HF — VHF — UHF
Date: 2023-03-01Last modified: 2023-03-07
Table of contents
Each operational frequency comes with its own advantages and disadvantages. But overall, VHF radios are better for outdoor use in large areas, and UHF radios are better for indoor or outdoor settings that are in close proximity.
UHF — Ultra High Frequency
- Between 300 MHz and 3 GHz
- UHF radio waves propagate mainly by line of sight
- They are blocked by hills and large buildings although the transmission through building walls is strong enough for indoor reception
- They are used for:
- television broadcasting
- cell phones
- satellite communication including GPS
- personal radio services including Wi-Fi and Bluetooth
- cordless phones
- The IEEE defines the UHF radar band as frequencies between 300 MHz and 1 GHz.
- Two other IEEE radar bands overlap the ITU UHF band:
- the L band between 1 and 2 GHz
- the S band between 2 and 4 GHz
- One of the biggest pros of UHF radios is that they do a much better job of penetrating barriers in urban locations, like concrete, steel, and wood.
- So this kind of radio is best suited for use indoors, including buildings with multiple floors, in industries such as:
- They also work well for businesses that function in both indoor and outdoor settings, where there are a lot of surrounding buildings.
VHF — Very high frequency
- From 30 MHz to 300 MHz
- Frequencies immediately below VHF are denoted high frequency (HF)
- The next higher frequencies are known as ultra high frequency (UHF)
- Common uses for VHF are:
- FM radio broadcasting
- television broadcasting
- two way land mobile radio systems (emergency, business, private use and military)
- long range data communication up to several tens of kilometers with radio modems
- amateur radio
- marine communications
- Air traffic control communications and air navigation systems (e.g. VOR, DME & ILS) work at distances of 100 kilometers or more to aircraft at cruising altitude.
- VHF was used for analog television stations in the US, and continues to be used for digital television.
- VHF band was an early choice for manpack radios used by ground troops to communicate within a local eight kilometer (five mile) area or so.
- Unlike HF, VHF transmissions lack the ability to utilize the Ionosphere and are limited to line-of-sight (LOS) communication
- This reduces radio emission clutter throughout an extended battlefield and limits the vulnerability to unfriendly interception.
HF — High frequency
- Between 1.6 MHz and 30 MHz
- The HF band is a major part of the shortwave band of frequencies
- Communication at these frequencies is often called shortwave radio
- Because radio waves in this band can be reflected back to Earth by the ionosphere layer in the atmosphere – a method known as “skip” or “skywave” propagation – these frequencies are suitable for long-distance communication across intercontinental distances.
- SSB — Single Side Band, a layer of ionization gases that resides between 100 and 700 km above the Earth surface.
- The band is used by international shortwave broadcasting stations (2.310
- 25.820 MHz), aviation communication, government time stations, weather stations, amateur radio and citizens band services, among other uses.
- Is vital for base stations communicating with each other over vast distances
- Is useful for linking remote regions to the outside world, as HF radio communications is not reliant on conventional communications infrastructure.
- STANAG 4539(QAM)
- coded data rates from 75 to 9600 bps
- uncoded data rate of 12k8 bps
- STANAG 4285(PSK)
- STANAG 4415(PSK NATO robust)
- STANAG 4529 (NB PSK)
- MIL-STD-188-110A (PSK)
- MIL-STD-188-110B Appendix F (QAM, ISB)