diff --git a/usrp/sps/range b/usrp/sps/range
new file mode 100755
index 0000000..dce7b1d
--- /dev/null
+++ b/usrp/sps/range
@@ -0,0 +1,53 @@
+#!/usr/bin/perl
+
+sub read
+{
+	local ($n) = "$_[0].fft";
+	local (@f);
+	local $i = 0;
+	local $ym, $v;
+
+	open(FILE, $n) || die "$n: $!";
+	while (<FILE>) {
+		chop;
+		push(@f, $_);
+		$ym = $_ unless defined $ym && $ym > $_;
+	}
+	close FILE;
+	for (@f) {
+		$v = $_-$ym;
+		$min[$i] = $v unless defined $min[$i] && $min[$i] < $v;
+		$max[$i] = $v unless defined $max[$i] && $max[$i] > $v;
+		$sum[$i] += $v;
+		$i++;
+	}
+}
+
+
+sub usage
+{
+	print STDERR "usage: $0\n";
+	exit(1);
+}
+
+
+&usage if @ARGV;
+
+#
+# @@@ for future study: use an x axis proportional to the center frequency,
+# instead of an absolute frequency.
+#
+
+for ($f = 2405; $f <= 2480; $f += 5) {
+	&read($f);
+	&read($f+1);
+	$n += 2;
+}
+
+$mhz_per_bin = 100.0/16/@sum;	# 100 MHz ADC, decimation 16
+
+$, = " ";
+for ($i = 0; $i != @sum; $i++) {
+	print $mhz_per_bin*($i-@sum/2)+0.5, "";
+	print $min[$i], $sum[$i]/$n, $max[$i], "\n";
+}
diff --git a/usrp/sps/row b/usrp/sps/row
index bdead06..f16517c 100755
--- a/usrp/sps/row
+++ b/usrp/sps/row
@@ -23,35 +23,55 @@ for prefix in "$@"; do
 		color=' bgcolor="#a0e0ff"'
 	fi
 	last=$prefix
-	
-	echo "<TR$color><TH>$prefix"
+
+	echo "<TR$color><TH>$prefix<TD align=\"center\">Offset"
 	f=2405
 	while [ $f -le 2480 ]; do
-		echo "<TD align="center">$f MHz"
+		echo "<TD align=\"center\">$f MHz"
 		f=`expr $f + 5`
 	done
 
-	echo "<TR><TD align="right">-0.5 MHz"
+	echo "<TR>"
+	echo "<TD><A href=\"$prefix.png\"><IMG src=\"$prefix-small.png\"></A>"
+	echo "<TD align="right">-0.5 MHz"
+
 	f=2405
 	while [ $f -le 2480 ]; do
-		./viz -f LiberationSans-Bold -p $prefix-$f.png $prefix $f
+		./viz -f LiberationSans-Bold -p $prefix-$f.png \
+		  -o $f.fft $prefix $f
 		convert -resize '15%' $prefix-$f.png $prefix-$f-small.png
 		echo "<TD><A href=\"$prefix-$f.png\"><IMG src=\"$prefix-$f-small.png\"></A>"
 		f=`expr $f + 5`
 	done
 
-	echo "<TR><TD align="right">+0.5 MHz"
+	echo "<TR>"
+	echo "<TD>"
+	echo "<TD align="right">+0.5 MHz"
+
 	f=2405
 	while [ $f -le 2480 ]; do
 		f1=`expr $f + 1`
-		./viz -f LiberationSans-Bold -p $prefix-$f1.png $prefix $f1
+		./viz -f LiberationSans-Bold -p $prefix-$f1.png \
+		  -o $f1.fft $prefix $f1
 		convert -resize '15%' $prefix-$f1.png $prefix-$f1-small.png
 		echo "<TD><A href=\"$prefix-$f1.png\"><IMG src=\"$prefix-$f1-small.png\"></A>"
 		f=`expr $f + 5`
 	done
 
-done
+	ffts=`
+	    f=2405
+	    while [ $f -le 2480 ]; do
+		echo $f.fft
+		echo \`expr $f + 1\`.fft
+		f=\`expr $f + 5\`
+	    done`
 
+	./range >_tmp
+	./vizr -f LiberationSans-Bold -p $prefix.png $prefix _tmp
+	rm -f $ffts _tmp
+
+	convert -resize '15%' $prefix.png $prefix-small.png
+done
 cat <<EOF
 </TABLE>
 EOF
diff --git a/usrp/sps/vizr b/usrp/sps/vizr
new file mode 100755
index 0000000..afe696f
--- /dev/null
+++ b/usrp/sps/vizr
@@ -0,0 +1,54 @@
+#!/bin/sh
+
+usage()
+{
+	echo "usage: $0 [-f font] [-p png_file] prefix range_file" 1>&2
+	exit 1
+}
+
+
+font=
+term=
+output=
+
+while true; do
+	case "$1" in
+	-f)	[ "$2" ] || usage
+		shift
+		font=$1;;
+	-p)	[ "$2" ] || usage
+		shift
+		term="set term png"
+		output="set output \"$1\"";;
+	-*)	usage;;
+	*)
+		break;;
+	esac
+	shift
+done
+
+[ "$2" ] || usage
+[ "$3" ] && usage
+
+prefix=$3
+file=$2
+
+gnuplot -persist <<EOF
+$term
+$output
+
+set label "$prefix" at graph 0.03, graph 0.93 font "$font,22"
+
+set xrange [-2.5:2.5]
+set yrange [-70:0]
+
+set mxtics 10
+set mytics 2
+set grid
+
+set xlabel "MHz from nominal frequency of test wave"
+
+plot "$file" using 1:4 with lines title "max" lt 2, \
+  "$file" using 1:3 with lines title "avg" lt 3, \
+  "$file" using 1:2 with lines title "min" lt 1
+EOF