Trunked on Ham?

[katt02]

Hi all,

Somewhat random question here, but is someone allowed to, with the help of a frequency coordinator, set up a trunked system on the ham bands? I know that nobody "owns" a specific frequency, but if the information to get on the system was public it should be considered a repeater, right? I've never seen it before because it would be so expensive, but would it be possible to set up a system?


Just a thought; What do you think about trunking on Ham?

Katt

 

[techman210]

I know of coordination bodies that have received applications for establishing trunking systems, but they have been rejected outright.

 

[nd5y]

I read that several years ago there was at least one ham LTR system. I don't remember how many repeaters it had.

The main problem with trunking and roaming on ham radio is complying with the station identification requirements.

 

[katt02]

I see what you mean about the identification; however, if someone had enough money to put up a recreational trunked system, they surely have the money or the means to create a system that can identify every 10 mins on all frequencies

 

[buddrousa]

But you have to identify and you would have no way of knowing what channel you were using.

 

[R8000]

No. Hams do not need trunking. Given the chance I would reject/vote down any proposal to allow it.

 

[AI7PM]

What purpose would a trunked system serve on ham? What need?

 

[bill4long]

Somewhat random question here, but is someone allowed to, with the help of a frequency coordinator, set up a trunked system on the ham bands? I know that nobody "owns" a specific frequency, but if the information to get on the system was public it should be considered a repeater, right? I've never seen it before because it would be so expensive, but would it be possible to set up a system? Just a thought; What do you think about trunking on Ham? Katt

1. You don't need to coordinate a repeater or repeater system. There are certain advantages in case of a conflict, but it's not necessary.
2. You'd probably want to use 900mhz since it is a very under-utilized band.
3. Identifying the freqs your transmitter uses would be difficult. You'd have to ID on every transmission or have some automatic IDer.
4. Setting up a trunking system would be a colossal waste of time and money. What would be the point?

 

[N2AL]

Great question! As Amateurs we are always looking to build new technology and test hypothesis. If 1.25 meters, 70 centimeters or 33 centimeters were used, where more band spacing and frequencies are available, this might actually work.
I would support this venture so long as it met F.C.C. requirements, such as proper frequency usage and identification for Amateur Radio. I am not sure if other hams would be able to use the system though, depending on how much the trunking radios would cost for each individual user.

 

[bill4long]

I see what you mean about the identification; however, if someone had enough money to put up a recreational trunked system, they surely have the money or the means to create a system that can identify every 10 mins on all frequencies

Easy to make the repeater radios ID. But you have to ID your own transmissions too, on each frequency your radio transmits on. Could be done bycoming up with some kind of auto IDing each time you key up, or you'd have to ID by voice on every key up.

The whole idea of trunking on ham radio seems particularly unnecessary and ridiculous to me.

 

[bill4long]

I know of coordination bodies that have received applications for establishing trunking systems, but they have been rejected outright.

Coordination is not necessary, but that's the least of the problems with a trunked ham system.

 

[AK9R]

I think some of you may be over-thinking the identification question.

§97.119 Station identification.
(a) Each amateur station, except a space station or telecommand station, must transmit its assigned call sign on its transmitting channel at the end of each communication, and at least every 10 minutes during a communication, for the purpose of clearly making the source of the transmissions from the station known to those receiving the transmissions. No station may transmit unidentified communications or signals, or transmit as the station call sign, any call sign not authorized to the station.
(b) The call sign must be transmitted with an emission authorized for the transmitting channel in one of the following ways:

(1) By a CW emission. When keyed by an automatic device used only for identification, the speed must not exceed 20 words per minute;​

(2) By a phone emission in the English language. Use of a phonetic alphabet as an aid for correct station identification is encouraged;​

(3) By a RTTY emission using a specified digital code when all or part of the communications are transmitted by a RTTY or data emission;​

(4) By an image emission conforming to the applicable transmission standards, either color or monochrome, of §73.682(a) of the FCC Rules when all or part of the communications are transmitted in the same image emission.​

It seems to me that if the user radio sends the user's callsign at the end of every transmission using a burst of 20 wpm CW, the rule is met. A 2-by-3 callsign will take about 5 seconds to send at 20 wpm. Is that too long to tie up the channel at the end of each transmission? Maybe so. Send it with RTTY and you're looking at 1-2 seconds, though that probably doesn't comply with (b)(3) since the rest of the message won't be sent with RTTY.

 

[nd5y]

It seems to me that if the user radio sends the user's callsign at the end of every transmission using a burst of 20 wpm CW, the rule is met. A 2-by-3 callsign will take about 5 seconds to send at 20 wpm. Is that too long to tie up the channel at the end of each transmission? Maybe so. Send it with RTTY and you're looking at 1-2 seconds, though that probably doesn't comply with (b)(3) since the rest of the message won't be sent with RTTY.

Nobody that I know of makes radio that can do that.
Yaesu System Fusion and D-STAR send the callsign programmed into the radio during each transmission but those modes don't have trunking.

 

[kayn1n32008]

1. You don't need to coordinate a repeater or repeater system. There are certain advantages in case of a conflict, but it's not necessary.
2. You'd probably want to use 900mhz since it is a very under-utilized band.
3. Identifying the freqs your transmitter uses would be difficult. You'd have to ID on every transmission or have some automatic IDer.
4. Setting up a trunking system would be a colossal waste of time and money. What would be the point?

1. Coordination is always a good idea.

2. Not a chance. The 33cm ISM band is swamped with all kinds of garbage. Especially WISPs. 900MHz is the last band I would want to put a repeater on.

3. Agreed. The US has pretty stringent ID requirements

4. Not really. Single channel LCP is perfect for a ham trunk set up. LCP does not neuter DMR by locking talk groups to time slots like convention IP site connect does. The other advantage is LCP, RAS and EP(we can use encryption in Canada) keeps the cheap junk radios from polluting your network.

5. There is a wide area, linked LCP system in Canada. Each site is a single repeater.


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[DaveNF2G]

The big question would be Why?

Assume that your ham trunking setup will include voice-over-control for each of the following scenarios.

If you trunk a ham repeater, one ham will still be able to talk on it at a time. If you use a protocol that allows for TDMA, then 2 hams will be able to talk at a time (also assuming VOC). That improves spectrum efficiency for that single repeater. In this scenario, trunking is unnecessary. TDMA increases the number of available talk paths.

Now trunk 2 ham repeaters together. With basic trunking, only one ham will be able to use both repeaters at the same time. Without simulcast, one ham would be able to use each repeater at the same time. No change in capacity, or a reduction in total capacity with simulcast.

Now do TDMA trunking with 2 ham repeaters. With simulcast, a maximum of 2 hams can use both repeaters at the same time. Still no improvement in spectrum efficiency. Without simulcast, 4 hams on 2 repeaters. Now you have to think about how often there are 4 separate conversations going on at the same time on your local repeaters. In my area, that is practically never, even though there are many accessible repeaters in the area.

For trunking to be cost-effective in the ham bands, several repeaters would have to be trunked. Trunking-capable repeaters and controllers are very expensive. Add the cost of back-end connectivity (IP over landline or RF) and possibly Internet access (for linking). Then, how many local hams are going to spend the bucks for trunking transceivers?

 

[kayn1n32008]

The big question would be Why?

Assume that your ham trunking setup will include voice-over-control for each of the following scenarios.

If you trunk a ham repeater, one ham will still be able to talk on it at a time. If you use a protocol that allows for TDMA, then 2 hams will be able to talk at a time (also assuming VOC). That improves spectrum efficiency for that single repeater. In this scenario, trunking is unnecessary. TDMA increases the number of available talk paths.

Now trunk 2 ham repeaters together. With basic trunking, only one ham will be able to use both repeaters at the same time. Without simulcast, one ham would be able to use each repeater at the same time. No change in capacity, or a reduction in total capacity with simulcast.

Now do TDMA trunking with 2 ham repeaters. With simulcast, a maximum of 2 hams can use both repeaters at the same time. Still no improvement in spectrum efficiency. Without simulcast, 4 hams on 2 repeaters. Now you have to think about how often there are 4 separate conversations going on at the same time on your local repeaters. In my area, that is practically never, even though there are many accessible repeaters in the area.

For trunking to be cost-effective in the ham bands, several repeaters would have to be trunked. Trunking-capable repeaters and controllers are very expensive. Add the cost of back-end connectivity (IP over landline or RF) and possibly Internet access (for linking). Then, how many local hams are going to spend the bucks for trunking transceivers?

Linked Capacity Plus does not have a control channel. With 2 repeaters, linked, you get 4 talk paths. You also don’t have garbage radios.

The biggest advantage to LCP is you are not stuck with strapped talkgroups. DMR-MARC is a perfect example. If you are using a TS-2 talkgroup, NOBODY can use any other TS-2 assigned talkgroup until the first users are done.


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[ka3jjz]

And for those who say coordination is not necessary, you might want to consider this; If your repeater is uncoordinated, and the other repeater is coordinated, it's the uncoordinated repeater's responsibility to resolve the conflict. Mike

 

[bill4long]

The big question would be Why?

Assume that your ham trunking setup will include voice-over-control for each of the following scenarios.

If you trunk a ham repeater, one ham will still be able to talk on it at a time. If you use a protocol that allows for TDMA, then 2 hams will be able to talk at a time (also assuming VOC). That improves spectrum efficiency for that single repeater. In this scenario, trunking is unnecessary. TDMA increases the number of available talk paths.

Now trunk 2 ham repeaters together. With basic trunking, only one ham will be able to use both repeaters at the same time. Without simulcast, one ham would be able to use each repeater at the same time. No change in capacity, or a reduction in total capacity with simulcast.

Now do TDMA trunking with 2 ham repeaters. With simulcast, a maximum of 2 hams can use both repeaters at the same time. Still no improvement in spectrum efficiency. Without simulcast, 4 hams on 2 repeaters. Now you have to think about how often there are 4 separate conversations going on at the same time on your local repeaters. In my area, that is practically never, even though there are many accessible repeaters in the area.

For trunking to be cost-effective in the ham bands, several repeaters would have to be trunked. Trunking-capable repeaters and controllers are very expensive. Add the cost of back-end connectivity (IP over landline or RF) and possibly Internet access (for linking). Then, how many local hams are going to spend the bucks for trunking transceivers?

Yeah, it"s ridiculous. But if he has to get it out of his system, then okay

 

[katt02]

Yeah, it"s ridiculous. But if he has to get it out of his system, then okay

well, the question I asked was not why would someone want to do this; cause I can tell you if I had the time and money I would love to do it. Anyways, its a matter of is it possible and how would it be done. Just the logic of the question such as how would one identify; how would coordination work; and would the FCC allow it.

I do believe it would be near impossible to get the money and materials to create a ham trunked system, but I am interested in how it would be done.

 

[DaveNF2G]

Well, an exploration of the technology is certainly not off-topic in ham radio. But trunking seems unsuited to the hobby generally.