From a65223c3c1fd0e28d7225bfae6ed68c83879d5e4 Mon Sep 17 00:00:00 2001
From: Jason Reiss <jreiss@multitech.com>
Date: Wed, 18 Nov 2020 11:54:30 -0600
Subject: Add tx power limit in global_conf.json

---
 lora_pkt_fwd/src/lora_pkt_fwd.c | 31 ++++++++++++++++++++++---------
 1 file changed, 22 insertions(+), 9 deletions(-)

diff --git a/lora_pkt_fwd/src/lora_pkt_fwd.c b/lora_pkt_fwd/src/lora_pkt_fwd.c
index e72671f..34996d4 100644
--- a/lora_pkt_fwd/src/lora_pkt_fwd.c
+++ b/lora_pkt_fwd/src/lora_pkt_fwd.c
@@ -175,9 +175,9 @@ static bool duty_cycle_enabled = false;
 static uint32_t duty_cycle_time_avail = 0;
 static uint32_t duty_cycle_period = 3600; // seconds in one hour
 static double duty_cycle_ratio = 0.10; // 10%
-static uint32_t duty_cycle_time_max = 3600 * 0.10 * 1000u; // max time-on-air in window 
-
+static uint32_t duty_cycle_time_max = 3600 * 0.10 * 1000u; // max time-on-air in window
 
+static int max_tx_power = -99;  // limit tx power sent from a network server
 
 /* statistics collection configuration variables */
 static unsigned stat_interval = DEFAULT_STAT; /* time interval (in sec) at which statistics are collected and displayed */
@@ -946,7 +946,7 @@ static int parse_gateway_configuration(const char * conf_file) {
         MSG("INFO: upstream PUSH_DATA time-out is configured to %u ms\n", (unsigned)(push_timeout_half.tv_usec / 500));
     }
 
-    
+
     /* duty-cycle limiting */
     val = json_object_get_value(conf_obj, "duty_cycle_enabled");
     if (json_value_get_type(val) == JSONBoolean) {
@@ -970,6 +970,12 @@ static int parse_gateway_configuration(const char * conf_file) {
         duty_cycle_time_max = duty_cycle_period * 1000u * duty_cycle_ratio;
     }
 
+    /* max tx power */
+    val = json_object_get_value(conf_obj, "max_tx_power");
+    if (val != NULL) {
+        max_tx_power = (int)json_value_get_number(val);
+        MSG("INFO: max tx power %d\n", (max_tx_power));
+    }
 
     /* packet filtering parameters */
     val = json_object_get_value(conf_obj, "best_packet_filter");
@@ -1580,7 +1586,7 @@ int main(int argc, char** argv)
             exit(EXIT_FAILURE);
         }
     }
-    
+
     i = pthread_create( &thrid_valid, NULL, (void * (*)(void *))thread_valid, NULL);
     if (i != 0) {
         MSG("ERROR: [main] impossible to create validation thread\n");
@@ -1731,7 +1737,7 @@ int main(int argc, char** argv)
         printf("# BEACON sent so far: %u\n", cp_nb_beacon_sent);
         printf("# BEACON rejected: %u\n", cp_nb_beacon_rejected);
         printf("### [JIT] ###\n");
-        
+
         /* get timestamp captured on PPM pulse  */
         pthread_mutex_lock(&mx_concent);
         i = lgw_get_trigcnt(&trig_tstamp);
@@ -1791,7 +1797,7 @@ int main(int argc, char** argv)
     pthread_cancel(thrid_jit); /* don't wait for jit thread */
     pthread_cancel(thrid_timersync); /* don't wait for timer sync thread */
     pthread_cancel(thrid_valid); /* don't wait for validation thread */
-        
+
     if (gps_enabled == true) {
         pthread_cancel(thrid_gps); /* don't wait for GPS thread */
 
@@ -2859,6 +2865,13 @@ void thread_down(void) {
             val = json_object_get_value(txpk_obj,"powe");
             if (val != NULL) {
                 txpkt.rf_power = (int8_t)json_value_get_number(val) - antenna_gain;
+
+                if (max_tx_power != -99) {
+                    if (txpkt.rf_power > max_tx_power - antenna_gain) {
+                        MSG("INFO: [down] tx power reduced tx power: % dBm attn gain: %d dBi\n", max_tx_power, antenna_gain);
+                        txpkt.rf_power = max_tx_power - antenna_gain;
+                    }
+                }
             }
 
             /* Parse modulation (mandatory) */
@@ -3111,7 +3124,7 @@ void thread_jit(void) {
                         pthread_mutex_unlock(&mx_meas_dw);
                         MSG("INFO: Beacon dequeued (count_us=%u)\n", pkt.count_us);
                     }
-                    
+
                     if (duty_cycle_enabled) {
                         time_on_air = (uint32_t)lgw_time_on_air(&pkt); /* in ms */
 
@@ -3348,7 +3361,7 @@ void thread_valid(void) {
 
             if (last.tv_sec != 0) {
                 // uint64(now.tv_sec) * 1000 + now.tv_nsec / 1000000
-                
+
                 duty_cycle_time_avail += difftimespec(now, last) * 1000u * duty_cycle_ratio;
 
                 if (duty_cycle_time_avail > duty_cycle_time_max) {
@@ -3358,7 +3371,7 @@ void thread_valid(void) {
 
             last = now;
         }
-        
+
         if (gps_enabled != true) {
             continue;
         }
-- 
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