Radios and Such...Astro, Trunking, Digital, APCO25

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N5OSU
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Radios and Such...Astro, Trunking, Digital, APCO25

Post by N5OSU »

alright guys i am confused,

I live in Ø Land (Denver) and we have one 900 Mhz repeater, what is the difference between astro, apco25, digital and trunking?

i would love to get further into radios but i do not have anyone to explain or guide me in the ways of radio.

Hellp!! Teach me!! Recommend a radio!!

i see you guys talking about astro this and trunking that, i feel like im on the outside of something really cool that i would love to be involved in.

:ham: :ham: :baby: :baby:
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exkalibur
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Post by exkalibur »

Well, I just woke up so this isn't going to be the best explaination ever, but hopefully it'll help.

ASTRO = The name of Motorola's digital offering. The original version of ASTRO was a technology called VSELP (Vector-Sum Excited Linear Prediction). This technology isn't used that much anymore. As an example, Cleaveland Ohio use this technology as do very few other areas. The current offering of ASTRO is called IMBE (Improved Multi-Band Excitation). There is also AMBE (Advanced Multi-Band Excitation) which is just starting to appear.

APCO 25 (or P-25) refers to a standard set by the Association of Public-Safety Communications Officials which refers to a Common Air Interface, a standard method for trunking and the set of standards defining all of that. The method of Digital Voice chosen to be a P25 standard is IMBE, which is the current Motorola ASTRO offering. The thinking is that you can use ANY make of radio, so long as it supports P25, and be able to talk to any other P25 radio out there.

Trunking is, simply put, a logical arrangement of voice channels. There's several types of Trunking out there, such as EDACS, LTR, MPT1327, Motorola Type II, etc... EDACS stands for Enhanced Digital Access Communications System and is the Trunking offering by GE/Ericsson/M\ACom/Tyco. EDACS systems use a control channel. LTR stands for Logic Trunked Radio, and is an open standard created by EF Johnson, and does not use a control channel, rather it uses sub-aubible messages on the various voice channels. MPT1327 is a European standard that has seen a few implementations in North America. It uses a control channel, and can be (very) loosely compared to LTR trunking, but it's got a much larger feature set. Finally, Motorola has various types of trunking. Their first offering is called Privacy Plus, or Type I trunking. This used a Fleet/Subfleet arrangement and used Fleet Maps, which is a royal PITA to program. They then came out with Type II trunking, which instead of using a Fleet/Subfleet arrangement, it just uses a talkgroup ID which is a hex value between 001 and FFE (FFF is a wildcard) and a radio ID which is a 4 digit hex value between 0001 and FFFE (FFFF is a wildcard). There's variations of Type II such as Smartnet, SmartZone and SmartZone Omni-Link, but they all work generally the same way.

I'm sure someone can do a better job explaining these things to you, but hopefully that'll get you going for now :)

-Mike
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N5OSU
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Post by N5OSU »

thanks man that clears alot of things up for me....can anyone suggest a decent astro radio?

that sounds like the portion i want to get into

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mr.syntrx
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Post by mr.syntrx »

I assume you'll be looking at second hand gear. For portable operation, get an ASTRO Saber or XTS-3000. For mobile, get an original ASTRO Spectra (I personally like the W3 model, with the control mic).

Make sure you check the flashcode first to make sure it does indeed do IMBE before you buy it.
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