Re: [Discuss-gnuradio] SBX TX/RX RX leakage

[gang li]

 Thanks for your reply. I dont have a dummy load in hand. Are there
any other ways to check that?

On Sat, Feb 9, 2013 at 2:35 AM, Ralph A. Schmid, dk5ras
<address@hidden> wrote:
> Just put 50 Ohm dummy loads onto the connectors and check for a signal, then
> you see if it is leakage or not :)
>
> Ralph.
>
>> -----Original Message-----
>> From: address@hidden
>> [mailto:address@hidden On Behalf Of
>> gang li
>> Sent: Friday, 08 February, 2013 23:47
>> To: Marcus D. Leech
>> Cc: address@hidden; address@hidden
>> Subject: Re: [Discuss-gnuradio] SBX TX/RX RX leakage
>>
>> Yes. I am doing full duplex on the same frequency, transmitting from
>> TX/RX and receiving on RX2 at the same time. When I put the antennas
>> far way from each other, the received signal amplitude is very low.
>> And when I change the distance between them, i found the received
>> signal amplitude is kind of stable. So i think maybe the leakage takes
>> the major. Am I right?
>>
>> On Fri, Feb 8, 2013 at 4:26 PM, Marcus D. Leech <address@hidden>
>> wrote:
>> > On 02/08/2013 04:10 PM, gang li wrote:
>> >>
>> >> When the signal received on RF2 port has a very weak strength, the
>> >> energy leaked from TX to RX will dominate in the total received
>> >> energy. I have observed this in my experiments. Are there any ways to
>> >> measure the leaked signal so i can compensate it? I am thinking a way
>> >> of by connecting the RF1 and RF2 ports with a long cable and 60db
>> >> attenuators. And then i record the received signal. I assume it is the
>> >> leaked signal from TX. Are there any better ways? Thanks for your
>> >> reply.
>> >>
>> >> Best,
>> >> Gang
>> >
>> > Are you TX/RX on the same frequency, or different frequencies?
>> >
>> > The usual way to deal with this on different-frequency setups is to use
> a
>> > duplexor, or a deep notch filter on the RX port, and probably boost your
>> >   antenna signal a bit with an external amplifier.
>> >
>> > But if this is *same-frequency* duplex, the on-board leakage is really
> minor
>> > compared to the coupling between your antennae.
>> >
>> >
>> >
>> > --
>> > Marcus Leech
>> > Principal Investigator
>> > Shirleys Bay Radio Astronomy Consortium
>> > http://www.sbrac.org
>> >
>> >
>>
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