Tetra And Nextel

[kalafoyi]

I've noticed Nextel sounds similar to TETRA. My question is; does the end of transmission "beep" get transmited through the input side or through the repeater? Also, does Sepura, Motorola, Nokia ect all have this roger beep feature? And also do they have the tone to let you know when you've hit the repeater and can start to talk.

Thanks everyone.

[C138Kaysone]

Umm who in the US uses tetra? I think some governments in Mexico uses it, When i saw was being used, I dont think tetra has a roger beep but nextel just have that one little faint beep at the end... Ill ask again and see, never got to really try to tetra system

[N_Jay]

Roger beep is usually implemented as a feature that can be enabled in the radio and is generated by the receiving radio (iDEN).

[C138Kaysone]

I just looked up at the nokia, looks pretty sweet! and its 800Mhz?

[citylink_uk]

Motorola still refuse to licence TETRA for the USA even though its one of the most popular trunking protocols with high profile national public safety networks all over Europe, Far East and as far as Australia. Apparently when they were picking the P25 standard, TETRA 'wasn't suitable' for the USA. The only reason why that I can think of is that allot of Public Safety systems in the USA seem to be very reliant on very few towers and TETRA is a infrastructure heavy system that hosts the radios leading to higher costs.

The benefit here is that TETRA users get lightweight and very cheap (around $350) radios whilst P25 users usually have to pay around $1200 for just one radio which is usually quite large, heavy and a more limited battery life.

Most handsets on this system do emit a talk permit tone when the PTT is pressed telling the user they have a channel to use and then on release of the PTT a very short high pitch beep to show the user has stopped transmitting.

Originally Posted by C138Kaysone

Umm who in the US uses tetra? I think some governments in Mexico uses it, When i saw was being used, I dont think tetra has a roger beep but nextel just have that one little faint beep at the end... Ill ask again and see, never got to really try to tetra system

[N_Jay]

Originally Posted by citylink_uk

Motorola still refuse to licence TETRA for the USA even though its one of the most popular trunking protocols with high profile national public safety networks all over Europe, Far East and as far as Australia. Apparently when they were picking the P25 standard, TETRA 'wasn't suitable' for the USA. The only reason why that I can think of is that allot of Public Safety systems in the USA seem to be very reliant on very few towers and TETRA is a infrastructure heavy system that hosts the radios leading to higher costs.

The benefit here is that TETRA users get lightweight and very cheap (around $350) radios whilst P25 users usually have to pay around $1200 for just one radio which is usually quite large, heavy and a more limited battery life.

Most handsets on this system do emit a talk permit tone when the PTT is pressed telling the user they have a channel to use and then on release of the PTT a very short high pitch beep to show the user has stopped transmitting.

TETRA is not a wide spread is people make it out to be. In Asia and Australia, it is primarily in the larger cities, with P25 preferred in other areas.

Sure the handsets are cheap, but the network is more the expensive enough to make up the difference (and maybe more).

Talk permit is a necessity as the number of sites goes up and the number of channels per site goes down, hence why you see it on TETRA and iDEN, but not as often on P25.

[EnidPuceflange]

Originally Posted by citylink_uk

Motorola still refuse to licence TETRA for the USA even though its one of the most popular trunking protocols with high profile national public safety networks all over Europe, Far East and as far as Australia. Apparently when they were picking the P25 standard, TETRA 'wasn't suitable' for the USA. The only reason why that I can think of is that allot of Public Safety systems in the USA seem to be very reliant on very few towers and TETRA is a infrastructure heavy system that hosts the radios leading to higher costs.

The benefit here is that TETRA users get lightweight and very cheap (around $350) radios whilst P25 users usually have to pay around $1200 for just one radio which is usually quite large, heavy and a more limited battery life.

Most handsets on this system do emit a talk permit tone when the PTT is pressed telling the user they have a channel to use and then on release of the PTT a very short high pitch beep to show the user has stopped transmitting.

Well, one of the big differences between P25 and Tetra would be the power output - since Tetra uses complex modulation, requiring a linear PA the terminals are heavily restricted as to the power output. P25 having a much simpler modulation (at least as far as the terminals are concerned) allows MUCH higher power outputs, and thus the area covered per tower is larger. This matters much more in the sparsely populated USA than in the much more urban European areas Tetra was intended to use.

Tetra does NOT scale well once you get out into rural areas with few towers, since the maximum power of even mobiles is limited.

An interesting question that nobody seems to be asking is this: since P25 has a much cruder and simpler RF system, why are those terminals not as cheap (or cheaper) as Tetra? And another interesting question that seems un-askable is why, given all of the perceived (and much touted) advantages of P25 in the USA is the P25 committee developing P25 phase 2, the TDMA version with all of the power and coverage issues of Tetra, but none of the established market and proven terminals?

Could it be that the manufacturers LIKE selling $5000 radios? And don't like the idea of selling $400 radios? Hmmmmm.....

[citylink_uk]

I definitely say that TETRA is as widespread on a worldwide basis as P25, as its high profile customers spread out from National Public Safety networks to large regional transportation systems and local governments. I believe that TETRA and P25 were developed at around the same time.

P25 was designed and accepted for use in the USA and does the job fine, but I can't help thinking that when Phase II comes knocking at the door Motorola will be asking the same customers for a complete system overhaul!

TDMA might even reduce coverage so those who have gone 'P25 on the cheap' might end up investing more in infrastructure this time around. At least TDMA should give better battery life, customers may be able to give up their 4500mah monster battery packs

[citylink_uk]

Originally Posted by EnidPuceflange

Could it be that the manufacturers LIKE selling $5000 radios? And don't like the idea of selling $400 radios? Hmmmmm.....

One word and three letters......Motorola APX

[v-v]

The advantage of P25 is that there are scanners., TETRA not.

For the UK and my country the Netherlands the using encryption,But Belgium not!
So uniden make a tetra scanner.



.

[AZScanner]

Originally Posted by v-v

The advantage of P25 is that there are scanners., TETRA not.

For the UK and my country the Netherlands the using encryption,But Belgium not!
So uniden make a tetra scanner.

.

Isn't TETRA encrypted by design? If not, since the radios are so relatively inexpensive why not just buy a TETRA handset? They're about the same price as a digital scanner anyway and probably would work alot better.

-AZ

[rdale]

Originally Posted by v-v

The advantage of P25 is that there are scanners., TETRA not.

I don't think that's really a concern for system builders. TETRA is all encrypted anyways, so the point is moot. No scanner will ever be made for it.

[C138Kaysone]

Thought you need a special card or something and license in order to use a tetra radio, plus it wont just work just for listening for how i was looking at it, plus no one in London can scan local police anyways due to the fact they are encrypted out the butt! maybe im wrong, maybe im right, i would like to have a tetra radio but then again what are the odds of them working better then the radios here?

[rdale]

As you said, TETRA is encrypted,so I'm not sure what you are asking about. A TETRA scanner will never exist.

[kayn1n32008]

And with no TETRA infrastructure in north america there is even less of a reason to have a TETRA radio.

[v-v]

Originally Posted by AZScanner

Isn't TETRA encrypted by design? If not, since the radios are so relatively inexpensive why not just buy a TETRA handset? They're about the same price as a digital scanner anyway and probably would work alot better.

-AZ

TETRA is a trunking network, if I buy a TETRA radio he does nothing.
You never come on the network. And it's very illegal!

[v-v]

Originally Posted by rdale

I don't think that's really a concern for system builders. TETRA is all encrypted anyways, so the point is moot. No scanner will ever be made for it.

Then say it again, Bulgiums (astrid) TETRA network is NOT encrypted.
U.K.(airwave) Netherlands (c2000) Germany (bdbos) and more europeen country's has TETRA networks with a very strong TEA encryption for the public safety networks.
Standard Tetra network doesn't have encryption.

Tetrapol (another digital system) networks are allways encrypted.

[Raccon]

v-v is right, TETRA is not always encrypted, it is an option.