Collected notes on the topic of radio communications.
Realize that the strict control of the ability to transmit is due to the fear of the state, they realize that radio is a decentralized form of communication that can be used to question their power.
Frequencies below about 30MHz are reflected off the atmosphere, thus they can follow the Earth's curvature. So these low frequency signals can sometimes be received by radios below the horizon hundreds of miles away. As a general rule, the lower the frequency, the greater distance it can travel. Unlike frequencies below 30MHz, radio waves in higher frequencies(VHF/UHF) travel in straight lines (line-of-sight) generally cannot travel beyond the horizon.
| VHF (Very High Frequency) | 130-174MHz |
| UHF (Ultra High Frequency) | 400-520MHz |
Multi-Use Radio Service
MURS comprises the following five frequencies:
| Channel | Frequency | Maximum authorized bandwidth | Channel name |
|---|---|---|---|
| 1 | 151.82 MHz | 11.25 kHz | MURS 1 |
| 2 | 151.88 MHz | 11.25 kHz | MURS 2 |
| 3 | 151.94 MHz | 11.25 kHz | MURS 3 |
| 4 | 154.57 MHz | 20.00 kHz | Blue Dot |
| 5 | 154.60 MHz | 20.00 kHz | Green Dot |
Family Radio Service
The FRS uses channelized frequencies around 462 and 467 MHz in the ultra high frequency (UHF) band.
Baofeng UV-9R Plus
- Frequency Range RX: 140-178/400-519MHz
- Frequency Range TX: 140-174/400-470MHz
- Channel Spacing: 2.5/5/6.25/12.5/20/25
- FM Radio Built-in 65.0MHz-108.0MHz
- Dual Watch/Dual Display/Dual Band
- PC Programable, Voice Prompt
- 50 CTCSS 105 CDCSS
- CTCSS Scanning
- 128 Channels