[USRP-users] B200/205 mini side connector

[Stanley, John P. via USRP-users]

I’ve scoured the web looking for more details about the side connector pins 
(jtag/gpio) on the B200/205 mini, and haven’t been able to find much. Is there 
a standard part number for the connector for fabricating a wiring 
harness/pigtail? I’m aware of the adapter cables Ettus sells, I have some on 
order, but the lead time right now is 30 days and I’d like a temporary solution 
in the interim for connecting to a jtag debugger using commodity parts. Is 
there a particular pin gauge/pitch that I should be using?
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Re: [USRP-users] DC Offset Calibration Issue for Rev. C UBX-40 daughter cards

[Stanley, John P. via USRP-users]

Thanks for the insight. Is this publicly documented anywhere? The USRP web 
manual (https://files.ettus.com/manual/page_calibration.html) still explicitly 
states to leave RF ports disconnected for calibration. Updating that page ASAP 
could save folks out there a lot of grief…

From: Michael West <michael.w...@ettus.com>
Date: Thursday, April 19, 2018 at 9:20 PM
To: "Stanley, John P." <john.stan...@jhuapl.edu>
Cc: ROBIN TORTORA <ti...@comcast.net>, "Stanley, John P. via USRP-users" 
<usrp-users@lists.ettus.com>
Subject: Re: [USRP-users] DC Offset Calibration Issue for Rev. C UBX-40 
daughter cards

Hi John/Robin:
The calibration utilities rely on leakage across the RF switch.  The newer UBX 
boards (rev C and later) have RF switches with much higher isolation.  The 
benefit is a lot less leakage from TX onto RX.  The drawback is that the 
calibration utilities will only work if you connect the TX/RX to the RX2 port 
with a 30 dB attenuator in line.
Regards,
Michael

On Thu, Apr 19, 2018 at 11:12 AM, Stanley, John P. via USRP-users 
<usrp-users@lists.ettus.com<mailto:usrp-users@lists.ettus.com>> wrote:
While uncalibrated LO leakage has never been great in the UBX for us, the dc 
offset calibration procedure has given us adequate enough improvement.  We’re 
generally using offset tuning, but we still need that extra 15-20 dB 
suppression we get from the calibration procedure.

The issue we’re seeing with these newer Rev C boards, though, is that the 
calibration doesn’t just fail to improve LO suppression; it actively makes it 
worse. Offset tuning is pretty fruitless when the LO spur alone is >0 dBm at 
the mid-point of available RF gain.


From: ROBIN TORTORA <ti...@comcast.net<mailto:ti...@comcast.net>>
Reply-To: ROBIN TORTORA <ti...@comcast.net<mailto:ti...@comcast.net>>
Date: Thursday, April 19, 2018 at 1:44 PM
To: "Stanley, John P. via USRP-users" 
<usrp-users@lists.ettus.com<mailto:usrp-users@lists.ettus.com>>, "Stanley, John 
P." <john.stan...@jhuapl.edu<mailto:john.stan...@jhuapl.edu>>
Subject: Re: [USRP-users] DC Offset Calibration Issue for Rev. C UBX-40 
daughter cards


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Re: [USRP-users] DC Offset Calibration Issue for Rev. C UBX-40 daughter cards

[Stanley, John P. via USRP-users]

While uncalibrated LO leakage has never been great in the UBX for us, the dc 
offset calibration procedure has given us adequate enough improvement.  We’re 
generally using offset tuning, but we still need that extra 15-20 dB 
suppression we get from the calibration procedure.

The issue we’re seeing with these newer Rev C boards, though, is that the 
calibration doesn’t just fail to improve LO suppression; it actively makes it 
worse. Offset tuning is pretty fruitless when the LO spur alone is >0 dBm at 
the mid-point of available RF gain.


From: ROBIN TORTORA <ti...@comcast.net>
Reply-To: ROBIN TORTORA <ti...@comcast.net>
Date: Thursday, April 19, 2018 at 1:44 PM
To: "Stanley, John P. via USRP-users" <usrp-users@lists.ettus.com>, "Stanley, 
John P." <john.stan...@jhuapl.edu>
Subject: Re: [USRP-users] DC Offset Calibration Issue for Rev. C UBX-40 
daughter cards

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