diff --git a/doc/erko_howto_tools.txt b/doc/erko_howto_tools.txt
index b60d6352af82b88beb876c037f76562c963af792..6ccd729eae009c39bbcef917d40a4d163a4ae811 100755
--- a/doc/erko_howto_tools.txt
+++ b/doc/erko_howto_tools.txt
@@ -21,6 +21,7 @@
 * Linux
 * ICT diensten
 * Python
+* Numpy, matplotlib.pyplot
 * Jupyter
 * Graphana
 * Zenodo DOI
@@ -170,10 +171,19 @@ run_rbf unb2b lofar2_unb2b_sdp_station_full_wg
 *******************************************************************************
 * scp from regtest
 *******************************************************************************
+mkdir hdl_build_results/20230108
+scp -rp regtest@dop349:/home/regtest/quartus_build_images_cron.log hdl_build_results/20230108/
+scp -rp regtest@dop349:/home/regtest/git/hdl/build/unb2c/quartus/lofar2_unb2c_sdp_station_full hdl_build_results/20230108/
+scp -rp regtest@dop349:/home/regtest/git/hdl/build/unb2b/quartus/lofar2_unb2b_sdp_station_full_wg hdl_build_results/20230108/
+scp -rp regtest@dop349:/home/regtest/git/hdl/build/unb2c/quartus/disturb2_unb2b_sdp_station_full hdl_build_results/20230108/
+scp -rp regtest@dop349:/home/regtest/git/hdl/build/unb2c/quartus/disturb2_unb2b_sdp_station_full_wg hdl_build_results/20230108/
 
-scp -rp regtest@dop349:/home/regtest/quartus_build_images_cron.log 20221218/
-scp -rp regtest@dop349:/home/regtest/git/hdl/build/unb2c/quartus/lofar2_unb2c_sdp_station_full 20221218/
+du -h -d 2
+df -h /home
 
+Synthesis neemt onegeveer 4GB voor Disturb image en 3GB voor SDP image, dus
+ongeveer 14GB / weekend. De regtest machine heeft nog 500GB vrij, dus we
+kunnen nog ongeveer 35x opslaan, voordat we moeten deleten.
 
 *******************************************************************************
 * Flash and reboot unb2
@@ -1108,6 +1118,27 @@ numpy tutorial:
 https://lwn.net/SubscriberLink/847039/3016fa7278000b77/
 
 
+*******************************************************************************
+* Numpy, matplotlib.pyplot
+*******************************************************************************
+
+a = 20
+plt.figure(figsize=(16, 6))
+plt.subplot(1, 2, 1)
+plt.plot(si_ampls[0:a], si_SSTs_dB[0:a])
+plt.title(f"SST as function of input sine amplitude [0:{a}>")
+plt.xlabel("si_ampl, ni_sigma [q]")
+plt.ylabel("SST [dB]")
+plt.grid()
+
+plt.subplot(1, 2, 2)
+plt.plot(si_ampls[a:], si_SSTs_dB[a:])
+plt.title(f"SST as function of input sine amplitude [{a}:{FS}>")
+plt.xlabel("si_ampl, ni_sigma [q]")
+plt.ylabel("SST [dB]")
+plt.grid()
+
+
 *******************************************************************************
 * Jupyter
 *******************************************************************************