FM Dig - ir - ee - do or don't?

For discussion of MGM (digimodes) on 4 m, e.g. PSK, FSK

Should the 4m bandplan be amended to reduce the spectrum allocated to digital ops

Yes
34
81%
No
3
7%
Don't Care
5
12%
 
Total votes : 42

FM Dig - ir - ee - do or don't?

Postby G7CNF » Fri 8 Dec 2006, 12:12

Sorry, here I am again.... another poll.

4m has seen a considerable increase in popularity over recent years, so much so that there are times it can be difficult finding a clear QRG on the FM portion of the band.

I am curious just what mandate exists for the current band plan which seems to give over an excessive proportion of spectrum to digital op's and internet linking when that bandwidth could be better used for telephony, especially when other bands have vastly larger allocations than 0.5Mhz?

Historically I have been at the forefront of promoting digital communications, as will be seen from my posts here and elsewhere but sometimes I feel we can have too much of a good thing?

I recognise that 4m is too small for traditional duplex repeater operation and that IRL can offset this shortcoming.

But... There are 15 x 12.5KHz channels starting at 70.3125 and 10 of these are allocated for digital and only 5 channels for telephony. This seems totally disproportionate in favour of digital, especially against the backdrop of new EU allocations, when the band can fill up with others not adhering to this structure.

Would it not make more sense to keep digital ops below 70.400 and equally weight telephony and digital? (With one channel maybe dedicated for Raynet / emergency communications?)

I do wonder if it is time to have a sensible discussion among the people who actually use the band as to how the band should be structured, especially against the backdrop of the 70.260 discussion which rages on.....

Your thoughts please.
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Postby G6GVI » Wed 13 Dec 2006, 09:19

You raise a fair point Nige.

Comparing the published bandplans for 4m, 6m and 2m, the 4m one does seem unduly prescriptive. Fair enough to have All Modes with 12.5kHz channels, but why go further than that? After all, the aren't the bandplans intended for the guidance of wise men?
However, I do believe that it is worth separating the voice and data channels: imagine the annoyance of loud AFSK bursts coming over a nice quiet chat, or the disruption of 5-minute voice transmissions to a packet data exchange!

From personal experience on 4m (14 years and over 6000 QSOs), the predominant mode in the top half of the band is analogue NBFM telephony (no surprise, considering what equipment is available). This sensibly occupies the channels around the calling channel (i.e. 70.375 to 70.475). What little digital (AFSK) I have heard has been either on 70.4875, or below 70.35.
It's worth saying that with just a 4-channel set, I have never struggled to find a clear FM voice channel.

Here is my suggestion for designation of the channelised section:
70.3 - 70.3625 digital (6 channels)
70.375 - 70.475 FM telephony (9 channels)
70.4875 digital

notes:
70.375 & 70.4 users must give priority to RAYNET operations
70.425 is used for GB2RS on Sunday mornings and evenings
70.45 is the calling channel: please do not hog it as a working channel
70.4125 and 70.3875 may be used for VoIP Internet links in some areas

(I've left 70.4875 as a legacy digital channel for now, as many of its users may only have crystal-controlled transceivers.)

Any comments? How do users feel about a 9:7 ratio between analogue and digital channels?
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Postby G7CNF » Wed 13 Dec 2006, 11:02

Ross.

That certainly gets my vote. I accept that for many users 4m can be quite dead at times, unless there is a local thriving 4m community. For my part, I am on a hill, 120masl, with a vertical at 17m on the top of the stack, needless to say my signal can be quite far reaching (I have a flat band footprint of well over 100 miles radius from IO81re.)

Two Sundays ago I had to abandon a QSO because because every 25kc channel I selected had a net, Raynet or other activity on it and was asked to move on.... As for the channels like 4375, 4875, there is constant digital activity heard at this location, so I cannot use them or I would interfere with these op's, which I am as careful as I can be, not to do!

With regards to your suggested allocations, they seem very sensible to me however I would like to suggest that at least one telephony channel be 'reserved' for emergency and Raynet communications or at least it is made very clear that if the channel is needed by the above-mentioned ops that users should QSY....

This may seem on the surface to be a selfish gesture however as each Es season goes by, there will be more and more users from the UK and many, many more users from CEPT joining our happy band on 4m.

During summer Es 2005, with G and OZ active, 4m was impossible, what will it be like when the rest of the EU joins us? Lets get this barn door fixed BEFORE the horse has bolted!
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Postby G6GVI » Wed 13 Dec 2006, 14:31

Two Sundays ago I had to abandon a QSO because because every 25kc channel I selected had a net, Raynet or other activity on it and was asked to move on....


Sounds like you need a beam Nige? :wink:
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Postby G7CNF » Wed 13 Dec 2006, 15:33

Too much stuff up there already :wink:
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Postby G3PTU » Thu 14 Dec 2006, 10:58

'GVI's proposals make a lot of sence, I cannot felt feeling (like others) the weight of space for digital modes is imballanced.
I think we should always bear in mind that any mode usually based on a transposer arangments can usually go anywhere, while the mass of Ex PMR boxes are bound by internal programing etc. This not withstanding that there ARE rock bound rigs still in use, perticuly AM equipment and as such we should not be unbdully mean in having an attitude against them.

In Practice in Yorkshire people appear to wander where they like based on .450 +/- 12.5Khz steps.

Maybe there should , seeing this is now open to discusion; a dedicated "parrot" frequency.

* It is interesting to note that the latest edition of Radcom descibes .260 as AM/FM calling.

David Long

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FM v Digital

Postby TONY » Fri 15 Dec 2006, 07:09

I sympathise with Nige when he can't find a clear channel for an FM qso, but like Ross I have never found difficulty in finding a clear channel from my QTH. The current band plan does favour digital modes at the expense of those using FM, so Ross's suggested amendment to the band plan would appear sensible. It would be interesting to see a comment from a digital user on this, but I don't think there would be any strong opposition to Ross's suggestion going forward as an official update as it comes from a very experienced user of the band. This proposal not withstanding, however, a directional aerial would help Nige, hi.
There is no suggestion of a change below 70.3MHz, so home bru VFO users like myself can wallow it the bands friendly nature as always. I have had cross mode AM/FM and SSB/CW QSO's down here, which contribute to the bands unique charm. Long may it continue.
TONY
 

Postby GW8IZR » Fri 15 Dec 2006, 08:03

Band planning is easy – just give everyone what they want and everyone is happy.

I’m not sure that the “digital usersâ€Â
73 de Paul GW8IZR
IO73TI Anglesey
http://www.gw8izr.com
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Re: FM Dig - ir - ee - do or don't?

Postby G4ASR » Sun 17 Dec 2006, 22:19

[quote="Nige-G7CNF"]Sorry, here I am again.... another poll.
<Snip>
Nigel G7CNF said . . . . .
I am curious just what mandate exists for the current band plan which seems to give over an excessive proportion of spectrum to digital op's and internet linking when that bandwidth could be better used for telephony, especially when other bands have vastly larger allocations than 0.5Mhz?
<Snip>

My reply is as follows....

The mandate for the current 4M band plan is actually quite old - 8-years old in fact.

The requirement to use a number of channels for digital usage came about
because of problems using similar frequencies within the 430MHz band.

There was an issue with the PRIMARY USER and alternative spectrum space was urgently needed by the RSGB Datacoms Committee (DCC).

Eight years ago in mid-1998 the RSGB VHF Committee (now disbanded) sanctioned the designation of these frequencies for data purposes.

Before implementation a full consultation exercise was carried out (see
RadCom, April 1999, p33 for details).

*****************************************

So that was the reason - and I must say that 8-years ago the n.b.f.m activity was less than it is in 2007.

I am in full agreement that this state of affairs should be discussed and I am pleased to see so many giving your views.

I am writing a small article which I will place on this web site soon.

At this point I wish to correct a comment that Nigel G7CNF has stated on the Home Page (published 13 Dec 06) "that the 4m bandplan will be discussed at the IARU Region 1 meeting next Spring, so please make your comments soon".

This is not correct - the 4M band plan will not be discussed.

The only discussion at the moment is regarding my proposal paper about moving the AM/FM Calling Frequency on 70.260MHz to 70.2625MHz.
However following feedback primarily from this forum I have decided to withdraw this proposal at the Vienna meeting.

We are however getting our knickers slightly in a twist as the UK usage of these channels is not an IARU issue. It is a national issue.
(The IARU band plan only shows 3 channels for packet radio usage.)

Band plans evolve and if it's found there is a need to re-assess/re-allocate
spectrum usage nationally (UK) then it can be accomplished via myself.

But you need to come up with a proposal that the (vast) majority of users agree with.

Cheers, David G4ASR

VHF Manager, RSGB and core member of the RSGB Spectrum Forum (core members are the HF, VHF, microwave managers & forum chairman).
I'm also a member of the IARU Region 1 vhf/uhf/microwaves committee.
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Postby G4ASR » Mon 18 Dec 2006, 22:36

Paul GW8IZR said .....

I’m not sure that the “digital usersâ€Â
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Postby G6GVI » Thu 21 Dec 2006, 09:10

Many thanks for those clarifications, Dave, and I'm delighted to hear that you're already receiving useful feedback from this Forum.
I hope that more contributors take up your invitation to provide constructive comments and suggestions, and help keep the UK bandplan in tune with the requirements of the majority of users.

73 de Ross.

P.S. I can say from personal experience over the last five years that during many tens of hours of (mainly weekend) portable operating from hilltop sites in IO83 and IO81, I've never had any problems with interference from digital modes, nor ever struggled to find a clear voice channel between 70.375 and 70.475MHz.
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Postby G7CNF » Thu 21 Dec 2006, 12:04

Many thanks also David for noting the weight of opinion which seems to exist on this issue. Briefly I would like to record that the homepage statement about 4m being discussed at IARU was an editorial change to my original posting....

As I mentioned at the beginning, I am and have been for a considerable time, an avid digital user and try whenever possible to encourage newcomers to the digital arts; the bandwidth benefits alone are often worth it. A few messages have come to me suggesting I am anti-digital; nothing could be further from the truth.

A few days ago I read out the 4m RSGB band plan to an amateur without an Internet connection, I cannot repeat his reaction here in good taste but suffice to say that his response was very much in line with 78% of votes (at the time of writing) and he furthermore stated that the digital allocation on 4m is bordering on the obscene.... His words not mine.

Users come and go, vogue changes in the end we must be governed by majority rule if fairness is to prevail, whilst acommodating the needs of any minorities.

The vote results thus far suggest a clear mandate from this forum as to how the spectrum should be allocated. Let common sense prevail before Cycle 24 peaks.....
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Postby G4WGT » Fri 22 Dec 2006, 16:19

I wish to aggree with the majority here. As the band is so narrow & there are many digital allocations on other larger bands the digital channels on 4 metres should be reduced.

Gary - G4WGT
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Postby G4ASR » Sun 24 Dec 2006, 11:36

Nigel said.....
The vote results thus far suggest a clear mandate from this forum as to how the spectrum should be allocated. Let common sense prevail before Cycle 24 peaks.....



But taking Devils Advocate here - how on earth can the results of 22 people be a clear mandate when I have clearly stated that over 90 call signs are already allocated and using the digital channels.

Your evidence shows that telephony users are in the minority!

This, of course, may not be correct - but it is oh so easy to make challenges to the 'evidence' when only telephony users are involved in the voting process.

The other problem is this. A huge number of digital operators are using these channels specifically because of an Notice of Variation (NoV) to their licence.

You can't, at a stroke, remove an NoV allocated by Ofcom.

End of Devils Advocate statement.

Happy Christmas, David
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Digi Channels

Postby G4WGT » Sun 24 Dec 2006, 15:15

David wrote-

"The other problem is this. A huge number of digital operators are using these channels specifically because of an Notice of Variation (NoV) to their licence."

For what reason is an NoV required to use/operate on a digital channel on 4M??
Gary - G4WGT.
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