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List:       usrp-users
Subject:    Re: [USRP-users] Gain difference in 4 RX on N310
From:       Marcus D Leech via USRP-users <usrp-users () lists ! ettus ! com>
Date:       2019-12-25 16:56:25
Message-ID: E13C78DD-5B67-48C0-B605-6A55F3AE6E0C () gmail ! com
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You won't be able to "see" the thermal noise of the terminator unless the gain is turned all the way up. Otherwise it's below the noise floor of the receiver. 



Sent from my iPhone

> On Dec 25, 2019, at 9:19 AM, Marcus Müller via USRP-users <usrp-users@lists.ettus.com> wrote:
> 
> Hi Baroch,
> 
> oh, that's interesting and I must admit I don't really know where to
> start looking into this, but let's take this top-down:
> How are you setting the gain, and how are you doing the capturing?
> My gut feeling tells me there's something in UHD not handling multi-
> channel gain setting right, but lacking an N310 on my desk right now, I
> can't just trace this with a debugger.
> How did you build and install your UHD?
> Best regards,
> Marcus
> 
>> On Wed, 2019-12-25 at 15:29 +0200, Baroch Oren via USRP-users wrote:
>> Hello.
>> I've been capturing with N310 on 4 channels simultaneously. A strange
>> behavioure occurs:
>> First experiment: capturing on a single channel when all the other 3
>> rx channels are terminated, I get a similar captured gain on every
>> one of the RX channels.
>> Second experiment: capturing simultaneously, channel 3 (RF2 RX2)
>> shows a decreased capture gain in about -14db. all other channels
>> show capture gain similar to first experiment.
>> Third experiment: capturing simultaneously on 4 channels, all inputs
>> terminated: thermal noise of same gain on all 4 channels.
>> 
>> Anyone has any clue for direction to further research this?
>> 
>> My setup: UHD_3.14.1.HEAD-0-g0347a6d8 on Ubuntu
>> 
>> Thanks,
>> Baroch Oren
>> 
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> 
> 
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