It seems we were largely overdriving the input. Subsequent testing has shown that things are still linear at higher gain indexes.
Sorry about that.
From: USRP-users usrp-users-bounces@lists.ettus.com on behalf of Kyle A Logue via USRP-users usrp-users@lists.ettus.com
Sent: Tuesday, March 15, 2016 14:23
To: Ettus Mail List; Eugene Grayver; Jared Dulmage; Eugene Grayver; Jared Dulmage
Subject: [USRP-users] E310 Added Low Frequency Noise w/Gain Above +24dB
E310 Users,
My colleagues and I have discovered that while the E310 has a configurable gain index from 0-76 dB, once you exceed a gain of 24 dB, the appears to vary sinusoidally at ~4.3 Hz by up to 2.5 dB. This won't be enough to affect all applications, but may have relevance if people are depending on RSSI measurements in short timescales.
The GIF attached shows three simultaneous recordings done on 3 E310s using the Release4 firmware synchronized with an external PPS source coming from a vector signal generator outputting a signal at 0dBm. That generator is being split 4 ways into 3 E310s and 1 spectrum analyzer. The spec-an shows no variation of signal power. The signal is 130 kbps BPSK signal @ fc = 2404 MHz
We don't know the origin of this oscillation, but hypothesize it may be from a voltage regulator.
Kyle Logue · The Aerospace Corporation · ETG-DCID · Senior MTS · 310.336.3038 · kyle.logue@aero.orgmailto:kyle.logue@aero.org
- False Alarm -
It seems we were largely overdriving the input. Subsequent testing has shown that things are still linear at higher gain indexes.
Sorry about that.
________________________________
From: USRP-users <usrp-users-bounces@lists.ettus.com> on behalf of Kyle A Logue via USRP-users <usrp-users@lists.ettus.com>
Sent: Tuesday, March 15, 2016 14:23
To: Ettus Mail List; Eugene Grayver; Jared Dulmage; Eugene Grayver; Jared Dulmage
Subject: [USRP-users] E310 Added Low Frequency Noise w/Gain Above +24dB
E310 Users,
My colleagues and I have discovered that while the E310 has a configurable gain index from 0-76 dB, once you exceed a gain of 24 dB, the appears to vary sinusoidally at ~4.3 Hz by up to 2.5 dB. This won't be enough to affect all applications, but may have relevance if people are depending on RSSI measurements in short timescales.
The GIF attached shows three simultaneous recordings done on 3 E310s using the Release4 firmware synchronized with an external PPS source coming from a vector signal generator outputting a signal at 0dBm. That generator is being split 4 ways into 3 E310s and 1 spectrum analyzer. The spec-an shows no variation of signal power. The signal is 130 kbps BPSK signal @ fc = 2404 MHz
We don't know the origin of this oscillation, but hypothesize it may be from a voltage regulator.
Kyle Logue · The Aerospace Corporation · ETG-DCID · Senior MTS · 310.336.3038 · kyle.logue@aero.org<mailto:kyle.logue@aero.org>
