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Discussion and technical support related to USRP, UHD, RFNoC
View all threadsSet TX gain has no effect for LFTX
Hello everyone,
I am using an USRP N210 with a LFRX and a LFTX card and I've just realized that the call to set_tx_gain has no effect for this configuration. First on the signal output power, but then I also check just after using the function set_tx_gain, the result is always 0dB when I call get_tx_gain. The signal does not change a bit between a configuration of gain at 0dB and a one at 6.5dB. I am using the UHD version 3.9.4 g2b5a88bb. My application for this test is pretty simple : I just copy the samples from the reception buffer to the emission buffer, with the same fullscale values between the two (but possibly a RX gain different from the TX gain).
Is this a problem with my version of UHD and should I upgrade to fix this ? I took a quick look at recent commits but haven't found anything that seemed relevant to my problem.
Best regards,
Laurent Louf.
[@@OPEN @@]
Hello,
if I'm not mistaken, LFRX and LFTX have no programmable gains (see
https://kb.ettus.com/LFTX/LFRX), so it makes sense that the set
functions don't change anything.
Best regards
Benjamin
Am 22.02.2017 um 15:14 schrieb LOUF Laurent via USRP-users:
Hello everyone,
I am using an USRP N210 with a LFRX and a LFTX card and I’ve just
realized that the call to set_tx_gain has no effect for this
configuration. First on the signal output power, but then I also check
just after using the function set_tx_gain, the result is always 0dB
when I call get_tx_gain. The signal does not change a bit between a
configuration of gain at 0dB and a one at 6.5dB. I am using the UHD
version 3.9.4 g2b5a88bb. My application for this test is pretty simple
: I just copy the samples from the reception buffer to the emission
buffer, with the same fullscale values between the two (but possibly a
RX gain different from the TX gain).
Is this a problem with my version of UHD and should I upgrade to fix
this ? I took a quick look at recent commits but haven’t found
anything that seemed relevant to my problem.
Best regards,
Laurent Louf.
[@@OPEN @@]
USRP-users mailing list
USRP-users@lists.ettus.com
http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
--
Karlsruher Institut für Technologie (KIT)
Institut für Hochfrequenztechnik und Elektronik
Benjamin Nuß
Wissenschaftlicher Mitarbeiter
Engesserstraße 5
Geb. 30.10
76131 Karlsruhe
Tel. +49-721-608-43178
Fax: +49-721-608-45027
E-Mail: benjamin.nuss@kit.edu
www.ihe.kit.edu
KIT - Die Forschungsuniversität in der Helmholtz-Gemeinschaft
Das KIT ist seit 2010 als familiengerechte Hochschule zertifiziert.
Hi everyone,
Official confirmation from the Ettus Support guys: Yep, the LF boards
don't have any adjustable gain, but a unity gain Opamp; that's why
setting the gain has no effect.
Best regards,
Marcus
On 02/22/2017 04:03 PM, Benjamin Nuss via USRP-users wrote:
Hello,
if I'm not mistaken, LFRX and LFTX have no programmable gains (see
https://kb.ettus.com/LFTX/LFRX), so it makes sense that the set
functions don't change anything.
Best regards
Benjamin
Am 22.02.2017 um 15:14 schrieb LOUF Laurent via USRP-users:
Hello everyone,
I am using an USRP N210 with a LFRX and a LFTX card and I’ve just
realized that the call to set_tx_gain has no effect for this
configuration. First on the signal output power, but then I also
check just after using the function set_tx_gain, the result is always
0dB when I call get_tx_gain. The signal does not change a bit between
a configuration of gain at 0dB and a one at 6.5dB. I am using the UHD
version 3.9.4 g2b5a88bb. My application for this test is pretty
simple : I just copy the samples from the reception buffer to the
emission buffer, with the same fullscale values between the two (but
possibly a RX gain different from the TX gain).
Is this a problem with my version of UHD and should I upgrade to fix
this ? I took a quick look at recent commits but haven’t found
anything that seemed relevant to my problem.
Best regards,
Laurent Louf.
[@@OPEN @@]
USRP-users mailing list
USRP-users@lists.ettus.com
http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
--
Karlsruher Institut für Technologie (KIT)
Institut für Hochfrequenztechnik und Elektronik
Benjamin Nuß
Wissenschaftlicher Mitarbeiter
Engesserstraße 5
Geb. 30.10
76131 Karlsruhe
Tel. +49-721-608-43178
Fax: +49-721-608-45027
E-Mail: benjamin.nuss@kit.edu
www.ihe.kit.edu
KIT - Die Forschungsuniversität in der Helmholtz-Gemeinschaft
Das KIT ist seit 2010 als familiengerechte Hochschule zertifiziert.
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Thanks, I discovered a copy-paste error in my function to validate a configuration, so I was using get_rx_gain_range for both RX and TX. Changing it to get_tx_gain_range returns that the gain is not programmable. But for RX, the range returned by the function is 0->6.5dB, by steps of 0.05dB. I'll have a look at the link you gave me, but as far as I'm concerned, my problem is solved.
[@@ THALES GROUP INTERNAL @@]
De : USRP-users [mailto:usrp-users-bounces@lists.ettus.com] De la part de Benjamin Nuss via USRP-users
Envoyé : mercredi 22 février 2017 16:03
À : usrp-users@lists.ettus.com
Objet : Re: [USRP-users] Set TX gain has no effect for LFTX
Hello,
if I'm not mistaken, LFRX and LFTX have no programmable gains (see https://kb.ettus.com/LFTX/LFRX), so it makes sense that the set functions don't change anything.
Best regards
Benjamin
Am 22.02.2017 um 15:14 schrieb LOUF Laurent via USRP-users:
Hello everyone,
I am using an USRP N210 with a LFRX and a LFTX card and I've just realized that the call to set_tx_gain has no effect for this configuration. First on the signal output power, but then I also check just after using the function set_tx_gain, the result is always 0dB when I call get_tx_gain. The signal does not change a bit between a configuration of gain at 0dB and a one at 6.5dB. I am using the UHD version 3.9.4 g2b5a88bb. My application for this test is pretty simple : I just copy the samples from the reception buffer to the emission buffer, with the same fullscale values between the two (but possibly a RX gain different from the TX gain).
Is this a problem with my version of UHD and should I upgrade to fix this ? I took a quick look at recent commits but haven't found anything that seemed relevant to my problem.
Best regards,
Laurent Louf.
[@@OPEN @@]
USRP-users mailing list
USRP-users@lists.ettus.commailto:USRP-users@lists.ettus.com
http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
--
Karlsruher Institut für Technologie (KIT)
Institut für Hochfrequenztechnik und Elektronik
Benjamin Nuß
Wissenschaftlicher Mitarbeiter
Engesserstraße 5
Geb. 30.10
76131 Karlsruhe
Tel. +49-721-608-43178
Fax: +49-721-608-45027
E-Mail: benjamin.nuss@kit.edumailto:benjamin.nuss@kit.edu
www.ihe.kit.eduhttp://www.ihe.kit.edu
KIT - Die Forschungsuniversität in der Helmholtz-Gemeinschaft
Das KIT ist seit 2010 als familiengerechte Hochschule zertifiziert.
The RX gain is not adjustable, either, on the daughterboard. It's just
that the DSP functionality can scale values. Mathematically, that has no
advantage at all, usually.
Best regards,
Marcus
On 02/22/2017 04:15 PM, LOUF Laurent via USRP-users wrote:
Thanks, I discovered a copy-paste error in my function to validate a
configuration, so I was using get_rx_gain_range for both RX and TX.
Changing it to get_tx_gain_range returns that the gain is not
programmable. But for RX, the range returned by the function is
0->6.5dB, by steps of 0.05dB. I’ll have a look at the link you gave
me, but as far as I’m concerned, my problem is solved.
[@@ THALES GROUP INTERNAL @@]
*De :*USRP-users [mailto:usrp-users-bounces@lists.ettus.com] De la
part de Benjamin Nuss via USRP-users
Envoyé : mercredi 22 février 2017 16:03
À : usrp-users@lists.ettus.com
Objet : Re: [USRP-users] Set TX gain has no effect for LFTX
Hello,
if I'm not mistaken, LFRX and LFTX have no programmable gains (see
https://kb.ettus.com/LFTX/LFRX), so it makes sense that the set
functions don't change anything.
Best regards
Benjamin
Am 22.02.2017 um 15:14 schrieb LOUF Laurent via USRP-users:
Hello everyone,
I am using an USRP N210 with a LFRX and a LFTX card and I’ve just
realized that the call to set_tx_gain has no effect for this
configuration. First on the signal output power, but then I also
check just after using the function set_tx_gain, the result is
always 0dB when I call get_tx_gain. The signal does not change a
bit between a configuration of gain at 0dB and a one at 6.5dB. I
am using the UHD version 3.9.4 g2b5a88bb. My application for this
test is pretty simple : I just copy the samples from the reception
buffer to the emission buffer, with the same fullscale values
between the two (but possibly a RX gain different from the TX gain).
Is this a problem with my version of UHD and should I upgrade to
fix this ? I took a quick look at recent commits but haven’t found
anything that seemed relevant to my problem.
Best regards,
Laurent Louf.
[@@OPEN @@]
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--
Karlsruher Institut für Technologie (KIT)
Institut für Hochfrequenztechnik und Elektronik
Benjamin Nuß
Wissenschaftlicher Mitarbeiter
Engesserstraße 5
Geb. 30.10
76131 Karlsruhe
Tel. +49-721-608-43178
Fax: +49-721-608-45027
E-Mail: benjamin.nuss@kit.edu mailto:benjamin.nuss@kit.edu
www.ihe.kit.edu http://www.ihe.kit.edu
KIT - Die Forschungsuniversität in der Helmholtz-Gemeinschaft
Das KIT ist seit 2010 als familiengerechte Hochschule zertifiziert.
USRP-users mailing list
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