Week 9 – Many Problems

This week, I downloaded a Nextion Display layout created by PD0DIB and modified it to include a system control page and an information page. After trying out the Nextion Driver Installer created by ON7LDS, I could get the screen to display information one time, but after switching pages, the data would disappear. To solve this problem, I looked at the Nextion Driver Installer script and followed most of the steps manually. Doing it this way also allowed me to switch the displayed CPU temperature from celsius to Fahrenheit. This pretty much solved the issues with the display.

In the Nextion Driver Installer Script, I followed this section:

if [ "$ND" = "" ]; then
    echo "+ No NextionDriver found, trying to install one."
    compileer
    $SYSTEMCTL
    $NDSTOP
    $MMDVMSTOP
    killall -q -I MMDVMHost
    killall -9 -q -I MMDVMHost
    if [ "$CHECK" = "PISTAR" ]; then 
        cp $DIR"/mmdvmhost.service.pistar" /usr/local/sbin/mmdvmhost.service
    fi
    if [ "$CHECK" = "JESSIE" ]; then 
        cp $DIR"/mmdvmhost.service.jessie" /lib/systemd/system/mmdvmhost.service
        cp $DIR"/mmdvmhost.timer.jessie" /lib/systemd/system/mmdvmhost.timer
        cp $DIR"/nextion-helper.service.jessie" /lib/systemd/system/nextion-helper.service
        if [ -e /etc/systemd/system/nextion-helper.service ]; then
            echo "+ there is already a link /etc/systemd/system/nextion-helper.service"
            echo "+ I'll leave it like that."
        else
            ln -s /lib/systemd/system/nextion-helper.service /etc/systemd/system/nextion-helper.service 
        fi
    fi
    cp NextionDriver $BINDIR
    echo "+ Check version :"
    NextionDriver -V
    checkversion
    helpfiles
    echo -e "+ NextionDriver installed\n"
    echo -e "+ -----------------------------------------------"
    echo -e "+ We will now start the configuration program ...\n"
    $DIR/NextionDriver_ConvertConfig $CONFIGDIR$CONFIGFILE
    herstart
    exit
fi

Basically all I did was the following:

  1. Stop MMDVMHost with “sudo service mmdvmhost stop”
  2. Download the Nextion Driver from github into the /tmp folder
  3. rpi-rw
    cd /tmp
    git clone https://github.com/on7lds/NextionDriver.git
    cd NextionDriver
    
  4. Compile the driver by running “make”
  5. Then you should end up with a binary called “NextionDriver”.
  6. Copy the binary into /usr/local/bin with
    sudo cp NextionDriver /usr/local/bin/NextionDriver
    
  7. This was all done AFTER running NextionDriverInstaller.sh on its own. So, my installation had all the helper files already installed before I ran through these commands.

Problem 2

The hotspot/repeater doesn’t startup right away like it does at home. I’m guessing this is because of the enterprise WiFi at my University. Sometimes the repeater starts right up and works perfectly and other times it does not work.

Problem 2 Solutions

  1. Create a simple script to reset the WiFi connection on the Pi and create a button on the Nextion Display Layout that would allow me to run this script.
  2. Use the same script, but have it run after the Pi is completely booted and add a line to restart the MMDVMHost service.

Problem 3

I could not always access the PiStar dashboard through the ethernet/crossover cable or through the University’s WiFi. Again sometimes I had no issues and other times it would not connect. At first I thought this was due to having both the ethernet and the WiFi running on the Pi, but after removing the ethernet, I had the same issue. I’m growing more suspicious of the enterprise WiFi. As for it not working over the crossover cable, I believe this is due to the fact that the computer is addressing itself with a self-assigned IP address (a 169 address). The problem appears intermittent.

Problem 3 Solutions

  1. Use the solutions for problem 2 as I believe the two problems may be related.
  2. Create a static IP on the Pi and the Computer for the ethernet connection.
  3. Change the PiStar firewall rule for the dashboard from “Private” to “Public.”

Going Forward

  1. Enable DMR and configure it.
  2. Install the Brandmeister control panel on PiStar.
  3. Program the DMR Radio.
  4. Create a blog post about programming the DSTAR and DMR radios.

I also wanted to create a 3D printed case for this project, however I am not sure I will have enough time to do that, especially with encountering these problems.

Week 8 – Setting TX & RX Offset

After setting up the MMDVM duplex hotspot board, it is necessary to adjust the transmit and receive offsets in the MMDVMHost expert editor section. Basically this corrects the transmit (TX) and receive (RX) frequency of the board, if they’re not on frequency.

I went to a fellow amateur radio operator’s house recently to test my board with his HP 8920A Service Monitor. According to this ham, the service monitor is about 30 years old and cost around $30,000 new. Every 2 years he has it calibrated to NIST standards and it is accurate to +/- 1 Hertz.

The back of the board recommends a TX and RX offset of 500 and then tells you to adjust until the BER or Bit Error Rate is less than 5%. With my friend’s help, I tested the output frequency of the repeater/hotspot board without setting any TX offset and the transmit frequency (FRQ) was about 442.999300Mhz. So I adjusted the TX offset to 500 and retested the transmit frequency. It appears to be getting closer, showing a frequency of about 442.999700Mhz. So I bumped the TX offset up to 800 and that brought the TX frequency up to approximately. 443.000000Mhz, which is right on frequency.

Setting the RX offset is a bit more difficult because there isn’t really a way to test that within Pi-Star. So, I transmitted to the repeater board with my DSTAR handheld and found that I had a bit error rate of 0.1% which really doesn’t need to be fixed.

0.1% Bit Error Rate

I set the RX offset equal to the TX offset (800) and that brought the bit error rate down to 0.0%, which is perfect.

0.0% Bit Error Rate

I also worked on installing the Nextion Display Driver, however I’m encountering problems with it. The screen layout disconnects from the MMDVMHost software every time the screen changes. I need to work on this a little bit more to solve that problem. I’m thinking the problem is the layout I used. I was testing with a layout from another ham that displays a lot of information and I think the screen has trouble keeping up with the amount of data. I will detail this process in my next post.

Week 5 – PiStar Setup Part 2 of 2

In this post I will explain how to update, upgrade, and configure the basic settings for Pi-Star. I will also explain how to register your amateur radio callsign for DSTAR and DMR use.

Part 1 of this post: https://n3tdm.tdmorris.com/week-4-setup-part-1/

First of all, for this project you MUST be a licensed Amateur Radio Operator. In the USA, that means passing a licensing exam and being assigned a callsign from the Federal Communications Commission (FCC). For licensing information check out the American Radio Relay League.

Register your Callsign for Dstar

  1. Follow the instructions to register your own callsign found here: http://www.dstargateway.org/D-Star_Registration.html
  2. After you receive your confirmation email, go to this page to learn how to assign terminal ID’s to your callsign (STEP 1 only). Terminal ID’s are just what they sound like, it’s an identifier for your individual station. If you’re just using one radio, you can typically set a terminal ID of a single space, however we’re setting up a repeater, so you would need the space terminal ID and whatever module you’re using B for 70CM or C for 2M frequencies.
  3. My terminal ID’s look like the following: 
  4. Here is more information on Terminal ID’s: https://wb1gof.dstargateway.org/DStarTerminalIDs.html
  5. After you’ve registered for DSTAR you need to get a CCS7 ID for DMR.

Get a ccs7 id number for DMR / DSTAR

  1. Head over to this site and fill out the form selecting the option for a private callsign and NOT a repeater. I’m going to be setting up a private repeater for experimentation so it won’t be running 24/7.
  2. Once your request is processed, you’ll receive an email containing your CCS7 ID number. Put that in a safe place.

Setup and Configure wifi

In order to configure this, because I had no way of getting the IP address from a headless Raspberry Pi, I connected a crossover cat5e cable between the Pi and a PC so I could connect into it and make adjustments.

That said, I want to first explain how I setup the enterprise WiFi for the Pi to work on Pitt’s wireless network.

    1. I followed the instructions located here: https://gist.github.com/chatchavan/3c58511e3d48f478b0c2
    2. First open a new tab in your browser and go to
      Windows: http://pistar/admin/expert/ssh_access.php
      macOS: http://pistar.local/admin/expert/ssh_access.php
    3. Enter “pi-star” without the quotes for the username and press enter.
    4. Enter “raspberry” for the password without quotes and press enter.
    5. You should be greeted with a screen spelling out PI-STAR.
    6. Now type
      sudo nano /etc/networking/interfaces
    7. You should see the following screen:
    8. Use the arrow keys to navigate the page and move down to the section that says
      allow-hotplug wlan1
      iface wlan1 inet manual
              wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf
    9. Erase the section above and enter the following:
      auto wlan1
      allow-hotplug wlan1
      iface wlan1 inet dhcp
      	pre-up wpa_supplicant -B -Dwext -i wlan1 -c/etc/wpa_supplicant/wpa_supplicant.conf
      	post-down killall -q wpa_supplicant
    10. Press CTRL+o and press enter, then press CTRL+x to exit the nano editor.
    11. Then go to the Configuration page of your Pi, then to the Expert tab, then click “WiFi” in the “Full Edit” line of editors.
    12. You should see a list of networks (probably just one) after a header of sorts
    13. Make sure the country code following “country=” matches your country code. In the USA it’s “country=US” without quotes.
    14. For the enterprise wifi you need to make a new network in this config file. For WIRELESS-PITTNET at the University of Pittsburgh at Bradford, I used the following settings. In this editor I set up the following network:
    15. Go back to your SSH access page in your browser and do the follow steps.
    16. Enter the following substituting YOUR_PASSWORD with your university email password leave the single quotes around your password. and press enter.
      echo -n 'YOUR_PASSWORD' | iconv -t utf16le | openssl md4
    17. Next copy the resulting random letters and numbers into the WiFi editor in the other tab after the colon where it says “password=hash:”
    18. Now go back to your SSH editor and clear your history by typing:
      history -c
    19. Press “Apply Changes” at the bottom of the page beneath the wifi editor.
    20. If you followed these steps correctly your pi should connect to WIRELESS-PITTNET.

Configure Pi-star

  1. In your browser go the main page of your Pi-Star dashboard at:
    Windows: http://pi-star/
    macOS: http://pi-star.local/
  2. You should see the following page:
  3. Start by selecting MMDVMHost and Duplex (repeaters) or Simplex (personal hotspots), then click apply changes.
  4. After the services are restarted, you should see the following page:
  5. I started the configuration process without the actual interface board, keep that in mind. I did not activate any services yet, however I set the hostname, the node callsign, the RX/TX Frequencies, the GPS coordinates, the town (in the format of “city”, “grid locator”, the country, the URL (this can be either a manual URL of the dashboard for the repeater or automatic and will default the QRZ page for the node callsign), the node type (public – anyone can use it / private – only the node callsign can use it), the time zone, and the dashboard language_country code.
  6. You can also setup the firewall if you wish. Private makes it only work within your local network, public will make it work from outside your network provided the correct ports are forwarded on the router.
  7. I left Auto AP on because if the Pi doesn’t/can’t make a network connection, it will create a wifi hotspot of it’s own so you can connect to it and configure the network settings.
  8. I left UPNP turned off. If your router also has UPNP, you can turn this feature on and Pi-Star will configure your router’s firewall to open the necessary ports.

I found a neat little circuit board on eBay that works with MMDVMHost software and is a mini personal repeater on a single board. I thought this would be a great way to demonstrate a repeater without having to bring in multiple radios, a power supply, the computer, etc. So I’m going to use the MMDVM_HS_Dual_Hat. The board on eBay is a cheaper Chinese “clone” of the original board which is pictured below.