About Band Plans
What is a band plan?
A band plan is an agreement that divides the RF spectrum into different bands or segments for different uses.
Internationally, the International Telecommunications Union (ITU) is responsible for allocating bands for each service such as fixed, mobile, broadcasting or amateur. Most countries follow the ITU frequency allocations very closely, but each country also has the right to vary its frequency allocations to suit local conditions.
In Australia, spectrum management is the responsibility of the Australian Communications and Media Authority (ACMA). It determines frequency allocations for all transmitting stations in Australia and its territories.
Band planning within the amateur bands follows the same pattern as international and national band planning. To make the best use of the available spectrum, our bands are divided into segments that are used for different purposes.
Why are band plans important?
Amateurs use a wide variety of different modes. Within one amateur band, activity can include CW, voice, satellite activity, digital modes and ATV. The best way of avoiding clashes is to set aside different band segments for each of these activities, so that we can all follow our own particular interests without causing interference to each other.
Apart from avoiding interference, band plans make it easier for us to find other amateurs with the same interests. If we want to make a CW or digital contact, or swap an SSTV picture, or just have a chat, we just need to check the band plan to see which frequencies are used for these different activities.
Band planning guidelines
Band plans need to be based on a number of factors:
They should take local conditions into account, but they should follow national and international practice where possible.
They should encourage spectrum efficiency, but they also need to provide each operating mode with a fair share of spectrum space.
They should take the popularity of each mode into account, while still providing enough spectrum space for less popular activities. For example, ATV requires far more bandwidth per operator than other modes. And activities such as EME are important regardless of the number of stations involved.
Band plans need to be flexible enough to adapt to changing needs, but they tend to lose support if they become too complex, or if they are changed too often. The aim must be to think ahead and to make sure that future options are not closed off.
Some operating modes require exclusive band segments, but others can coexist with similar modes in the same part of the band. So our bands plans will include a mixture of exclusive and shared segments.
HF band plans
On the HF bands, the band plans are divided into three main segments for the three most popular modes. The division is based on whether or not the mode can be copied by ear, and also on the amount of bandwidth it requires.
CW - no longer compulsory but still very popular;
Digital data modes including RTTY, packet and newer digital modes;
On most HF bands, the band plan reserves about 20 per cent of the band for CW, about 10 per cent for digital data modes, and the rest for SSB. These different segments are subject to change over time as operating habits change.
The division into three basic mode groups also accommodates other modes:
AM: There is also some AM activity, mainly in the upper end of the SSB segments of the 160 and 80 metre bands.
SSTV: Image modes such as SSTV are sent as SSB signals, so these modes are used on internationally standard frequencies within the SSB segment.
Beacons: On bands between 30 metres and 10 metres, there are also spot frequencies or band segments reserved for beacons. Most beacons use CW but they have their own exclusive frequencies to avoid interference to or from other stations.
FM operation: There is FM activity - both simplex and repeaters - on frequencies above 29 MHz, so the 10 metre band plan has a separate FM segment. (FM is not used on lower bands because of its wide bandwidth.)
VHF-UHF and microwave band plans
The VHF-UHF band plans are more complex because of the wider range of different modes used on these bands. These modes range from narrow band weak signal modes to wideband data or ATV.
The four main divisions in the VHF-UHF band plans are:
Weak signal modes:
The weak signal segments are used for DX operation. The weak signal segment of each VHF-UHF band includes recommended frequencies or segments for CW, SSB and narrow band digital modes. Weak signal operators tend to switch between SSB and CW to suit the conditions, so most CW activity is on, or close to, the SSB calling frequency. Digital modes have separate frequencies because they cannot be copied by ear.
The weak signal segment in each VHF-UHF band occupies 400 kHz. Immediately above the weak signal segment in each band there is a 200 kHz segment for beacons. The weak signal and beacon segments should be kept clear of other activity - it is easy to accidentally cause interference to a signal that may be too weak to hear.
FM simplex and repeater segments:
FM is not compatible with modes like CW and SSB, so each band plan includes separate segments for FM. These segments are further divided into separate channels for simplex and repeater activity. The FM segments also include recommended frequencies for modes such as packet and SSTV, which normally use FM mode on these bands. On 70 cm and higher bands, there are also band segments reserved for use by repeater links.
New digital voice repeaters also operate in the same band segments as FM repeaters.
These segments are kept clear for stations working AMSAT satellites.
On 70 cm and higher bands, there is enough spectrum to allow the use of fast-scan ATV and wideband data modes. These modes require a large bandwidth but have a low power density, so they operate in their own exclusive band segments.
Calling frequencies are not used on the HF bands. But on the VHF-UHF bands, the band plans include various calling frequencies for different purposes, including weak signal DX calling frequencies and national FM calling frequencies. These frequencies are "meeting places" and should be used only to make initial contact before moving to another frequency. If someone is "hogging" the frequency, nobody else can make calls or hear calls from other stations.
Frequencies and band segments for special purposes
The VHF-UHF band plans include band segments and frequencies for special purposes. These include:
Packet radio and APRS;
Non-voice modes like SSTV and RTTY;
Simplex IRLP or Echolink gateways;
Channels reserved for use by WICEN;
On the 70cm and higher bands, segments for wideband modes including ATV.
These channels or band segments should be kept clear of other activity so they can be used for their particular purposes.
Keeping the band plans up to date
The band plans are always under review, to keep up to date with new operating techniques and changing patterns of activity. The band plans apply in all states, so any proposed changes need to be discussed to avoid any conflicts or clashes. It is also important to make band plan changes in an evolutionary way - nobody likes too many changes too often.
If a proposed new application or technique requires a change to the band plan, or if you are aware of any band planning problems in your area, please advise the Technical Advisory Committee. The email address is firstname.lastname@example.org.
Further details of the current band plans and related material are on the Band Plan Data page - click this Link.
Page Last Updated: Saturday 8 October 2011 at 16:49 hours