Category: Airband

RTLSDR-Airband V3 Released

Thanks to RTL-SDR.com reader Lee Donaghy for writing in and little us know that RTLSDR-Airband was recently updated to include SoapySDR support. This allows the software to now work with almost any SDR including the RTL-SDR, Airspy, SDRplay, HackRF, LimeSDR and more. They have also removed the 8-channels per device limitation and applied various bug fixes too. The full changelog is posted at the end of this post.

RTLSDR-Airband is a Linux based command line tool that allows you to simultaneously monitor multiple AM or FM channels per SDR within the same chunk of bandwidth. It is great for monitoring narrowband communications such as aircraft control and can be used to feed websites like liveatc.net, or for use with a Icecast server, or simply for continuously recording multiple channels to an MP3 file locally. It is also very useful for those running on low powered computing hardware who want software that uses less CPU power than a full GUI program like GQRX or CubicSDR.

Version 3.0.0 (Feb 10, 2018):

  • Major overhaul of the SDR input code - now it's modular and hardware-agnostic (no longer tightly coupled with librtlsdr).
  • Support for SoapySDR vendor-neutral SDR library - any SDR which has a plugin for SoapySDR shall now work in RTLSDR-Airband.
  • Support for Mirics DVB-T dongles via libmirisdr-4 library.
  • Support for RTLSDR is now optional and can be disabled at compilation stage.
  • Removed the 8-channels-per-device limit in multichannel mode.
  • Configurable per-device sampling rate.
  • Configurable FFT size.
  • Support for multibyte input samples.
  • Support for rawfile outputs (ie. writing raw I/Q data from a narrowband channel to a file for processing with other programs, line GNUradio or csdr).
  • INCOMPATIBLE CHANGE: removed rtlsdr_buffers global configuration option; buffer count can now be adjusted with a per-device "buffers" option.
  • INCOMPATIBLE CHANGE: removed syslog global configuration option; syslog logging is now enabled by default, both in foreground and background mode. To force logging to standard error, use -e command line option.
  • Added -F command line option for better cooperation with systemd. Runs the program in foreground, but without textual waterfalls. Together with -e it allows running rtl_airband as a service of type "simple" under systemd. Example rtl_airband.service file has been adjusted to reflect this change.
  • Added type device configuration option. It sets the device type (ie. the input driver which shall be used to talk to the device). "rtlsdr" is assumed as a default type for backward compatibility. If RTLSDR support has been disabled at compilation stage, then there is no default type - it must be set manually, or the program will throw an error on startup.
  • Frequencies in the config can now be expressed in Hz, kHz, MHz or GHz for improved readability.
  • Lots of bugfixes.
  • Rewritten documentation on Github Wiki.

Running a NAS, Torrentbox and ADS-B RTL-SDR Server all on the same Raspberry Pi 3

Most readers are familiar with the Raspberry Pi 3 and how it can be used with RTL-SDR applications such as ADS-B reception. However, one does not need to dedicate an entire Pi 3 to a single task as they are more than powerful enough to run multiple applications at once.

Over on his blog 'Radio for Everyone' Akos has uploaded a tutorial that shows how he set his Raspberry Pi 3 up as a simultaneous Network Attached Storage (NAS), Torrentbox  and ADS-B server. A NAS is simply a hard drive or other data storage device that can be accessed easily over a network instead of having to be connected directly to a PC. A torrentbox is a device such as a Raspberry Pi 3 running torrent software so that you can download torrent files 24/7 without needing a PC on all the time.

Akos' tutorial shows how to set everything up from scratch, starting from writing the Raspbian SD Card and connecting to it via SSH. He then goes on to show how to install the torrent software, set up the NAS and finally set up ADS-B reception.

Pi 3 as a NAS, torrentbox and ADS-B server.
Pi 3 as a NAS, torrentbox and ADS-B server.

New Product: RTL-SDR Blog 1090 MHz ADS-B LNA

We're happy to announce the release of our new high performance low noise amplifier (LNA) for improving 1090 MHz ADS-B reception. The LNA uses a low noise figure high linearity two stage MGA-13116 amplifier chip and three stages of filtering to ensure that strong signals or interference will not overload either the amplifier or SDR dongle.

The LNA is currently only available from our Chinese warehouse, and costs US$24.95 including shipping. Please note that the price may increase slightly in the future, and that Amazon USA may not be stocked until March.

Click here to visit our store

RTLBlog_LNA_Product_Flat
RTLBlog_LNA_Product_PCB_Flat

An LNA can help improve ADS-B reception by reducing the noise figure of the system and by helping to overcome losses in the coax cable and/or any other components such as switches and connector in the signal path. To get the best performance from an LNA, the LNA needs to be positioned close to the antenna, before the coax to the radio.

The gain of the RTL-SDR Blog ADS-B LNA is 27 dB's at 1090 MHz, and out of band signals are reduced by at least 60 - 80 dB's. Attenuation in the broadcast FM band and below 800 MHz is actually closer to over 100 dB's. In the LNA signal path there is first a low insertion loss high pass filter that reduces the strength of any broadcast FM, TV, pager or other similar signals that are usually extremely strong. Then in between the first and second stage of the LNA is a SAW filter tuned for 1090 MHz. A second SAW filter sits on the output of the LNA. The result is that strong out of band signals are significantly blocked, yet the LNA remains effective at 1090 MHz with a low ~1 dB noise figure.

The LNA is also protected against ESD damage with a gas discharge tube and low capacitance ESD diode. But please always remember that your antenna must also be properly grounded to prevent ESD damage.

Finally please note that this LNA requires bias tee power to work. Bias tee power is when the DC power comes through the coax cable. The RTL-SDR V3 has bias tee power built into it and this can be activated in software. See the V3 users guide for information on how to activate it. Alternatively if you don't own a dongle with bias tee built in, then an external bias tee can be used and those can be found fairly cheaply on eBay. Finally, if you are confident with soldering SMT components, then there are also pads and a 0 Ohm resistor slot on the PCB to install an LDO and power the LNA directly.

Specification Summary:

  • Frequency: 1090 MHz
  • Gain: 27 dB @ 1090 MHz
  • Return Loss: -16 dB @ 1090 MHz (SWR = 1.377)
  • Noise Figure: ~1 dB
  • Out of band attenuation: More than 60 dB
  • ESD Protection: Dual with GDT and ESD Diode
  • Power: 3.3 - 5V via bias tee only, 150 mA current draw
  • Enclosure: Aluminum enclosure
  • Connectors: Two SMA Female (Male to Male adapter included)

Testing

We tested our new LNA against another ADS-B LNA with filter built in that is sold by another company and the FlightAware Prostick+ dongle in an environment with strong out of band signals such as pagers, broadcast FM, DVB-T and GSM signals. The results showed that the RTL-SDR Blog ADS-B LNA gathered the most ADS-B packets. In the tests both LNA's were connected on the receiver side to be fair to the FA dongle. Improved performance could be achieved by moving the LNA to the antenna side.

Other ADS-B LNA vs RTL-SDR Blog ADS-B LNA Received Messages
FlightAware Prostick+ vs RTL-SDR Blog ADS-B LNA Received Messages

Checking in SDR# for out of band signals also showed that the RTL-SDR Blog ADS-B LNA significantly reduces those strong out of band signals, whereas the others have trouble blocking them out. Below we show the results as well as some measurements.

RTL Blog ADS-B LNA @ 1090 MHz

RTL Blog ADS-B LNA @ 1090 MHz

Other ADS-B LNA @ 1090 MHz

Other ADS-B LNA @ 1090 MHz

FlightAware Prostick+ @ 1090 MHz

FlightAware Prostick+ @ 1090 MHz

RTL Blog ADS-B LNA tuned to Broadcast FM

RTL Blog ADS-B LNA tuned to Broadcast FM

Other ADS-B LNA tuned to Broadcast FM

Other ADS-B LNA tuned to Broadcast FM

FlightAware Protstick+ tuned to Broadcast FM

FlightAware Protstick+ tuned to Broadcast FM

RTL Blog ADS-B LNA tuned to a DVB-T Signal

RTL Blog ADS-B LNA tuned to a DVB-T Signal

Other ADS-B LNA tuned to a DVB-T Signal

Other ADS-B LNA tuned to a DVB-T Signal

FlightAware Prostick+ tuned to a DVB-T Signal

FlightAware Prostick+ tuned to a DVB-T Signal

RTL Blog ADS-B LNA tuned to a GSM Signal

RTL Blog ADS-B LNA tuned to a GSM Signal

Other ADS-B LNA tuned to a GSM Signal

Other ADS-B LNA tuned to a GSM Signal

FlightAware Prostick+ tuned to a GSM Signal

FlightAware Prostick+ tuned to a GSM Signal

Gain Measurements

Gain Measurements

Return Loss

Return Loss

Simulated Gain/Attenuation

Simulated Gain/Attenuation

Conclusion

This RTL-SDR Blog ADS-B LNA can significantly improve ADS-B reception, especially if you are in an environment with strong out of band signals. Even if you are not, the low noise figure design will improve reception regardless.

RTLSDR-Airband V3 Released

Thanks to RTL-SDR.com reader Lee Donaghy for writing in and little us know that RTLSDR-Airband was recently updated to include SoapySDR support. This allows the software to now work with almost any SDR including the RTL-SDR, Airspy, SDRplay, HackRF, LimeSDR and more. They have also removed the 8-channels per device limitation and applied various bug fixes too. The full changelog is posted at the end of this post.

RTLSDR-Airband is a Linux based command line tool that allows you to simultaneously monitor multiple AM or FM channels per SDR within the same chunk of bandwidth. It is great for monitoring narrowband communications such as aircraft control and can be used to feed websites like liveatc.net, or for use with a Icecast server, or simply for continuously recording multiple channels to an MP3 file locally. It is also very useful for those running on low powered computing hardware who want software that uses less CPU power than a full GUI program like GQRX or CubicSDR.

Version 3.0.0 (Feb 10, 2018):

  • Major overhaul of the SDR input code - now it's modular and hardware-agnostic (no longer tightly coupled with librtlsdr).
  • Support for SoapySDR vendor-neutral SDR library - any SDR which has a plugin for SoapySDR shall now work in RTLSDR-Airband.
  • Support for Mirics DVB-T dongles via libmirisdr-4 library.
  • Support for RTLSDR is now optional and can be disabled at compilation stage.
  • Removed the 8-channels-per-device limit in multichannel mode.
  • Configurable per-device sampling rate.
  • Configurable FFT size.
  • Support for multibyte input samples.
  • Support for rawfile outputs (ie. writing raw I/Q data from a narrowband channel to a file for processing with other programs, line GNUradio or csdr).
  • INCOMPATIBLE CHANGE: removed rtlsdr_buffers global configuration option; buffer count can now be adjusted with a per-device "buffers" option.
  • INCOMPATIBLE CHANGE: removed syslog global configuration option; syslog logging is now enabled by default, both in foreground and background mode. To force logging to standard error, use -e command line option.
  • Added -F command line option for better cooperation with systemd. Runs the program in foreground, but without textual waterfalls. Together with -e it allows running rtl_airband as a service of type "simple" under systemd. Example rtl_airband.service file has been adjusted to reflect this change.
  • Added type device configuration option. It sets the device type (ie. the input driver which shall be used to talk to the device). "rtlsdr" is assumed as a default type for backward compatibility. If RTLSDR support has been disabled at compilation stage, then there is no default type - it must be set manually, or the program will throw an error on startup.
  • Frequencies in the config can now be expressed in Hz, kHz, MHz or GHz for improved readability.
  • Lots of bugfixes.
  • Rewritten documentation on Github Wiki.

Running a NAS, Torrentbox and ADS-B RTL-SDR Server all on the same Raspberry Pi 3

Most readers are familiar with the Raspberry Pi 3 and how it can be used with RTL-SDR applications such as ADS-B reception. However, one does not need to dedicate an entire Pi 3 to a single task as they are more than powerful enough to run multiple applications at once.

Over on his blog 'Radio for Everyone' Akos has uploaded a tutorial that shows how he set his Raspberry Pi 3 up as a simultaneous Network Attached Storage (NAS), Torrentbox  and ADS-B server. A NAS is simply a hard drive or other data storage device that can be accessed easily over a network instead of having to be connected directly to a PC. A torrentbox is a device such as a Raspberry Pi 3 running torrent software so that you can download torrent files 24/7 without needing a PC on all the time.

Akos' tutorial shows how to set everything up from scratch, starting from writing the Raspbian SD Card and connecting to it via SSH. He then goes on to show how to install the torrent software, set up the NAS and finally set up ADS-B reception.

Pi 3 as a NAS, torrentbox and ADS-B server.
Pi 3 as a NAS, torrentbox and ADS-B server.

New Product: RTL-SDR Blog 1090 MHz ADS-B LNA

We're happy to announce the release of our new high performance low noise amplifier (LNA) for improving 1090 MHz ADS-B reception. The LNA uses a low noise figure high linearity two stage MGA-13116 amplifier chip and three stages of filtering to ensure that strong signals or interference will not overload either the amplifier or SDR dongle.

The LNA is currently only available from our Chinese warehouse, and costs US$24.95 including shipping. Please note that the price may increase slightly in the future, and that Amazon USA may not be stocked until March.

Click here to visit our store

RTLBlog_LNA_Product_Flat
RTLBlog_LNA_Product_PCB_Flat

An LNA can help improve ADS-B reception by reducing the noise figure of the system and by helping to overcome losses in the coax cable and/or any other components such as switches and connector in the signal path. To get the best performance from an LNA, the LNA needs to be positioned close to the antenna, before the coax to the radio.

The gain of the RTL-SDR Blog ADS-B LNA is 27 dB's at 1090 MHz, and out of band signals are reduced by at least 60 - 80 dB's. Attenuation in the broadcast FM band and below 800 MHz is actually closer to over 100 dB's. In the LNA signal path there is first a low insertion loss high pass filter that reduces the strength of any broadcast FM, TV, pager or other similar signals that are usually extremely strong. Then in between the first and second stage of the LNA is a SAW filter tuned for 1090 MHz. A second SAW filter sits on the output of the LNA. The result is that strong out of band signals are significantly blocked, yet the LNA remains effective at 1090 MHz with a low ~1 dB noise figure.

The LNA is also protected against ESD damage with a gas discharge tube and low capacitance ESD diode. But please always remember that your antenna must also be properly grounded to prevent ESD damage.

Finally please note that this LNA requires bias tee power to work. Bias tee power is when the DC power comes through the coax cable. The RTL-SDR V3 has bias tee power built into it and this can be activated in software. See the V3 users guide for information on how to activate it. Alternatively if you don't own a dongle with bias tee built in, then an external bias tee can be used and those can be found fairly cheaply on eBay. Finally, if you are confident with soldering SMT components, then there are also pads and a 0 Ohm resistor slot on the PCB to install an LDO and power the LNA directly.

Specification Summary:

  • Frequency: 1090 MHz
  • Gain: 27 dB @ 1090 MHz
  • Return Loss: -16 dB @ 1090 MHz (SWR = 1.377)
  • Noise Figure: ~1 dB
  • Out of band attenuation: More than 60 dB
  • ESD Protection: Dual with GDT and ESD Diode
  • Power: 3.3 - 5V via bias tee only, 150 mA current draw
  • Enclosure: Aluminum enclosure
  • Connectors: Two SMA Female (Male to Male adapter included)

Testing

We tested our new LNA against another ADS-B LNA with filter built in that is sold by another company and the FlightAware Prostick+ dongle in an environment with strong out of band signals such as pagers, broadcast FM, DVB-T and GSM signals. The results showed that the RTL-SDR Blog ADS-B LNA gathered the most ADS-B packets. In the tests both LNA's were connected on the receiver side to be fair to the FA dongle. Improved performance could be achieved by moving the LNA to the antenna side.

Other ADS-B LNA vs RTL-SDR Blog ADS-B LNA Received Messages
FlightAware Prostick+ vs RTL-SDR Blog ADS-B LNA Received Messages

Checking in SDR# for out of band signals also showed that the RTL-SDR Blog ADS-B LNA significantly reduces those strong out of band signals, whereas the others have trouble blocking them out. Below we show the results as well as some measurements.

RTL Blog ADS-B LNA @ 1090 MHz

RTL Blog ADS-B LNA @ 1090 MHz

Other ADS-B LNA @ 1090 MHz

Other ADS-B LNA @ 1090 MHz

FlightAware Prostick+ @ 1090 MHz

FlightAware Prostick+ @ 1090 MHz

RTL Blog ADS-B LNA tuned to Broadcast FM

RTL Blog ADS-B LNA tuned to Broadcast FM

Other ADS-B LNA tuned to Broadcast FM

Other ADS-B LNA tuned to Broadcast FM

FlightAware Protstick+ tuned to Broadcast FM

FlightAware Protstick+ tuned to Broadcast FM

RTL Blog ADS-B LNA tuned to a DVB-T Signal

RTL Blog ADS-B LNA tuned to a DVB-T Signal

Other ADS-B LNA tuned to a DVB-T Signal

Other ADS-B LNA tuned to a DVB-T Signal

FlightAware Prostick+ tuned to a DVB-T Signal

FlightAware Prostick+ tuned to a DVB-T Signal

RTL Blog ADS-B LNA tuned to a GSM Signal

RTL Blog ADS-B LNA tuned to a GSM Signal

Other ADS-B LNA tuned to a GSM Signal

Other ADS-B LNA tuned to a GSM Signal

FlightAware Prostick+ tuned to a GSM Signal

FlightAware Prostick+ tuned to a GSM Signal

Gain Measurements

Gain Measurements

Return Loss

Return Loss

Simulated Gain/Attenuation

Simulated Gain/Attenuation

Conclusion

This RTL-SDR Blog ADS-B LNA can significantly improve ADS-B reception, especially if you are in an environment with strong out of band signals. Even if you are not, the low noise figure design will improve reception regardless.

Tom’s Radio Room Tests and Reviews the RTL-SDR Blog Multipurpose Dipole Kit

Over on his YouTube channel Tom Stiles (hamrad88) has been experimenting with and reviewing our multipurpose dipole kit. Tom is a ham radio YouTuber who runs a show that produces content often, so we encourage you to subcribe to his channel if you're interested. Tom reviewed our dipole kit over a series of 5 videos which we link here [1: Discussing the product], [2: Unboxing], [3: First ADS-B Tests], [4: Second ADS-B Tests], [5: Third ADS-B Tests]. We post have embedded video 2 and 5 below.

In his testing Tom finds that using the antenna in the vertical orientation improves ADS-B performance. This is expected as ADS-B signals are vertically polarized, and so the antenna should be too. By using the included suction cup mount Tom is able to get the antenna attached to his window which improves reception by getting the antenna as close to the outdoors as possible. This is an expected use case for the antenna, and it's good to see that good results are being had!

If you're interested in the set please see our store at www.rtl-sdr.com/store, or use the links provided in Tom's videos. We also have a tutorial and use case demonstrations for our dipole kit available at www.rtl-sdr.com/DIPOLE.

A High Performance RTL-SDR ADS-B Receiver Build Guide

ADS-B Setup in an outdoor enclosure. Includes FlightAware ADS-B Antenna, FlightAware RTL-SDR Dongle, Raspberry Pi, POE Splitter.
ADS-B Setup in an outdoor enclosure. Includes FlightAware ADS-B Antenna, FlightAware RTL-SDR Dongle, Raspberry Pi, POE Splitter.

Over on Imgur and Reddit user Mavericknos has uploaded a very nice pictorial guide where he shows how he's built a high performance RTL-SDR based ADS-B receiver that can be mounted outside in a waterproof enclosure.

He uses a FlightAware dongle, which is an RTL-SDR optimized for best ADS-B reception when placed directly at the mast/antenna. For an antenna he uses the FlightAware ADS-B antenna, which we've reviewed in the past and found to be one of the best value ADS-B antennas available on the market. To process the data, a Raspberry Pi is used and it is powered via power over Ethernet (POE). If you didn't already know, power over Ethernet (not to be confused with Ethernet over powerline) is simply running power through unused wires inside an Ethernet cable. It is a convenient method of powering remote devices and giving them a network connection at the same time. The whole package is enclosed in a waterproof case, and the antenna attached to the top.

Putting the RTL-SDR and computing device at the antenna removes any loss from long coax runs, and the POE connection provides a tidy cabling scheme. The FlightAware dongle is a good choice for mounting directly at the mast or antenna because it has a built in low noise figure LNA. If using coax cabling instead, and keeping the RTL-SDR and Raspberry Pi inside, then it would be better to mount an LNA at the mast and power it through the coax via a bias tee.

All components in the build.
All components in the build.

 

Outernet Dreamcatcher Setup with ADS-B dump1090 and PiAware Tutorial

The Outernet Dreamcatcher is a single board PC with a built in RTL-SDR. It has a TCXO and two SMA ports, one being amplified and filtered for L-band applications and the other being a regular port for all other applications.

With built in computing hardware the Dreamcatcher can be used as a standalone unit for various applications. As the Dreamcatcher is now on sale we've decided to create a brief tutorial that shows how to set one up as a cheap ADS-B aircraft radar receiver, and also how to set it up as a PiAware feeder. PiAware is software that allows you to feed FlightAware.com which is an ADS-B aggregatpr.

Any simple SMA antenna can be used, like our Dipole kit, an old RTL-SDR whip antenna, or even a short piece of wire.

We also have a previous review of the Dreamcatcher available here. In the past the main problem with the $59 USD Dreamcatcher was that you could get a more powerful Raspberry Pi 3 and RTL-SDR dongle for a similar price. But now at the sale price of $39 USD the Dreamcatcher is definitely a great deal.

Note that we'd recommend NOT purchasing the Dreamcatcher specifically for the Outernet data signal as we're unsure exactly how long that signal will continue to be broadcasting for. 

The Outernet Dreamcatcher
The Outernet Dreamcatcher

What follows below is a tutorial that shows how to set up a Dreamcatcher. The tutorial installs dump1090 at the same time, but afterwards could be used for a number of other applications.

Continue reading

RadioForEveryone New Posts: Antenna Weatherproofing, NooElec Nano 3 Review, ADS-B Antenna Shootout

Over on his blog 'Radio for Everyone' author Akos has uploaded three new posts. The first shows how to cheaply weatherproof antenna connections by wrapping electrical/plumbing tape around the connection. He shows and example with the FlightAware ADS-B antenna.

The second post is a review of the relatively new NooElec Nano 3, which is a small form factor RTL-SDR that comes with a TCXO and metal case. Akos shows how the form factor is good for using it with Mobile phones. Akos opens the unit up and shows us how the unit is sandwiched inside the metal case with two thermal pads for improved heat dissipation. Later in the review he also discusses the MCX connector, TCXO and heat.

The third post compares three commercially sold antennas at ADS-B reception. The compared antennas are the FlightAware ($45) and Jetvision ($90) ADS-B antennas as well as our RTL-SDR Blog general purpose dipole ($10). The results show that the Jetvision antenna performs the best followed by the FlightAware and then the dipole. However we note that Akos has incorrectly used the dipole as he did not orient it as a vertical dipole.

Radio For Everyone: Nano 3 Size Comparison
Radio For Everyone: Nano 3 Size Comparison

Showing what VOR and ILS Aviation Signals Look like in SDR#

Over on YouTube user RedWhiteandPew has uploaded two videos showing what VOR and ILS signals look like in SDR# with an RTL-SDR dongle. VOR and ILS are both radio signals used for navigation in aviation. 

VOR stands for VHF Omnidirectional Range and is a way to help aircraft navigate by using fixed ground based beacons. The beacons are specially designed in such a way that the aircraft can use the beacon to determine a bearing towards the VOR transmitter. VOR beacons are found between 108 MHz and 117.95 MHz.

RedWhiteandPew writes:

Here I am picking up the VOR beacon from KSJC. The coolest part is at the end of the video. I believe the signal moving back and forth is caused by the Doppler effect, because VORs transmit their signals in a circular pattern. The VOR wiki article has a GIF that shows how it works here https://en.wikipedia.org/wiki/VHF_omn…. If you play and pause the video at different points before I zoom in, you can see that the two signals on the side are the opposite phase.

ILS stands for Instrument Landing System and is a radio system that enables aircraft to land on a runway safely even without visual contact. It works by using highly directional antennas to create four directional lobes (two in the horizontal plane, two in the vertical) that are used to try and ensure the aircraft is centered and leveled on the approach correctly. The ILS frequencies are at 108.1 – 111.95 MHz for the horizontal ‘localizer’, and at 329.15-335.0 MHz for the vertical ‘glide slope’.

RedWhiteandPew writes:

Here I have tuned into one of KSJC’s ILS frequencies. You are able to hear the faint identifier beeping transmitting its ISL ID code which is ISJC. For comparison, I used to morse code translator website.

The reason I am hearing ISJC and not ISLV even though they are on the same frequency is because the localizers transmitting the signal are directional along the length of the runway. Since I am located to the south east of the airport, and I am within its transmitting beam, I am able to listen to it on a scanner.

If you’re interested in these signals then this previous post about actually decoding them might be of interest to you.