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Re: Maximum input level usb audio
Hi Giovanni
Thank you!
David
Il Ven 14 Ago 2020, 18:28 Giovanni Franza < gfranza@...> ha scritto: Hi David,
when I built a 4 phases example I fed I/Q in L/R audio using stock audio block in Gnuradio.
Only thing to remember is to launch periodically the CAT command allowing audio as I/Q.
No idea of the levels, sorry :-(
Regards,
Giovanni - HB9EIK
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Re: Eladit.com site down?
Thanks Andy, I must have missed an announcement about the site
change. It looks like the shop section is still being worked on.
Neil G4DBN
The old site can still be found at the Wayback Machine
toggle quoted messageShow quoted text
On 14/08/2020 22:15, Andreas Rehberg
wrote:
Am 14.08.20, 21:16 schrieb "MM6IXE via groups.io"
<sota@...>:
It’s been like that for a while
for me
Iain
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Re: Eladit.com site down?
Am 14.08.20, 21:16 schrieb "MM6IXE via groups.io" <sota@...>:
toggle quoted messageShow quoted text
It’s been like that for a while
for me
Iain
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Re: Eladit.com site down?
It’s been like that for a while
for me
Iain
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I can't reach sdr.eladit.com or any of the variants other than shop.eladit.com, have I missed a maintenance notice, or is there a fault? Neil http://g4dbn.uk
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USB Audio I/Q Mode - what is it?
Andy G4JNT
What IS this IQ mode that can be set by the CAT IQ command m? Is it to the internal soundcard, and if so, what advantage does if offer over normal single audio channel ? What bandwidth is available, is it plus/minus the normal Tx filter ? If so I assume it goes down to true DC, unlike a real soiundcard that typically has a low cut off at a few tens of Hz
On Fri, 14 Aug 2020 at 17:28, Giovanni Franza < gfranza@...> wrote: Hi David,
when I built a 4 phases example I fed I/Q in L/R audio using stock audio block in Gnuradio.
Only thing to remember is to launch periodically the CAT command allowing audio as I/Q.
No idea of the levels, sorry :-(
Regards,
Giovanni - HB9EIK
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Re: Maximum input level usb audio
Giovanni Franza
Hi David,
when I built a 4 phases example I fed I/Q in L/R audio using stock audio block in Gnuradio.
Only thing to remember is to launch periodically the CAT command allowing audio as I/Q.
No idea of the levels, sorry :-(
Regards,
Giovanni - HB9EIK
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Maximum input level usb audio
Hi All,
I do some math supposing that ssb modulator is based on hilbert transformer. With little information available and my calculation may be possible that maximum input level is 0.4-0.5 in order to keep normalized modulator output to -1/+1. I'm going to try IQ input in the next days..I assume that I (or Q) is right input of tx USB port and Q(or I) is left input of tx USB port. Giovanni HB9EIK or I2PHD do you have some more informations (that can be shared..of course) on this topic.
Regards
David IW5BNL
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Thank you for accept my request to join the group.
I am waiting for the availability of the S3.
73s
Francesco Di Giovanni - IN3XZP
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Re: FDM-DUO feature suggestion
#elad
Giovanni Franza
To all people interested,
I've made a first attempt to compile in win32 using mingw.
As aspected portmidi is there and it seems to exists a port of pthreads.
But no hope with termio (for now) so, at the moment, there are some work to be done to port the program under Win10.
Regards,
Giovanni - HB9EIK
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Re: FDM-DUO feature suggestion
#elad
Giovanni Franza
Hi All,
attached you can find the last version of the program.
Using -i switch you can "program" the interface:
move a command then input the field requested, using the keyboard and following the instrucions.
Remember that "keys" send 2 commands: one at key down other at key up.
Hope this helps,
Giovanni - HB9EIK
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Re: FDM-DUO feature suggestion
#elad
Giovanni Franza
Hi All,
attached is a tarball with a working version also with jog "query".
When the operator is turning jog after a certain period of inactivity the program send a query CAT command to know the value stored in the DUO.
As for the previous version the tar, unrolled, create a folder. Go on this folder and do a "make" to generate the program.
To use the program launch the program as, for example:
./play -d 1 -m 3 -n /dev/ttyUSB0 -s 115200
where:
-d 1 ask for debug
-m 3 ask for midi device 3
-n /dev/ttyUSB0 indicate the device connected with DUO CAT
-s 115200 set the serial CAT speed (must match the one on the DUO menu #70)
to obtain help use
./play -h
to obtain a list of midi devices use
to avoid debug omit -d 1 from the parameters.
The file init.txt sets the command used: the one in the folder is for DJControlCompact and set NoisBlanker, NoiseLimiter, Att, Low pass filter, TX/RX and frequency.
If you have other midi devices use the debug to know bank and keys values sent and modify init.txt accordingly.
Beta tester are wellcomed!
Giovanni - HB9EIK
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Re: Maximum usb input driving signal elad duo
Hi All
I agree with Andy 88db of dynamic are still extremely good. I suspect that this reduced dynamics depend how the internal modulator is implemented. I'm doing some math..I will show my calculations in the next days. I think that is also available a IQ input for transmitting,infact the duo cat documentation show a CAT command to turn on IQ input for transmitting. I suspect that sw2 software use this input for transmitting and,probably,full resolution is available here. I note that in transmitting part of sw2 software IQ graph are show with axis limit -1/+1.. I will investigate more.....
Regards
David IW5BNL
It's not a lot of dynamic range loss really. If the maximum value for the soundcard input is +/- 13000 out of 32768, that's still 14 bits worth of dynamic range (actually 14.6 bits if you can get your head around fractional bit sizes)
That still allows for 88dB of dynamic range - and we're talking about transmit here. Which is still rather better than you'll ever be interested in.
On Mon, 10 Aug 2020 at 16:33, Chris Bartram < chris@...> wrote:
Thanks Andy,
That was my original understanding, so many thanks for the
clarification. I think I went into brain fart mode - probably as
the result of excessive plumbing and tiling!
It's interesting that Elad seem to have thrown-away quite a lot
of potential TX dynamic range. However, without full design data,
I'm certainly not going to comment, except to say that I applaud
the detective work which you and David are doing to understand it.
73
Chris G4DGU
On 10/08/2020 14:41, Andy G4JNT wrote:
NO NO
NO Chris
The 0dBm
output is linear up to 0dBm output in analogue / RF terms
What
we're talking about is the digital drive word to the internal
soundcard in order to get that signal level.
It looks
as if only values in the range up to perhaps +/-13000 are
valid. So there is something like 7-8 dB of effective gain
from DDS level to 0dBm point.
Don't
forget, the 0dBm comes direct from the DDS so it's a
hard upper limit. Set by logic rather than compression or
voltage clipping or anything.
It's
odd, though as David reports, that matches WSJT-X drive
spot-on. I doubt very much it was designed that way.
On Mon, 10 Aug 2020 at 14:28,
Chris Bartram < chris@...>
wrote:
Hello Andy,
I'm just starting to think about connecting the 0dBm
output of my FDM-DUO to my transverters. I'm a little
unclear about the results you have reported - it's
probably just too hot! I think you are saying that the
output is linear up to about -8dBm from the 0dBm port on
144MHz. Is that correct?
73
Chris G4DGU
On 10/08/2020 12:43, Andy G4JNT wrote:
Sri
Folks
Looks
like a BIG correction is needed.
I've
just done a quick test using the pre-recorded .WAV
files and it's as you suggested. Full output from
the 0dBm port is achieved with, in my case, about 7 to
8dB back-off from full scale.
Setting
the DUO as default soundcard, controlling PTT via the
CAT interface and playing the .WAV files using the
Windows inbuilt playwav facility I looked at the 0dBm
output on a scope. It needed a file generated at
-8dB (0.4 voltage) of full scale to see a noticeable
decrease in amplitude on the scope. Which is higher
than you saw, at I think 0.1, but still lower than I
expected.
With
the desktop PC, large screen monitor, oscilloscope and
stuff on, it was far too hot in the upstairs shack in
this weather to spend more than a few minutes doing
this so I'll investigate fuller, later. I can use
the .WAV files as calibration, then use TCUBE written
by I2PHD o generate a continuously valuable tone in
amplitude or frequency. That will really map-out the
ampltude response.
I
did generate some two-tone .WAV files, and TCUBE can
generate a two tone waveform, so that will be the way
forward. I'm pretty certain TCUBE gives full-scale
digits at it's maximum setting, but at least I can now
properly calibrate it.
Hi Andy
As you make some measurement in the
next days I suggest to generate a wave file with
two tones so you can measure the IM.
I'm also reading the data sheet of
duo integrated sound card.
The chip is capable 16 or 24 bits
resolutions..
If Franco or someone from Elad can
just comment this result and providing us scale
Factor (If any...) will very useful.
Regards
David
IW5BNL
Hi Andy
Very good idea.
I'm working with Linux.
I suspect that in the gnuradio
/Linux pulse audio chain is some scale Factor
that I don't know.
I will investigate more.
David
IW5BNL
I
generate .WAV files from first
principles. They use a pure 16 bit
integer
Then
replay them via teh soundcard of choice.
Unfortunately
the wav.play function works with the
default soundcard so for this test I will
need to temporarily make the Duo my
default soundcard ! So allteh Windows
bings and chimes will appear on it.
I
have plenty of third party software that
generates tones and itest signals, but no
proof that full scale is actually filling
the 16 bit integer in any of them.
I
could write my own, but it's easier to
generate .Wav, and I have a whole suite of
software to generate all sorts of signals
as a wav.
One
USB soundcard I use a lot is the PCM2900
USB audio device. That has one wonderful
property - the reference for the A/D
appears on a pin of the chip. So it is
possible, by measuring this DC level, to
relate the exact voltage that will appear
for any 16 bit integer sent, and the same
for the sound input.
Hi Andy
How you generate the
audio USB signal.
David
IW5BNL
I'll
do some tests tomorrow. But I'm
pretty certain that when tested
before, a peak audio of the full
16 bit word was required to get
maximum out of the 0dBm port. I
do remember thinking "how well
designed"
Hi all
I do some
meeasuraments.
As I'm on
country home I have only a
power meter and the capability
to measure the tx signal using
the monitoring rx of duo.
I generate a two
tone signal with gu radio and
send it to duo USB.
By monitoring
the internal rx I can measure
the spectrum of duo rx by a
another gnuradio script that
capture the 192khz sample rate
rx out (available on rx
usbvport).
Everithink is
perfectly linear until a USB
audio signal of 0.1 pk
normalized signal.
Increasing over
0.1 we start to see
intermodulation.
0.1 is exactly
the point where the output
power is saturated.
For this
measurement the audio input of
duo was adjusted to 100% in
pulse audio control.
Of course
reducing the pulse audio below
100% the level of saturation
increase.
So the asumption
that -1/1 is the limit isn't
correct as depend on pulse
audio level adjustment.
The good news is
that I now know the maximum
USB audio level before start
to intermodulated.
The modulator
inside duo working extremely
well in the correct range of
driving signal linear is
perfect.
Ciao
David
IW5BNL
Hi all,
Thank for
information and answer.
I'm driving a small amp on
hf band (60w) so duo power
is adjusted on 3 watts out.
I have to
make some more accurate
measurement but,look
like,that changing USB
driving from 0.5/-0.5 to
1/-1 peak power don't
change.May be issue is on
the saturation of my
external amplifier.Next
days I will made some more
accurate meeasuraments.
I encourage
elad crew to produce more
documentation on it.
David
IW5BNL
Ditto, and even if
I want to, I have a
perfectly good HF PA,
-3dBm in gives 200
Watts out, all boxed
up with switched low
pass filters and
absolutely bomb-proof
with mismatched loads
(that's been tested,
intentionally, several
times)
On
Sat, 8 Aug 2020 at
18:38, Neil Smith
G4DBN < neil@...>
wrote:
Good point, I
would have bought
that version in a
heartbeat. The
amp and TX filters
are almost zero
use to me. But
then I have weird
minority interests
and don't use the
HF bands much at
all these days.
Neil G4DBN
On 08/08/2020
18:28, Andy G4JNT
wrote:
A full scale
signed 16 bit
integer, sine
wave, (RMS =
23170)
generates 0dBm
out of the low
power port.
Can't speak
for teh power
amp - never
used it.
In fact, what
isn't there a
lower cost
version of thd
FDM withuut
the 5W amp and
all harmonic
filters.
Just a 0dBm
port on
transmit
On
Sat, 8 Aug
2020 at 18:20,
Neil Smith
G4DBN < neil@...> wrote:
Hi David, I
found it
worked OK with
normalised +-1
peak amplitude
when using the
0dBm output,
but I didn't
try it when
driving the PA
stage. I was
only using FM,
so I don't
know what the
IMD
performance
was like at
higher levels.
It would be
interesting to
know where you
start to see
any sign of
non-linearity
between the
level in
gnuradio and
the actual
power output
via the PA.
Also, what
happens when
the power is
set lower than
MAX. Does
full scale on
the USB device
input still
correspond to
full output,
or does the
USB device
level start to
flatten out
sooner?
Easy enough
to test with
simple tones
(or pairs of
tones) I
guess.
Neil G4DBN
On
08/08/2020
17:43, DAVID
IW5BNL wrote:
If that translates
to a full
scale 16 bit
integer drive
to the
soundcard then
I guess so
Hi
Andy
Thank
you for your
prompt
answer.
Normalize
-1/1 as gnu
radio audio
output is
normalize.
Is
it correct?
David
Full scale -32768
/ 32767 or
0x8000 /
0x7FFF peak
to peak is
full power
Nice and simple,
easy to
remember
Hi
all,
I'm
writing a ssb
compressor
using
gnuradio.It
work well but
I don't really
know maximum
driving signal
of duo USB
internal sound
card to
produce full
output power.
I
proceed
adjusting the
input USB
audio level
little bit
lower that the
level where
the output
peak power is
saturated (
for saturated
output power I
mean the
maximum level
on USB audio
that even
increasing the
audio output
power don't
increase).
Apparently
look like a
sort of alc is
present or
simply
increasing the
level the
modulator is
saturate.
Is
it somewhere a
document
and/or
information
showing
correlation
between input
USB audio and
output power
(on ssb
mode..)
Thank
you
David
IW5BNL
--
Neil
http://g4dbn.uk
--
Chris Bartram G4DGU
--
Chris Bartram G4DGU
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RFRScanner replaces all RadioFrequency programs.
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Re: Maximum usb input driving signal elad duo
Andy G4JNT
It's not a lot of dynamic range loss really. If the maximum value for the soundcard input is +/- 13000 out of 32768, that's still 14 bits worth of dynamic range (actually 14.6 bits if you can get your head around fractional bit sizes)
That still allows for 88dB of dynamic range - and we're talking about transmit here. Which is still rather better than you'll ever be interested in.
On Mon, 10 Aug 2020 at 16:33, Chris Bartram < chris@...> wrote:
Thanks Andy,
That was my original understanding, so many thanks for the
clarification. I think I went into brain fart mode - probably as
the result of excessive plumbing and tiling!
It's interesting that Elad seem to have thrown-away quite a lot
of potential TX dynamic range. However, without full design data,
I'm certainly not going to comment, except to say that I applaud
the detective work which you and David are doing to understand it.
73
Chris G4DGU
On 10/08/2020 14:41, Andy G4JNT wrote:
NO NO
NO Chris
The 0dBm
output is linear up to 0dBm output in analogue / RF terms
What
we're talking about is the digital drive word to the internal
soundcard in order to get that signal level.
It looks
as if only values in the range up to perhaps +/-13000 are
valid. So there is something like 7-8 dB of effective gain
from DDS level to 0dBm point.
Don't
forget, the 0dBm comes direct from the DDS so it's a
hard upper limit. Set by logic rather than compression or
voltage clipping or anything.
It's
odd, though as David reports, that matches WSJT-X drive
spot-on. I doubt very much it was designed that way.
On Mon, 10 Aug 2020 at 14:28,
Chris Bartram < chris@...>
wrote:
Hello Andy,
I'm just starting to think about connecting the 0dBm
output of my FDM-DUO to my transverters. I'm a little
unclear about the results you have reported - it's
probably just too hot! I think you are saying that the
output is linear up to about -8dBm from the 0dBm port on
144MHz. Is that correct?
73
Chris G4DGU
On 10/08/2020 12:43, Andy G4JNT wrote:
Sri
Folks
Looks
like a BIG correction is needed.
I've
just done a quick test using the pre-recorded .WAV
files and it's as you suggested. Full output from
the 0dBm port is achieved with, in my case, about 7 to
8dB back-off from full scale.
Setting
the DUO as default soundcard, controlling PTT via the
CAT interface and playing the .WAV files using the
Windows inbuilt playwav facility I looked at the 0dBm
output on a scope. It needed a file generated at
-8dB (0.4 voltage) of full scale to see a noticeable
decrease in amplitude on the scope. Which is higher
than you saw, at I think 0.1, but still lower than I
expected.
With
the desktop PC, large screen monitor, oscilloscope and
stuff on, it was far too hot in the upstairs shack in
this weather to spend more than a few minutes doing
this so I'll investigate fuller, later. I can use
the .WAV files as calibration, then use TCUBE written
by I2PHD o generate a continuously valuable tone in
amplitude or frequency. That will really map-out the
ampltude response.
I
did generate some two-tone .WAV files, and TCUBE can
generate a two tone waveform, so that will be the way
forward. I'm pretty certain TCUBE gives full-scale
digits at it's maximum setting, but at least I can now
properly calibrate it.
Hi Andy
As you make some measurement in the
next days I suggest to generate a wave file with
two tones so you can measure the IM.
I'm also reading the data sheet of
duo integrated sound card.
The chip is capable 16 or 24 bits
resolutions..
If Franco or someone from Elad can
just comment this result and providing us scale
Factor (If any...) will very useful.
Regards
David
IW5BNL
Hi Andy
Very good idea.
I'm working with Linux.
I suspect that in the gnuradio
/Linux pulse audio chain is some scale Factor
that I don't know.
I will investigate more.
David
IW5BNL
I
generate .WAV files from first
principles. They use a pure 16 bit
integer
Then
replay them via teh soundcard of choice.
Unfortunately
the wav.play function works with the
default soundcard so for this test I will
need to temporarily make the Duo my
default soundcard ! So allteh Windows
bings and chimes will appear on it.
I
have plenty of third party software that
generates tones and itest signals, but no
proof that full scale is actually filling
the 16 bit integer in any of them.
I
could write my own, but it's easier to
generate .Wav, and I have a whole suite of
software to generate all sorts of signals
as a wav.
One
USB soundcard I use a lot is the PCM2900
USB audio device. That has one wonderful
property - the reference for the A/D
appears on a pin of the chip. So it is
possible, by measuring this DC level, to
relate the exact voltage that will appear
for any 16 bit integer sent, and the same
for the sound input.
Hi Andy
How you generate the
audio USB signal.
David
IW5BNL
I'll
do some tests tomorrow. But I'm
pretty certain that when tested
before, a peak audio of the full
16 bit word was required to get
maximum out of the 0dBm port. I
do remember thinking "how well
designed"
Hi all
I do some
meeasuraments.
As I'm on
country home I have only a
power meter and the capability
to measure the tx signal using
the monitoring rx of duo.
I generate a two
tone signal with gu radio and
send it to duo USB.
By monitoring
the internal rx I can measure
the spectrum of duo rx by a
another gnuradio script that
capture the 192khz sample rate
rx out (available on rx
usbvport).
Everithink is
perfectly linear until a USB
audio signal of 0.1 pk
normalized signal.
Increasing over
0.1 we start to see
intermodulation.
0.1 is exactly
the point where the output
power is saturated.
For this
measurement the audio input of
duo was adjusted to 100% in
pulse audio control.
Of course
reducing the pulse audio below
100% the level of saturation
increase.
So the asumption
that -1/1 is the limit isn't
correct as depend on pulse
audio level adjustment.
The good news is
that I now know the maximum
USB audio level before start
to intermodulated.
The modulator
inside duo working extremely
well in the correct range of
driving signal linear is
perfect.
Ciao
David
IW5BNL
Hi all,
Thank for
information and answer.
I'm driving a small amp on
hf band (60w) so duo power
is adjusted on 3 watts out.
I have to
make some more accurate
measurement but,look
like,that changing USB
driving from 0.5/-0.5 to
1/-1 peak power don't
change.May be issue is on
the saturation of my
external amplifier.Next
days I will made some more
accurate meeasuraments.
I encourage
elad crew to produce more
documentation on it.
David
IW5BNL
Ditto, and even if
I want to, I have a
perfectly good HF PA,
-3dBm in gives 200
Watts out, all boxed
up with switched low
pass filters and
absolutely bomb-proof
with mismatched loads
(that's been tested,
intentionally, several
times)
On
Sat, 8 Aug 2020 at
18:38, Neil Smith
G4DBN < neil@...>
wrote:
Good point, I
would have bought
that version in a
heartbeat. The
amp and TX filters
are almost zero
use to me. But
then I have weird
minority interests
and don't use the
HF bands much at
all these days.
Neil G4DBN
On 08/08/2020
18:28, Andy G4JNT
wrote:
A full scale
signed 16 bit
integer, sine
wave, (RMS =
23170)
generates 0dBm
out of the low
power port.
Can't speak
for teh power
amp - never
used it.
In fact, what
isn't there a
lower cost
version of thd
FDM withuut
the 5W amp and
all harmonic
filters.
Just a 0dBm
port on
transmit
On
Sat, 8 Aug
2020 at 18:20,
Neil Smith
G4DBN < neil@...> wrote:
Hi David, I
found it
worked OK with
normalised +-1
peak amplitude
when using the
0dBm output,
but I didn't
try it when
driving the PA
stage. I was
only using FM,
so I don't
know what the
IMD
performance
was like at
higher levels.
It would be
interesting to
know where you
start to see
any sign of
non-linearity
between the
level in
gnuradio and
the actual
power output
via the PA.
Also, what
happens when
the power is
set lower than
MAX. Does
full scale on
the USB device
input still
correspond to
full output,
or does the
USB device
level start to
flatten out
sooner?
Easy enough
to test with
simple tones
(or pairs of
tones) I
guess.
Neil G4DBN
On
08/08/2020
17:43, DAVID
IW5BNL wrote:
If that translates
to a full
scale 16 bit
integer drive
to the
soundcard then
I guess so
Hi
Andy
Thank
you for your
prompt
answer.
Normalize
-1/1 as gnu
radio audio
output is
normalize.
Is
it correct?
David
Full scale -32768
/ 32767 or
0x8000 /
0x7FFF peak
to peak is
full power
Nice and simple,
easy to
remember
Hi
all,
I'm
writing a ssb
compressor
using
gnuradio.It
work well but
I don't really
know maximum
driving signal
of duo USB
internal sound
card to
produce full
output power.
I
proceed
adjusting the
input USB
audio level
little bit
lower that the
level where
the output
peak power is
saturated (
for saturated
output power I
mean the
maximum level
on USB audio
that even
increasing the
audio output
power don't
increase).
Apparently
look like a
sort of alc is
present or
simply
increasing the
level the
modulator is
saturate.
Is
it somewhere a
document
and/or
information
showing
correlation
between input
USB audio and
output power
(on ssb
mode..)
Thank
you
David
IW5BNL
--
Neil
http://g4dbn.uk
--
Chris Bartram G4DGU
--
Chris Bartram G4DGU
|
|
|
Re: Maximum usb input driving signal elad duo
Thanks Andy,
That was my original understanding, so many thanks for the
clarification. I think I went into brain fart mode - probably as
the result of excessive plumbing and tiling!
It's interesting that Elad seem to have thrown-away quite a lot
of potential TX dynamic range. However, without full design data,
I'm certainly not going to comment, except to say that I applaud
the detective work which you and David are doing to understand it.
73
Chris G4DGU
toggle quoted messageShow quoted text
On 10/08/2020 14:41, Andy G4JNT wrote:
NO NO
NO Chris
The 0dBm
output is linear up to 0dBm output in analogue / RF terms
What
we're talking about is the digital drive word to the internal
soundcard in order to get that signal level.
It looks
as if only values in the range up to perhaps +/-13000 are
valid. So there is something like 7-8 dB of effective gain
from DDS level to 0dBm point.
Don't
forget, the 0dBm comes direct from the DDS so it's a
hard upper limit. Set by logic rather than compression or
voltage clipping or anything.
It's
odd, though as David reports, that matches WSJT-X drive
spot-on. I doubt very much it was designed that way.
On Mon, 10 Aug 2020 at 14:28,
Chris Bartram < chris@...>
wrote:
Hello Andy,
I'm just starting to think about connecting the 0dBm
output of my FDM-DUO to my transverters. I'm a little
unclear about the results you have reported - it's
probably just too hot! I think you are saying that the
output is linear up to about -8dBm from the 0dBm port on
144MHz. Is that correct?
73
Chris G4DGU
On 10/08/2020 12:43, Andy G4JNT wrote:
Sri
Folks
Looks
like a BIG correction is needed.
I've
just done a quick test using the pre-recorded .WAV
files and it's as you suggested. Full output from
the 0dBm port is achieved with, in my case, about 7 to
8dB back-off from full scale.
Setting
the DUO as default soundcard, controlling PTT via the
CAT interface and playing the .WAV files using the
Windows inbuilt playwav facility I looked at the 0dBm
output on a scope. It needed a file generated at
-8dB (0.4 voltage) of full scale to see a noticeable
decrease in amplitude on the scope. Which is higher
than you saw, at I think 0.1, but still lower than I
expected.
With
the desktop PC, large screen monitor, oscilloscope and
stuff on, it was far too hot in the upstairs shack in
this weather to spend more than a few minutes doing
this so I'll investigate fuller, later. I can use
the .WAV files as calibration, then use TCUBE written
by I2PHD o generate a continuously valuable tone in
amplitude or frequency. That will really map-out the
ampltude response.
I
did generate some two-tone .WAV files, and TCUBE can
generate a two tone waveform, so that will be the way
forward. I'm pretty certain TCUBE gives full-scale
digits at it's maximum setting, but at least I can now
properly calibrate it.
Hi Andy
As you make some measurement in the
next days I suggest to generate a wave file with
two tones so you can measure the IM.
I'm also reading the data sheet of
duo integrated sound card.
The chip is capable 16 or 24 bits
resolutions..
If Franco or someone from Elad can
just comment this result and providing us scale
Factor (If any...) will very useful.
Regards
David
IW5BNL
Hi Andy
Very good idea.
I'm working with Linux.
I suspect that in the gnuradio
/Linux pulse audio chain is some scale Factor
that I don't know.
I will investigate more.
David
IW5BNL
I
generate .WAV files from first
principles. They use a pure 16 bit
integer
Then
replay them via teh soundcard of choice.
Unfortunately
the wav.play function works with the
default soundcard so for this test I will
need to temporarily make the Duo my
default soundcard ! So allteh Windows
bings and chimes will appear on it.
I
have plenty of third party software that
generates tones and itest signals, but no
proof that full scale is actually filling
the 16 bit integer in any of them.
I
could write my own, but it's easier to
generate .Wav, and I have a whole suite of
software to generate all sorts of signals
as a wav.
One
USB soundcard I use a lot is the PCM2900
USB audio device. That has one wonderful
property - the reference for the A/D
appears on a pin of the chip. So it is
possible, by measuring this DC level, to
relate the exact voltage that will appear
for any 16 bit integer sent, and the same
for the sound input.
Hi Andy
How you generate the
audio USB signal.
David
IW5BNL
I'll
do some tests tomorrow. But I'm
pretty certain that when tested
before, a peak audio of the full
16 bit word was required to get
maximum out of the 0dBm port. I
do remember thinking "how well
designed"
Hi all
I do some
meeasuraments.
As I'm on
country home I have only a
power meter and the capability
to measure the tx signal using
the monitoring rx of duo.
I generate a two
tone signal with gu radio and
send it to duo USB.
By monitoring
the internal rx I can measure
the spectrum of duo rx by a
another gnuradio script that
capture the 192khz sample rate
rx out (available on rx
usbvport).
Everithink is
perfectly linear until a USB
audio signal of 0.1 pk
normalized signal.
Increasing over
0.1 we start to see
intermodulation.
0.1 is exactly
the point where the output
power is saturated.
For this
measurement the audio input of
duo was adjusted to 100% in
pulse audio control.
Of course
reducing the pulse audio below
100% the level of saturation
increase.
So the asumption
that -1/1 is the limit isn't
correct as depend on pulse
audio level adjustment.
The good news is
that I now know the maximum
USB audio level before start
to intermodulated.
The modulator
inside duo working extremely
well in the correct range of
driving signal linear is
perfect.
Ciao
David
IW5BNL
Hi all,
Thank for
information and answer.
I'm driving a small amp on
hf band (60w) so duo power
is adjusted on 3 watts out.
I have to
make some more accurate
measurement but,look
like,that changing USB
driving from 0.5/-0.5 to
1/-1 peak power don't
change.May be issue is on
the saturation of my
external amplifier.Next
days I will made some more
accurate meeasuraments.
I encourage
elad crew to produce more
documentation on it.
David
IW5BNL
Ditto, and even if
I want to, I have a
perfectly good HF PA,
-3dBm in gives 200
Watts out, all boxed
up with switched low
pass filters and
absolutely bomb-proof
with mismatched loads
(that's been tested,
intentionally, several
times)
On
Sat, 8 Aug 2020 at
18:38, Neil Smith
G4DBN < neil@...>
wrote:
Good point, I
would have bought
that version in a
heartbeat. The
amp and TX filters
are almost zero
use to me. But
then I have weird
minority interests
and don't use the
HF bands much at
all these days.
Neil G4DBN
On 08/08/2020
18:28, Andy G4JNT
wrote:
A full scale
signed 16 bit
integer, sine
wave, (RMS =
23170)
generates 0dBm
out of the low
power port.
Can't speak
for teh power
amp - never
used it.
In fact, what
isn't there a
lower cost
version of thd
FDM withuut
the 5W amp and
all harmonic
filters.
Just a 0dBm
port on
transmit
On
Sat, 8 Aug
2020 at 18:20,
Neil Smith
G4DBN < neil@...> wrote:
Hi David, I
found it
worked OK with
normalised +-1
peak amplitude
when using the
0dBm output,
but I didn't
try it when
driving the PA
stage. I was
only using FM,
so I don't
know what the
IMD
performance
was like at
higher levels.
It would be
interesting to
know where you
start to see
any sign of
non-linearity
between the
level in
gnuradio and
the actual
power output
via the PA.
Also, what
happens when
the power is
set lower than
MAX. Does
full scale on
the USB device
input still
correspond to
full output,
or does the
USB device
level start to
flatten out
sooner?
Easy enough
to test with
simple tones
(or pairs of
tones) I
guess.
Neil G4DBN
On
08/08/2020
17:43, DAVID
IW5BNL wrote:
If that translates
to a full
scale 16 bit
integer drive
to the
soundcard then
I guess so
Hi
Andy
Thank
you for your
prompt
answer.
Normalize
-1/1 as gnu
radio audio
output is
normalize.
Is
it correct?
David
Full scale -32768
/ 32767 or
0x8000 /
0x7FFF peak
to peak is
full power
Nice and simple,
easy to
remember
Hi
all,
I'm
writing a ssb
compressor
using
gnuradio.It
work well but
I don't really
know maximum
driving signal
of duo USB
internal sound
card to
produce full
output power.
I
proceed
adjusting the
input USB
audio level
little bit
lower that the
level where
the output
peak power is
saturated (
for saturated
output power I
mean the
maximum level
on USB audio
that even
increasing the
audio output
power don't
increase).
Apparently
look like a
sort of alc is
present or
simply
increasing the
level the
modulator is
saturate.
Is
it somewhere a
document
and/or
information
showing
correlation
between input
USB audio and
output power
(on ssb
mode..)
Thank
you
David
IW5BNL
--
Neil
http://g4dbn.uk
--
Chris Bartram G4DGU
--
Chris Bartram G4DGU
|
|
|
Re: Maximum usb input driving signal elad duo
Hi Andy
I think we need some feedback from elad team or some comment on this result. Maybe also i2phd or Giovanni HB9EIK can help
Regards
David IW5BNL
NO NO NO Chris
The 0dBm output is linear up to 0dBm output in analogue / RF terms What we're talking about is the digital drive word to the internal soundcard in order to get that signal level. It looks as if only values in the range up to perhaps +/-13000 are valid. So there is something like 7-8 dB of effective gain from DDS level to 0dBm point.
Don't forget, the 0dBm comes direct from the DDS so it's a hard upper limit. Set by logic rather than compression or voltage clipping or anything.
It's odd, though as David reports, that matches WSJT-X drive spot-on. I doubt very much it was designed that way.
On Mon, 10 Aug 2020 at 14:28, Chris Bartram < chris@...> wrote:
Hello Andy,
I'm just starting to think about connecting the 0dBm output of my
FDM-DUO to my transverters. I'm a little unclear about the results
you have reported - it's probably just too hot! I think you are
saying that the output is linear up to about -8dBm from the 0dBm
port on 144MHz. Is that correct?
73
Chris G4DGU
On 10/08/2020 12:43, Andy G4JNT wrote:
Sri
Folks
Looks
like a BIG correction is needed.
I've
just done a quick test using the pre-recorded .WAV files and
it's as you suggested. Full output from the 0dBm port is
achieved with, in my case, about 7 to 8dB back-off from full
scale.
Setting
the DUO as default soundcard, controlling PTT via the CAT
interface and playing the .WAV files using the Windows
inbuilt playwav facility I looked at the 0dBm output on a
scope. It needed a file generated at -8dB (0.4 voltage) of
full scale to see a noticeable decrease in amplitude on the
scope. Which is higher than you saw, at I think 0.1, but
still lower than I expected.
With
the desktop PC, large screen monitor, oscilloscope and stuff
on, it was far too hot in the upstairs shack in this weather
to spend more than a few minutes doing this so I'll
investigate fuller, later. I can use the .WAV files as
calibration, then use TCUBE written by I2PHD o generate a
continuously valuable tone in amplitude or frequency. That
will really map-out the ampltude response.
I did
generate some two-tone .WAV files, and TCUBE can generate a
two tone waveform, so that will be the way forward. I'm
pretty certain TCUBE gives full-scale digits at it's maximum
setting, but at least I can now properly calibrate it.
Hi Andy
As you make some measurement in the next
days I suggest to generate a wave file with two tones so
you can measure the IM.
I'm also reading the data sheet of duo
integrated sound card.
The chip is capable 16 or 24 bits
resolutions..
If Franco or someone from Elad can just
comment this result and providing us scale Factor (If
any...) will very useful.
Regards
David
IW5BNL
Hi Andy
Very good idea.
I'm working with Linux.
I suspect that in the gnuradio /Linux
pulse audio chain is some scale Factor that I don't
know.
I will investigate more.
David
IW5BNL
I
generate .WAV files from first principles. They
use a pure 16 bit integer
Then
replay them via teh soundcard of choice.
Unfortunately
the wav.play function works with the
default soundcard so for this test I will need to
temporarily make the Duo my default soundcard !
So allteh Windows bings and chimes will appear on
it.
I
have plenty of third party software that generates
tones and itest signals, but no proof that full
scale is actually filling the 16 bit integer in
any of them.
I
could write my own, but it's easier to generate
.Wav, and I have a whole suite of software to
generate all sorts of signals as a wav.
One
USB soundcard I use a lot is the PCM2900 USB audio
device. That has one wonderful property - the
reference for the A/D appears on a pin of the
chip. So it is possible, by measuring this DC
level, to relate the exact voltage that will
appear for any 16 bit integer sent, and the same
for the sound input.
Hi Andy
How you generate the audio USB
signal.
David
IW5BNL
I'll
do some tests tomorrow. But I'm pretty
certain that when tested before, a peak
audio of the full 16 bit word was required
to get maximum out of the 0dBm port. I do
remember thinking "how well designed"
Hi all
I do some meeasuraments.
As I'm on country home I
have only a power meter and the
capability to measure the tx signal
using the monitoring rx of duo.
I generate a two tone
signal with gu radio and send it to
duo USB.
By monitoring the
internal rx I can measure the spectrum
of duo rx by a another gnuradio script
that capture the 192khz sample rate rx
out (available on rx usbvport).
Everithink is perfectly
linear until a USB audio signal of 0.1
pk normalized signal.
Increasing over 0.1 we
start to see intermodulation.
0.1 is exactly the point
where the output power is saturated.
For this measurement the
audio input of duo was adjusted to
100% in pulse audio control.
Of course reducing the
pulse audio below 100% the level of
saturation increase.
So the asumption that
-1/1 is the limit isn't correct as
depend on pulse audio level
adjustment.
The good news is that I
now know the maximum USB audio level
before start to intermodulated.
The modulator inside duo
working extremely well in the correct
range of driving signal linear is
perfect.
Ciao
David
IW5BNL
Hi all,
Thank for
information and answer.
I'm driving a small amp on hf band
(60w) so duo power is adjusted on 3
watts out.
I have to make some
more accurate measurement but,look
like,that changing USB driving
from 0.5/-0.5 to 1/-1 peak power
don't change.May be issue is on
the saturation of my external
amplifier.Next days I will made
some more accurate meeasuraments.
I encourage elad
crew to produce more documentation
on it.
David
IW5BNL
Ditto,
and even if I want to, I have
a perfectly good HF PA, -3dBm
in gives 200 Watts out, all
boxed up with switched low
pass filters and absolutely
bomb-proof with mismatched
loads (that's been tested,
intentionally, several times)
On Sat, 8
Aug 2020 at 18:38, Neil Smith
G4DBN < neil@...>
wrote:
Good point, I would have
bought that version in a
heartbeat. The amp and TX
filters are almost zero
use to me. But then I
have weird minority
interests and don't use
the HF bands much at all
these days.
Neil G4DBN
On 08/08/2020 18:28,
Andy G4JNT wrote:
A full scale
signed 16 bit integer,
sine wave, (RMS =
23170) generates 0dBm
out of the low power
port. Can't speak
for teh power amp -
never used it.
In fact, what
isn't there a lower
cost version of thd
FDM withuut the 5W amp
and all harmonic
filters. Just a 0dBm
port on transmit
On
Sat, 8 Aug 2020 at
18:20, Neil Smith
G4DBN < neil@...>
wrote:
Hi David, I found
it worked OK with
normalised +-1
peak amplitude
when using the
0dBm output, but I
didn't try it when
driving the PA
stage. I was only
using FM, so I
don't know what
the IMD
performance was
like at higher
levels.
It would be
interesting to
know where you
start to see any
sign of
non-linearity
between the level
in gnuradio and
the actual power
output via the
PA. Also, what
happens when the
power is set lower
than MAX. Does
full scale on the
USB device input
still correspond
to full output, or
does the USB
device level start
to flatten out
sooner?
Easy enough to
test with simple
tones (or pairs of
tones) I guess.
Neil G4DBN
On 08/08/2020
17:43, DAVID
IW5BNL wrote:
If that translates
to a full
scale 16 bit
integer drive
to the
soundcard then
I guess so
Hi
Andy
Thank
you for your
prompt
answer.
Normalize
-1/1 as gnu
radio audio
output is
normalize.
Is
it correct?
David
Full scale -32768
/ 32767 or
0x8000 /
0x7FFF peak
to peak is
full power
Nice and simple,
easy to
remember
Hi
all,
I'm
writing a ssb
compressor
using
gnuradio.It
work well but
I don't really
know maximum
driving signal
of duo USB
internal sound
card to
produce full
output power.
I
proceed
adjusting the
input USB
audio level
little bit
lower that the
level where
the output
peak power is
saturated (
for saturated
output power I
mean the
maximum level
on USB audio
that even
increasing the
audio output
power don't
increase).
Apparently
look like a
sort of alc is
present or
simply
increasing the
level the
modulator is
saturate.
Is
it somewhere a
document
and/or
information
showing
correlation
between input
USB audio and
output power
(on ssb
mode..)
Thank
you
David
IW5BNL
--
Neil
http://g4dbn.uk
--
Chris Bartram G4DGU
|
|
|
Re: Maximum usb input driving signal elad duo
Andy G4JNT
NO NO NO Chris
The 0dBm output is linear up to 0dBm output in analogue / RF terms What we're talking about is the digital drive word to the internal soundcard in order to get that signal level. It looks as if only values in the range up to perhaps +/-13000 are valid. So there is something like 7-8 dB of effective gain from DDS level to 0dBm point.
Don't forget, the 0dBm comes direct from the DDS so it's a hard upper limit. Set by logic rather than compression or voltage clipping or anything.
It's odd, though as David reports, that matches WSJT-X drive spot-on. I doubt very much it was designed that way.
On Mon, 10 Aug 2020 at 14:28, Chris Bartram < chris@...> wrote:
Hello Andy,
I'm just starting to think about connecting the 0dBm output of my
FDM-DUO to my transverters. I'm a little unclear about the results
you have reported - it's probably just too hot! I think you are
saying that the output is linear up to about -8dBm from the 0dBm
port on 144MHz. Is that correct?
73
Chris G4DGU
On 10/08/2020 12:43, Andy G4JNT wrote:
Sri
Folks
Looks
like a BIG correction is needed.
I've
just done a quick test using the pre-recorded .WAV files and
it's as you suggested. Full output from the 0dBm port is
achieved with, in my case, about 7 to 8dB back-off from full
scale.
Setting
the DUO as default soundcard, controlling PTT via the CAT
interface and playing the .WAV files using the Windows
inbuilt playwav facility I looked at the 0dBm output on a
scope. It needed a file generated at -8dB (0.4 voltage) of
full scale to see a noticeable decrease in amplitude on the
scope. Which is higher than you saw, at I think 0.1, but
still lower than I expected.
With
the desktop PC, large screen monitor, oscilloscope and stuff
on, it was far too hot in the upstairs shack in this weather
to spend more than a few minutes doing this so I'll
investigate fuller, later. I can use the .WAV files as
calibration, then use TCUBE written by I2PHD o generate a
continuously valuable tone in amplitude or frequency. That
will really map-out the ampltude response.
I did
generate some two-tone .WAV files, and TCUBE can generate a
two tone waveform, so that will be the way forward. I'm
pretty certain TCUBE gives full-scale digits at it's maximum
setting, but at least I can now properly calibrate it.
Hi Andy
As you make some measurement in the next
days I suggest to generate a wave file with two tones so
you can measure the IM.
I'm also reading the data sheet of duo
integrated sound card.
The chip is capable 16 or 24 bits
resolutions..
If Franco or someone from Elad can just
comment this result and providing us scale Factor (If
any...) will very useful.
Regards
David
IW5BNL
Hi Andy
Very good idea.
I'm working with Linux.
I suspect that in the gnuradio /Linux
pulse audio chain is some scale Factor that I don't
know.
I will investigate more.
David
IW5BNL
I
generate .WAV files from first principles. They
use a pure 16 bit integer
Then
replay them via teh soundcard of choice.
Unfortunately
the wav.play function works with the
default soundcard so for this test I will need to
temporarily make the Duo my default soundcard !
So allteh Windows bings and chimes will appear on
it.
I
have plenty of third party software that generates
tones and itest signals, but no proof that full
scale is actually filling the 16 bit integer in
any of them.
I
could write my own, but it's easier to generate
.Wav, and I have a whole suite of software to
generate all sorts of signals as a wav.
One
USB soundcard I use a lot is the PCM2900 USB audio
device. That has one wonderful property - the
reference for the A/D appears on a pin of the
chip. So it is possible, by measuring this DC
level, to relate the exact voltage that will
appear for any 16 bit integer sent, and the same
for the sound input.
Hi Andy
How you generate the audio USB
signal.
David
IW5BNL
I'll
do some tests tomorrow. But I'm pretty
certain that when tested before, a peak
audio of the full 16 bit word was required
to get maximum out of the 0dBm port. I do
remember thinking "how well designed"
Hi all
I do some meeasuraments.
As I'm on country home I
have only a power meter and the
capability to measure the tx signal
using the monitoring rx of duo.
I generate a two tone
signal with gu radio and send it to
duo USB.
By monitoring the
internal rx I can measure the spectrum
of duo rx by a another gnuradio script
that capture the 192khz sample rate rx
out (available on rx usbvport).
Everithink is perfectly
linear until a USB audio signal of 0.1
pk normalized signal.
Increasing over 0.1 we
start to see intermodulation.
0.1 is exactly the point
where the output power is saturated.
For this measurement the
audio input of duo was adjusted to
100% in pulse audio control.
Of course reducing the
pulse audio below 100% the level of
saturation increase.
So the asumption that
-1/1 is the limit isn't correct as
depend on pulse audio level
adjustment.
The good news is that I
now know the maximum USB audio level
before start to intermodulated.
The modulator inside duo
working extremely well in the correct
range of driving signal linear is
perfect.
Ciao
David
IW5BNL
Hi all,
Thank for
information and answer.
I'm driving a small amp on hf band
(60w) so duo power is adjusted on 3
watts out.
I have to make some
more accurate measurement but,look
like,that changing USB driving
from 0.5/-0.5 to 1/-1 peak power
don't change.May be issue is on
the saturation of my external
amplifier.Next days I will made
some more accurate meeasuraments.
I encourage elad
crew to produce more documentation
on it.
David
IW5BNL
Ditto,
and even if I want to, I have
a perfectly good HF PA, -3dBm
in gives 200 Watts out, all
boxed up with switched low
pass filters and absolutely
bomb-proof with mismatched
loads (that's been tested,
intentionally, several times)
On Sat, 8
Aug 2020 at 18:38, Neil Smith
G4DBN < neil@...>
wrote:
Good point, I would have
bought that version in a
heartbeat. The amp and TX
filters are almost zero
use to me. But then I
have weird minority
interests and don't use
the HF bands much at all
these days.
Neil G4DBN
On 08/08/2020 18:28,
Andy G4JNT wrote:
A full scale
signed 16 bit integer,
sine wave, (RMS =
23170) generates 0dBm
out of the low power
port. Can't speak
for teh power amp -
never used it.
In fact, what
isn't there a lower
cost version of thd
FDM withuut the 5W amp
and all harmonic
filters. Just a 0dBm
port on transmit
On
Sat, 8 Aug 2020 at
18:20, Neil Smith
G4DBN < neil@...>
wrote:
Hi David, I found
it worked OK with
normalised +-1
peak amplitude
when using the
0dBm output, but I
didn't try it when
driving the PA
stage. I was only
using FM, so I
don't know what
the IMD
performance was
like at higher
levels.
It would be
interesting to
know where you
start to see any
sign of
non-linearity
between the level
in gnuradio and
the actual power
output via the
PA. Also, what
happens when the
power is set lower
than MAX. Does
full scale on the
USB device input
still correspond
to full output, or
does the USB
device level start
to flatten out
sooner?
Easy enough to
test with simple
tones (or pairs of
tones) I guess.
Neil G4DBN
On 08/08/2020
17:43, DAVID
IW5BNL wrote:
If that translates
to a full
scale 16 bit
integer drive
to the
soundcard then
I guess so
Hi
Andy
Thank
you for your
prompt
answer.
Normalize
-1/1 as gnu
radio audio
output is
normalize.
Is
it correct?
David
Full scale -32768
/ 32767 or
0x8000 /
0x7FFF peak
to peak is
full power
Nice and simple,
easy to
remember
Hi
all,
I'm
writing a ssb
compressor
using
gnuradio.It
work well but
I don't really
know maximum
driving signal
of duo USB
internal sound
card to
produce full
output power.
I
proceed
adjusting the
input USB
audio level
little bit
lower that the
level where
the output
peak power is
saturated (
for saturated
output power I
mean the
maximum level
on USB audio
that even
increasing the
audio output
power don't
increase).
Apparently
look like a
sort of alc is
present or
simply
increasing the
level the
modulator is
saturate.
Is
it somewhere a
document
and/or
information
showing
correlation
between input
USB audio and
output power
(on ssb
mode..)
Thank
you
David
IW5BNL
--
Neil
http://g4dbn.uk
--
Chris Bartram G4DGU
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|
Re: Maximum usb input driving signal elad duo
Hello Andy,
I'm just starting to think about connecting the 0dBm output of my
FDM-DUO to my transverters. I'm a little unclear about the results
you have reported - it's probably just too hot! I think you are
saying that the output is linear up to about -8dBm from the 0dBm
port on 144MHz. Is that correct?
73
Chris G4DGU
toggle quoted messageShow quoted text
On 10/08/2020 12:43, Andy G4JNT wrote:
Sri
Folks
Looks
like a BIG correction is needed.
I've
just done a quick test using the pre-recorded .WAV files and
it's as you suggested. Full output from the 0dBm port is
achieved with, in my case, about 7 to 8dB back-off from full
scale.
Setting
the DUO as default soundcard, controlling PTT via the CAT
interface and playing the .WAV files using the Windows
inbuilt playwav facility I looked at the 0dBm output on a
scope. It needed a file generated at -8dB (0.4 voltage) of
full scale to see a noticeable decrease in amplitude on the
scope. Which is higher than you saw, at I think 0.1, but
still lower than I expected.
With
the desktop PC, large screen monitor, oscilloscope and stuff
on, it was far too hot in the upstairs shack in this weather
to spend more than a few minutes doing this so I'll
investigate fuller, later. I can use the .WAV files as
calibration, then use TCUBE written by I2PHD o generate a
continuously valuable tone in amplitude or frequency. That
will really map-out the ampltude response.
I did
generate some two-tone .WAV files, and TCUBE can generate a
two tone waveform, so that will be the way forward. I'm
pretty certain TCUBE gives full-scale digits at it's maximum
setting, but at least I can now properly calibrate it.
Hi Andy
As you make some measurement in the next
days I suggest to generate a wave file with two tones so
you can measure the IM.
I'm also reading the data sheet of duo
integrated sound card.
The chip is capable 16 or 24 bits
resolutions..
If Franco or someone from Elad can just
comment this result and providing us scale Factor (If
any...) will very useful.
Regards
David
IW5BNL
Hi Andy
Very good idea.
I'm working with Linux.
I suspect that in the gnuradio /Linux
pulse audio chain is some scale Factor that I don't
know.
I will investigate more.
David
IW5BNL
I
generate .WAV files from first principles. They
use a pure 16 bit integer
Then
replay them via teh soundcard of choice.
Unfortunately
the wav.play function works with the
default soundcard so for this test I will need to
temporarily make the Duo my default soundcard !
So allteh Windows bings and chimes will appear on
it.
I
have plenty of third party software that generates
tones and itest signals, but no proof that full
scale is actually filling the 16 bit integer in
any of them.
I
could write my own, but it's easier to generate
.Wav, and I have a whole suite of software to
generate all sorts of signals as a wav.
One
USB soundcard I use a lot is the PCM2900 USB audio
device. That has one wonderful property - the
reference for the A/D appears on a pin of the
chip. So it is possible, by measuring this DC
level, to relate the exact voltage that will
appear for any 16 bit integer sent, and the same
for the sound input.
Hi Andy
How you generate the audio USB
signal.
David
IW5BNL
I'll
do some tests tomorrow. But I'm pretty
certain that when tested before, a peak
audio of the full 16 bit word was required
to get maximum out of the 0dBm port. I do
remember thinking "how well designed"
Hi all
I do some meeasuraments.
As I'm on country home I
have only a power meter and the
capability to measure the tx signal
using the monitoring rx of duo.
I generate a two tone
signal with gu radio and send it to
duo USB.
By monitoring the
internal rx I can measure the spectrum
of duo rx by a another gnuradio script
that capture the 192khz sample rate rx
out (available on rx usbvport).
Everithink is perfectly
linear until a USB audio signal of 0.1
pk normalized signal.
Increasing over 0.1 we
start to see intermodulation.
0.1 is exactly the point
where the output power is saturated.
For this measurement the
audio input of duo was adjusted to
100% in pulse audio control.
Of course reducing the
pulse audio below 100% the level of
saturation increase.
So the asumption that
-1/1 is the limit isn't correct as
depend on pulse audio level
adjustment.
The good news is that I
now know the maximum USB audio level
before start to intermodulated.
The modulator inside duo
working extremely well in the correct
range of driving signal linear is
perfect.
Ciao
David
IW5BNL
Hi all,
Thank for
information and answer.
I'm driving a small amp on hf band
(60w) so duo power is adjusted on 3
watts out.
I have to make some
more accurate measurement but,look
like,that changing USB driving
from 0.5/-0.5 to 1/-1 peak power
don't change.May be issue is on
the saturation of my external
amplifier.Next days I will made
some more accurate meeasuraments.
I encourage elad
crew to produce more documentation
on it.
David
IW5BNL
Ditto,
and even if I want to, I have
a perfectly good HF PA, -3dBm
in gives 200 Watts out, all
boxed up with switched low
pass filters and absolutely
bomb-proof with mismatched
loads (that's been tested,
intentionally, several times)
On Sat, 8
Aug 2020 at 18:38, Neil Smith
G4DBN < neil@...>
wrote:
Good point, I would have
bought that version in a
heartbeat. The amp and TX
filters are almost zero
use to me. But then I
have weird minority
interests and don't use
the HF bands much at all
these days.
Neil G4DBN
On 08/08/2020 18:28,
Andy G4JNT wrote:
A full scale
signed 16 bit integer,
sine wave, (RMS =
23170) generates 0dBm
out of the low power
port. Can't speak
for teh power amp -
never used it.
In fact, what
isn't there a lower
cost version of thd
FDM withuut the 5W amp
and all harmonic
filters. Just a 0dBm
port on transmit
On
Sat, 8 Aug 2020 at
18:20, Neil Smith
G4DBN < neil@...>
wrote:
Hi David, I found
it worked OK with
normalised +-1
peak amplitude
when using the
0dBm output, but I
didn't try it when
driving the PA
stage. I was only
using FM, so I
don't know what
the IMD
performance was
like at higher
levels.
It would be
interesting to
know where you
start to see any
sign of
non-linearity
between the level
in gnuradio and
the actual power
output via the
PA. Also, what
happens when the
power is set lower
than MAX. Does
full scale on the
USB device input
still correspond
to full output, or
does the USB
device level start
to flatten out
sooner?
Easy enough to
test with simple
tones (or pairs of
tones) I guess.
Neil G4DBN
On 08/08/2020
17:43, DAVID
IW5BNL wrote:
If that translates
to a full
scale 16 bit
integer drive
to the
soundcard then
I guess so
Hi
Andy
Thank
you for your
prompt
answer.
Normalize
-1/1 as gnu
radio audio
output is
normalize.
Is
it correct?
David
Full scale -32768
/ 32767 or
0x8000 /
0x7FFF peak
to peak is
full power
Nice and simple,
easy to
remember
Hi
all,
I'm
writing a ssb
compressor
using
gnuradio.It
work well but
I don't really
know maximum
driving signal
of duo USB
internal sound
card to
produce full
output power.
I
proceed
adjusting the
input USB
audio level
little bit
lower that the
level where
the output
peak power is
saturated (
for saturated
output power I
mean the
maximum level
on USB audio
that even
increasing the
audio output
power don't
increase).
Apparently
look like a
sort of alc is
present or
simply
increasing the
level the
modulator is
saturate.
Is
it somewhere a
document
and/or
information
showing
correlation
between input
USB audio and
output power
(on ssb
mode..)
Thank
you
David
IW5BNL
--
Neil
http://g4dbn.uk
--
Chris Bartram G4DGU
|
|
|
Re: Maximum usb input driving signal elad duo
Hi Andy,
I have exactly same result. This morning I generate a full scale 1500khz tone and the point of output power saturation is achieved adjusting audio level at-7.8 db. This means that the wait adjustment suggested by elad application note aren't correct. The right setting for wsjt-x software is: 1) full power setting on wsjt-x software 2) -7.8db setting in elad duo input.
With this setting the system is perfectly linear and the output RF spectrum match perfectly the spectrum generated by wsjt-x software.
David IW5BNL
Sri Folks Looks like a BIG correction is needed. I've just done a quick test using the pre-recorded .WAV files and it's as you suggested. Full output from the 0dBm port is achieved with, in my case, about 7 to 8dB back-off from full scale.
Setting the DUO as default soundcard, controlling PTT via the CAT interface and playing the .WAV files using the Windows inbuilt playwav facility I looked at the 0dBm output on a scope. It needed a file generated at -8dB (0.4 voltage) of full scale to see a noticeable decrease in amplitude on the scope. Which is higher than you saw, at I think 0.1, but still lower than I expected.
With the desktop PC, large screen monitor, oscilloscope and stuff on, it was far too hot in the upstairs shack in this weather to spend more than a few minutes doing this so I'll investigate fuller, later. I can use the .WAV files as calibration, then use TCUBE written by I2PHD o generate a continuously valuable tone in amplitude or frequency. That will really map-out the ampltude response.
I did generate some two-tone .WAV files, and TCUBE can generate a two tone waveform, so that will be the way forward. I'm pretty certain TCUBE gives full-scale digits at it's maximum setting, but at least I can now properly calibrate it.
Hi Andy
As you make some measurement in the next days I suggest to generate a wave file with two tones so you can measure the IM. I'm also reading the data sheet of duo integrated sound card. The chip is capable 16 or 24 bits resolutions.. If Franco or someone from Elad can just comment this result and providing us scale Factor (If any...) will very useful.
Regards
David IW5BNL
Hi Andy
Very good idea. I'm working with Linux. I suspect that in the gnuradio /Linux pulse audio chain is some scale Factor that I don't know. I will investigate more.
David IW5BNL
I generate .WAV files from first principles. They use a pure 16 bit integer Then replay them via teh soundcard of choice.
Unfortunately the wav.play function works with the default soundcard so for this test I will need to temporarily make the Duo my default soundcard ! So allteh Windows bings and chimes will appear on it.
I have plenty of third party software that generates tones and itest signals, but no proof that full scale is actually filling the 16 bit integer in any of them. I could write my own, but it's easier to generate .Wav, and I have a whole suite of software to generate all sorts of signals as a wav.
One USB soundcard I use a lot is the PCM2900 USB audio device. That has one wonderful property - the reference for the A/D appears on a pin of the chip. So it is possible, by measuring this DC level, to relate the exact voltage that will appear for any 16 bit integer sent, and the same for the sound input.
Hi Andy
How you generate the audio USB signal.
David IW5BNL
I'll do some tests tomorrow. But I'm pretty certain that when tested before, a peak audio of the full 16 bit word was required to get maximum out of the 0dBm port. I do remember thinking "how well designed"
Hi all
I do some meeasuraments. As I'm on country home I have only a power meter and the capability to measure the tx signal using the monitoring rx of duo. I generate a two tone signal with gu radio and send it to duo USB. By monitoring the internal rx I can measure the spectrum of duo rx by a another gnuradio script that capture the 192khz sample rate rx out (available on rx usbvport). Everithink is perfectly linear until a USB audio signal of 0.1 pk normalized signal. Increasing over 0.1 we start to see intermodulation. 0.1 is exactly the point where the output power is saturated. For this measurement the audio input of duo was adjusted to 100% in pulse audio control. Of course reducing the pulse audio below 100% the level of saturation increase. So the asumption that -1/1 is the limit isn't correct as depend on pulse audio level adjustment. The good news is that I now know the maximum USB audio level before start to intermodulated. The modulator inside duo working extremely well in the correct range of driving signal linear is perfect.
Ciao
David IW5BNL
Hi all, Thank for information and answer. I'm driving a small amp on hf band (60w) so duo power is adjusted on 3 watts out. I have to make some more accurate measurement but,look like,that changing USB driving from 0.5/-0.5 to 1/-1 peak power don't change.May be issue is on the saturation of my external amplifier.Next days I will made some more accurate meeasuraments. I encourage elad crew to produce more documentation on it.
David IW5BNL
Ditto, and even if I want to, I have a perfectly good HF PA, -3dBm in gives 200 Watts out, all boxed up with switched low pass filters and absolutely bomb-proof with mismatched loads (that's been tested, intentionally, several times)
On Sat, 8 Aug 2020 at 18:38, Neil Smith G4DBN < neil@...> wrote:
Good point, I would have bought that version in a heartbeat. The
amp and TX filters are almost zero use to me. But then I have
weird minority interests and don't use the HF bands much at all
these days.
Neil G4DBN
On 08/08/2020 18:28, Andy G4JNT wrote:
A full
scale signed 16 bit integer, sine wave, (RMS = 23170)
generates 0dBm out of the low power port. Can't speak for
teh power amp - never used it.
In fact,
what isn't there a lower cost version of thd FDM withuut the
5W amp and all harmonic filters. Just a 0dBm port on
transmit
On Sat, 8 Aug 2020 at 18:20,
Neil Smith G4DBN < neil@...> wrote:
Hi David, I found it worked OK with normalised +-1 peak
amplitude when using the 0dBm output, but I didn't try it
when driving the PA stage. I was only using FM, so I
don't know what the IMD performance was like at higher
levels.
It would be interesting to know where you start to see
any sign of non-linearity between the level in gnuradio
and the actual power output via the PA. Also, what
happens when the power is set lower than MAX. Does full
scale on the USB device input still correspond to full
output, or does the USB device level start to flatten out
sooner?
Easy enough to test with simple tones (or pairs of tones)
I guess.
Neil G4DBN
On 08/08/2020 17:43, DAVID IW5BNL wrote:
If
that translates to a full scale 16 bit integer
drive to the soundcard then I guess so
Hi Andy
Thank you for your prompt
answer.
Normalize -1/1 as gnu radio
audio output is normalize.
Is it correct?
David
Full
scale -32768 / 32767 or 0x8000 /
0x7FFF peak to peak is full power
Nice
and simple, easy to remember
Hi all,
I'm writing a ssb
compressor using gnuradio.It work well
but I don't really know maximum
driving signal of duo USB internal
sound card to produce full output
power.
I proceed adjusting the
input USB audio level little bit lower
that the level where the output peak
power is saturated ( for saturated
output power I mean the maximum level
on USB audio that even increasing the
audio output power don't increase).
Apparently look like a sort of alc is
present or simply increasing the level
the modulator is saturate.
Is it somewhere a
document and/or information showing
correlation between input USB audio
and output power (on ssb mode..)
Thank you
David
IW5BNL
--
Neil
http://g4dbn.uk
|
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