My Pi-Star Hot Spot construction project.

Your results will vary....

So, I bought this kit from Ebay. The selection criteria was demanding. I wanted a kit with the case, and I wanted something in stock here in the US so I didn't have to wait months to come from China.


Here is what I got.






The Pi Zero is on the top, with the 2 smaller headers already to go, soldered onto the board.






Here it is, assembled and mounted in the case.


The finished product! Insert the SD card, Feed 5 volts into the far right USB connector and you are good to go! Wait.... what's on that SD card?

So, first go to RadioID.net to register and get your ID number. You will need to submit a JPG of your official FCC license that you got from the FCC when you got or renewed your license. They tell you how to access the FCC site if you don't have a digital copy of your license. They will verify your license and email you a link to get your ID number. Mine took a few hours. This legally puts you on DMR. You may also need ID numbers for D-Star and Fusion. I didn't do that.

Now, with the legalities out of the way, go to PiStar.uk. Select Downloads. Download the latest Pi_Star_Rpi.... zip file. Then go to Pi-Star tools, Wifi builder. Put in the name and password for your wifi. It will generate a configuration file for you to save. Use Etcher to burn the zip file onto the SD card. When it is done, copy the configuration file to the boot directory. The boot directory is FAT32, so windows should see it. The rest is EXT4 format, which windows will not recognize, but you don't need it to. If you don't do the wifi configuration, Pi-Star will boot up creating it's own wifi network. Connect you computer or smartfone to that network. Point your browser to Pi-Star.local and you should find a wifi configuration page. So, put the SD card in and power it up. You can connect a monitor, keyboard and mouse for fun to the hot spot. You can watch it boot, but it is running "Headless". Command line only... no graphical user interface (GUI).

So, your Hot Spot is up, you just have to tell it who you are and what you want to do. Point your browser to pi-star and your Dashboard should come up. Click Configure. There will be several sections to configure. Do them one section at a time and click Apply Changes for each section. It will take some time to update.

The first section is Control Software. MMDVM Host and Simplex modem should be already selected. Click Apply Changes. (It was suggested somewhere to Apply Changes even it you didn't change anything to be sure the config files are updated for all sections)

The next section is General Configuration. Host name is pi-star. Change it if you have multiple hot spots. They can't have the same name. Put your Call Sing in, the frequency you want your hot spot to operate on, your lat, long, city, grid number, country and state. url: http://www.qrz.com/db/(Your_call_sign). APRS host: noam.aprs2.net, America/New York, english_us. Click Apply changes. It will tell you that you have no modem selected. When it comes back, select STM-32-DVM / MMDVM_HS-Raspberry Pi Hat (GPIO) Click Apply Changes.

You will now see a MMDVMHost Configuration section. Turn on DMR and / or whatever interfaces you want on. Select MMDVM Display Type OLED Type 3. Click Apply Changes.

When it comes back, you will see a place to enter your DMR number in General Configuration. Enter it and click Apply Changes.

Now you will see a DMR Configuration section. In DMR Master, select BM_United_States_3102 or one of the 4 US masters. click Apply Changes.

On the Firewall, I turned off uPNP. It doesn't seem to matter on or off. Down at the bottom, you can change your password from the default raspberry.

You can go to brandmeister.network and register there. You can then go to your dashboard there and set up static groups.

A GOOD CODEPLUG IN YOUR RADIO AND YOU SHOULD BE ON THE AIR!

Eventually you may want to update software and firmware. From the dashboard, there is an Update Link to update the pi-star software. To do other updates, you will need to open up a terminal to access the pi zero. You can find one at Configuration. Select Expert at the top. It will warn you. Select SSH Access. You can enter commands here, but you can't cut and paste to this terminal. If you open up a terminal on your computer, enter ssh pi-star@pi-star. It will ask for your password. It was raspberry before you changed it. Here you can cut and paste to save a lot of typing.

For a firmware update, copy this into the terminal:

sudo pistar-mmdvmhshatflash hs_hat

it will go to github, download and install firmware, reboot

To update the raspberry pi OS, copy this into the terminal, one line at a time:

rpi-rw

sudo su -

apt-get update

apt-get upgrade --fix-missing --fix-broken -y

cd /usr/local/bin

git reset --hard origin/master

cd /usr/local/sbin

git reset --hard origin/master

cd /var/www/dashboard

git reset --hard origin/master

reboot

If your hot spot came with offset correction numbers, from the dashboard, select Configuration, Expert, MMDVMHost. Go down to modem Put the numbers in RXOffset and TXOffset. Apply Changes and test. You are looking to minimize the BER (Bit Error Rate) values on your dashboard in use. You can play with these values to minimize the rate. These values may change over time and need to be tweaked. You are changing the actual transmit and receive frequency of your hot spot in Hertz.

There is a built in calibration routine to match your hot spot frequency to your radio. You can try it. It lets you measure the hot spot frequency to center on your radio then you calculate your offset. The instructions are here:

http://www.k9npx.com/2019/02/hotspot-offset-calibration.html?m=1

Here is a good video on setting up a Pi-Star hot spot:

https://www.youtube.com/watch?v=B5G4gYDdJeQ


Here is a video comparing CODEC quality. Notice DMR quality last, the higher pitched female voice distorted more than the lower pitched male voice due to the low sampling rate:

https://cwh050.blogspot.com/2018/01/the-audio-sounds-bad-why.html


Here is a video of a DMR net. The audio quality differs with voice pitch and amplitude, probably as well as other factors that we aren't privy to.


https://www.youtube.com/watch?v=7o1TxI0lZfQ


Catch you on 31368!

Jim K2BHM

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Came across this nice guide written by KE0FHS on setting up a Pi-Star hotspot and also how to use it in a cross mode configuration. A lot of good up to date information here. Enjoy! https://amateurra