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Discussion and technical support related to USRP, UHD, RFNoC

UHD support for TDD mode in AD9361?

zcao@c3commsystems.com

Sun, Oct 23, 2016 4:02 AM

Hi,

We would like to prototype a small CSMA network using multiple E310 nodes. In such a network, all nodes use the frequency to transmit and receive. We plan to use a single antenna per node. We think that AD9361 TDD mode would be sufficient for our purpose.

However, after inspecting the UHD code, it seems that AD9361 TDD operation is not supported by UHD. Register 0x013 and related ENSM registers are set to support FDD. We couldn’t find anywhere in UHD that these registers are modified to operate AD9361 in TDD. In addition, the digital interface mode is set to be FDD as well in e300_defaults.hpp. In fact, we could only find one instance of “TDD” throughout the UHD code base. It is a comment in file db_ubx.cpp

Can you explain why AD9361 TDD model is not supported? Do you have any suggestions regarding using E310 nodes to build a single frequency network?

Thanks,
Zhongren

Hi, We would like to prototype a small CSMA network using multiple E310 nodes. In such a network, all nodes use the frequency to transmit and receive. We plan to use a single antenna per node. We think that AD9361 TDD mode would be sufficient for our purpose. However, after inspecting the UHD code, it seems that AD9361 TDD operation is not supported by UHD. Register 0x013 and related ENSM registers are set to support FDD. We couldn’t find anywhere in UHD that these registers are modified to operate AD9361 in TDD. In addition, the digital interface mode is set to be FDD as well in e300_defaults.hpp. In fact, we could only find one instance of “TDD” throughout the UHD code base. It is a comment in file db_ubx.cpp Can you explain why AD9361 TDD model is not supported? Do you have any suggestions regarding using E310 nodes to build a single frequency network? Thanks, Zhongren

Michael West

Mon, Oct 24, 2016 3:45 PM

Hi Zhongren,

The RF switches between the AD9361 and the SMB connectors provide TDD
capability, so it is unnecessary to put the AD9361 in that mode. Choosing
the TX/RX antenna for receive should be all that is necessary.

Regards,
Michael

On Sat, Oct 22, 2016 at 9:02 PM, zcao--- via USRP-users <
usrp-users@lists.ettus.com> wrote:

Hi,

We would like to prototype a small CSMA network using multiple E310 nodes.
In such a network, all nodes use the frequency to transmit and receive. We
plan to use a single antenna per node. We think that AD9361 TDD mode would
be sufficient for our purpose.

However, after inspecting the UHD code, it seems that AD9361 TDD operation
is not supported by UHD. Register 0x013 and related ENSM registers are set
to support FDD. We couldn’t find anywhere in UHD that these registers are
modified to operate AD9361 in TDD. In addition, the digital interface mode
is set to be FDD as well in e300_defaults.hpp. In fact, we could only find
one instance of “TDD” throughout the UHD code base. It is a comment in file
db_ubx.cpp

Can you explain why AD9361 TDD model is not supported? Do you have any
suggestions regarding using E310 nodes to build a single frequency network?

Thanks,
Zhongren

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Hi Zhongren, The RF switches between the AD9361 and the SMB connectors provide TDD capability, so it is unnecessary to put the AD9361 in that mode. Choosing the TX/RX antenna for receive should be all that is necessary. Regards, Michael On Sat, Oct 22, 2016 at 9:02 PM, zcao--- via USRP-users < usrp-users@lists.ettus.com> wrote: > Hi, > > We would like to prototype a small CSMA network using multiple E310 nodes. > In such a network, all nodes use the frequency to transmit and receive. We > plan to use a single antenna per node. We think that AD9361 TDD mode would > be sufficient for our purpose. > > However, after inspecting the UHD code, it seems that AD9361 TDD operation > is not supported by UHD. Register 0x013 and related ENSM registers are set > to support FDD. We couldn’t find anywhere in UHD that these registers are > modified to operate AD9361 in TDD. In addition, the digital interface mode > is set to be FDD as well in e300_defaults.hpp. In fact, we could only find > one instance of “TDD” throughout the UHD code base. It is a comment in file > db_ubx.cpp > > Can you explain why AD9361 TDD model is not supported? Do you have any > suggestions regarding using E310 nodes to build a single frequency network? > > Thanks, > Zhongren > > > > > > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >