Pi-Star: Sharing your public hotspot

Have you noticed that HVDN has not posted much about DMR or even things relating to the different digital voice modes for a while?    Did you look closely at the photo above for some laughs?

Our focus has been on community growth and awareness via the massive June Hudson River Radio Relay event, a mini QRP HVDN field day, helping to support the USMA at West Point triathlon via APRStt this past August and most recently, spending the day at the Old Rhinebeck Aerodrome to support the OMARC K2A effort.

Plus, with a new weekly commitment to support UNDR Net, there has not been much free time to do much else this summer as HVDN prepares for a series of fall season events. 

A reminder from Brian W2BRM today that we have not chatted in a while, made me think I should go find something interesting to write about related to Pi-Star as I try to find the time to do a short video about a duplex hotspot to be included in Pete N2MCI's upcoming presentation about the basics of hotspots to the OMARC club coming up in a few weeks time.

Public Hotspot

Many people are afraid to touch certain buttons in Pi-Star, but I am not one of those.  Most people use a hotspot to just provide communications for themselves which means your hotspot is in private mode and only lets a radio programmed with your DMR ID to use your hotspot.

If you click the button under "General Configuration" from private to public, here is what will happen.

Up until recently, changing to a "public" hotspot would allow for anyone to use your hotspot.  This is helpful at public events as an example if many people have a DMR radio and it makes sense for them to all be on one hotspot for internet communications, while local use can take place via a standard simplex channel.

If you want anyone to be able to use your hotspot, leave the "DMR Access List" box blank.

Alternatively, you can add a list of DMR ID's separated by a comma which would allow only your closest trusted friends to also use your hotspot.

Be sure to remember to hit "apply changes" when adding or deleting DMR ID's. 

Bigger picture use case

Now, lets say your club has a DMR repeater that is managed by a Pi-Star interface on your favorite DMR network like Brandmeister or TGIF.  Using this feature could be helpful to ensure that only members of your club are permitted to use the DMR repeater instead of anyone else.  

While this can be considered exclusionary and not the best way to portray amateur radio, this feature may be helpful to help promote the use of certain talk groups on a repeater rather than a hotspot. Should an issue happen where preventing a specific user is needed, this feature can permit that also.

There are many ways this feature can be used, so feel free to share some comments below on how you may wish to use this or not.

-Steve K2GOG & HVDN Team

SDR: Let's Walk To The Space Station?

I had high aspirations on Wednesday to do a base-band SDR recording of a scheduled International Space Station (ISS) contact with a school in Ashford,  Connecticut. 

Burger Hill at Drayton Grant Park Rhinebeck, NY 12572

The weather was nice, so I decided to trudge up the measly 550 feet of Burger Hill for amazing views and to maybe cross paths with a passersby or two interested in what I was up to with my collection of equipment. 

What is a base-band recording?  Think of it like recording a television show with a DVR or VCR.  The only difference is a base-band recording lets you record a wide block of spectrum say from 162 to 163 MHz and be able to point and click on any activity received for later playback. This would be like recording multiple movies, news and sitcoms on different channels all at the same time.

Bummer: Well, no activity from the ISS on 145.800 MHz at 14:39 PM ET (1839 UTC). 

As it turns out, the ISS contact was cancelled at the last minute due to an experiment in the Columbus module that would have prevented the use of the functional radio in that part of the space station. 

The radio to be used was actually considered the spare radio as the main radio after years of service no longer is functional.  A replacement is supposed to be sent up before the end of 2018.

I only found out about this change of schedule on a Facebook Group that I joined once I got home which is more up to date than all my usual sources such as the official ARISS Project website, AMSAT mailing lists and various NASA pages.

Serena Auñón-Chancellor, KG5TMT preparing the
NanoRacks Cubesat Deployer-14

This just goes to show that social media is still the best spot for breaking news!

Looking on the bright side...

All was not lost though. Not many minutes later at 15:02 ET was a pass of the elderly SO-50 satellite and I quickly made a contact with Tom, K8TL in grid EM89, 500+ miles away from me in FN31 thanks to this "repeater in the sky".

All that was needed was 1 watt of transmit power & a directional antenna! 

However, the down-link for the SO-50 satellite is centered on 436.795 MHz and there was someone using digital voice on that frequency which made it hard to make more contacts as SO-50 reached its apex and started to move out of range.

I did not have a DMR capable radio with me, but I am pretty sure that is what mode it was and it was local versus coming from the satellite. 

Listen:  Do you hear a "digital sound" on 436.795 MHz?

Trespasser!!

No hot spot or repeater stations appeared listed on Brandmeister on that frequency in the satellite band, so it could be some joker or ill informed amateur about the suggested ARRL and ITU band plan just intentionally interfering. Rhinebeck is pretty much far away from any "majorly" strong out of band signals that could have interfered, so it had to be an amateur radio operator.

I knew the signal was also local because if it was somehow coming in from SO-50 by someone transmitting DMR on the VHF up-link of 145.850 MHz, it would have come from the direction of the satellite and not from another direction to my south west at a "terrestrial" elevation.

This sort of interference makes me sad because 436.795 MHz is well known for over 16 years that this is where SO-50 transmits back to earth on.

There are plenty of other frequencies that can be used for digital voice that would not interfere with those interested in satellite communications.

Lets change the subject back to base-band

While I was at the great location of Burger Hill, I decided to do a 30 second base band recording of the weather band from 162-163 though should anyone wish to test it out since every NWS channel is in use from that location.

A "Normal" Recording:

A center frequency of 162.475999 MHz with a bandwidth of 15 kHz can easily be recorded and played back using pretty much any audio player, but only just that one frequency can be heard. The file size is 1.9 MB. Play: Standard AF Recording (1.9 MB)

Play: Standard AF Recording (1.9 MB)

A "Base-band" Recording: 

Compared to the "Standard AF Recording", the base-band recording for the same 30 seconds is 60.9 MB or 3105% larger. However, you can listen to any signal of any bandwidth in any mode across the entire 162 to 163 MHz captured for 30 seconds.

SDR# will help you visualize the entire 1 MHz wide
recording without needing a radio

In order to play the base-band file, you can not use a regular audio application or otherwise the sound might sound like an Imperial Probe Droid from Star Wars.

Play/Download:  IQ Base Band File (60.9 MB)

If you are a Star Wars fan, you know the
audio I reference from Echo Base on the ice planet Hoth

Ham Solo: Return of the SDR#

Download and install the popular SDR# program and select the "IQ File" option as shown. 

Then navigate to where the "IQ Base-band File" was saved and press play in SDR#

From the Burger Hill location and its good line of site, multiple weather stations were received as well as a few other signals not related to the weather.

Hudson Valley National Weather Service (NWS) stations
broadcasting 24/7 on the 162 MHz spectrum

Hopefully this article gave you a taste of a few interesting things you can do with amateur radio or use equipment for a dual purpose unrelated just to ham radio.

Next time there is a planned live ISS contact receivable from the Hudson Valley, we will definitely try to get that recording, just as long as the astronauts do not get busy at the last minute! 

Check Out The HVDN STEM Project Here

Search for more satellite and space related content on HVDN 

MMDVM JumboSPOT board: Mods you may need

This is the JumboSPOT board that was/is sold on ebay and other online places. This board along with a Rasberry Pi Zero and a SD card loaded with PiStar makes up a Digital Radio Hotspot.

Depending on when you purchased your board and for what price, you may need certain modifications. The following mods have ONLY be tested / verified on the above board. As with anything in life, you take on the risk and responsibilities of preforming these mods. If you don't know what you are doing, STOP and don't do it!

Antenna mod

If you installed the SMA connector at P3 and plan to use the included SMA external Antenna you need to remove the cap ( see A in above picture ). This removes the connection to the internal ceramic Antenna ( not shown about ) at AE1. Bottom line is that you should not run two Antenna's so removing C28 makes sure that only Antenna is P3.

Flash FW mod

Most early boards shipped with only the 10 pin connector soldered as in the above picture. This meant that you were unable to flash updates to the STM32A103 microcontroller chip. Thus the two pins in the above picture ( marked B and in the red rectangle ) need to be connected to the Rasberry Pi's GPIO pins 20 and 21 which will be right below them.

It is a direct pass through, NOT a jumper as most people assume. So you just need to add a female header to your JumboSPOT board and a male header to the Raspberry Pi. Current boards place a 10 pin female header on both sides of the JumboSpot, which will work, but only thoes two pins are needed. Once the pins are connected you will be able to use the PiStar Firmware update script to update your JumboSpot to the latest version of HS_HAT which is displayed on the PiStar admin page.

OLED display mod

If you just purchased the JumboSPOT board it most likely did not come with an OLED display. You can add one later on if you like. Just look for " 0.96" I2C IIC SPI Serial 128X64 White OLED LCD LED Display Module for ArduinoG9K " or similar. The display gets connect to the top row in the above picture ( refrence "C" ) and not the bottom row that is marked. The main issue is that the pins must match the board pins which are listed above. From left to right they are [3.3v] [GND] [SCL] [SDA] So since you solder the display so that it's facing out the screen you purchase should match that config like so:

 I was able to find this module for 450% less then the ones listed as compatible to the JumbSPOT so don't get fooled by the seller, you can use compatible modules as long as it has the correct pins and supports "I2C IIC SPI Serial". Also note that the display will NOT turn on unless you have it configured and PiStar attaches to a server on the Internet ( as in Brandmister etc ). In PiStar http://pi-star.local/admin/configure.php make sure you have it configured as in:

Adding Ethernet to your Pi Zero mod

This one requires no-soldering! Just chose the correct part from eBay or your favorite Chinese vendor. The PiStar distribution will support an Ethernet adapter out of the box. It's even smart enough to use Ethernet over WiFi and fall back to WiFi if Ethernet fails. But which one to get. If you search for "MMDVM Hotspot Ethernet Adapter" you will be paying the most you can pay. If you look for "Micro USB 2.0 to Ethernet 10/100 RJ45 Network LAN Adapter" you will find ones EIGHT TIMES less! Make sure that it supports Linux and you will be safe. Also I suggest getting one more then you need. When I ordered three, only two worked. Since I only needed two it was worth buying extra ( these parts are really REALLY cheap and cheaply made ).

 

What do you think?

Please leave constructive comments. If you have mods of your own please share. Like most of you out there I was attracted to this hobby because I could MOD things, make them better! So pitch in and share your knowledge!

Using a JumboSPOT via bridged Wi-Fi

On a recent business trip, I left my trusty GL i.Net GL-AR150 at home by accident and could not use my new JumboSPOT unless I used my mobile hot spot feature on my mobile phone to give it the internet access it needs.

JumboSPOT running Pi-Star in DMR only mode

The GL-AR150 is a travel Wi-Fi router which I have plugged in to the ethernet port on my laptop to share its internet connection and create a wi-fi hotspot. This setup essentially lets me take hotel wi-fi and then rebroadcast it so that other devices could use the internet. The laptop essentially acts as a router of sorts in this configuration taking wireless hotel internet, translating it to wired internet and then turning it back into wireless internet.  Make sense?

GL-AR150 multi purpose travel router

Since its always annoying to keep my mobile phone charged up while traveling, I figured it would be a good experiment to see what range too expect from a 10mW DMR hotspot from the 39th  floor of the hotel and out into the city of  Atlanta.  Not having the AR150 with me prevented me from trying this, so I had to find another solution instead of setting up my mobile phone hotspot function, which worked great to make a contact via TG 31368 the previous evening.



Connectify to the rescue!

I found this application named Connectify to do what the hardware I left behind but via software and it works great! It took the hotel Wi-Fi SSID and creates a new access point using the laptop wi-fi to then rebroadcast to the SSID I set up and had in place on the JumboSPOT.

    

   

I would highly recommend the Connectify application to be used in a  travel situation much like I describe above in order to get on DMR with a JumboSPOT.   This is slightly more elegant than the DV4MINI I have used before with my laptop or the GL-AR150 and OpenSPOT combination when traveling. 

Connectify is currently running a 70% coupon on top of it, so get it while you can. You will need the MAX version, not the LITE one. This application will find many more uses aside from just using it to connect the JumboSPOT, which is now my go to device for travel along with the MD-380 for DMR operation. This trip proved a benefit that came out of an annoyance afterall.

An optional, but recommended addition is to also use the "Speedify" VPN application to provide a secure connection and the ability to monitor latency and loss in addition to the upload and download speed reported in the "Connectify" application. Speedify is free for up to 1GB of data transfer a month which seems more than enough if only using this for use with the JumboSPOT.

After about an hour of listening in to a few talk groups with active discussion, only used 3MB of download and all traffic was less than 30ms latency.

http://www.connectify.me/