Computes reference input power in fiber during design

input power is computed at design time: so let's record it and
use it instead of p_span_i for reference channel fiber loss computation.
Note that this loss parameter is only used for visualisation purpose.

Signed-off-by: EstherLerouzic <[email protected]>
Change-Id: I16bd792bd6079ce521aafadcf5e21922aa3b4c81

gnpy/core/elements.py

@@ -486,6 +486,7 @@ def __init__(self, *args, params=None, **kwargs):
                                        f"({1e-3 * self.params.length} km), boundaries excluded.")
         self.lumped_losses = db2lin(- lumped_losses_power)  # [linear units]
         self.z_lumped_losses = array(z_lumped_losses) * 1e3  # [m]
+        self.ref_pch_in_dbm = None
 
     @property
     def to_json(self):
@@ -635,6 +636,12 @@ def __call__(self, spectral_info):
         self._psig_in = sum(spectral_info.signal)
         self.propagate(spectral_info)
         self.update_pref(spectral_info)
+        # In case of Raman, the resulting loss of the fiber is not equivalent to self.loss
+        # because of Raman gain. The resulting loss is:
+        # power_out - power_in. We use the total signal power (sum on all channels) to compute
+        # this loss.
+        loss = round(lin2db(self._psig_in / sum(spectral_info.signal)), 2)
+        self.pch_out_db = self.ref_pch_in_dbm - loss
         return spectral_info
 
 

gnpy/core/network.py

@@ -410,6 +410,33 @@ def set_roadm_input_powers(network, roadm, equipment, pref_ch_db):
             )
 
 
+def set_fiber_input_power(network, fiber, equipment, pref_ch_db):
+    """Set reference powers at fiber input for a reference channel.
+    Supposes that target power out of ROADMs and amplifiers are consistent.
+    This is only for visualisation purpose
+    """
+    ref_carrier = ReferenceCarrier(baud_rate=equipment['SI']['default'].baud_rate,
+                                   slot_width=equipment['SI']['default'].spacing)
+    loss = 0.0
+    node = next(network.predecessors(fiber))
+    while isinstance(node, elements.Fused):
+        loss += node.loss
+        previous_node = node
+        node = next(network.predecessors(node))
+    if isinstance(node, (elements.Fiber, elements.RamanFiber)) and node.ref_pch_in_dbm is not None:
+        fiber.ref_pch_in_dbm = node.ref_pch_in_dbm - loss - node.loss
+    if isinstance(node, (elements.Fiber, elements.RamanFiber)) and node.ref_pch_in_dbm is None:
+        set_fiber_input_power(network, node, equipment, pref_ch_db)
+        fiber.ref_pch_in_dbm = node.ref_pch_in_dbm - loss - node.loss
+    elif isinstance(node, elements.Roadm):
+        fiber.ref_pch_in_dbm = \
+            node.get_per_degree_ref_power(degree=previous_node.uid, ref_carrier=ref_carrier) - loss
+    elif isinstance(node, elements.Edfa):
+        fiber.ref_pch_in_dbm = pref_ch_db + node._delta_p - node.out_voa - loss
+    elif isinstance(node, elements.Transceiver):
+        fiber.ref_pch_in_dbm = pref_ch_db - loss
+
+
 def add_roadm_booster(network, roadm):
     next_nodes = [n for n in network.successors(roadm)
                   if not (isinstance(n, elements.Transceiver) or isinstance(n, elements.Fused) or isinstance(n, elements.Edfa))]
@@ -604,7 +631,7 @@ def build_network(network, equipment, pref_ch_db, pref_total_db, no_insert_edfas
     # =>for code clarity (at the expense of speed):
 
     roadms = [r for r in network.nodes() if isinstance(r, elements.Roadm)]
-
+    transceivers = [t for t in network.nodes() if isinstance(t, elements.Transceiver)]
     if not no_insert_edfas:
         for fiber in fibers:
             split_fiber(network, fiber, bounds, target_length, equipment)
@@ -621,12 +648,15 @@ def build_network(network, equipment, pref_ch_db, pref_total_db, no_insert_edfas
 
     for roadm in roadms:
         set_roadm_per_degree_targets(roadm, network)
+    for roadm in roadms + transceivers:
         set_egress_amplifier(network, roadm, equipment, pref_ch_db, pref_total_db)
     for roadm in roadms:
         set_roadm_input_powers(network, roadm, equipment, pref_ch_db)
-
-    trx = [t for t in network.nodes() if isinstance(t, elements.Transceiver)]
-    for t in trx:
-        next_node = next(network.successors(t), None)
-        if next_node and not isinstance(next_node, elements.Roadm):
-            set_egress_amplifier(network, t, equipment, 0, pref_total_db)
+    for fiber in [f for f in network.nodes() if isinstance(f, (elements.Fiber, elements.RamanFiber))]:
+        set_fiber_input_power(network, fiber, equipment, pref_ch_db)
+
+    # trx = [t for t in network.nodes() if isinstance(t, elements.Transceiver)]
+    # for t in trx:
+    #     next_node = next(network.successors(t), None)
+    #     if next_node and not isinstance(next_node, elements.Roadm):
+    #         set_egress_amplifier(network, t, equipment, 0, pref_total_db)

tests/test_amplifier.py

@@ -234,6 +234,7 @@ def test_amp_behaviour(tilt_target, delta_p):
     fiber = [n for n in network.nodes() if isinstance(n, Fiber)][0]
     fiber.params.con_in = 0
     fiber.params.con_out = 0
+    fiber.ref_pch_in_dbm = 0.0
     si = create_input_spectral_information(f_min=191.3e12, f_max=196.05e12, roll_off=0.15, baud_rate=64e9, power=0.001,
                                            spacing=75e9, tx_osnr=None)
     si = fiber(si)

tests/test_science_utils.py

@@ -26,7 +26,7 @@
 def test_fiber():
     """Test the accuracy of propagating the Fiber."""
     fiber = Fiber(**load_json(TEST_DIR / 'data' / 'test_science_utils_fiber_config.json'))
-
+    fiber.ref_pch_in_dbm = 0.0
     # fix grid spectral information generation
     spectral_info_input = create_input_spectral_information(f_min=191.3e12, f_max=196.1e12, roll_off=0.15,
                                                             baud_rate=32e9, power=1e-3, spacing=50e9, tx_osnr=40.0,
@@ -73,7 +73,7 @@ def test_raman_fiber():
                                                             ref_carrier=ReferenceCarrier(baud_rate=32e9, slot_width=50e9))
     SimParams.set_params(load_json(TEST_DIR / 'data' / 'sim_params.json'))
     fiber = RamanFiber(**load_json(TEST_DIR / 'data' / 'test_science_utils_fiber_config.json'))
-
+    fiber.ref_pch_in_dbm = 0.0
     # propagation
     spectral_info_out = fiber(spectral_info_input)