Forum: GNU Radio RFX900 full duplex limitations

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11d7aa1c72334e1525b6d5f928ed96db?d=identicon&s=25 Newell Jensen (Guest)
on 2008-12-16 08:54
(Received via mailing list)
On the pdf from ettus.com (for the RFX900 daughterboard and the like) it
says that:

• Full-duplex capable (with some limitations)

Does anyone know what those limitations are or is there more specific
information somewhere?
We were specifically looking at the RFX900 board.

Thanks.

--
Newell

http://www.gempillar.com
Before enlightenment: chop wood, carry water
After enlightenment: code, build circuits
675175af18f74772d42dd5ce1bf2dc8b?d=identicon&s=25 Per Zetterberg (Guest)
on 2008-12-16 10:22
(Received via mailing list)
I guess the transmitter leaks into the receiver. This may be worse when
the
frequencies are close - multiples of 64MHz should probably be avoided.
I
have also sometimes noticed that the gain of the receiver changes
slightly
when the transmitter is activitated. This may be no issue in many
applications. My guess is that this is due to that the gain of the
AD8437
slightly changes when the voltage on the board drops due to an increased
power consumption.



BR/
Per


  _____

From: discuss-gnuradio-bounces+per.zetterberg=ee.kth.se@gnu.org
[mailto:discuss-gnuradio-bounces+per.zetterberg=ee.kth.se@gnu.org] On
Behalf
Of Newell Jensen
Sent: den 16 december 2008 08:54
To: gnuradio mailing list
Subject: [Discuss-gnuradio] RFX900 full duplex limitations


On the pdf from ettus.com (for the RFX900 daughterboard and the like) it
says that:

. Full-duplex capable (with some limitations)

Does anyone know what those limitations are or is there more specific
information somewhere?
We were specifically looking at the RFX900 board.

Thanks.

--
Newell

http://www.gempillar.com
Before enlightenment: chop wood, carry water
After enlightenment: code, build circuits
D0072e69d706bb3ca211d33a1b536e2c?d=identicon&s=25 Johnathan Corgan (Guest)
on 2008-12-16 22:27
(Received via mailing list)
On Mon, Dec 15, 2008 at 11:53 PM, Newell Jensen <pillar2012@gmail.com>
wrote:

> • Full-duplex capable (with some limitations)
>
> Does anyone know what those limitations are or is there more specific
> information somewhere?

The isolation between the transmitter and receiver is only about 30db
(primarily the leakage through the antenna switching network).

Depending on what you are transmitting, this can impact the first
receiver amplifier, causing IMD and raising the noise floor
unacceptably.

-Johnathan
11d7aa1c72334e1525b6d5f928ed96db?d=identicon&s=25 Newell Jensen (Guest)
on 2008-12-16 22:32
(Received via mailing list)
On Tue, Dec 16, 2008 at 1:24 PM, Johnathan Corgan <
jcorgan@corganenterprises.com> wrote:

> On Mon, Dec 15, 2008 at 11:53 PM, Newell Jensen <pillar2012@gmail.com>
> wrote:
>
> > • Full-duplex capable (with some limitations)
> >
> > Does anyone know what those limitations are or is there more specific
> > information somewhere?
>
> The isolation between the transmitter and receiver is only about 30db
> (primarily the leakage through the antenna switching network).


Is this for the TX/RX port or are you also refering to the TX and RX2
ports?  If I use the RX2 port to receive with its own antenna and the
TX/RX
port with its own antenna is the isolation still about 30 dB?

Thanks for the replies.

--
Newell

http://www.gempillar.com
Before enlightenment: chop wood, carry water
After enlightenment: code, build circuits
D0072e69d706bb3ca211d33a1b536e2c?d=identicon&s=25 Johnathan Corgan (Guest)
on 2008-12-16 22:39
(Received via mailing list)
On Tue, Dec 16, 2008 at 1:28 PM, Newell Jensen <pillar2012@gmail.com>
wrote:

> Is this for the TX/RX port or are you also refering to the TX and RX2
> ports?  If I use the RX2 port to receive with its own antenna and the TX/RX
> port with its own antenna is the isolation still about 30 dB?

I may have misspoken.  In the full duplex configuration, there are two
switches worth of isolation between them, each of them at least 25dB
isolation, but there may be other leakage paths, including coupling
through the common power line.  It's probably worth measuring.

-Johnathan
965108e996db460e6ae03b71dba2e8ef?d=identicon&s=25 David Burgess (Guest)
on 2008-12-16 23:31
(Received via mailing list)
If you actually measure this please share you results.

-- David

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...... Original Message .......
On Tue, 16 Dec 2008 13:38:16 -0800 "Johnathan Corgan"
<jcorgan@corganenterprises.com> wrote:
>On Tue, Dec 16, 2008 at 1:28 PM, Newell Jensen <pillar2012@gmail.com>
wrote:
>
>> Is this for the TX/RX port or are you also refering to the TX and RX2
>> ports?  If I use the RX2 port to receive with its own antenna and the
TX/RX
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