A 2020 update

By: noreply@blogger.com (Patrick Mannion)

10 September 2020 at 15:46

Yes, I know. It's been a while since I posted, just under a year. Unfortunately, as we all know, 2020 is not a normal year.

Aside from attending the amateur radio training session for the 2020 Boston Marathon, the Marathon was delayed until September and ultimately cancelled and replaced with a virtual event. The same goes for the 2020 Head of the Charles Regatta.

I was planning on going to my first Hamvention, but that too was cancelled. As was the May and October editions of NEAR-Fest. My last hope for some ham action was the Northeast HamXposition, but alas, it was also cancelled. As have all the monthly MIT Fleas for the year.

It's not all bad though, we've still had NSRA meetings via Zoom and continued them into summer, which usually is a break period for the club. Also, there have been virtual ham expos and fests online, such as the QSO Today Ham Expo and the HamXposition is going virtual too.

I just recently got back from a 3 month work deployment on Nantucket, I didn't really use their repeater much to do be being busy with work and mic shyness, but it was good nonetheless, and I did do alot of shortwave listening while I was there. I did manage to check in the NSRA's Sunday Night Net via Echolink a lot.

Now that I got back home, I turned my virtual scanner back on, which I've migrated to a Raspberry Pi 4 because of Wi-Fi issues with the Lenovo ThinkCentre.

But that's been my year in ham and radio in general in a nutshell.

My own virtual scanner

Scanning the Airwaves

By: noreply@blogger.com (Patrick Mannion)

17 June 2019 at 21:01

In February of this year, using a leftover Lenovo ThinkCentre M73 Tiny, that was original intended to be used a home theater PC, I made a "scanner" using it and 3 RTL-SDR USB dongles.

All thanks to Luke Berndt's Trunk Recorder project.

Trunk Recorder

Trunk Recorder is open source software written by Luke, that using various SDRs such as the HackRF, RTL-SDR-based USB dongles and Ettus USRPs among others, allows the capture and recording of Project 25 (P25) and Motorola SmartNet trunked radio systems plus conventional systems that are P25 or analog too.

It runs on Linux, macOS and even on a Raspberry Pi (although it's recommended to be a Pi 3 because the rest probably won't be able to keep up). You can either build it yourself from the source code or use Docker like I did to get it up and running.

After configuring a JSON file that sets all the parameters for the instance you plan on running, a CSV file that defines the talkgroups you want to record, you should be good to go.

OpenMHz

Luke also runs OpenMHz, a website that hosts the recordings you make if you so desire. It's not like Broadcastify where it's a continuous stream, it's more of an on-demand style although it autoplays the next recording when it comes online, making it almost stream-like. There is a script that can be executed also using Liquidsoap to allow you to stream to Broadcastify and other providers.

My setup

I setup an instance of Trunk Recorder to record the Massport P25 system, which is part of the greater Commonwealth of Massachusetts Interoperability Radio System (CoMIRS). Specifically, the airport side of Massport's operations, specifically the public safety and aviation operations, which consists of Massport Aviation Operations, Massport Fire Rescue and Massachusetts State Police's Troop F which covers Logan Airport.

Using the ThinkCentre and the three RTL-SDR USB dongles and mag-mount antennas, I am to capture what I want.

It's taken some tweaking but I think I finally found the right configuration because if the audio doesn't decode, it results in 44 byte, 0 second files that are unplayable, although it will take time.

If you want to give a listen to my system, just go to https://openmhz.com/system/bosops.