vhf and uhf

[cucinadio]

yhea i know im pretty green when it come to thingd but guys could someone please tell me the differance between the two!!!!

cheers

[JDNSW]

Difference in frequency - the names refer to two different bands of radio frequencies - VHF 30-300MHz, UHF 300-3000MHz.

But I think you may be referring to the two "CB" bands.

The first one, sometimes referred to as VHF, operates around 27MHz so is strictly HF not VHF. It operates with either AM or SSB modulation. Equipment is cheap and readily available, effective antennae are quite large. Reliable range is a little more than line of sight, but very long range, even worldwide, is not uncommon, and is, in fact, one of the problems - you can expect to get a lot of interference from anywhere. Now much less popular than it used to be, but still quite a few with it.

The newer, UHF system, operates around 477MHz, using FM modulation. Range is a little more than line of sight. Equipment is readily available, although a bit dearer, and very cheap handhelds have become available in recent years. A lot less interference, although it is so popular that there may be problems in urban areas. Most long distance trucks carry it, as do most rural emergency vehicles, and it is used with many rural homesteads and farm vehicles. Antenae are a lot smaller than the 27MHz ones for the same gain.

Both bands can be used without a licence for either the equipment or operator, an input power is limited by law to 5w. Particularly in the UHF band this is not much of a drawback, as the only advantage of higher power is to talk over the top of others, since increased power does little to increase range.

John

[Xavie]

JDNSW, i could be wrong but it looks like your crossing true cb or 27mhz radio with vhf?

My understanding was more that VHF is used marine and Aircraft and that the gear was much more expensive then 27mhz and more in line with UHF costs.

It is not that widely used for recreation purposes and more for industry but it has good quality line of sight appeal but that's about it for Rec. users.

Xavier

[Lotz-A-Landies]

yhea i know im pretty green when it come to thingd but guys could someone please tell me the differance between the two!!!!

cheers
Everyone has to learn sometimes.

UHF and VHF refer to the bands or range of frequencies that the radio operates in.

UHF is the abbreviation for Ultra High Frequency
VHF is the abbreviation for Very High Frequency
another one you may want to know about is High Frequency (HF)

For 4WD purposes the main ones people want to know about are the Citizens Band ( CB ) frequencies and also some of the lower HF frequencies which are used for outback travel VKS737 and RFDS radios.

CB Radios
There are two sets of frequencies allocated to the Citizens Bands, which can be used by members of the public at no licence fee provided they use approved equipment.

27MHz (HF) CB 40 channels 5 watts between 26.965 MHz and 27.405 MHz in amplitude modulation, rarely used these days, gives reasonable cover for hilly terrain over distances of between 5 to 15 Kilometres, the AM sign wave be split into half waveforms (Single Side Band) which allows the signal to be skipped over hundreds of kilometres (unreliably so don't count on it as your only form of emergency backup).

UHF CB (477 MHz) 40 channels 5 watts between 476.425 MHz to 477.400 MHz in frequency modulation. Basically line of sight communication, affected by hilly terrain up to distances of only about 5 kilometers, although there are UHF repeaters in cities and along major highways that allow transmissions via the repeater over longer distances.

HF VKS737 and the Royal Flying Doctor Service maintain frequencies operating in the low frequencies of the HF band 3 MHz to 13 MHz using powerful transceivers. A licence is required to operate a set in the HF spectrum. A mobile HF set is usually able to transmit with a power of 100 watts and have reliable communications of more than 20 kilometres using line of sight and thousands of kilometres using atmospheric skip. These are ideal for remote travel and a handful of bases spread across the country can give cover to the whole continent. Many new HF sets can also do telephone interconnection (telcall) where you "beacon" a telcall base-station and it connects your radio into the telephone system.

Very High Frequency - is limited to commercial, marine and aviation use and a licence is required. They operate in FM usually at 25 watts and give reasonable communication over 20 to 25 Kilometres. The LROCV maintains a VHF channel licence and members can apply to join the network.

Hope this helps a little.

Diana

[JDNSW]

JDNSW, i could be wrong but it looks like your crossing true cb or 27mhz radio with vhf?

My understanding was more that VHF is used marine and Aircraft and that the gear was much more expensive then 27mhz and more in line with UHF costs.

It is not that widely used for recreation purposes and more for industry but it has good quality line of sight appeal but that's about it for Rec. users.

Xavier

You are right, and as I said, 27MHz is not VHF, but I suspect that is what the original question was aiming at.

VHF is not available for any two way transmissions except by licenced stations and licenced operators. The main VHF communications bands are Marine - 156 - 62MHz and Aviation 108-136MHz, both of which are long established international bands, and both are used by both recreational and professional operators, and as I said all stations and operators are licenced (I have both marine and aviation licences, for example) (maximum power in both is normally 25w, particularly useful in aviation where line of sight can be a very long way). Also in the VHF band are some television channels and the FM broadcast band.

John

[cucinadio]

Difference in frequency - the names refer to two different bands of radio frequencies - VHF 30-300MHz, UHF 300-3000MHz.

But I think you may be referring to the two "CB" bands.

The first one, sometimes referred to as VHF, operates around 27MHz so is strictly HF not VHF. It operates with either AM or SSB modulation. Equipment is cheap and readily available, effective antennae are quite large. Reliable range is a little more than line of sight, but very long range, even worldwide, is not uncommon, and is, in fact, one of the problems - you can expect to get a lot of interference from anywhere. Now much less popular than it used to be, but still quite a few with it.

The newer, UHF system, operates around 477MHz, using FM modulation. Range is a little more than line of sight. Equipment is readily available, although a bit dearer, and very cheap handhelds have become available in recent years. A lot less interference, although it is so popular that there may be problems in urban areas. Most long distance trucks carry it, as do most rural emergency vehicles, and it is used with many rural homesteads and farm vehicles. Antenae are a lot smaller than the 27MHz ones for the same gain.

Both bands can be used without a licence for either the equipment or operator, an input power is limited by law to 5w. Particularly in the UHF band this is not much of a drawback, as the only advantage of higher power is to talk over the top of others, since increased power does little to increase range.

John


JDNSW, i could be wrong but it looks like your crossing true cb or 27mhz radio with vhf?

My understanding was more that VHF is used marine and Aircraft and that the gear was much more expensive then 27mhz and more in line with UHF costs.

It is not that widely used for recreation purposes and more for industry but it has good quality line of sight appeal but that's about it for Rec. users.

Xavier


Everyone has to learn sometimes.

UHF and VHF refer to the bands or range of frequencies that the radio operates in.

UHF is the abbreviation for Ultra High Frequency
VHF is the abbreviation for Very High Frequency
another one you may want to know about is High Frequency (HF)

For 4WD purposes the main ones people want to know about are the Citizens Band ( CB ) frequencies and also some of the lower HF frequencies which are used for outback travel VKS737 and RFDS radios.

CB Radios
There are two sets of frequencies allocated to the Citizens Bands, which can be used by members of the public at no licence fee provided they use approved equipment.

27MHz (HF) CB 40 channels 5 watts between 26.965 MHz and 27.405 MHz in amplitude modulation, rarely used these days, gives reasonable cover for hilly terrain over distances of between 5 to 15 Kilometres, the AM sign wave be split into half waveforms (Single Side Band) which allows the signal to be skipped over hundreds of kilometres (unreliably so don't count on it as your only form of emergency backup).

UHF CB (477 MHz) 40 channels 5 watts between 476.425 MHz to 477.400 MHz in frequency modulation. Basically line of sight communication, affected by hilly terrain up to distances of only about 5 kilometers, although there are UHF repeaters in cities and along major highways that allow transmissions via the repeater over longer distances.

HF VKS737 and the Royal Flying Doctor Service maintain frequencies operating in the low frequencies of the HF band 3 MHz to 13 MHz using powerful transceivers. A licence is required to operate a set in the HF spectrum. A mobile HF set is usually able to transmit with a power of 100 watts and have reliable communications of more than 20 kilometres using line of sight and thousands of kilometres using atmospheric skip. These are ideal for remote travel and a handful of bases spread across the country can give cover to the whole continent. Many new HF sets can also do telephone interconnection (telcall) where you "beacon" a telcall base-station and it connects your radio into the telephone system.

Very High Frequency - is limited to commercial, marine and aviation use and a licence is required. They operate in FM usually at 25 watts and give reasonable communication over 20 to 25 Kilometres. The LROCV maintains a VHF channel licence and members can apply to join the network.

Hope this helps a little.

Diana


You are right, and as I said, 27MHz is not VHF, but I suspect that is what the original question was aiming at.

VHF is not available for any two way transmissions except by licenced stations and licenced operators. The main VHF communications bands are Marine - 156 - 62MHz and Aviation 108-136MHz, both of which are long established international bands, and both are used by both recreational and professional operators, and as I said all stations and operators are licenced (I have both marine and aviation licences, for example) (maximum power in both is normally 25w, particularly useful in aviation where line of sight can be a very long way). Also in the VHF band are some television channels and the FM broadcast band.

John


grazi guys,

very good explanation and i get now and as i allways say " you learn somthing every day"


cheers guys :twobeers: