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MPT-1327 and TETRA Forum For general discussion of MPT-1327 and TETRA Trunking Technologies

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Old 03-31-2012, 11:11 AM
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Default Does TETRA allow analog transmissions?

Does TETRA allow analog transmissions or is it just digital? I've read that it is the worlds "most used" radio protocal, so I was curious if they have analog capabilities like P25 does in the US for migrating to digital from analog. I'd like to learn more about TETRA since I will be moving to Europe in the next year. Also does it have conventional mode or just trunking? Thanks!
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Old 03-31-2012, 11:44 AM
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TETRA is strictly digital. There is no analog at all. There can be DMO (Direct Mode Operation) which is simplex and some mobiles can be set to gateway mode to repeat traffic from a mobile at the edge of the network to an area with no coverage. As far as I know DMO and gateway are not always present on all systems and there are no conventional repeaters.
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Old 04-01-2012, 12:35 AM
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Originally Posted by nd5y View Post
TETRA is strictly digital. There is no analog at all. There can be DMO (Direct Mode Operation) which is simplex and some mobiles can be set to gateway mode to repeat traffic from a mobile at the edge of the network to an area with no coverage. As far as I know DMO and gateway are not always present on all systems and there are no conventional repeaters.

DMO has nothing to do with Tetra infrastructure, the feature is based on terminal only. Gateway is a specific terminal funcion, being a bridge between DMO and TMO.

And yes, there are conventional tetra repeaters, used to improve indoor signal

Edit: tetra is digital
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Old 04-01-2012, 1:12 PM
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TETRA is always digital, regardless if it's TMO or DMO. There is no analog mode for migrating, although the TETRA infrastructure and some radios allow a connection with conventional/analog systems via 4-wire E&M interface.

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And yes, there are conventional tetra repeaters, used to improve indoor signal
Or tunnels and outdoor areas but I think with conventional repeaters he meant base stations with repeater function (as used in analog systems), not what sometimes is called a "booster".

Depending on the vendor TETRA Base Stations (TBS) may also work in a stand-alone mode, i.e. without connection to a TETRA switch. Some TBS even allow features such as SDS/Status messages or individual calls in stand-alone mode.
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Old 04-01-2012, 1:24 PM
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Yes, based on the Tetra standard, you can connect the system to other networks ( analog radio, telephone etc). You can even participate in the Tetra group call with landline telephone.

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Depending on the vendor TETRA Base Stations (TBS) may also work in a stand-alone mode, i.e. without connection to a TETRA switch. Some TBS even allow features such as SDS/Status messages or individual calls in stand-alone mode.
In the Cassisidian system the feature is called fallback
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Old 04-02-2012, 11:42 AM
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Quote:
Originally Posted by smr View Post
Yes, based on the Tetra standard, you can connect the system to other networks ( analog radio, telephone etc).
I don't think such interconnections are based on the TETRA standard since many of them already existed long before TETRA (like the aforementioned 4w E&M), and with TETRA being digital the standard would certainly not specify any analog signaling.

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You can even participate in the Tetra group call with landline telephone.
Or from a GSM phone, CDMA phone etc., and you can also make or receive private calls to/from virtually any system that can be interconnected somehow, subject to the vendor of the TETRA system and the interfaces available (4w E&M, ISDN etc.).

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In the Cassisidian system the feature is called fallback
The Cassidian fallback mode assumes that the TBS is normally connected to their TETRA switch via a transmission link but when said link is interrupted the TBS enters the so-called Fallback Mode.
When the link is up the switch will download parameters like frequencies to the base station, which are then also used in Fallback mode.
In Stand-alone Mode the TBS is configured locally and does not require a connection to a switch first, think single-site system or a mobile TETRA base station for example. I guess that comes closest to a conventional repeater.

Motorola calls it Local Site Trunking btw, not sure if they differentiate further between "fallback" and "stand-alone" mode.
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Old 04-02-2012, 12:28 PM
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Raccon, you have better English wording than I, generally that is what I met about the interconnections

However I am not familiar with the Stand-alone Mode, will look into that tomorrow. Although I have not met a mobile base station without the connection to switch.
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Old 04-02-2012, 12:34 PM
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Along similar lines, are there any TETRA SUs out there that are capable of analog? For migration and legacy operation that is.
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Old 04-02-2012, 12:51 PM
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Quote:
Originally Posted by exkalibur View Post
Along similar lines, are there any TETRA SUs out there that are capable of analog? For migration and legacy operation that is.
What's a SU?
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Old 04-02-2012, 5:21 PM
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Subscriber unit.
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Old 04-05-2012, 1:30 PM
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Subscriber unit.
I see. AFAIK there is currently no TETRA terminal (SU) on the market that offers an analog mode.

You can however connect a TETRA and an analog radio back-2-back to enable communication between the two; not practical for handheld units but workable for mobiles installed in a vehicle for example.

You can also link TETRA and analog systems at the infrastructure level, thus allowing communication between analog and digital radio users for inter-agency operation (temporary or permanently) or during migration, which might be more reliable and cheaper than using radios back-2-back (in particular where you have a lot of analog channels that need to be connected with the TETRA system).
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