Change in osmo-trx[master]: lms: Use a default Tx gain value of 64 dB.

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Harald Welte gerrit-no-reply at lists.osmocom.org
Thu Nov 29 12:22:19 UTC 2018


Harald Welte has uploaded this change for review. ( https://gerrit.osmocom.org/12008


Change subject: lms: Use a default Tx gain value of 64 dB.
......................................................................

lms: Use a default Tx gain value of 64 dB.

As recommended by Lime Microsystems, the Tx gain should be around
61..66 dB when using 16 bit signed integer samples to full scale
(which we do since Change-Id I71702feaa11f53e7614a6938a984dd748405474a)

This default value is used only as long as osmo-bts-trx doesn't change
it using a 'osmotrx tx-attenuation' override setting.  So the safe
default configuration should be to use osmo-trx after this patch
with no 'osmotrx tx-attenuation' setting in osmo-bts-trx configuration.

Change-Id: Id018b27b1d8a2f48d60b29e688583c9a5ac49a81
---
M Transceiver52M/device/lms/LMSDevice.cpp
1 file changed, 3 insertions(+), 2 deletions(-)



  git pull ssh://gerrit.osmocom.org:29418/osmo-trx refs/changes/08/12008/1

diff --git a/Transceiver52M/device/lms/LMSDevice.cpp b/Transceiver52M/device/lms/LMSDevice.cpp
index 1cda4f9..25b8198 100644
--- a/Transceiver52M/device/lms/LMSDevice.cpp
+++ b/Transceiver52M/device/lms/LMSDevice.cpp
@@ -221,8 +221,9 @@
 		if (LMS_EnableChannel(m_lms_dev, LMS_CH_TX, i, true) < 0)
 			return false;
 
-		// Set gains to midpoint
-		setTxGain((minTxGain() + maxTxGain()) / 2, i);
+		/* use a magic value recommended by Lime Microsystems (61..66 dB) */
+		setTxGain(64.0);
+		// Set Rx gain to midpoint
 		setRxGain((minRxGain() + maxRxGain()) / 2, i);
 
 		m_lms_stream_rx[i] = {};

-- 
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Gerrit-Project: osmo-trx
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: Id018b27b1d8a2f48d60b29e688583c9a5ac49a81
Gerrit-Change-Number: 12008
Gerrit-PatchSet: 1
Gerrit-Owner: Harald Welte <laforge at gnumonks.org>
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