Amateur radio digital voice rant

[KF5YDR]

I think we can all agree that in spite of the implementation differences, TRBO is DMR compatible.

 

[prcguy]

Here is a great comparison of several digital formats and analog in field conditions and on ham frequencies. The field test starts about 20min into the video. Episode 161: Yaesu's System (Con)Fusion - YouTube
prcguy

 

[N4KVE]

That was interesting. They pretty much sounded the same. Remember, the P25, & DMR radios were down 20% tx power, but it's nice that on the hammy radios you can hit a button to change modes. But I can understand why that feature isn't available on the commercial radios. Like I said before, go with the mode that your friends use.

 

[prcguy]

I thought it was a good general comparison, but antennas could be responsible for some of the differences in signal levels and decoding.
prcguy

That was interesting. They pretty much sounded the same. Remember, the P25, & DMR radios were down 20% tx power, but it's nice that on the hammy radios you can hit a button to change modes. But I can understand why that feature isn't available on the commercial radios. Like I said before, go with the mode that your friends use.

 

[kayn1n32008]

I thought it was a good general comparison, but antennas could be responsible for some of the differences in signal levels and decoding.

prcguy

Agreed. Admittedly the did say it was not scientific though.

It would be neat to see this kind of comparison using mobiles, at the same power level, using a common antenna, that does not move.

 

[JRayfield]

MOTOTRBO trunking is proprietary to them. So it is not 'standard'. They developed Capacity Plus and Connect Plus before the DMR Tier 3 standard was finished and adopted.

I was under the impression that the DMR standards do not include any encryption. Maybe that's changed - I'll have to pull up the latest documentation and check that out.

MOTOTRBO is Tier 2 compliant.

John Rayfield, Jr. CETma
W0PM

Does the Motorola implementation of tier 3 trunking also adhere to the standard? What about aes encryption not being available in the us even though it's in the standard as well?

Let's be honest, trbo is only dmr compliant in conventional (tier 1) operations. Throw trunking into the mix and it's just as proprietary as smartnet/smartzone trunking

 

[JRayfield]

Yes, and exactly the same with the P25 standard.

John Rayfield, Jr. CETma
W0PM

Not relevent to Amateur Radio, to be honest, since over the air encryption is fobidden. And, as I said, the ETSI specifications PERMIT manufacturer specific extensions, which is what underlies the MotoTRBO implementation.

 

[rapidcharger]

John, I didn't want to derail the other thread in the PA room but how exactly does the 2 time slots on a single simplex frequency work? Is that a firmware update? What radios is that compatible with?

 

[kayn1n32008]

Does the Motorola implementation of tier 3 trunking also adhere to the standard? What about aes encryption not being available in the us even though it's in the standard as well?

Standards are great, but there is nothing preventing a company from deviating from the standard with their own features.

Motorola does this with P25.

While Motorola has made AES encryption available to European customers, they have decided to not sell this feature to their North American in order to 'force' their North American customers to purchase much more expensive P25 systems for those that want real voice security.

BUT the beauty of this is that those customers that want to implement DMR with AES encryption, rather than P25 will choose a vendor other than Mororola that IS making DMR systems with AES encryption available in North America.

Either they will make it available in DMR or lose business to companies may sell DMR systems with AES encryption in North America.

But really, as an amateur radio operator this is really a moot point anyways... Encryption is not allowed, and I doubt there will ever be a trunk system deployed by ham operators.

Let's be honest, trbo is only dmr compliant in conventional (tier 1) operations. Throw trunking into the mix and it's just as proprietary as smartnet/smartzone trunking

As stated above TRBO is DMR tier 2 compliant, and that is really all that matters to amateur radio operators.



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[szron]

and I doubt there will ever be a trunk system deployed by ham operators.

I wouldn't be so sure

 

[KF5YDR]

I doubt there will ever be a trunk system deployed by ham operators.

Don't be so sure! I'm agitating locally to get people interested in the idea of a wide-area trunking system. We have a couple linked repeaters and a couple wide-area coverage ones up on the buildings downtown, but they don't have total coverage (at least for HT's). It'd be rad to have a common network with different talkgroups taking the place of individual repeaters with their own group of regulars. Would really simplify emcomm too.

 

[kayn1n32008]

Don't be so sure! I'm agitating locally to get people interested in the idea of a wide-area trunking system. We have a couple linked repeaters and a couple wide-area coverage ones up on the buildings downtown, but they don't have total coverage (at least for HT's). It'd be rad to have a common network with different talkgroups taking the place of individual repeaters with their own group of regulars. Would really simplify emcomm too.

What protocol?


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[KF5YDR]

What protocol?

Haha, not nearly there yet! I'm pretty partial to Motorola, especially since that gives us access to so much surplus public safety gear, so probably SmartZone or ASTRO 25. Although honestly, a TRBO system would probably be a lot easier to set up.

 

[grem467]

The issue with part 97 trunking would be the issue of station ID on the control channel.

Under part 90 rules, the lowest frequency in a trs is the one to id for the entire system. Furthermore in a smartzone and moto 7.x p25 system control channels cannot be set to id in the manager. You could set voice channels to id, regardless of frequency.

This limitation would need to be overcome to legally deploy cc based trunking in the amateur bands.

 

[KF5YDR]

That's true. I wonder if having an analog FM ID transmitted on the control channel every ten minutes would be possible. As I understand it, P25 can mix analog and digital on the same repeater, is it possible to do the same on the CC?

 

[grem467]

No. On a p25 system it's all digital. The manager allows you to check the control channel box or the BSI (base station id) but not both.

It might be possible to build a circuit to have the station tx interrupt, use a second transmitter just to send an Id then reenable the cc transmitter. It would throw the rest of the system in failsoft and take a few seconds to recover though.

You would generate out of range on the subscribers and a pile of errors on the manager.

I also have read others say that a 24/7 control channel could be considered broadcasting, but the system does respond to radios on the input. To me what would be the difference between that and a repeater with an infinite hang time.

 

[KF5YDR]

Also Part 97 for allows remote control, and if a control channel isn't remote control I don't know what is.

 

[JRayfield]

What you're stating for Part 90 only applies on 800 mhz. On UHF and VHF part 90, ID must be used on all channels in a trunked system.

A better trunking format to use on Part 97 might be one that does not use a control channel, such as Linked Capacity Plus.

John Rayfield, Jr. CETma
W0PM

The issue with part 97 trunking would be the issue of station ID on the control channel.

Under part 90 rules, the lowest frequency in a trs is the one to id for the entire system. Furthermore in a smartzone and moto 7.x p25 system control channels cannot be set to id in the manager. You could set voice channels to id, regardless of frequency.

This limitation would need to be overcome to legally deploy cc based trunking in the amateur bands.