K <ky1k@p...> wrote: OK, now I'm really confused........... Welcome to the club :-) If I fire up my softrock-40 on my computer that has the ability to
sample at 48 Khz (with the center frequency at 7056 KHz).... Yes to all. I thought only a 96 Khz bandwidth card would give a 48 KHz spectral display.... Here's the deal. Shannon's Theorem tells you that you need 2N bits/sec to capture N bits of bandwidth. If you're only sampling the real part, ie in mono, that means you need to sample at 2F to capture a bandwidth of F. However, since the QSD samples in Quadrature, you're getting a *complex* signal, ie stereo. Those are your 2N bits, 2 channels x N bits/channel. Therefore with complex sampling you can sample at F to capture bandwidth F. It doesn't save anything in terms of the *total* bandwidth, which is still 2N bits, but it lets you use D/A converters only half as fast. Except you need two of them. 73 Frank AB2KT
|
--- In softrock40@..., KY1K <ky1k@p...> wrote: OK, now I'm really confused........... Oh, and remember: Shannon's Theorem only addresses bandwidth, not absolute frequency. Having the signal sampled in quadrature means the phase of the signal is disambiguated, since the I and Q parts are Hilbert Transforms of one another (all frequencies are 90 degrees out of phase with one another), and therefore they have different symmetries around 0. With real signals, which have even symmetry, you don't know which is positive and which is negative -- they're effectively the same whether you regard time as running forward or backward. With complex signals, you know which direction is earlier and which is later. (That, btw, is one theoretical reason for preferring complex sampling. Signals in quadrature are much easier to deal with when they include time-dependent modulation and transients.) That means that positive and negative frequencies are not mirrors of one another, as they are with real-only sampling. The total bandwidth is still 48kHz, so the frequency excursion is +/-(48/2)kHz. 73 Frank AB2KT
|
