New CH for UHF CB From 40-80ch From ACMA

[raymond999]

There are a number of options relating to the technical framework for licensing use of the 400 MHz band that are being explored. In broad terms these can be grouped into options related to:

reduced channel bandwidth and re-packing;

increased spectrum sharing; and

facilitating change of use of the spectrum.

Each is discussed below. The options are not mutually exclusive. It may be optimal to pursue some of the options to increase spectrum sharing and options to reduce channel bandwidth and re-pack the spectrum.


Reduced channel bandwidth and re-packing

Use of analog FM radio equipment requiring 25 kHz channels is well established in the 400 MHz band and has been for many years. Overall, around 70 per cent of the frequency assignments in the 400 MHz band are to systems using 25 kHz or greater bandwidth.

Use of the 400 MHz band is dominated by the land mobile and fixed (point-to-point) services. Table 2 shows the percentage of assignments above and below or equal to 12.5 kHz bandwidth for these service types.

Table 2: Bandwidth percentage – Land Mobile and Fixed (Point-to-Point) Assignments

For the land mobile service, 63.1 per cent of frequency assignments are to 25 kHz channels, implying that around this percentage of equipment in use requires a bandwidth of 25 kHz. There appears to be scope to significantly decrease the amount of spectrum used for the land mobile service by moving towards increased use of 12.5 kHz equipment. Land mobile equipment using 12.5 kHz channels is readily available and offers virtually identical performance to 25 kHz equipment.

For the fixed (point-to-point) service, 25 kHz equipment dominates, accounting for 97.7 per cent of assignments. A justification for a 25 kHz (or greater) bandwidth requirement for point-to-point links is to support higher data rates for digital signals.



Table 3 shows the type of emission carried by these links: analog telephony or a digital signal. It shows that 72 per cent carry analog voice and 28 per cent of them carry digital information. The digital systems are potentially unable to move to narrower bandwidths due to data rate requirements. The analog systems, however, have the potential to reduce bandwidth to 12.5 kHz.

Table 3: Breakdown of emission types for land mobile and fixed (point-topoint) assignments


Overall growth in the number of radio systems in congested areas can be achieved by freeing up more spectrum. There appears to be scope for a migration of all land mobile and most fixed (point-to-point) systems from 25 kHz to 12.5 kHz.

A process of ‘channel splitting’, whereby an occupied 25 kHz channel is converted to two 12.5 kHz channels, may be used to make new channels available.1 This practice is evident in Sydney and Brisbane where growth in the overall number of land mobile systems operating in accordance with the 400 MHz Plan has occurred despite congestion of the band.2

Figure 4 shows spectrum use for land mobile services in south eastern Australia in Segment K of the 400 MHz Plan.3

The figure on the left represents the current deployment, where both 12.5 kHz and 25 kHz services are in operation. The figure on the right demonstrates the reduction in licence congestion in the event that all existing 25 kHz services were converted to 12.5 kHz bandwidth.


1 Although the splitting of 25 kHz channels is not consistent with the 400 MHz plan, accredited persons are able to assign 12.5 kHz services in segments of the band designated for 25 kHz channelling. This is possible because the 400 MHz plan is an administrative band plan, and therefore lacks the statutory obligations associated with Frequency Band Plans.

2 In Melbourne, growth in the number of assignments in congested parts of the band seems to have been provided by the increased use of low power services.

3 See Attachment 2 for information on the part of the band referred to as segment K.



Figure 4: Spectrum use for land mobile services in south eastern Australia in Segment K of the 400 MHz Plan. The vertical shaded scale denotes the number of channels allocated (from zero to all).

Information is sought on the issues that a migration to 12.5 kHz systems will raise. What are the costs? How much time would be needed for such a migration?



Migrating from 25 kHz to 12.5 kHz

In the replanning processes for the VHF bands that occurred in the 1990s, a strategy of on-channel bandwidth reduction was used to optimise the availability of spectrum while minimising disruption to users (see Figure 5). Licensees using 25 kHz equipment on a particular channel migrate to a 12.5 kHz system on that channel. Base equipment needs to be updated at the time of migration, but mobiles can be incrementally replaced or upgraded. Over time, the spaces between channels open up and other 12.5 kHz assignments can be made. For the VHF land mobile bands this process took around ten years.

ACMA is considering imposing restrictions on the assignment of new frequencies to 25 kHz analog FM systems within the frequency ranges 403–420 MHz and 450–520 MHz. Existing 25 kHz systems would still be able to operate and expand for a limited time, but new analog systems requiring 25 kHz channels would not generally be permitted.

In time, measures would be imposed to create incentives to reduce and possibly to remove 25 kHz analog FM assignments in this spectrum. Such measures could include pricing incentives to encourage users to move from 25 kHz to 12.5 kHz assignments. Alternatively administrative action by ACMA to not renew 25 kHz assignments after a certain date is an option.

A transition from 25 kHz to 12.5 kHz channelling would appear to be a good candidate for a geographically based phased approach where measures to enforce bandwidth reductions are delayed in areas with lower congestion.



ACMA seeks comments on the factors that should be taken into account in seeking to reduce and ultimately remove 25 kHz analog FM land mobile equipment from the band.

ACMA seeks comments regarding the proposal to migrate to 12.5 kHz assignments.

What type of approaches should be considered by ACMA to facilitate migration away from the use of 25 kHz analog FM systems in the 400 MHz band?

Potential options for migration

A number of options are available to support a migration from 25 kHz to 12.5 kHz channels:

The ‘Interleave’ method (see Figure 5) which interleaves 12.5 kHz channels with the existing 25 kHz raster. A new 12.5 kHz channel is assigned to the same centre frequency as the current 25 kHz channel. When an adjacent channel is converted to 12.5 kHz, an extra 12.5 kHz channel can be inserted between the two on the 12.5 kHz raster.

This option would offer a relatively soft migration path for users as the mobile fleet can be upgraded over time. A disadvantage is that additional channels are not available immediately because new channels are only released when two or more adjacent channels become clear.

The ‘Offset’ method (Figure 6) which divides a current 25 kHz channel in two so that two 12.5 kHz channels can immediately be inserted with centre frequencies offset by 6.25 kHz to the 25 kHz raster.

This method would provide simple splitting, but causes more complexity in the channel raster definition as centre frequencies are not reused. Base equipment and mobiles would usually need to be replaced and/or retuned all at once, to avoid interference issues from the adjacent channel. Some accredited persons have advised that they are already using this option occasionally for clients when adjacent channels are not available.

Another option is for a group of 25 kHz channels to migrate into a block of 12.5 kHz channels (Figure 7), thus freeing up contiguous blocks of spectrum for other purposes.

This option would require extensive retuning and replacement of equipment as well as a complete re-coordination of systems. The advantage of this approach is that it would create blocks of unencumbered spectrum that could be easily and efficiently re-farmed.



Figure 7: Block channel bandwidth reduction migration path.

If ACMA concludes that a migration to 12.5 kHz operation of 25 kHz analog FM systems within the frequency ranges 403–420 MHz and 450–520 MHz is important to the replanning of this spectrum, what are the implications for stakeholders of the different approaches discussed above?

What would be the preferred bandwidth reduction migration path if ACMA decided to mandate a migration to 12.5 kHz channelling?



UHF Citizen Band—increase in available channels

The UHF Citizen Band (CB) comprises forty 25 kHz channels. Use of UHF CB is supported by a class licence. Anyone may operate UHF CB equipment provided that operation and the equipment used is in keeping with the conditions of the licence. Users do not have to apply for a licence and no fees are payable by CB radio users.

UHF CB equipment is cheap compared to typical land mobile equipment. Eight repeater channels are available, increasing the potential range of use to tens of kilometres. Australians are enthusiastic users of UHF CB for business and personal purposes. The main disadvantage to users is that no protection from interference is offered and therefore channels may be subject to congestion.

In light of the overall considerations in the band outlined in this paper, including the possibility of a reduction in channel bandwidth elsewhere in the band, it may be desirable to extend this potential bandwidth reduction to UHF CB. The existing 25 kHz channel bandwidth would be reduced to 12.5 kHz via an appropriate migration scheme.



For an environment such as UHF CB, where there is a very large quantity of existing equipment in use, a scheme where the old and new equipment have a degree of compatibility is desirable. This may suggest that the interleave method of yielding more channels could be the most appropriate.1

If an 80 channel UHF CB band is to be implemented, ACMA anticipates that there would be a period of time during which existing equipment using 25 kHz bandwidth would be permitted to continue operation, and new 80 channel 12.5 kHz equipment would also be permitted to operate. After the phase-out date only the use of 12.5 kHz channel equipment would be authorised. Use of 25 kHz bandwidth UHF CB equipment would not be supported.

It is acknowledged that arrangements would need to be addressed to preserve the utility of the emergency channels throughout any transitional period.

ACMA seeks views on increasing the number of UHF CB channels from 40 to 80 by the implementation of 12.5 kHz channelisation, with a corresponding phase-out of 25 kHz channel equipment.



Accommodating more digital land mobile

Overseas trends and research indicate that there will be a significant increase in the use of digital modulation schemes for land mobile equipment in the future. Generally digital land mobile equipment uses the spectrum at least as, and in many cases more, efficiently than analog systems.

There are a number of digital technologies in use by land mobile equipment around the world. TETRA equipment requires an RF channel bandwidth of 25 kHz, but uses Time Division Multiple Access (TDMA) techniques so that up to four communications channels are supported within this bandwidth. TETRA usually employs a frequency split of 10 MHz (with 5, 7 and 8 MHz also part of the TETRA standard for 400 MHz).

APCO equipment is able to support a wide range of frequency splits,2 with 9 MHz being commonly used in the United States.

Current Australian arrangements effectively prevent the operation of TETRA in the 403–420 MHz and 450–500 MHz ranges as the available frequency splits for duplex operation are not compatible.

ACMA seeks comments on the future requirement for digital land mobile operation and ways that ACMA can facilitate greater use of this more spectrally efficient technology.



1 See discussion above in section Migrating from 25 kHz channels to 12.5 kHz channels.

2 For example the Metropolitan Mobile Radio (MMR) network in Victoria is an APCO network employing frequency splits of 4, 5.5, 6 and 9.5 MHz.


Here is a (Eg Frequency on UHF CB)
Right now user 25khz Stepped
476.425.0 Mhz
476.450.0 Mhz
New 12.5 khz Stepped
476.425.0 Mhz
476.437.5 Mhz
476.450.0 Mhz

NOTE This Post Will Delete By 18/07/2008

[Zebedee]

There are a number of options relating to the technical framework for licensing use of the 400 MHz band that are being explored.

Hi Raymond999,

Is this post all your own text, or has it been sourced from somewhere else?


Cheers,

[raymond999]

There are a number of options relating to the technical framework for licensing use of the 400 MHz band that are being explored.

Hi Raymond999,

Is this post all your own text, or has it been sourced from somewhere else?


Cheers,

How do ACMA Pland update uhf cb radio from 40 ch right now useing 25khz Stepped geting mor ch acma have to cut down to 12.5khz Stepped get mor ch that y Nws 80ch UHF CB Radio
That Y

[celestial_insight]

There are a number of options relating to the technical framework for licensing use of the 400 MHz band that are being explored.

Hi Raymond999,

Is this post all your own text, or has it been sourced from somewhere else?


Cheers,

How do ACMA Pland update uhf cb radio from 40 ch right now useing 25khz Stepped geting mor ch acma have to cut down to 12.5khz Stepped get mor ch that y Nws 80ch UHF CB Radio
That Y

Doesn't look like it is his text somehow...

[ConstableCare]

Hi Raymond999,

Is this post all your own text, or has it been sourced from somewhere else?


Cheers,

How do ACMA Pland update uhf cb radio from 40 ch right now useing 25khz Stepped geting mor ch acma have to cut down to 12.5khz Stepped get mor ch that y Nws 80ch UHF CB Radio
That Y

Doesn't look like it is his text somehow...

Certainly not if its the same "Raymond" we so dearly love from Channel 8

Cheers, CC

[Bonez]

Certainly not if its the same "Raymond" we so dearly love from Channel 8

Cheers, CC

10 points for you

[Clontarf[X]]

Interesting convo about that, and Helen. Go the Kings Park HandHeld Squad

[ConstableCare]

Certainly not if its the same "Raymond" we so dearly love from Channel 8

Cheers, CC

10 points for you

Only 10 points Blake....oooooooohhhhhhh

Cheers, CC

[Zebedee]

I'm not sure who Raymond is, but my query was because we have a policy here about posting material that is not your own. Generally it should be done with the permission of the original creator, or at the very least it should be attributed correctly.

I'll close this thread now as I have my doubts on the legitimacy of the post as being written by the poster.

Raymond999 - if you want the thread re-opened, please let me know whether you are in fact the original author, or if you aren't, where the text came from.

Thanks.

[radiotech]

The article that Raymond refers to is:
http://www.acma.gov.au/WEB/STANDARD/pc=PC_311117

Page 36 to be precise.

I am in favor of such a plan coming into place, but there are numerous issues on how to roll it this out if it does end up passing through. My thoughts will be laid out below in no particular format.

If we were granted an extra 40 channels, the new radios in production would be made in accordance to the new frequency allocations starting with channel one at 476.425 and channel two at 476.4375 as the article states. But if we want to keep the frequencies for the current plan the same as the new plan (so both channel two's are the same ect) then they would need to make channel forty one start at 476.4375 and forty two at 476.4625 in between the existing channels. It's logic is simple but messy.

The frequencies would be all over the place but would keep current radios on the same channels and frequencies as the new radios, I would not like to talk on channel 3 on my new radio to find that it is channel 2 on the current radios, how confusing! That is why they need to consider starting ch41 at 476.4375 as opposed to 476.925 the current ch21.

As far as repeaters go, I would support a channel 9 repeater coming into play only if there is a demand for the extra repeater channel. Any more and it becomes a frequency circus, imagine using a channel 12 repeater? It makes no sense, but an addition would be nice.

If they went and changed the frequencies around so the radios don't match each other (new and current) what they could do is put the repeater input channels on a reserved set of frequencies that are not accessible by the operator, but have it hard coded into the duplex feature to transmit there. This way you don't get business operators transmitting on the input channels without having any idea that they are on a repeater input. In theory, channel 1 could be a repeater receive for the user, while the radio transmits on 71 to the repeater. Channel 71 should not be made available on the new radios but be accessible it if 1 duplex is enabled.

Or choose the later, and go for a whole new 40ch UHF CB band to come into effect with channel one starting at 476.4375 - have the power output changed to 25w to make it more "want" to change to it. Have it licensed and have the ACMA police it properly.

All that said, they want to phase out the existing 25khz spaced equipment, can hardly see that one happening in any great hurry.

There are endless possibilities that open up, we need to make sure they choose the right one. Have your say and email your thoughts and submissions to freqplan@acma.gov.au - as a scanner nut (not to much of a CB guy) I would like to see our input heard.

My official submission will be made in days to come, I need to lay it out so that I can properly support my own claims and ideas. But I would like others to share their thoughts on a new frequency /radio plan to support 80 UHF CB channels.

[VK6DF]

new frequency allocations starting with channel one at 476.475 and channel two at 476.4375

I thought channel one was 476.425...

The ACMA should just open the doors and let the flooding begin. if your on wide band (25khz) who cares and if your on narrow band (12.5khz) deal with the splatter/ interference. if u don't like it go to 1 of the other 79 channels.

Poor old ACMA are running out of space in the commercial bands and new equipment is capable of more. so i think its a great idea. like they said it took 10years for VHF to fully change over. there would definitely have to be a cut off point, if your not on the new system by date X then don't complain coz we will tell ya to buy a new radio/ reprog it for narrow band.

Good on them. cant wait. and its not as if there isn't people using narrow band (12.5k) channels on UHF CB any way

[radiotech]

new frequency allocations starting with channel one at 476.475 and channel two at 476.4375

I thought channel one was 476.425...

Oops, edited. 476.425 is channel one again!

There are a few people very rarely using 12.5khz spaced channels on UHF CB, then again they also use an imaginary channel 41 which is 477.425 - even that frequency isn't a part of the proposed new channels... Anyone sense law breakers?

If you have a radio capable of transmitting on frequencies, it isn't to hard to find an unused frequency within (for example) 100kms from your town and use it for simplex operating. Getting caught is your responsibility, but it would get you away from various ferals on UHF CB.

[TA-team Member]

I think it cost me about $80 a year for a uhf commercial freq in the 475Mhz range. there is a lil more up front cost (about $150) which includes first year and admin fee's but then after that its cheap as, and that was lic for out of metro area use. they are a bit more expensive for metro freq.. hence why a lot of ppl use CB because every man and his dog sells motorola uhf cb h/h radio's for cheaper then the price to build them..

... buy a can of coke and get 2 uhf cb h/h absolutely free.

[celestial_insight]

The article that Raymond refers to is:
http://www.acma.gov.au/WEB/STANDARD/pc=PC_311117

Page 36 to be precise.

I am in favor of such a plan coming into place, but there are numerous issues on how to roll it this out if it does end up passing through. My thoughts will be laid out below in no particular format.

If we were granted an extra 40 channels, the new radios in production would be made in accordance to the new frequency allocations starting with channel one at 476.425 and channel two at 476.4375 as the article states. But if we want to keep the frequencies for the current plan the same as the new plan (so both channel two's are the same ect) then they would need to make channel forty one start at 476.4375 and forty two at 476.4625 in between the existing channels. It's logic is simple but messy.

The frequencies would be all over the place but would keep current radios on the same channels and frequencies as the new radios, I would not like to talk on channel 3 on my new radio to find that it is channel 2 on the current radios, how confusing! That is why they need to consider starting ch41 at 476.4375 as opposed to 476.925 the current ch21.

As far as repeaters go, I would support a channel 9 repeater coming into play only if there is a demand for the extra repeater channel. Any more and it becomes a frequency circus, imagine using a channel 12 repeater? It makes no sense, but an addition would be nice.

If they went and changed the frequencies around so the radios don't match each other (new and current) what they could do is put the repeater input channels on a reserved set of frequencies that are not accessible by the operator, but have it hard coded into the duplex feature to transmit there. This way you don't get business operators transmitting on the input channels without having any idea that they are on a repeater input. In theory, channel 1 could be a repeater receive for the user, while the radio transmits on 71 to the repeater. Channel 71 should not be made available on the new radios but be accessible it if 1 duplex is enabled.

Or choose the later, and go for a whole new 40ch UHF CB band to come into effect with channel one starting at 476.4375 - have the power output changed to 25w to make it more "want" to change to it. Have it licensed and have the ACMA police it properly.

All that said, they want to phase out the existing 25khz spaced equipment, can hardly see that one happening in any great hurry.

There are endless possibilities that open up, we need to make sure they choose the right one. Have your say and email your thoughts and submissions to freqplan@acma.gov.au - as a scanner nut (not to much of a CB guy) I would like to see our input heard.

My official submission will be made in days to come, I need to lay it out so that I can properly support my own claims and ideas. But I would like others to share their thoughts on a new frequency /radio plan to support 80 UHF CB channels.

radiotech, you are quite correct about the arranging of the frequencies and channel numbers. This happened to VHF Marine when they split the bandwidth to increase the channels. Rather than explain it all, here is a link that will do it for me:
http://www.marscan.com/marine.htm