UHDDevice: Compute TxGain on UHD API based on expected Tx output power

Right now, according to a few measurements taken on B210, we expect the
Tx Gain at UHD level to relate 1:1 with the slope in Tx output power
given a specific band.

If more fine-grained results are wanted or some device doesn't follow a
1:1 slope relationship, functions TxGain2TxPower and TxPower2TxGain need
to be adapted/improved.

Change-Id: I6f432465dce5c6ec1f1bc4653f6149efb18c3f43

2 files changed, 55 insertions, 44 deletions

diff --git a/Transceiver52M/device/uhd/UHDDevice.cpp b/Transceiver52M/device/uhd/UHDDevice.cpp
index 93dde4b..d1f61d3 100644
--- a/Transceiver52M/device/uhd/UHDDevice.cpp
+++ b/Transceiver52M/device/uhd/UHDDevice.cpp
@@ -212,12 +212,23 @@ static void uhd_msg_handler(uhd::msg::type_t type, const std::string &msg)
 }
 #endif
 
+/* So far measurements done for B210 show really close to linear relationship
+ * between gain and real output power, so we simply adjust the measured offset
+ */
+static double TxGain2TxPower(const dev_band_desc &desc, double tx_gain_db)
+{
+	return desc.nom_out_tx_power - (desc.nom_uhd_tx_gain - tx_gain_db);
+}
+static double TxPower2TxGain(const dev_band_desc &desc, double tx_power_dbm)
+{
+	return desc.nom_uhd_tx_gain - (desc.nom_out_tx_power - tx_power_dbm);
+}
+
 uhd_device::uhd_device(size_t tx_sps, size_t rx_sps,
 		       InterfaceType iface, size_t chan_num, double lo_offset,
 		       const std::vector<std::string>& tx_paths,
 		       const std::vector<std::string>& rx_paths)
 	: RadioDevice(tx_sps, rx_sps, iface, chan_num, lo_offset, tx_paths, rx_paths),
-	  tx_gain_min(0.0), tx_gain_max(0.0),
 	  rx_gain_min(0.0), rx_gain_max(0.0),
 	  band((enum gsm_band)0), tx_spp(0), rx_spp(0),
 	  started(false), aligned(false), drop_cnt(0),
@@ -256,6 +267,7 @@ void uhd_device::get_dev_band_desc(dev_band_desc& desc)
 
 void uhd_device::init_gains()
 {
+	double tx_gain_min, tx_gain_max;
 	uhd::gain_range_t range;
 
 	if (dev_type == UMTRX) {
@@ -320,13 +332,43 @@ void uhd_device::set_rates()
 	LOGC(DDEV, INFO) << "Rates configured for " << desc.str;
 }
 
-double uhd_device::setTxGain(double db, size_t chan)
+double uhd_device::setRxGain(double db, size_t chan)
 {
+	if (chan >= rx_gains.size()) {
+		LOGC(DDEV, ALERT) << "Requested non-existent channel " << chan;
+		return 0.0f;
+	}
+
+	usrp_dev->set_rx_gain(db, chan);
+	rx_gains[chan] = usrp_dev->get_rx_gain(chan);
+
+	LOGC(DDEV, INFO) << "Set RX gain to " << rx_gains[chan] << "dB (asked for " << db << "dB)";
+
+	return rx_gains[chan];
+}
+
+double uhd_device::getRxGain(size_t chan)
+{
+	if (chan >= rx_gains.size()) {
+		LOGC(DDEV, ALERT) << "Requested non-existent channel " << chan;
+		return 0.0f;
+	}
+
+	return rx_gains[chan];
+}
+
+double uhd_device::setPowerAttenuation(int atten, size_t chan) {
+	double db;
+	dev_band_desc desc;
+
 	if (chan >= tx_gains.size()) {
 		LOGC(DDEV, ALERT) << "Requested non-existent channel" << chan;
 		return 0.0f;
 	}
 
+	get_dev_band_desc(desc);
+	db = TxPower2TxGain(desc, desc.nom_out_tx_power - atten);
+
 	if (dev_type == UMTRX) {
 		std::vector<std::string> gain_stages = usrp_dev->get_tx_gain_names(0);
 		if (gain_stages[0] == "VGA" || gain_stages[0] == "PA") {
@@ -348,42 +390,17 @@ double uhd_device::setTxGain(double db, size_t chan)
 
 	LOGC(DDEV, INFO) << "Set TX gain to " << tx_gains[chan] << "dB (asked for " << db << "dB)";
 
-	return tx_gains[chan];
+	return desc.nom_out_tx_power - TxGain2TxPower(desc, tx_gains[chan]);
 }
-
-double uhd_device::setRxGain(double db, size_t chan)
-{
-	if (chan >= rx_gains.size()) {
-		LOGC(DDEV, ALERT) << "Requested non-existent channel " << chan;
-		return 0.0f;
-	}
-
-	usrp_dev->set_rx_gain(db, chan);
-	rx_gains[chan] = usrp_dev->get_rx_gain(chan);
-
-	LOGC(DDEV, INFO) << "Set RX gain to " << rx_gains[chan] << "dB (asked for " << db << "dB)";
-
-	return rx_gains[chan];
-}
-
-double uhd_device::getRxGain(size_t chan)
-{
-	if (chan >= rx_gains.size()) {
-		LOGC(DDEV, ALERT) << "Requested non-existent channel " << chan;
-		return 0.0f;
-	}
-
-	return rx_gains[chan];
-}
-
-double uhd_device::getTxGain(size_t chan)
-{
+double uhd_device::getPowerAttenuation(size_t chan) {
+	dev_band_desc desc;
 	if (chan >= tx_gains.size()) {
 		LOGC(DDEV, ALERT) << "Requested non-existent channel " << chan;
 		return 0.0f;
 	}
 
-	return tx_gains[chan];
+	get_dev_band_desc(desc);
+	return desc.nom_out_tx_power - TxGain2TxPower(desc, tx_gains[chan]);
 }
 
 int uhd_device::getNominalTxPower(size_t chan)
@@ -1007,7 +1024,6 @@ bool uhd_device::setTxFreq(double wFreq, size_t chan)
 {
 	uint16_t req_arfcn;
 	enum gsm_band req_band;
-	dev_band_desc desc;
 
 	if (chan >= tx_freqs.size()) {
 		LOGC(DDEV, ALERT) << "Requested non-existent channel " << chan;
@@ -1036,12 +1052,6 @@ bool uhd_device::setTxFreq(double wFreq, size_t chan)
 		return false;
 
 	band = req_band;
-
-	/* Update Max Tx Gain */
-	get_dev_band_desc(desc);
-	tx_gain_max = desc.nom_uhd_tx_gain;
-	LOGCHAN(chan, DDEV, INFO) << "Updating max Gain to " << tx_gain_max
-				   << " dB based on GSM band information";
 	return true;
 }
 
diff --git a/Transceiver52M/device/uhd/UHDDevice.h b/Transceiver52M/device/uhd/UHDDevice.h
index d87caf2..2c428ca 100644
--- a/Transceiver52M/device/uhd/UHDDevice.h
+++ b/Transceiver52M/device/uhd/UHDDevice.h
@@ -101,6 +101,9 @@ public:
 	double maxRxGain(void) { return rx_gain_max; }
 	double minRxGain(void) { return rx_gain_min; }
 
+	double setPowerAttenuation(int atten, size_t chan);
+	double getPowerAttenuation(size_t chan = 0);
+
 	int getNominalTxPower(size_t chan = 0);
 
 	double getTxFreq(size_t chan);
@@ -131,10 +134,9 @@ public:
 	};
 
 private:
-	double setTxGain(double db, size_t chan);
-	double getTxGain(size_t chan = 0);
-	double maxTxGain(void) { return tx_gain_max; }
-	double minTxGain(void) { return tx_gain_min; }
+	double setTxGain(double db, size_t chan) {OSMO_ASSERT(false); return 0.0f; }
+	double getTxGain(size_t chan = 0) { OSMO_ASSERT(false); return 0.0f; };
+	double maxTxGain(void) { OSMO_ASSERT(false); return 0.0f; };
 
 	uhd::usrp::multi_usrp::sptr usrp_dev;
 	uhd::tx_streamer::sptr tx_stream;
@@ -144,7 +146,6 @@ private:
 
 	double tx_rate, rx_rate;
 
-	double tx_gain_min, tx_gain_max;
 	double rx_gain_min, rx_gain_max;
 
 	std::vector<double> tx_gains, rx_gains;