added multi-sat search;

test_01.php

@@ -43,6 +43,12 @@ $ARGMAX_OURSIDE_2D = 0.0;  // Allow  argmax outside of the measured range by thi
 // Modem never allows wrong satellite to have signal strength above 29, and tries to maintain 30 for the correct one when the signal falls below.
 // So these values can not be used for peaking(maybe only remove 30 if the signal is going down?)
 $HUGHES_BAD_STRENGTHS = array(29,30);
+$HUGHES_THRESHOLD = 30;  // if less - wrong satellite
+$GUARD_AZIMUTH    = 2.0; // (degrees) do not look for satellites closer than this to alerady found
+$GUARD_STEP       = 1.0; // (degrees) If will peak on the same satellite, increase guard range on that side
+$AZ_TOL           = 0.7; // (degrees) If satellites azimuths differ by less than this - they are the same
+$MAX_ARC_TILT     = 0.2; // maximal local satellite arc tilt near a known satellite
+$SAT_AZ_STEP      = 0.5; // (degrees) mark found satellites with this resolution
 
 
 
@@ -117,7 +123,7 @@ $wnd_az = 0;
 $wnd_el = 0;
 $scan_step = 1.0;
 $min_strength = $MODEM_THRESHOLD;
-
+$full_search = 0;
 if (isset($_GET["dbg"]))          { $dbg=myval($_GET["dbg"]);}
 if (isset($_GET["multi"]))        { $multi=myval($_GET["multi"]);}
 if (isset($_GET["az"]))           { $DishAngle[0] = myfval($_GET["az"]);}
@@ -128,17 +134,59 @@ if (isset($_GET["wnd_az"]))       { $wnd_az =       myfval($_GET["wnd_az"]);}
 if (isset($_GET["wnd_el"]))       { $wnd_el =       myfval($_GET["wnd_el"]);}
 if (isset($_GET["scan_step"]))    { $scan_step =    myfval($_GET["scan_step"]);}
 if (isset($_GET["min_strength"])) { $min_strength = myfval($_GET["min_strength"]);}
+if (isset($_GET["full_search"]))  { $full_search = 1;}
 $scan_mode = ($wnd_az > 0) || ($wnd_el > 0);
+if (!$scan_mode){
+    $full_search = 0;
+}
+
+if ($full_search){
+    $rslt = lockToSatellite($min_strength, $DishAngle, $wnd_az, $wnd_el, $scan_step);
+    $xml = new SimpleXMLElement("<?xml version='1.0'?><motosat/>");
+    $State =          $xml_state->State+0; // 1 - Ready, 2 - Busy
+    $busy = ($State & 2) != 0;
+    $SignalQuality = myfval(explode(",",$xml_state->SignalQuality)[0]);
+    // print result to XML
+    
+//    $xml->addChild ('Success',(string) $Success );
+    $xml->addChild ('SignalQuality',(string) $SignalQuality );
+//    if (isset($DishAngle1D)){
+//        $xml->addChild ('DishAngle1D',$DishAngle1D );
+//   }
+//    if (isset($DishAngle2D)){
+//        $xml->addChild ('DishAngle2D',$DishAngle2D );
+//    }
+    $xml->addChild ('DishAngle',$xml_state->DishAngle );
+    $xml->addChild ('DishCount',$xml_state->DishCountt );
+    $xml->addChild ('busy',(string) $busy );
+    $xml->addChild ('State',(string) $State );
+    
+    $rslt=$xml->asXML();
+    header("Content-Type: text/xml");
+    header("Content-Length: ".strlen($rslt)."\n");
+    header("Pragma: no-cache\n");
+    // allow CORS: needed for multicam controls
+    header('Access-Control-Allow-Origin: *');
+    printf($rslt);
+    
+    
+    
+    exit (0);
+
+}
+
 
 if ($scan_mode){
     $xml_state = scan_window($min_strength, $DishAngle, $wnd_az, $wnd_el, $scan_step);
     $Success =       $xml_state->Success;
     
     if (intval ($Success)){
-        $Success = peakAzimuthOrElevation($xml_state, 0, $AZ_PLAY,$AZ_RESCAN, $AZ_RESCAN_STEP, $USABLE_FRACT, $USABLE_POW, $ARGMAX_OURSIDE);
+        $rslt = peakAzimuthOrElevation($xml_state, 0, $AZ_PLAY,$AZ_RESCAN, $AZ_RESCAN_STEP, $USABLE_FRACT, $USABLE_POW, $ARGMAX_OURSIDE);
+        $Success = ($rslt === 1)? 1 : 0;
         $xml_state = simplexml_load_file($motosat_url);
         if (intval ($Success)){
-            $Success = peakAzimuthOrElevation($xml_state, 1, $EL_PLAY,$EL_RESCAN, $EL_RESCAN_STEP, $USABLE_FRACT, $USABLE_POW, $ARGMAX_OURSIDE);
+            $rslt = peakAzimuthOrElevation($xml_state, 1, $EL_PLAY,$EL_RESCAN, $EL_RESCAN_STEP, $USABLE_FRACT, $USABLE_POW, $ARGMAX_OURSIDE);
+            $Success = ($rslt === 1)? 1 : 0;
             $xml_state = simplexml_load_file($motosat_url);
             $DishAngle1D = $xml_state->DishAngle;
             if (intval ($Success) && $ADJUST_2D){
@@ -193,6 +241,228 @@ header('Access-Control-Allow-Origin: *');
 printf($rslt);
 exit (0);
 
+function lockToSatellite($min_strength, $DishAngle, $wnd_az, $wnd_el, $scan_step)
+{
+    global $motosat_url, $dbg_file, $SAT_AZ_STEP, $GUARD_AZIMUTH, $GUARD_STEP, $AZ_TOL, $MAX_ARC_TILT;
+    global $AZ_PLAY, $AZ_RESCAN, $AZ_RESCAN_STEP, $USABLE_FRACT, $USABLE_POW, $ARGMAX_OURSIDE;
+    global $EL_PLAY,$EL_RESCAN, $EL_RESCAN_STEP, $HUGHES_THRESHOLD, $ADJUST_2D;
+    global $AZ_2D_RANGE, $EL_2D_RANGE, $AZ_2D_STEP, $EL_2D_STEP, $ARGMAX_OURSIDE_2D;
+    $xml_state = simplexml_load_file($motosat_url);
+    $DishAngleCenter =  getDishAngles ($xml_state); // will go there if failed
+    $DishAngleCenter[0] = $DishAngle[0];
+    $DishAngleCenter[1] = $DishAngle[1]; 
+    $empty_az = array(); // array of pairs: ('low'=>min, "high"=>max) for scanned empoty azimuths in degrees
+    $satellites =array();// array of ('az'=>az, "el"=> el, 'strength'-> strength, 'guard_low', 'guard_high') in degrees for each foubnd satellite
+    $num_az_steps =  (int) ceil ($wnd_az/$SAT_AZ_STEP);
+    $az_min = $DishAngle[0] - $wnd_az/2;
+//    $az_max = $az_min + ($num_az_steps)* $SAT_AZ_STEP;
+    while (true) { // loop until found correct satellite, or failed
+        $az_array = array_fill(0, $num_az_steps + 1, 0);
+        // mark already scanned emty ranges
+        foreach ($empty_az as $range){
+            $i_min = (int) ceil (($range['low'] - $az_min)/$SAT_AZ_STEP);
+            $i_max = (int) floor(($range['high'] - $az_min)/$SAT_AZ_STEP);
+            if ($i_min < 0) $i_min = 0;
+            if ($i_max > $num_az_steps) $i_max = $num_az_steps;
+            for ($i = $i_min; $i <= $i_max; $i++){
+                $az_array[$i] = -1;
+            }
+            
+        }
+        // Exclude each satellite with its guard range
+        foreach ($satellites as $indx => $azels){
+            $i_min = (int) round (($azels['az'] - $azels['guard_low'])/$SAT_AZ_STEP);
+            $i_max = (int) round (($azels['az'] + $azels['guard_high'])/$SAT_AZ_STEP);
+            if ($i_min < 0) $i_min = 0;
+            if ($i_max > $num_az_steps) $i_max = $num_az_steps;
+            for ($i = $i_min; $i <= $i_max; $i++){
+                $az_array[$i] = $indx +1; // number of satellite, starting from 1
+            }
+        }
+        // Find azimuth range to scan
+        for ($i_low = 0; ($i_low <= $num_az_steps) && ($az_array[$i_low] == 0); $i_low++ );
+        if ($i_low > $num_az_steps) { // all searched, no luck
+            // Here is te exit from thye loop !
+            return array ('satellite' => null, 'satellites' => $satellites, 'empty' => $empty_az);
+        }
+        for ($i_high = $i_low; ($i_high < $num_az_steps) && ($az_array[$i_high+1] == 0); $i_high++);
+        
+        // setup new scan range
+        $az_low =  $az_min + $i_low  * $SAT_AZ_STEP;
+        $az_high = $az_min + $i_high * $SAT_AZ_STEP;
+        $low_end_sat  =  ($i_low > 0)?              $az_array[$i_low - 1] : -1;
+        $high_end_sat  = ($i_high < $num_az_steps)? $az_array[$i_high + 1] : -1;
+        $az_range = $az_high - $az_low;
+        $az_center = ($az_high + $az_low) / 2;
+        if ($low_end_sat < 0){
+            if ($high_end_sat < 0) { // both ends unknown
+                $el_center = $DishAngleCenter[1];
+                $el_range  = $wnd_el;
+            } else { // satellite on the right only 
+                $el_center = $satellites[$high_end_sat -1]['el'];
+                $el_range  = $MAX_ARC_TILT * $az_range;
+            }
+        } else {
+            if ($high_end_sat < 0) {// satellite on the left only 
+                $el_center = $satellites[$low_end_sat -1]['el'];
+                $el_range =  $MAX_ARC_TILT * $az_range;
+            } else { // both ends have satellites
+                $el_center = ($satellites[$high_end_sat -1]['el'] + $satellites[$low_end_sat -1]['el']) / 2 ;
+                $el_range =  abs($satellites[$high_end_sat -1]['el'] - $satellites[$low_end_sat -1]['el']);
+            }
+        }
+//        $xml_state = simplexml_load_file($motosat_url);
+//        $DishAnglesNow =  getDishAngles ($xml_state); // will go there if failed
+//        $dir = ($DishAnglesNow[0] < $az_center) ? 1 : 0;
+        
+        // Do scanning of the range
+        if ($dbg_file !== null) {
+            fprintf($dbg_file, "==== Scanning sky window : center (az:%f7.3 el:%f7.3) az_range=%f7.3, el_range = %f7.3 ====\n",
+               $az_center, $el_center, $az_range, $el_range);
+        }
+        
+        $xml_state = simplexml_load_file($motosat_url);
+        $DishAnglesScan =  getDishAngles ($xml_state); // will go there if failed
+        $DishAnglesScan[0] = $az_center;
+        $DishAnglesScan[1] = $el_center;
+        $xml_state = scan_window($min_strength, $DishAnglesScan, $az_range, $el_range, $scan_step);
+        $success =   intval ($xml_state->Success);
+        if (!$success) {
+            //    $empty_az = array(); // array of pairs: ('low'=>min, "high"=>max) for scanned empoty azimuths in degrees
+            $empty_az[] = array('low'=> $az_low, 'high' => $az_high);
+            if ($dbg_file !== null) {
+                fprintf($dbg_file, ">>>>> Failed to find any satellites in the window : center (az:%f7.3 el:%f7.3) az_range=%f7.3, el_range = %f7.3 >>>>>\n",
+                    $az_center, $el_center, $az_range, $el_range);
+            }
+            continue; // to next azimuth range
+        }
+        // Did found some satellite - peak azimuth
+        // peakAzimuthOrElevation - limit range to scan range, do not allow max to be outside of the scan range!
+        $minmax = array($az_low, $az_high);
+        $rslt_az = peakAzimuthOrElevation($xml_state, 0, $AZ_PLAY, $AZ_RESCAN, $AZ_RESCAN_STEP, $USABLE_FRACT, $USABLE_POW, $ARGMAX_OURSIDE, $minmax);
+        $success_az = ($rslt_az ===1) ? 1 : 0;
+        
+        $xml_state = simplexml_load_file($motosat_url);
+        $DishAnglesPeakAz =  getDishAngles ($xml_state); // after peaking azimuth
+        $az_sat = $DishAnglesPeakAz[0];
+        if (!$success_az){ // what could be wrong here? tried to peak on existing satellite but was prohibited to go outside of the range?
+            if ($dbg_file !== null) {
+                fprintf($dbg_file, "**** Failed peaking azimuth - assuming that the peak was outside of the scan range, belonging to other satellite\n");
+                fprintf($dbg_file, "Peaking error: %s\n", $rslt_az);
+//                fprintf($dbg_file, "For now will only try to recover if the end of scan range was a satellite found before\n");
+            }
+            if (($low_end_sat > 0) && (($rslt_az == 'first element') || ($rslt_az == 'too low'))){
+                $sat = $satellites[$low_end_sat - 1];
+                if (($az_sat - $sat['az']) < $AZ_TOL + $AZ_RESCAN_STEP){ // accepting larger tolerance
+                    $satellites[$indx]['guard_high'] += $GUARD_STEP; // search range was on the right, increasing high guard range for the satellite
+                    if ($dbg_file !== null) {
+                        fprintf($dbg_file, "**** Increasing high guard range of the satellite :\n".print_r($satellites[$indx]));
+                    }
+                    continue;
+                }
+            }
+
+            if ((high_end_sat > 0) && (($rslt_az == 'last element') || ($rslt_az == 'too high'))){
+                $sat = $satellites[$high_end_sat - 1];
+                if (($sat['az'] - $az_sat) < $AZ_TOL + $AZ_RESCAN_STEP){ // accepting larger tolerance
+                    $satellites[$indx]['guard_low'] += $GUARD_STEP; // search range was on the left, increasing low guard range for the satellite
+                    if ($dbg_file !== null) {
+                        fprintf($dbg_file, "**** Increasing low guard range of the satellite :\n".print_r($satellites[$indx]));
+                    }
+                    continue;
+                }
+            }
+            // other errors - for now discarding that range completely
+            if ($dbg_file !== null) {
+                fprintf($dbg_file, "**** Other azimuth peaking errors(%s), discarding last search range %f7.3 < %f7.3\n",
+                    $rslt_az, $az_low, $az_high);
+            }
+            $empty_az[] = array($az_low, $az_high);
+            continue;
+        }
+        
+        // compare azimuth to already known satellites
+        foreach ($satellites as $indx => $sat){
+            if (abs($az_sat - $sat['az']) < $AZ_TOL){ // it is the same satellite as already found
+                if ($az_center < $sat['az']) {
+                    $satellites[$indx]['guard_low'] += $GUARD_STEP; // search range was on the left, increasing low guard range for the satellite
+                    if ($dbg_file !== null) {
+                        fprintf($dbg_file, "**** Increasing low guard range of the satellite:\n".print_r($satellites[$indx]));
+                    }
+                    
+                } else {
+                    $satellites[$indx]['guard_high'] += $GUARD_STEP;// search range was on the right, increasing high guard range for the satellite
+                    if ($dbg_file !== null) {
+                        fprintf($dbg_file, "**** Increasing high guard range of the satellite:\n".print_r($satellites[$indx]));
+                    }
+                }
+                continue; // recalculate azimuth range, try again
+            }
+        }
+        // got new satellite, peak elevation
+        $rslt_el = peakAzimuthOrElevation($xml_state, 1, $EL_PLAY,$EL_RESCAN, $EL_RESCAN_STEP, $USABLE_FRACT, $USABLE_POW, $ARGMAX_OURSIDE);
+        $Success_el = ($rslt_el === 1)? 1 : 0;
+        if ($dbg_file !== null) {
+            fprintf($dbg_file, "**** Peak elevation success = %d\n",$Success_el);
+            if (!$Success_el){
+                fprintf($dbg_file, "**** Peak elevation error: %s\n",$rslt_el);
+            }
+        }
+        $modem_strength = getModemStrength();
+        $xml_state = simplexml_load_file($motosat_url);
+        $DishAngleSat = $xml_state->DishAngle;
+        $satellite = array(
+            'az' => $DishAngleSat[0],
+            "el" => $DishAngleSat[1],
+            'strength' => $modem_strength,
+            'guard_low' => $GUARD_AZIMUTH,
+            'guard_high' => $GUARD_AZIMUTH
+        );
+        if ($dbg_file !== null) {
+            fprintf($dbg_file, "**** Got a satellite\n".print_r($satellite, 1));
+        }
+        // See if it is Hughes modem
+        if ($modem_strength < $HUGHES_THRESHOLD){
+            if ($dbg_file !== null) {
+                fprintf($dbg_file, "**** Satellite modem strength is too low (%f < %f) not a target satellite, continuing search\n",$modem_strength, $HUGHES_THRESHOLD);
+            }
+            $satellites[] = $satellite;
+            continue;
+        }
+        if ($dbg_file !== null) {
+            fprintf($dbg_file, "**** Found target satellite, modem strength is %f >= %f\n",$modem_strength, $HUGHES_THRESHOLD);
+        }
+        
+        if ($ADJUST_2D){
+            if ($dbg_file !== null) {
+                fprintf($dbg_file, "**** 2D peaking requested, performing it\n");
+            }
+            $rslt_2d = peak2D($xml_state, $AZ_PLAY, $EL_PLAY, $AZ_2D_RANGE, $EL_2D_RANGE, $AZ_2D_STEP, $EL_2D_STEP, $USABLE_FRACT, $USABLE_POW, $ARGMAX_OURSIDE_2D);
+            $Success_2d = $rslt_2d;
+            $xml_state = simplexml_load_file($motosat_url);
+            
+            if ($dbg_file !== null) {
+                fprintf($dbg_file, "**** 2D peaking returned: ".$rslt_2d."\n");
+            }
+            
+            if ($Success_2d){
+                $modem_strength = getModemStrength();
+                $xml_state = simplexml_load_file($motosat_url);
+                $DishAngleSat = $xml_state->DishAngle;
+                $satellite = array(
+                    'az' => $DishAngleSat[0],
+                    "el" => $DishAngleSat[1],
+                    'strength' => $modem_strength,
+                    'guard_low' => $GUARD_AZIMUTH,
+                    'guard_high' => $GUARD_AZIMUTH
+                );
+            }
+            $satellites[] = $satellite;
+            return array ('satellite' => $satellite, 'satellites' => $satellites, 'empty' => $empty_az);
+        }
+    }
+}
+
 function peak2D($xml_state, $az_play, $el_play, $az_range, $el_range, $az_step, $el_step, $fract, $pow = 1.0, $argmax_outside=0.0){
     global $motosat_url, $dbg_file;
     if ($xml_state === null){
@@ -268,36 +538,66 @@ function peak2D($xml_state, $az_play, $el_play, $az_range, $el_range, $az_step,
 }
 
 
-
-function peakAzimuthOrElevation($xml_state, $el_not_az, $azel_play, $azel_range, $azel_step, $fract, $pow = 1.0, $argmax_outside=0.2){
+// return ===1 if OK, else error text string from findMax1D
+function peakAzimuthOrElevation($xml_state, $el_not_az, $azel_play, $azel_range, $azel_step, $fract, $pow = 1.0, $argmax_outside = 0.2, $minmax=null)
+{
     global $motosat_url, $dbg_file;
-    if ($xml_state === null){
+    if ($xml_state === null) {
         $xml_state = simplexml_load_file($motosat_url);
     }
-    $DishAngle =  getDishAngles ($xml_state);
-    $motor =     $el_not_az ? 1: 0; 
+    $DishAngle = getDishAngles($xml_state);
+    $motor = $el_not_az ? 1 : 0;
     $direction = $el_not_az ? "ELEVATION" : "AZIMUTH";
 
     $azel_start_center = $DishAngle[$motor];
-    //move to sart rescan azimuth minus mechanical play
-    $DishAngle[$motor] = $azel_start_center - $azel_play - $azel_range/2;
+    // move to sart rescan azimuth minus mechanical play
+    $DishAngle[$motor] = $azel_start_center - $azel_play - $azel_range / 2;
     moveElAzSk_degrees($DishAngle);
     $scan_strengths = Array();
-    for ($azel = $azel_start_center - $azel_range/2;
-         $azel < ($azel_start_center + $azel_range/2 + $azel_step);
-         $azel += $azel_step){
+    $azel_min = $azel_start_center - $azel_range / 2;
+    $azel_max = $azel_start_center + $azel_range / 2 + $azel_step;
+    if ($minmax !== null) {
+        if ($azel_min < $minmax[0]){
+            $azel_min = $minmax[0];
+        }
+        if ($azel_max < $minmax[1]){
+            $azel_max = $minmax[1];
+        }
+    }
+    if (($azel_max - $azel_min) < $azel_step){
+        if ($dbg_file !== null) {
+            fprintf($dbg_file, "==== $direction scan range to small min = %f, max = %f: ====\n", $azel_min, $azel_max);
+        }
+        return 'small range';
+    }
+    if (($azel_max - $azel_min) < 2.01 * $azel_step){
+        $azel_step = ($azel_max - $azel_min) / 2.01; // at least 3 samples
+        if ($dbg_file !== null) {
+            fprintf($dbg_file, "==== $direction scan range to small min = %f, max = %f new step = %f: ====\n", $azel_min, $azel_step);
+        }
+    }
+        
+    
+    for ($azel = $azel_min; $azel < $azel_max; $azel += $azel_step) {
         $DishAngle[$motor] = $azel;
         moveElAzSk_degrees($DishAngle); // to be on the safe side re-read xml
-             $modem_strength= getModemStrength();
+        $modem_strength = getModemStrength();
         $scan_strengths[] = $modem_strength;
     }
     if ($dbg_file !== null) {
         fprintf($dbg_file, "==== $direction scan strengths: ====\n");
         fprintf($dbg_file, print_r($scan_strengths, 1));
     }
-     $rel_argmax = findMax1d($scan_strengths, $fract, $pow, $argmax_outside);
-    if ($rel_argmax !== null) {
-        $azel_argmax = $azel_start_center - $azel_range / 2 + $azel_step * $rel_argmax;
+    // $rel_argmax = findMax1d($scan_strengths, $fract, $pow, $argmax_outside);
+    $rslt = findMax1d($scan_strengths, $fract, $pow, $argmax_outside);
+    $rel_argmax = $rslt['argmax'];
+    if (isset($rslt['err'])){
+        if ($dbg_file !== null) {
+            fprintf($dbg_file, "****** Failed to find maximum for $direction, going to known position.\n");
+        }
+    }
+
+    $azel_argmax = $azel_min + $azel_step * $rel_argmax;
     if ($dbg_file !== null) {
         fprintf($dbg_file, "reltive argmax = %f\n", $rel_argmax);
         fprintf($dbg_file, "$direction argmax = %f (was %f)\n", $azel_argmax, $azel_start_center);
@@ -313,16 +613,10 @@ function peakAzimuthOrElevation($xml_state, $el_not_az, $azel_play, $azel_range,
         fprintf($dbg_file, "====== Moving $direction to argmax position = %f\n", $DishAngle[$motor]);
     }
     moveElAzSk_degrees($DishAngle);
-        return 1; // success
-    } else {
-        // for now - move back
-        if ($dbg_file !== null) {
-            fprintf($dbg_file, "****** Failed to find maximum for $direction, going to known position.\n");
-        }
-        $DishAngle[$motor] = $azel_start_center;
-        moveElAzSk_degrees($DishAngle);
-        return 0; // failed
+    if (isset($rslt['err'])){
+        return $rslt['err'];
     }
+    return 1; // success
 }
 
 function findMax2d($data, $fract, $pow, $frac_outside = 0.2){ // $pow not yet used
@@ -512,7 +806,17 @@ function findMax1d($data, $fract, $pow, $frac_outside = 0.2){
             $argmax = $k;
         } else if ($v < $min) $min = $v;
     }
-    $threshold = $min + ($max-$min)*$fract;
+    
+    if ($argmax == 0){
+        return array('argmax'=>$argmax,'err'=>'first element');
+    }
+
+    if ($argmax >= (sizeof($data) -1)){
+        return array('argmax'=>$argmax,'err'=>'last element');
+    }
+    
+    
+    $threshold = $min + ($max-$min) * $fract;
     $k_min = $argmax;
     while (($k_min > 0) && ($data[$k_min - 1] >= $threshold)){
         $k_min--;
@@ -569,7 +873,7 @@ function findMax1d($data, $fract, $pow, $frac_outside = 0.2){
         if ($dbg_file) {
             fprintf($dbg_file, "Could not find maximum (NaN): coeff = \n".print_r($rslt,1)."\n");
         }
-        return null; // no maximum
+        return array('argmax'=>$argmax,'err'=>'NaN coefficients');
     }
     
     
@@ -577,7 +881,7 @@ function findMax1d($data, $fract, $pow, $frac_outside = 0.2){
         if ($dbg_file) {
             fprintf($dbg_file, "Could not find maximum coeff = \n".print_r($rslt,1)."\n");
         }
-        return null; // no maximum
+        return array('argmax'=>$argmax,'err'=>'a2 >= 0');
     }
     $rel_argmax = $argmax - $rslt[1] / (2 * $rslt[2]);
     if ($rel_argmax < -($frac_outside * sizeof($data))){
@@ -585,15 +889,15 @@ function findMax1d($data, $fract, $pow, $frac_outside = 0.2){
             fprintf($dbg_file, "argmax is too low = %f, range=%d\n",$rel_argmax,sizeof($data) );
         }
         
-        return null; // too low
+        return array('argmax'=>$rel_argmax,'err'=>'too low');
     }
     if ($rel_argmax > ((1.0 + $frac_outside) * sizeof($data))){
         if ($dbg_file) {
             fprintf($dbg_file, "argmax is too high = %f, range=%d\n",$rel_argmax,sizeof($data) );
         }
-        return null; // too low
+        return array('argmax'=>$rel_argmax,'err'=>'too high');
     }
-    return $rel_argmax; // $rslt;
+    return array('argmax'=>$rel_argmax,'err'=>null); // $rslt;
 }
 
 /**
@@ -607,12 +911,19 @@ function findMax1d($data, $fract, $pow, $frac_outside = 0.2){
  * @param  $wnd_az - full range of azimuth scan in degrees
  * @param  $wnd_el - full range of elevation scan in degrees
  * @param  $scan_step - elevation scan step
+ * @param  $dir - 0: start scanning from right to left, 1 : first scan from left to right,
+ *                    null - determine direction automatically from the current azimuth 
  * @return SimpleXMLElement - 
  */
-function scan_window($threshold, $DishAngleCenter, $wnd_az, $wnd_el, $scan_step){
+function scan_window($threshold, $DishAngleCenter, $wnd_az, $wnd_el, $scan_step, $dir = null){
     global $motosat_url,$LATE_STOP_AZ,$dbg_file;
+    if ($dir === null) {
+        $xml_state = simplexml_load_file($motosat_url);
+        $DishAnglesNow = getDishAngles($xml_state); // will go there if failed
+        $dir = ($DishAnglesNow[0] < $DishAngleCenter[0]) ? 1 : 0;
+    }
+    
     $DishAngle = Array($DishAngleCenter[0],$DishAngleCenter[1],$DishAngleCenter[2]);
-    $dir = 0;
     for ($delta_el = 0.0; $delta_el < $wnd_el/2; $delta_el += $scan_step) {
         $passes = ($delta_el > 0.0)? 2 : 1;
         for ($pass = 0; $pass < $passes; $pass++) {
@@ -681,7 +992,7 @@ function scan_window($threshold, $DishAngleCenter, $wnd_az, $wnd_el, $scan_step)
                  return $xml_state;
              }
         }
-        $dir = 1-$dir;
+        $dir = 1 - $dir;
     }
     moveElAzSk_degrees($DishAngleCenter);