The RTL-SDR (RTL2832U-based Software Defined Radio) is a versatile device that can tune into a broad range of frequencies.
Depending on the specific model and configuration, the RTL-SDR can typically cover frequencies from 500 kHz to 1.75 GHz.
Here’s a detailed frequency list showing what you can listen to with an RTL-SDR, categorized by bands and types of communication:
Table of Contents
General Frequency Coverage of RTL-SDR
- Lower Bound: Approximately 500 kHz (with the RTL-SDR v4)
- Upper Bound: Approximately 1.75 GHz (1700 MHz to 1766 MHz, depending on the tuner).
Common Frequency Bands and Uses for RTL-SDR
HF (High Frequency) Band (3 MHz – 30 MHz)
Note: Listening to HF frequencies with an earlier version of RTL-SDR often requires upconverters or direct sampling modifications.
- 3.5 – 4.0 MHz: 80-meter amateur radio band.
- 7.0 – 7.3 MHz: 40-meter amateur radio band.
- 10.1 – 10.15 MHz: 30-meter amateur radio band.
- 14.0 – 14.35 MHz: 20-meter amateur radio band.
- 18.068 – 18.168 MHz: 17-meter amateur radio band.
- 21.0 – 21.45 MHz: 15-meter amateur radio band.
- 24.89 – 24.99 MHz: 12-meter amateur radio band.
- 28.0 – 29.7 MHz: 10-meter amateur radio band.
VHF (Very High Frequency) Band (30 MHz – 300 MHz)
- 30 – 50 MHz: VHF low band, used for various communications including public safety and business.
- 50 – 54 MHz: 6-meter amateur radio band.
- 54 – 88 MHz: TV broadcast channels 2-6 (not used for TV in many regions anymore).
- 88 – 108 MHz: FM broadcast band.
- 108 – 137 MHz: Airband for VHF aircraft communications.
- 118 – 137 MHz: Civil aircraft communications.
- 137 – 144 MHz: Weather satellites and data transmission (NOAA satellites).
- 144 – 148 MHz: 2-meter amateur radio band.
- 148 – 174 MHz: VHF high band, used for public safety, business, and marine communications.
- 154.570 and 154.600 MHz: MURS (Multi-Use Radio Service) channels.
- 162.400 – 162.550 MHz: NOAA weather radio frequencies.
- 156.050 – 162.025 MHz: Marine VHF communication channels.
- 174 – 216 MHz: TV broadcast channels 7-13.
UHF (Ultra High Frequency) Band (300 MHz – 3 GHz)
- 300 – 450 MHz: Military, satellite, and various commercial communications.
- 380 – 400 MHz: Government and military communication.
- 406 – 420 MHz: Government and public safety.
- 430 – 450 MHz: 70-centimeter amateur radio band.
- 450 – 470 MHz: UHF business band and public safety.
- 462.550 – 462.725 MHz: GMRS (General Mobile Radio Service) channels.
- 467.550 – 467.725 MHz: GMRS repeater input frequencies.
- 470 – 512 MHz: UHF TV channels 14-20 (used for various communications in some regions).
- 512 – 698 MHz: TV broadcast channels 21-51 (in the process of being repurposed in many regions).
- 698 – 806 MHz: LTE band and public safety.
- 806 – 902 MHz: Various commercial and public safety communications.
- 902 – 928 MHz: ISM band (Industrial, Scientific, and Medical).
- Used for unlicensed communication, including some amateur radio (33 cm band) and low-power devices.
- 928 – 960 MHz: Paging and commercial communication.
- 1240 – 1300 MHz: 23-centimeter amateur radio band.
- 1300 – 1700 MHz: Military and commercial communication, including radar and satellite downlinks.
Notable Signals to Explore
Broadcast FM Radio (88 – 108 MHz)
- Popular music and talk radio stations.
Weather Satellites (137 – 138 MHz)
- NOAA satellite weather images and data.
Air Traffic Control (118 – 137 MHz)
- Communications between aircraft and ground controllers.
Marine VHF (156 – 162 MHz)
- Ship-to-ship and ship-to-shore communications.
Amateur Radio Bands (Various)
- Conversations, digital modes, and experiments by ham radio operators.
Public Safety and Business Radio (150 – 174 MHz, 450 – 470 MHz)
- Police, fire, EMS, and commercial communications.
NOAA Weather Radio (162.400 – 162.550 MHz)
- Continuous weather updates and alerts.
Amateur Satellite (145.8 – 146.0 MHz and 435 – 438 MHz)
- Communication with orbiting satellites.
TV Signals (54 – 88 MHz, 174 – 216 MHz, 470 – 698 MHz)
- Over-the-air TV broadcasts (varies by region).
Digital Modes and Data
Decoding modes like ACARS (aircraft), AIS (ship tracking), and ADS-B (aircraft position data).
Tips for Using RTL-SDR
- Antenna: Use the appropriate antenna for the frequency range you are interested in. Multi-band antennas or specific antennas for HF, VHF, or UHF can significantly improve reception.
- Software: Use SDR software like SDR#, HDSDR, or GQRX to scan and decode different frequencies.
- Adjust Settings: Experiment with gain, bandwidth, and filter settings in your SDR software to optimize signal reception.
- Legal Compliance: Always ensure you are compliant with local regulations regarding listening and decoding certain frequencies.
Summary
With an RTL-SDR, you can explore a vast range of frequencies and discover many interesting signals. Whether you’re into listening to aircraft communications, monitoring weather satellites, or exploring amateur radio bands, the RTL-SDR provides a gateway to the fascinating world of radio waves.
Of course! Here is a comprehensive list of Frequently Asked Questions (FAQs) for an article on RTL-SDR frequency lists, structured to be helpful for both beginners and experienced users.
Frequently Asked Questions
Basics & Getting Started
Q1: What is an RTL-SDR?
A: An RTL-SDR is a very inexpensive USB software-defined radio (SDR) dongle. Originally designed for receiving digital TV (DVB-T), it was discovered that with special software, it could be used as a wideband radio scanner to listen to a vast range of radio signals.
Q2: What is a frequency list and why do I need one?
A: A frequency list is a curated catalog of known radio frequencies and their purposes (e.g., 121.500 MHz for aviation emergency). The RTL-SDR can tune across a huge spectrum, and a frequency list acts like a map, telling you where to find interesting signals instead of searching blindly through static.
Q3: What frequencies can the RTL-SDR actually receive?
A: Most common RTL-SDR dongles (like the RTL2832U and R820T2) can typically receive signals from approximately 24 MHz to 1766 MHz. This covers a massive range including air traffic, public safety radio, FM radio, amateur radio, weather satellites, and much more. Note: they cannot transmit, only receive.
Q4: Is it legal to listen to these frequencies?
A: In most countries, it is perfectly legal to listen to any radio transmission that is not intentionally encrypted (like military or certain government communications) or is not considered a “private” two-way conversation (e.g., cell phones, which are also encrypted and outside the RTL-SDR’s range anyway). It is illegal to divulge or act upon the content of any transmission you are not intended to hear. Always check your local laws.
Finding & Using Frequencies
Q5: Where can I find a good frequency list for my area?
A: The best lists are local. Great resources include:
- RadioReference.com: The best source for up-to-date, location-based frequencies for public safety, aviation, and business radio (especially for the US/Canada).
- Local amateur radio clubs: Ham radio operators often have detailed local knowledge.
- National databases: For things like NOAA weather radio, air traffic control, and railroad frequencies, which are often standardized nationally.
- Satellite frequency lists: Websites like RTL-SDR.com and SatNOGS maintain lists for NOAA and other satellites.
Q6: I put in a frequency but I only hear noise or a weird digital buzzing. Why?
A: This is common! You are likely hearing one of two things:
- A digital modulation mode: Signals like P25 (used by police), DMR, or NXDN sound like loud buzzing or gargling to your ears. You need special software like DSD+ Fast Lane or SDR# with the right plugin to decode them into audio.
- Encrypted traffic: The transmission is scrambled and cannot be decoded, even with the right software.
Q7: How do I know what type of signal I’m looking at (e.g., FM, AM, USB)?
A: Your SDR software (like SDR#, SDR++, etc.) has a “mode” or “demodulation” selector. Common modes are:
- WFM: Wide FM (for FM radio broadcasts).
- NFM: Narrow FM (for most two-way communications like police, fire, and business radios).
- AM: Amplitude Modulation (for aircraft, AM radio, and some older systems).
- USB/LSB: Upper/Lower Sideband (used by amateur radio operators and HF communications).
Q8: What are some “cool” or common frequencies to start with?
A: Here are some reliable and often active ones to get you started:
- NOAA Weather Radio: 162.400, 162.425, 162.450, 162.475, 162.500, 162.525, 162.550 MHz (US/Canada).
- Airband – Aircraft Emergencies: 121.500 MHz (VHF Guard).
- Airband – Air Traffic Control: Search for your local airport’s tower/approach frequencies on RadioReference.
- FM Radio Broadcast Band: 87.5 – 108.0 MHz (obviously!).
- Marine VHF: Channel 16 (156.800 MHz) is the international hailing and distress channel.
Technical & Troubleshooting
Q9: I see a strong signal on my waterfall display, but I can’t hear anything. What’s wrong?
A: Check these common issues:
- Wrong Mode: You’re likely using the wrong demodulator. A police signal (NFM) will be silent if you have the mode set to AM.
- Squelch: Your squelch setting might be too high, blocking the audio. Turn it down.
- Muted Audio: Check your audio output settings in the SDR software and your computer’s volume.
Q10: Why do I need an upconverter?
A: The standard RTL-SDR has poor performance below roughly 24-30 MHz, which is the HF/shortwave band. An upconverter is a device that shifts these low frequencies up into a range where the RTL-SDR can receive them well, allowing you to listen to international shortwave broadcasts, amateur radio HF bands, and more.
Q11: My signals seem weak. How can I improve reception?
A: The tiny antenna that comes with the RTL-SDR is notoriously poor.
- Get a better antenna: A simple discone or dipole antenna designed for the frequencies you’re interested in will make a massive difference.
- Get it outside/by a window: Place the antenna as high and clear of obstructions as possible.
- Use an LNA (Low-Noise Amplifier): This boosts weak signals before they enter the dongle, which is especially useful for receiving satellites.
Q12: What software should I use with my RTL-SDR?
A: Popular choices include:
- SDR# (SDRSharp): Very popular for Windows, great for beginners.
- SDR++: Cross-platform (Windows, Mac, Linux), modern, and feature-rich.
- GQRX: The standard for Linux and Mac users.
- SDRangel: Very powerful and advanced, for complex tasks like satellite decoding.
Disclaimer: This information is for educational purposes only. Always comply with your local laws and regulations regarding radio reception.