Tetra VS P25 phase 2 system

[thecanadiangod]

Hi folks, I am curious, is there any big advantage on having a tetra system vs a P25phase 2 system?

(And yes I know I could use AI, but I prefer humans who actually know what they are talking about)

 

[KE9EGF]

P25 Phase 2 is two timeslots in a 12.5 kHz bandwidth. TETRA, however, has four timeslots in a 25 kHz bandwidth, while one is used for control, making room for three user channels. But, considering you are in Ottawa, you will likely never see TETRA, as it is almost exclusively used in Europe (it was formerly known as Trans-European Trunked Radio). TETRA's data transfer is also considered slow by modern standards and it was meant for lower frequencies, giving it better geographical coverage (usually in the ~380-450 MHz range, very rarely above).

 

[Ubbe]

I think that Tetra uses a higher degree of safety to let the system run in case of any mishaps, like some communication lines being cut or flooding of the control room and those kind of disasters. So Tetra could be preferred when critical communications are needed that must not fail, like at airports or underground subways and similar services.

But improvements are always made at system levels so its hard to tell if it today will have any big advantages. But the voice codecs used in Tetra seems to be vastly superior to the ones used in P25. If you are able to listen to any streams from a Tetra system, or monitor it by yourself, then you can immediately hear the difference in audio quality.

/Ubbe

 

[kayn1n32008]

But, considering you are in Ottawa, you will likely never see TETRA, as it is almost exclusively used in Europe

There are two TETRA systems in use in Toronto, one being the TTC system.

 

[Whiskey3JMC]

But, considering you are in Ottawa, you will likely never see TETRA, as it is almost exclusively used in Europe
it was meant for lower frequencies, giving it better geographical coverage (usually in the ~380-450 MHz range, very rarely above).

Mostly but not exclusively. Although there are fewer than 100 RRDB documented Tetra systems (many more undocumented I'm sure), they exist sparsely in the USA, Canada, Asia, Australia among other places outside of Europe. Also quite a few are 700, 800+MHz

RadioReference Database

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[thecanadiangod]

There are two TETRA systems in use in Toronto, one being the TTC system.

So basically the only benefit is user capacity and voice quality?

 

[KE9EGF]

There are two TETRA systems in use in Toronto, one being the TTC system.

Did not know this, SIGIDWIKI just says it is used around Europe.

 

[Ubbe]

I believe Tetra are also used at one or two airports in US.

/Ubbe

 

[K2NEC]

New Jersey Transit also has a large multi-state Tetra system

 

[nhfdcadet]

the CT offshore wind project is using a TETRA system from what I'm told

 

[kayn1n32008]

Did not know this, SIGIDWIKI just says it is used around Europe.

2 other TETRA systems I know of in Canada are the Calgary Airport, in Alberta and BC Hydro. There are a handful of systems in the US as well

 

[EuropeanUser]

Hi folks, I am curious, is there any big advantage on having a tetra system vs a P25phase 2 system?

(And yes I know I could use AI, but I prefer humans who actually know what they are talking about)

I don't know a lot about P25, but I know the voice quality of P25 Phase two is comparable to DMR, and that it uses TDMA with two time slots with 12.5 kHz channel width. As such I'm going to talk just about the advantages of TETRA here.

TETRA uses TDMA with 4 time slots per carrier. Each base station can have multiple carriers. The smallest ones may support just two, but larger ones can handle 12 or even more and can be linked. Each carrier uses 25 kHz channel bandwidth. The number of time slots available simultaneously for voice or data is N-1. One timeslot is used for control messages.

TETRA has two general modes of operation. TMO and DMO. TMO is Trunked Mode Operation, and DMO is Direct Mode Operation. DMO is kinda like simplex when used as is.

There are some interesting features available with TETRA that I'm not sure if they are available with P25. DMO Repeater mode allows a terminal to act as a repeater for a smaller isolated area if needed, and Gateway mode allows a terminal to act as a gateway to provide coverage for other terminals. For example a vehicle mounted terminal in gateway mode can provide system coverage for handheld terminals that can't reach the site on their own. Can for example be used by police officers entering a building with poor coverage to gateway through their police vehicle.

DMO Repeater mode is a cost effective way to provide temporary repeater coverage using just a handheld terminal, or a mobile unit connected to a well placed antenna for example.

The voice quality of TETRA is a lot better than P25 Phase 2. After talking over DMR, that has similar voice quality to P25 P2 as mentioned, using TETRA is like night and day. It's not analog good, but it's not too far off.

TETRA terminals can also be used to make full duplex phone calls between terminals, or to the general phone network if linked.

The only real drawbacks I can think of in general is cost and 25 kHz channel width, and how complex even a simple system can be to set up.

And this is not even touching the security features of which there are many.


TLDR:
Pros: Voice quality, flexible operation.
Cons: Cost, complexity.