How to use a rpi zero as a USB to Ethernet forwarder for Adalm Pluto

ZR6TG has written up a good tutorial on how to use a rpi zero as a USB to Ethernet forwarder for QO-100 satellite. This enables you to get rid of your active USB extender cable and makes it possible to place the pluto and dish far away from the shack. Click below to check it out.

https://www.zr6tg.co.za/2022/08/07/plutosdr-on-network-via-raspberry-pi/

D-Link DCS-2670L IP-camera with audio in Blue Iris (howto)

D-Link IP cameras are fairly OK and available IP cameras. On several of my sites I have video surveillance with AI and motion detection incl. thermal and night vision. However the D-Link DCS-2670L wide angle camera is known to be difficult to get working with Audio. Either the audio is crackling, there is no audio or there is distortion. The solution was simple: use DCS2030/21xx RTSP profile in Blue Iris

DCS-2670L setting in Blue Iris
DCS-2670L setting in Blue Iris. Audio and video works.

What time series database to use for IoT systems?

While most of the tutorials online nowadays describe influxdb as a very good time series database we discovered that there are some serious considerations you should do before selecting a time series database for your next IoT project.

Here are some findings we did and questions we should have asked when we researched and selected time series databases for a new design of an IoT system:

  • To design a stable database engine suitable for production typically takes 10+ years of user feedback and experience from smaller scale testing and continuous improvements. Several of the “high ranking” databases has not been around for that long
  • mySQL and ORACLE have stable database engines by now, but they are not time series databases
  • Influx has rewritten their database engine several times over a period of few years. This may be a hint to that they are still struggling to converge on a stable database design
  • We found several very worrying statements in bug reports related to influx such as “please help, our production database is suddenly corrupt”, “the database has crashed, the backup is also corrupt. There must be something fundamentally wrong with storage”, “we have discontinued functions iusedthisextensivelyandthereisnowayaroundit() in the next release due to a complete rewrite of the database engine” etc.
  • Some databases have very inefficient compression algorithms. They will compress, but when trying to read from a compressed table, the penalty is pretty big and it goes too slow forcing you to use uncompressed tables
  • Some databases do not support writing to compressed tables (!). You have to decompress before writing. This takes a lot of time. And there is no API support to check if you try to write to a compressed table. You have to resort to parsing log messages before writing. Yes it is true.
  • Even if a database shows up high in a ranking, it may be because of it has the highest growth rate. That does not tell you much. If you look closer, you may discover that all the big guys already use more conservative and well proven time series database systems. That people reading tutorials download and install influxdb does not mean that Google, Facebook, Amazon etc uses it. It does not mean that it is the best time series database available.
  • Some databases claim to support continuous aggregates. However did you benchmark and test properly that the functions used for reading from the aggregates are stable, does not require 100% CPU, and does not crash your database engine? You may be in for a surprise.
  • Some time series databases does not have support for regular data types and regular SQL syntax. This means you will have to have TWO databases. One for configuration data and one for time series.
  • Some time series databases from the cloud vendors are extremely expensive as soon as you come up into production. Did you actually check the cost? If not you may be in for a BIG surprise.
  • Even plotting time series in a web browser may be too slow. Did you check if your time series database can decimate and deliver data to your front end in real time?

 

Glitch protection for tube amplfiers with HV PSUs

 

OE5JFL has implemented the same idea for quenching the HV discharge current as I wrote about back in approx 2012. The idea is to short the anode PSU caps thru an inductor and a solid state device when an overcurrent event thru the tube occurs. The inductor prevents the current to raise to dangerous levels as the inductor tries to prevent the current dI/dt by building a magnetic field.

The above figure1 shows OE5JFLS thyristor circuit and 100-500uH inductor

Thyristors for voltages >1000 Volts are very expensive. For higher voltages you can use a cascade as shown above in Figure 2. I use four thyristors in series, switched by optocouplers, in my 3.5kV supply.

Figure 3 above shows a circuit for screen protection sreen in case of no anode voltage or screen overcurrent. Ig2>100mA will toggle the Flip-Flop via the optocoupler. The relay goes off and disconnects the screen. Voltage comes back after pushing the RESET key. Using the ordinary Z-diode stabilisation, overcurrent is limited to a harmless value during switching delay of the relay.

Overcurrent trip: High current in anode circuit caused by arcing or short circuit generates voltage drop across 10Ohm resistor. Flip-Flop toggles (Pin 3 low), switches off transformer and fires SCR to short HV capacitor.

For restart one has to switch off S1, the main power supply switch, and switch it on again after a few seconds. The series inductance for SCR protection is made from 10m of enamelled copper wire. Trip current is set by the 39k/8k2 voltage divider.

Before you test the circuit by producing a short, you should follow the step by step procedure, which is outlined as follows:

  1. Connect TP2 to ground, switch S1 on and short Pin 6 (CD4011) to ground. ===> Transformer must be off.
  2. S1 on, after plate voltage coming up, ground TP1 (transformer off), and then Pin 6 (CD4011). ===> SCR must fire now and ground high voltage.
  3. S1 on, ground Pin 6. ===> Transformer must be off and HV must be shorted.
  4. After successfully completing these tests, you should short the HV output with a thin wire to ground (0.12mm). This wire must not be melted when the HV-supply is shut down by the overcurrent protection.

PROCEED WITH CAUTION, THE AUTHOR IS NOT RESPONSIBLE FOR INJURY OR EQUIPMENT DAMAGE.

Credit to OE5JFL for the schematics and writeups. 

https://www.qsl.net/oe5jfl/flashover.htm

 

Solar wind event of 12.May.2021

The 12.May.2021 solar event caused major openings on 10 meters and above. I did this screen capture of the solar wind intensity to save for reference. One noteable observation is that the Bz magnetic measurement went to negative 20 for a moment. That is pretty significant.

Quatar Oscar 100 Geostationary Satellite / QO-100, Es’Hailsat, new Facebook Group for licensed radio amateurs

There is a new Facebook group for Quatar Oscar 100 Geostationary Satellite. (QO-100, Es’Hailsat). Licensed radio amateurs are welcome to join via the link below! (Exclusively for licenced radio amateurs by the respective government administrations).
Members typically discuss equipment, design of equipment, antenna designs, post QSO videos and sound recordings etc.   https://www.facebook.com/groups/252645695661305/

cover photo, No photo description available.

Securing your node-red editor and dashboard on the Raspberry Pi

If you leave your node-red installation on your rpi running without a password you will be hacked and soon owned by people using your rpi as a bit coin mining device. It is easy to set a password for the editor and for the dashboard!:

Node-red is installed in /home/pi/.node-red (the . dot in front means you will normally not be able to see the directory as the dot means it is hidden. Therefore, set up your file manager to show hidden files. Alternatively, if you are using the terminal you can use ls -a or ls -al in the /home/pi directory to see all that is there).

Edit the settings.js file with

nano settings.js

Uncomment this section in the settings.js file:

adminAuth: {
type: "credentials",
users: [{
username: "admin",
password:"xxxhash key is pasted herexxxx",
permissions: "*"
}]
},

You will need to generate a hash with node-red-admin and type the hash-pw command. The hash key you paste above in the field xxxhash key is pasted herexxxx (keep the ” ” signs and dont mess up the [ ] {} , stuff).

You will probably have to install the node-red-admin tools (google how to do that with npm) to be able to use node-red-admin

For the dashboard you do the same procedure but you now un-comment this line

httpNodeAuth: {user:"user",pass:"xxxxdashboard hash key is pasted herexxxx"},

Make sure to keep all commas etc!
If you are uncertain to what directory your rpi reads the settings.js file from, you can start the node-red with node-red-pi and look at the messages in the console. It will report the location and file it uses. Dont edit the wrong settings.js file … there are several installed on your pi it seems

Restart the node red
IMPORTANT! CLEAR THE CACHE of your web browser. If not you will not see the password on the editor and the dashboard, as node-red uses cache quite heavily. See https://support.mozilla.org/en-US/kb/how-clear-firefox-cache for how to clear Firefox cache

Too low power Modification for ICOM IC-7100

I recently bought a second hand Icom IC-7100 HF radio for a reasonable price. This radio is known for a very conservative approach to internal ALC on the power output. This causes the output power to not go above approx 75-80W (PEP) as measured on my LPA-100 wattmeter in PEP mode with 14,5V DC input. Of course, there is no need to overdrive any linear amplifier, however Icom engineers have probably overdone it a bit on the conservative side on this radio (?).

There are two published mods that are possible on this radio. I did only one of the mods that involves a jumper from C1509 to ground, because the other mod that involves a 10uF capacitor is reported to cause modulation issues on FM and AM.

The PEP output power increased from 75-80W PEP to approx 140-145W PEP (14,5V DC input). Note: PEP, not average. On a sidenote the peak to average ratio also improved. There is no need to have PEP output of more than 100-110W PEP by the way.

The mod is easy:

  • Unplug the radio DC lead and all other leads incl. the antenna connector
  • Use an antistatic mat and handlead
  • Remove the back cover
  • Locate the C1509 and the ground lug
  • Solder a small jumper from the C1509 to the ground lug
  • Check carefully that you didn’t spill any solder residue on the PCB
  • Blow with compressed air to remove any residue
  • Close the radio

IC-7100 mod. (I did steal this picture from radio aficion website)

I did also upgrade the firmware to :

  • CPU 1.11
  • DSP 1.03

The firmware upgrade did have a small but insignificant effect on the PEP output power according to what I found. The hardware mod, did have a signficant impact as the DSP is led to believe that the output power is lower than it is.

Disclaimer:

  • All mods are done on your own risk!
  • You may void the warranty of your radio if carrying out this mod
  • I will not be held responsible for any problems, malfunctions, defects, indirect consequences or any other issues caused by the mod
  • Do at all times follow the license regulations of your country
  • Check that your bandwidth is not excessive
  • Check that your harmonic content is well below maximum allowed