Welcome back to Sarah from the SignalsEverywhere YouTube channel who has recently returned to producing videos from a hiatus. In her latest video, Sarah shows off her new OP25 Mobile Control Head Android App which allows you to implement a full P25 digital radio scanner at a fraction of the cost of a commercial digital scanner. In the past, Sarah had released a similar application written for the Raspberry Pi but has decided to shift her focus to writing an equivalent Android app that is less clunky and can be deployed for a lower cost.
The app controls and displays information from the OP25 software that runs on a Raspberry Pi with RTL-SDR connected. It works by using a server application on the Raspberry Pi that manipulates the OP25 instance and its configuration files.
Sarah writes:
The application is a wrapper for OP25 that uses a raspberry pi and an android device to provide users with a mobile control head for their OP25 P25 scanner setup. Currently it's just a basic application but I'll be adding features like automatic site switching, etc.
Wir haben den SharkRF openSPOT 4 Pro für euch getestet. Unsere Erfahrungsbericht. Wenn es keine Infrastruktur wie Relais in deinem Einzugsbereich gibt, du aber dennoch am Funkbetrieb teilhaben möchtest, bietet sich ein Hotspot an. Dieses, meist kleine, Gerät ermöglicht es dir, deine Funkgeräte und Zubehör zu verwenden, so das richtiges Funk-Feeling aufkommt. Der Unterschied liegt … SharkRF openSPOT 4 Pro: Hotspot für die Hosentasche weiterlesen
Ein Dualband Mobilfunkgerät mit abnehmbarem Bedienteil, das sowohl analoges FM, DMR, C4FM, P25, NXDN und D-STAR kann? Du träumst wohl! …Oder etwa nicht? Nicht wenn es nach Jerry Wanger KK6LFS von Connect Systems Inc. geht: Mit dem CS800D Plus soll der Traum endlich in Erfüllung gehen. Einführung und Historie Aber der Reihe nach: Ich selbst … CS800D Plus – Eierlegende Wollmilchsau des Digitalfunks? weiterlesen
Before I begin though, I must go over Sensitive Security Information or SSI. SSI is a designation used by TSA which is coded in federal regulation that states that SSI "is information that, if publicly released, would be detrimental to transportation security."
SSI is essentially sensitive but unclassified information. As I work for TSA, I am automatically a "covered person" who is required to protect such information. Therefore, I am limited in what I can I use and say on anything that is considered SSI.
However, most of the sources I'm using for this blog post are publicly available third-party sources which are not SSI or if it is a TSA source, was not marked SSI.
History of TSA
TSA was founded in the aftermath of the destructive September 11th terrorist attacks which showed how weak and complacent the aviation security industry had become in the United States. I say industry because it was a literal sub-industry of security companies usually subcontracted by the airlines to provide screening services with weak oversight by the Federal Aviation Administration and it's sub-office, the Office of Civil Aviation Security.
For the first couple of months, TSA was nothing more than a dozen people in a small basement office at the Department of Transportation (DOT) headquarters until February 2002 when TSA more or less absorbed the FAA's Office of Civil Aviation Security and continued until November 19, 2002, the one year deadline imposed by Congress to have all aviation security activities overseen by TSA.
TSA Field Operations
Before I begin describing radio infrastructure, I should probably give you an overview of how TSA's field operations work. TSA oversees about approximately 460 airports, the number fluctuates because many of the smaller airports are seasonal or see irregular air service that comes and goes based on the airline.
Airports are divided in 5 categories of security, at the top end is Category X, these are your major international airports in major metropolitan areas, below that are Category I airports, these are airports in say smaller cities or secondary commercial airports in a major metropolitan area say like Dallas Love Field (DAL), Houston Hobby (HOU) or Chicago Midway (MDW). At the other end of the spectrum are Category IV airports; these airports are essentially your small Podunk general aviation airport that has commercial service through say the Essential Air Service.
Just like the airlines, TSA field operations are based on a hub-spoke model. Most Category X and I airports have Category II, III and IV spokes. For example, here in Massachusetts, my airport, Boston Logan International (BOS) is the hub for the rest of the state such Worcester Regional (ORH), Hanscom Field (BED), Westover Metropolitan (CEF) and the airports on the Cape and Island (ACK, HYA, MVY and PVC), and since 2014 also oversees Maine's airports.
At these hub airports, there is a small operations center known as the Coordination Center, which is essentially the clearing house for all information in the area of responsibility. If an incident happens at a checkpoint or a baggage area, the TSA officers (TSOs) will call it in and the Coordination Center will make the proper notifications to local or state law enforcement, our explosives specialists or our regulatoryinspectors if needed.
The TSOC Watch Floor
These Coordination Centers in turn report to TSA's national operations center, the Transportation Security Operations Center or TSOC. TSOC is essentially the national clearinghouse, all incidents reported go to TSOC. Unlike the Coordination Centers which are just staffed by TSA employees, TSOC has TSA employees along with employees from various other government agencies, such as other DHS agencies, the FAA and FBI serving as liaisons.
TSA's Frequencies and Radios
Frequencies
Since TSA and the FAA were essentially under the same department at the beginning, that being the Department of Transportation. The FAA gave away a chunk of their land-mobile VHF frequencies to TSA, so it could set up it's land mobile network. It should be noted, that even though the frequencies maybe the same at many airports, each airport land mobile radio system is an independent system, they are not interlinked into a national network or even regional networks.
The large airports will have repeaters, but smaller airports might not need one and just run simplex.
Radios
(Note: I started at TSA in 2008, so what they used for radios prior to me starting is hazy and I can't find much on the Internet, unless the radios we were using in 2008, were there since day one.)
The first radios used were MotorolaXTS5000 P25 radios in Model I and Model III versions, along with XTL5000 consolette base stations and Motorola Quantar repeaters.
In 2009, as part of a major TSA project known as "Checkpoint Evolution", one of the sub-projects was introducing "Whisper Radios" to "quiet" the checkpoint. These "Whisper radios" were analog Icom F50V radios using voice inversion scrambling in an attempt to mask the communications.
In 2015, TSA completed a contract with RELM Wireless (now BK Technologies) to purchase their KNG series of P25 radios to replace both the Motorolas and the Icom "Whisper" radios. This acquisition only affected the portables and repeaters, which also came from RELM/BK. The Motorola consolettes remain, although most have been replaced by ones from Motorola's APX series of radios.
In 2018, TSA posted a request for information on FedBizOpps looking to once again upgrade their LMR infrastructure. However, there was something different about this solicitation, instead of once again requesting VHF radios, the TSA was requesting UHF radios instead.
It seems that TSA is going to give up the VHF frequencies for UHF frequencies, returning them to the FAA or having the National Telecommunications and Information Administration (NTIA) reassign them.
700/800 MHz Bands
I have seenoccasionalreferences on FedBizOpps to TSA acquiring radios that can be used in the 700 & 800 MHz public safety bands.
My scientific wild-ass guess is that it has to do with radio interoperability purposes allowing TSA and requisite airport and public safety authorities to communicate if need be.
TSA on Shortwave
Unlike many other government agencies, like some of the those in DHS, such as U.S. Customs and Border Protection (CBP), the Federal Emergency Management Administration (FEMA) or the U.S. Coast Guard, TSA never had the need for high frequency spectrum.
For example, CBP has COTHEN, the Customs Over The Horizon Enforcement Network, mostly for air and marine assets under CBP's Air and Marine Operations division. The Coast Guard has plenty of HF spectrum from being a military service. FEMA has the FEMA National Radio System (FNARS) and DHS' new Cybersecurity and Infrastructure Security Agency (CISA) runs the SHARES (SHAred RESources) HF network.
However, that all changed with Hurricane Katrina, TSA had communication problems with getting information between headquarters and Louis Armstrong New Orleans International Airport (MSY). Landline, mobile and even satellite phone service was impacted, according to former TSA Administrator Kip Hawley's book, Permanent Emergency.
In fact, TSA has three specialist positions dedicated solely to emergency communications for this purpose located strategically across the country, along with hundreds of other employees who possess an amateur radio licence and MARS training to operate the equipment TSA uses to participate in MARS.
Private Radios for Private Companies
When TSA was established, that previously mentioned sub-industry of aviation security companies didn't disappear. A pilot program was established that took five airports of the five security categories and had private security companies provide the screening personnel with TSA oversight. That pilot program evolved into the Screening Partnership Program or SPP.
As there are various private screening companies (and one airport itself handling screening, that being Jackson Hole Airport [JAC] in Wyoming) under contract and those contracts change every few years with new bids (or in one case revocation for performance), it's hard to keep track of what the private companies use for radios. Being that they want to keep things cheap, I'm assuming they use cheaper radios and from what I've heard, it's mostly been of the Digital Mobile Radio (DMR) variety.
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.
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.
A while back I blogged about how to listen to DMR using a SDR. I tried to do the same with D-Star, but was having problems. I ended up reaching out to the author. He just released a fix, so if you download / install from now on, you shouldn't run into the head banging that I was.
I am not going to lie, it doesn't sound the best. There was no information for coder's to work off of, so what we have is rather crude, but intelligible.
If you are looking to help improve it, start here. This is from the folks from the community that brought us what we have today.
There was also this tip from user "groovy"
If anybody wants to continue the research / work, I suggest you look
at the osmocom GMR code that Sylvain Munaut worked on. Those phones use
a similar codec - I believe with longer frames for the satellite
latency. Initially he used the mbelib code, enhanced it for things like
tone support, but he later rewrote the synthesis code completely. See
OsmocomGMR for his presentations and source code.
Unless other developers take this on, DVSI releases specs, or you switch
to a hardware-based decoder like the thumbDV, I don't see the dstar
voice quality improving in the short term.
I'd love to see further work on OP25. More so on the transmit part (hooked to analog radio, perhaps using the MMDVM hardware/Arduino.
Anyone care to join forces with Max?
Perhaps an update to Johnathan Naylor's (2009) GUI Linux client that
would decode and generate GMSK using a soundcard and interface to a
radio with a 9600 Baud packet connector. ..
Wouldn't mind a way to hook op25 to Allstar either :-)
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