What is RF Modulation?
RF Modulation is how analog or digital information is conveyed using radio waves.
In technical terms, it’s transmitting a signal within a carrier frequency by combining an alternating frequency or amplitude onto the carrier wave.
Digital Modulation Techniques Used:
Below are familiar products or services, sorted into categories. All of these send digital information using RF from point A to point B. All of these can be implemented without an internet connection.
Category: Local Networking
Example application: Creating a LAN (Local Area Network) for sharing data (files) between multiple devices. Requires a central router, a “brain” to route data traffic to local IP addresses (server→client) using ftp or http.
IEEE standard of wireless local area networks; 802.11 (aka Wi-Fi) modulation: OFDM, BPSK, QAM
Frequency range: UHF→2.4-2.5 GHz, SHF→5.725-5.875 GHz (20/40/60/80 MHz BW)
IEEE standard of wired local area networks; 802.3 (aka S/UTP or “Ethernet”) modulation: PAM (some versions)
Frequency range: 1-2,000 MHz (depending on category) (BW depends on ethernet standard)
Category: One broadcast, Nearly Infinite Users
Example application: Sending live digital data to a nearly infinite amount of users using RF over the air
Radio Controlled Clocks (WWVB) modulation: ASK
Frequency range: LF→59.995 to 60.005 kHz (1 Hz BW)
Service is available legally for free? YES
ATSC 1.0 (digital broadcast television) modulation: 8VSB
Frequency range: VHF→54 to 72 MHz, 76 to 88 MHz, 174 to 216 MHz, UHF→470 to 608 MHz (6MHz BW)
Service is available legally for free? YES
ATSC 3.0 (digital broadcast television) modulation: OFDM w/ QPSK, QAM
Frequency range: VHF→54 to 72 MHz, 76 to 88 MHz, 174 to 216 MHz, UHF→470 to 608 MHz (6MHz BW)
Service is available legally for free? YES
HD Radio (digital data stream within FM and AM radio frequency bands) modulation: OFDM
Frequency range: MF→540 to 1600 kHz (up to 10 kHz BW*), VHF→88 to 108 MHz (up to 200kHz BW*)
Service is available legally for free? YES
Satellite TV modulation: QPSK, 8PSK, APSK, QAM
Frequency range: SHF→3.7 to 4.2 GHz (C-band), 18 to 27 GHz (K-band)
Service is available legally for free? YES (learn more at ftasat.wnyovertheair.com)
Category: One broadcast, Limited Users
Example application: A smartphone broadcasts a digital signal to a pair of headphones using RF over the air
Bluetooth modulation: GFSK, π/4 DQPSK, 8DPSK
Frequency range: UHF→2400 to 2483.5 MHz (including guard bands 2 MHz wide at the bottom and 3.5 MHz wide at the top)
The internet’s great, but there’s many ways to stay connected in this digital age without internet.
Wi-Fi ≠ Internet
Digital ≠ Internet
Also, most RF services are free too.
Tune an ATSC 1.0 transmission, send it over your LAN, and using Wi-Fi, stream it to your iPhone, and listen to it using Bluetooth headphones.
No internet required.