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Discussion and technical support related to USRP, UHD, RFNoC
View all threadsX440 Noise Figure
Hello,
I have been trying to estimate the Noise Figure of the X440. I looked
through all the documentation I could find and couldn't find it anywhere,
so I tried to calculate it myself.
It looks like the ZU2xDR RFSoC has a NSD of -146dBFS/Hz @ 2.4GHz (
https://docs.amd.com/r/en-US/ds926-zynq-ultrascale-plus-rfsoc/RF-ADC-Performance-Characteristics)
and the Full Scale Input is 1Vppd (0.707Vrms) @ 100ohms (
https://docs.amd.com/r/en-US/ds926-zynq-ultrascale-plus-rfsoc/RF-ADC-Electrical-Characteristics)
.
Based on this information I calculate NSD of -139dBm/Hz [-146dBFS/Hz +
10log10(0.707^2/100Ω*1000)], so -139dBm/Hz - -174dBm/Hz gives Noise Figure
of 35dB? Add the 1.5 insertion loss of the TCM2-63WX+ on the Daughterboard (
https://files.ettus.com/manual/page_fbx.html), gives an approximate noise
figure of the X440 at 36.5dB for 2.4GHz.
Is this correct? Seems high, I don't have much experience calculating noise
figure from ADC's so I'm wondering if I'm missing something.
Thanks,
Steve
On 28/08/2024 18:04, Steve Hamn wrote:
Hello,
I have been trying to estimate the Noise Figure of the X440. I looked
through all the documentation I could find and couldn't find it
anywhere, so I tried to calculate it myself.
It looks like the ZU2xDR RFSoC has a NSD of -146dBFS/Hz @ 2.4GHz
(https://docs.amd.com/r/en-US/ds926-zynq-ultrascale-plus-rfsoc/RF-ADC-Performance-Characteristics)
and the Full Scale Input is 1Vppd (0.707Vrms) @ 100ohms
(https://docs.amd.com/r/en-US/ds926-zynq-ultrascale-plus-rfsoc/RF-ADC-Electrical-Characteristics)
.
Based on this information I calculate NSD of -139dBm/Hz [-146dBFS/Hz +
10log10(0.707^2/100Ω*1000)], so -139dBm/Hz - -174dBm/Hz gives Noise
Figure of 35dB? Add the 1.5 insertion loss of the TCM2-63WX+ on the
Daughterboard (https://files.ettus.com/manual/page_fbx.html), gives an
approximate noise figure of the X440 at 36.5dB for 2.4GHz.
Is this correct? Seems high, I don't have much experience calculating
noise figure from ADC's so I'm wondering if I'm missing something.
Thanks,
Steve
"Naked" ADCs are inherently very very noisy devices. Since the X440 has
no RF pre-processing of any importance, you'd at
least need a low-noise filtered front-end to beat the inherent ADC
noise into insignificance. For other USRP radios, mostly,
that's already taken care of, and the receiver noise-figure is much
more "respectable" (not, radio astronomy respectable,
but adequate to put onto an over-the-air antenna).
Hi Marcus,
Thanks. Understood, that all makes sense to me. Part of this is I'm trying
to understand the base Noise Figure as a starting point so I can design my
filtered low noise front end as you suggest.
I guess you're confirming that 36.5dB is expected from the X440 and there's
nothing crazy wrong about my math.
Thanks,
Steve
On Wed, Aug 28, 2024, 3:15 PM Marcus D. Leech patchvonbraun@gmail.com
wrote:
On 28/08/2024 18:04, Steve Hamn wrote:
Hello,
I have been trying to estimate the Noise Figure of the X440. I looked
through all the documentation I could find and couldn't find it
anywhere, so I tried to calculate it myself.
It looks like the ZU2xDR RFSoC has a NSD of -146dBFS/Hz @ 2.4GHz
(
and the Full Scale Input is 1Vppd (0.707Vrms) @ 100ohms
(
.
Based on this information I calculate NSD of -139dBm/Hz [-146dBFS/Hz +
10log10(0.707^2/100Ω*1000)], so -139dBm/Hz - -174dBm/Hz gives Noise
Figure of 35dB? Add the 1.5 insertion loss of the TCM2-63WX+ on the
Daughterboard (https://files.ettus.com/manual/page_fbx.html), gives an
approximate noise figure of the X440 at 36.5dB for 2.4GHz.
Is this correct? Seems high, I don't have much experience calculating
noise figure from ADC's so I'm wondering if I'm missing something.
Thanks,
Steve
"Naked" ADCs are inherently very very noisy devices. Since the X440 has
no RF pre-processing of any importance, you'd at
least need a low-noise filtered front-end to beat the inherent ADC
noise into insignificance. For other USRP radios, mostly,
that's already taken care of, and the receiver noise-figure is much
more "respectable" (not, radio astronomy respectable,
but adequate to put onto an over-the-air antenna).
USRP-users mailing list -- usrp-users@lists.ettus.com
To unsubscribe send an email to usrp-users-leave@lists.ettus.com
On 28/08/2024 18:36, Steve Hamn wrote:
Hi Marcus,
Thanks. Understood, that all makes sense to me. Part of this is I'm
trying to understand the base Noise Figure as a starting point so I
can design my filtered low noise front end as you suggest.
I guess you're confirming that 36.5dB is expected from the X440 and
there's nothing crazy wrong about my math.
Might be a bit high, but like I said, ADCs have notoriously-high
equivalent noise figure. I don't think anyone at NI/Emerson
has done a "hard characterization" of the equivalent noise figure,
because, well, it's always going to be "somewhere around
horrific". Nobody would likely expect to connect this directly to an
antenna (except maybe on HF) and expect good results...
Thanks,
Steve
On Wed, Aug 28, 2024, 3:15 PM Marcus D. Leech
patchvonbraun@gmail.com wrote:
On 28/08/2024 18:04, Steve Hamn wrote:
Hello,
I have been trying to estimate the Noise Figure of the X440. I
looked
through all the documentation I could find and couldn't find it
anywhere, so I tried to calculate it myself.
It looks like the ZU2xDR RFSoC has a NSD of -146dBFS/Hz @ 2.4GHz
(https://docs.amd.com/r/en-US/ds926-zynq-ultrascale-plus-rfsoc/RF-ADC-Performance-Characteristics)
and the Full Scale Input is 1Vppd (0.707Vrms) @ 100ohms
(https://docs.amd.com/r/en-US/ds926-zynq-ultrascale-plus-rfsoc/RF-ADC-Electrical-Characteristics)
.
Based on this information I calculate NSD of -139dBm/Hz
[-146dBFS/Hz +
10log10(0.707^2/100Ω*1000)], so -139dBm/Hz - -174dBm/Hz gives Noise
Figure of 35dB? Add the 1.5 insertion loss of the TCM2-63WX+ on the
Daughterboard (https://files.ettus.com/manual/page_fbx.html),
gives an
approximate noise figure of the X440 at 36.5dB for 2.4GHz.
Is this correct? Seems high, I don't have much experience
calculating
noise figure from ADC's so I'm wondering if I'm missing something.
Thanks,
Steve
"Naked" ADCs are inherently very very noisy devices. Since the
X440 has
no RF pre-processing of any importance, you'd at
least need a low-noise filtered front-end to beat the inherent ADC
noise into insignificance. For other USRP radios, mostly,
that's already taken care of, and the receiver noise-figure is
much
more "respectable" (not, radio astronomy respectable,
but adequate to put onto an over-the-air antenna).
_______________________________________________
USRP-users mailing list -- usrp-users@lists.ettus.com
To unsubscribe send an email to usrp-users-leave@lists.ettus.com
Here's an article that may help with your NF calculations.
"Calculating noise figure and third-order intercept in ADCs"
https://www.ti.com/lit/an/slyt090/slyt090.pdf
I wrote a little C program from it.
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
int main(int argc, char **argv)
{
double k, t, dBm1Hz, dBm500Hz;
double vpp, p, sinad, rate, VdBm, dBHz, dBmHz;
if (argc != 4) {
fprintf(stderr, "usage: bdr <p-p voltage> <sinad> <sample
rate>\n");
exit(-1);
}
vpp = atof(argv[1]);
sinad = atof(argv[2]);
rate = atof(argv[3]);
k = 1.38064852e-23;
t = 290.0;
p = k * t * 1 * 1000.0;
dBm1Hz = 10.0 * log10(p);
p = k * t * 500 * 1000.0;
dBm500Hz = 10.0 * log10(p);
p = (vpp * vpp) / (50 * 8);
VdBm = (10.0 * log10(p)) + 30;
dBHz = 10.0 * log10(rate / 2);
dBmHz = (VdBm - 1) - sinad - dBHz;
printf("overload = %.2f dBm\n", VdBm);
printf("Noise Figure = %.2f dB, %.2f dBm/Hz\n", dBmHz - dBm1Hz, dBmHz);
printf("MDS in 500 Hz bandwidth = %.2f dBm\n", dBm500Hz + (dBmHz -
dBm1Hz));
printf("500 Hz Dynamic Range = %.2f dB\n", VdBm - (dBm500Hz +
(dBmHz - dBm1Hz)));
return 0;
}
Ron
On 8/28/24 15:36, Steve Hamn wrote:
Hi Marcus,
Thanks. Understood, that all makes sense to me. Part of this is I'm
trying to understand the base Noise Figure as a starting point so I
can design my filtered low noise front end as you suggest.
I guess you're confirming that 36.5dB is expected from the X440 and
there's nothing crazy wrong about my math.
Thanks,
Steve
On Wed, Aug 28, 2024, 3:15 PM Marcus D. Leech
patchvonbraun@gmail.com wrote:
On 28/08/2024 18:04, Steve Hamn wrote:
Hello,
I have been trying to estimate the Noise Figure of the X440. I
looked
through all the documentation I could find and couldn't find it
anywhere, so I tried to calculate it myself.
It looks like the ZU2xDR RFSoC has a NSD of -146dBFS/Hz @ 2.4GHz
(https://docs.amd.com/r/en-US/ds926-zynq-ultrascale-plus-rfsoc/RF-ADC-Performance-Characteristics)
and the Full Scale Input is 1Vppd (0.707Vrms) @ 100ohms
(https://docs.amd.com/r/en-US/ds926-zynq-ultrascale-plus-rfsoc/RF-ADC-Electrical-Characteristics)
.
Based on this information I calculate NSD of -139dBm/Hz
[-146dBFS/Hz +
10log10(0.707^2/100Ω*1000)], so -139dBm/Hz - -174dBm/Hz gives Noise
Figure of 35dB? Add the 1.5 insertion loss of the TCM2-63WX+ on the
Daughterboard (https://files.ettus.com/manual/page_fbx.html),
gives an
approximate noise figure of the X440 at 36.5dB for 2.4GHz.
Is this correct? Seems high, I don't have much experience
calculating
noise figure from ADC's so I'm wondering if I'm missing something.
Thanks,
Steve
"Naked" ADCs are inherently very very noisy devices. Since the
X440 has
no RF pre-processing of any importance, you'd at
least need a low-noise filtered front-end to beat the inherent ADC
noise into insignificance. For other USRP radios, mostly,
that's already taken care of, and the receiver noise-figure is
much
more "respectable" (not, radio astronomy respectable,
but adequate to put onto an over-the-air antenna).
_______________________________________________
USRP-users mailing list -- usrp-users@lists.ettus.com
To unsubscribe send an email to usrp-users-leave@lists.ettus.com
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To unsubscribe send an email tousrp-users-leave@lists.ettus.com
On 28/08/2024 19:36, Ron Economos via USRP-users wrote:
Here's an article that may help with your NF calculations.
"Calculating noise figure and third-order intercept in ADCs"
https://www.ti.com/lit/an/slyt090/slyt090.pdf
I wrote a little C program from it.
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
int main(int argc, char **argv)
{
double k, t, dBm1Hz, dBm500Hz;
double vpp, p, sinad, rate, VdBm, dBHz, dBmHz;
if (argc != 4) {
fprintf(stderr, "usage: bdr <p-p voltage> <sinad> <sample
rate>\n");
exit(-1);
}
vpp = atof(argv[1]);
sinad = atof(argv[2]);
rate = atof(argv[3]);
k = 1.38064852e-23;
t = 290.0;
p = k * t * 1 * 1000.0;
dBm1Hz = 10.0 * log10(p);
p = k * t * 500 * 1000.0;
dBm500Hz = 10.0 * log10(p);
p = (vpp * vpp) / (50 * 8);
VdBm = (10.0 * log10(p)) + 30;
dBHz = 10.0 * log10(rate / 2);
dBmHz = (VdBm - 1) - sinad - dBHz;
printf("overload = %.2f dBm\n", VdBm);
printf("Noise Figure = %.2f dB, %.2f dBm/Hz\n", dBmHz - dBm1Hz,
dBmHz);
printf("MDS in 500 Hz bandwidth = %.2f dBm\n", dBm500Hz + (dBmHz -
dBm1Hz));
printf("500 Hz Dynamic Range = %.2f dB\n", VdBm - (dBm500Hz +
(dBmHz - dBm1Hz)));
return 0;
}
Ron
Before getopt(), before dinosaurs, there was raw processing of argv[],
like a boss :) :)
You and I must be of a similar era :)
Actually, I learned C before <stdio.h> even existed. That was a "modern
luxury" when I started using it :)
On 8/28/24 15:36, Steve Hamn wrote:
Hi Marcus,
Thanks. Understood, that all makes sense to me. Part of this is I'm
trying to understand the base Noise Figure as a starting point so I
can design my filtered low noise front end as you suggest.
I guess you're confirming that 36.5dB is expected from the X440 and
there's nothing crazy wrong about my math.
Thanks,
Steve
On Wed, Aug 28, 2024, 3:15 PM Marcus D. Leech
patchvonbraun@gmail.com wrote:
On 28/08/2024 18:04, Steve Hamn wrote:
Hello,
I have been trying to estimate the Noise Figure of the X440. I
looked
through all the documentation I could find and couldn't find it
anywhere, so I tried to calculate it myself.
It looks like the ZU2xDR RFSoC has a NSD of -146dBFS/Hz @ 2.4GHz
(https://docs.amd.com/r/en-US/ds926-zynq-ultrascale-plus-rfsoc/RF-ADC-Performance-Characteristics)
and the Full Scale Input is 1Vppd (0.707Vrms) @ 100ohms
(https://docs.amd.com/r/en-US/ds926-zynq-ultrascale-plus-rfsoc/RF-ADC-Electrical-Characteristics)
.
Based on this information I calculate NSD of -139dBm/Hz
[-146dBFS/Hz +
10log10(0.707^2/100Ω*1000)], so -139dBm/Hz - -174dBm/Hz gives
Noise
Figure of 35dB? Add the 1.5 insertion loss of the TCM2-63WX+ on
the
Daughterboard (https://files.ettus.com/manual/page_fbx.html),
gives an
approximate noise figure of the X440 at 36.5dB for 2.4GHz.
Is this correct? Seems high, I don't have much experience
calculating
noise figure from ADC's so I'm wondering if I'm missing something.
Thanks,
Steve
"Naked" ADCs are inherently very very noisy devices. Since the
X440 has
no RF pre-processing of any importance, you'd at
least need a low-noise filtered front-end to beat the inherent
ADC
noise into insignificance. For other USRP radios, mostly,
that's already taken care of, and the receiver noise-figure is
much
more "respectable" (not, radio astronomy respectable,
but adequate to put onto an over-the-air antenna).
_______________________________________________
USRP-users mailing list -- usrp-users@lists.ettus.com
To unsubscribe send an email to usrp-users-leave@lists.ettus.com
USRP-users mailing list --usrp-users@lists.ettus.com
To unsubscribe send an email tousrp-users-leave@lists.ettus.com
USRP-users mailing list --usrp-users@lists.ettus.com
To unsubscribe send an email tousrp-users-leave@lists.ettus.com