diff --git a/lib/ldpc/jtmode_codes/160-80-sf4.results b/lib/ldpc/jtmode_codes/160-80-sf4.results
index d63e6bb2b..97e214613 100644
--- a/lib/ldpc/jtmode_codes/160-80-sf4.results
+++ b/lib/ldpc/jtmode_codes/160-80-sf4.results
@@ -1,4 +1,4 @@
-sf4 160,80 ldpc, Eb/N0_dB, ngood, nundet, 10^6 trials
+sf4 160,80 ldpc 2x3/8x4 seed=3, Eb/N0_dB, ngood, nundet, 10^6 trials
 columns 2,3 decoder uses variable sigma, columns 4,5 decoder uses fixed sigma=0.9 
 -0.5 2906 0  10862 5
 0.0 18899 1  34663 6
diff --git a/lib/ldpc/jtmode_codes/compare.lab b/lib/ldpc/jtmode_codes/compare.lab
index cfab60b59..a90fc637e 100644
--- a/lib/ldpc/jtmode_codes/compare.lab
+++ b/lib/ldpc/jtmode_codes/compare.lab
@@ -1,2 +1,4 @@
-5.1 0.005   "(198,72) JTMSK" 
-3.1 0.0003  "(160,80) LDPC"
+3.9 0.15   "(198,72) JTMSK" 
+2.7 0.003  "(174,87) LDPC"
+5.6 0.00003  "(160,80) LDPC"
+5.6 0.00008   "(140,80) LDPC"
diff --git a/lib/ldpc/jtmode_codes/fig_compare.gnuplot b/lib/ldpc/jtmode_codes/fig_compare.gnuplot
index 73bec798a..8ef39c12e 100644
--- a/lib/ldpc/jtmode_codes/fig_compare.gnuplot
+++ b/lib/ldpc/jtmode_codes/fig_compare.gnuplot
@@ -15,11 +15,13 @@ set logscale y
 plot [-1:6] [1e-6:1] \
    "160-80-sf4.results" using 1:(1000000-$2)/1000000 with linespoints lt 2 lw 2 pt 2, \
    "160-80-sf4.results" using 1:($3/1000000) with linespoints lt 2 lw 2 pt 2, \
-   "160-80-sf4.results" using 1:(1000000-$4)/1000000 with linespoints lt 3 lw 2 pt 4, \
-   "160-80-sf4.results" using 1:($5/1000000) with linespoints lt 2 lw 3 pt 4, \
-   "ldpc-144-72-sf2.results" using 1:(1000000-$2)/1000000 with linespoints lt 3 lw 2 pt 5, \
-   "ldpc-144-72-sf2.results" using 1:($3/1000000) with linespoints lt 3 lw 2 pt 5, \
-   "jtmskcode.results" using 1:(1000000-$4)/1000000 with linespoints lt 1 lw 2 pt 7, \
+   "jtmskcode.results" using 1:(100000-$2)/100000 with linespoints lt 1 lw 2 pt 7, \
    "jtmskcode.results" using 1:($5/1000000) with linespoints lt 1 lw 2 pt 7, \
+   "140-80-sf5.results" using 1:(100000-$2)/100000 with linespoints lt 4 lw 2 pt 4, \
+   "140-80-sf5.results" using 1:($3/100000) with linespoints lt 4 lw 2 pt 4, \
+   "174-87-sf6.results" using 1:(1000000-$2)/1000000 with linespoints lt 5 lw 2 pt 5, \
+   "174-87-sf6.results" using 1:($3/1000000) with linespoints lt 5 lw 2 pt 5, \
    "compare.lab" with labels
 exit
+#   "160-80-sf4.results" using 1:(1000000-$4)/1000000 with linespoints lt 3 lw 2 pt 4, \
+#   "160-80-sf4.results" using 1:($5/1000000) with linespoints lt 2 lw 3 pt 4, \
diff --git a/lib/ldpc/jtmode_codes/jtmskcode.results b/lib/ldpc/jtmode_codes/jtmskcode.results
index 96bdbfbea..740f533b7 100644
--- a/lib/ldpc/jtmode_codes/jtmskcode.results
+++ b/lib/ldpc/jtmode_codes/jtmskcode.results
@@ -1,5 +1,5 @@
 rate 1/2 constraint len 13, bpsk, ngood, nbad 10^5 trials, 10^6 trials
--0.50  1470  4  
+-0.50  1470  4 
  0.00  4403  2 43968 30
  0.50 11167  2 111824 33
  1.00 24082  1 238157 21
@@ -7,7 +7,7 @@ rate 1/2 constraint len 13, bpsk, ngood, nbad 10^5 trials, 10^6 trials
  2.00 63417  0 634824 14
  2.50 81290  1 812206 2
  3.00 92388  0 924507 2
- 3.50 97560  0
- 4.00 99390  0
- 4.50 99864  0
- 5.00 99977  0
+ 3.50 97560  0 975836 0
+ 4.00 99390  0 993832 0
+ 4.50 99864  0 998695 0
+ 5.00 99977  0 999771 0
diff --git a/lib/ldpc/jtmode_codes/ldpc-160-80 b/lib/ldpc/jtmode_codes/ldpc-160-80
deleted file mode 100755
index a869650cf..000000000
--- a/lib/ldpc/jtmode_codes/ldpc-160-80
+++ /dev/null
@@ -1,32 +0,0 @@
-#!/bin/sh
-# this script characterizes a single code over a narrow range of Eb/No
-# note relationship between noise standard deviation, sigma, and Eb/No:
-# Eb/No = 1/(2*R*sigma^2)
-# If R=1/2, then Eb/No = 1/sigma^2  Right? Check this. 
-
-set -e  # Stop if an error occurs
-set -v  # Echo commands as they are read
-
-#make-ldpc ldpc-160-80.pchk 80 160 3 evenboth 2x3/8x4 no4cycle
-
-cp ldpc-160-80-2x3-8x4-sf4.pchk ldpc-160-80.pchk
-make-gen  ldpc-160-80.pchk ldpc-160-80.gen dense
-rand-src  ldpc-160-80.src 1 80x1000000
-encode    ldpc-160-80.pchk ldpc-160-80.gen ldpc-160-80.src \
-          ldpc-160-80.enc
-
-rate=0.5
-for i in `seq -1 10`;
-do
-  db=$(echo "scale=5; $i/2.0" | bc)
-  ebno=$(echo "scale=5; e(0.1*$db*l(10.0))" | bc -l)
-  sigma=$(echo "scale=5; 1/sqrt(2*$rate*$ebno)" | bc)
-  echo db $db ebno $ebno sigma $sigma
-
-  transmit ldpc-160-80.enc ldpc-160-80.rec 1 awgn $sigma
-  decode   ldpc-160-80.pchk ldpc-160-80.rec ldpc-160-80.dec awgn 0.9\
-         prprp 250
-  verify   ldpc-160-80.pchk ldpc-160-80.dec ldpc-160-80.gen \
-         ldpc-160-80.src 
-
-done
diff --git a/lib/ldpc/jtmode_codes/ldpc-174-87-sf6.pchk b/lib/ldpc/jtmode_codes/ldpc-174-87-sf6.pchk
new file mode 100644
index 000000000..f6bd06deb
Binary files /dev/null and b/lib/ldpc/jtmode_codes/ldpc-174-87-sf6.pchk differ
diff --git a/lib/ldpc/jtmode_codes/ldpc-search b/lib/ldpc/jtmode_codes/ldpc-search
new file mode 100755
index 000000000..bdbd7caf7
--- /dev/null
+++ b/lib/ldpc/jtmode_codes/ldpc-search
@@ -0,0 +1,22 @@
+#!/bin/sh
+# search for a good code
+n=160
+k=72
+m=$((n-k))
+
+set -e  # Stop if an error occurs
+
+rand-src  ldpc.src 2 "$k"x1000000
+
+for i in `seq 1 1000`
+do
+  seed=$i
+  echo seed $seed
+  make-ldpc ldpc.pchk $m $n $seed evenboth 2x3/8x4 no4cycle
+  make-gen  ldpc.pchk ldpc.gen dense
+  encode    ldpc.pchk ldpc.gen ldpc.src ldpc.enc
+  transmit ldpc.enc ldpc.rec 1 awgn 0.8
+  decode   ldpc.pchk ldpc.rec ldpc.dec awgn 0.80 prprp 250
+  verify   ldpc.pchk ldpc.dec ldpc.gen ldpc.src
+done
+
diff --git a/lib/ldpc/jtmode_codes/ldpc-waterfall b/lib/ldpc/jtmode_codes/ldpc-waterfall
new file mode 100755
index 000000000..75388d8be
--- /dev/null
+++ b/lib/ldpc/jtmode_codes/ldpc-waterfall
@@ -0,0 +1,38 @@
+#!/bin/sh
+# this script characterizes a single code over a range of Eb/N0
+# note relationship between noise standard deviation, sigma, and Eb/No:
+# Eb/No = 1/(2*R*sigma^2)
+# If R=1/2, then Eb/No = 1/sigma^2 
+
+set -e  # Stop if an error occurs
+#set -v  # Echo commands as they are read
+
+n=174
+k=87
+m=$((n-k))
+seed=4
+ntrials=1000000
+
+rate=$(echo "scale=5; $k/$n" | bc)
+echo n=$n k=$k rate=$rate m=$m
+
+make-ldpc ldpc.pchk "$m" "$n" $seed evenboth 2x3/8x4 no4cycle
+
+make-gen  ldpc.pchk ldpc.gen dense
+rand-src  ldpc.src 1 "$k"x"$ntrials"
+encode    ldpc.pchk ldpc.gen ldpc.src ldpc.enc
+
+for i in `seq -1 10`;
+do
+  db=$(echo "scale=5; $i/2.0" | bc)
+  ebno=$(echo "scale=5; e(0.1*$db*l(10.0))" | bc -l)
+  sigma=$(echo "scale=5; 1/sqrt(2*$rate*$ebno)" | bc)
+  echo db $db ebno $ebno sigma $sigma
+
+  transmit ldpc.enc ldpc.rec 1 awgn $sigma
+  decode   ldpc.pchk ldpc.rec ldpc.dec awgn $sigma\
+         prprp 250
+  verify   ldpc.pchk ldpc.dec ldpc.gen \
+         ldpc.src 
+
+done