The noobie post....

Forum for the promotion and understanding of digital voice on the amateur bands.

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The noobie post....

Post by KF4ZTO » Thu Jan 20, 2005 9:16 am

Hey all, I'm interested in this new digital mode stuff, but I know nothing about it, I'm a young ham and I can see this is where the hobby (or at least the non-CW-nazi/old geezer) part of the hobby is going.

So I'm just interested in some background info on digital voice and such, because it seems pretty darn cool.

kd5ing

Post by kd5ing » Thu Jan 20, 2005 4:05 pm

I have questions as well.

When I talked to the Alinco folks at hamvention they said their digital radios would work with analog repeaters.

Is that the same for the P25 radios?

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Post by grem467 » Thu Jan 20, 2005 5:09 pm

no, you need a repeater capable of ASTRO, ie Quantar/Quantro.
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..

Post by batdude » Thu Jan 20, 2005 5:29 pm

personally (my take here)

alinco builds TOTAL CRAP radios.


but - they deserve two :vestman: :vestman: for being the first to market with a digital format to cheapo ham rigs.

no, their radios will NOT run through analog repeaters - this was described in the initial QST review of the radio.



doug

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Post by Wardriver » Thu Jan 20, 2005 8:06 pm

I was at Michigan State University today talking with one of my old professors. The janitor in the book store had a ASTRO!!

I saw him later and asked him about his radio...........Dude must have thought I was fricking nuts!!

Turned out he was a part time fireman and he talks to all his cop buddies on channel 1.

All this talk of ASTRO has me convinced, I need to learn more about this digital world you guys are on.
The pessimist sees difficulty in every opportunity. The optimist sees the opportunity in every difficulty" --Winston Churchill

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Post by grem467 » Thu Jan 20, 2005 8:27 pm

once ya go << BRAAAAAAP >> ya dont go back!!
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Post by grem467 » Thu Jan 20, 2005 8:30 pm

seriously though, i was listening to my buddies talk astro last nite on the repeater and astro was clear as a bell, when they went to analog, the radio didnt even bother to unmute, the signal was so weak.

whats so amazing about that you ask?

i was using my XTS on the rubber duck antenna in the house 50 miles away
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Post by bobsflying » Thu Jan 20, 2005 9:08 pm

I'm usually found on the ScanOnt group that Bryan owns...

Added this to his FAQ.... feel free to rip it apart - wrote it at work the other day... It's been simplified for the scanner user, not TXing ;)

---

What is “digital” radio?

One word that you will see bounced around on the Scanont group, or other related radio websites is the use of the term “digital” or “they’re on digital”. Don’t worry, it’s not as complicated as you think – you’ll just require the proper hardware to listen in!

First, let’s explain why digital radio is being implemented. Many people feel that it’s a push towards locking out listeners, but in reality it’s combination of three major factors:

Narrowband Requirements

Radio spectrum is a natural resource that has become quite clogged as it’s so popular. As such, narrowband requirements have been introduced into the commercial spectrum to make more room for others users. Digital radio allows more efficient use of bandwidth of the spectrum. Not to mention, digital radio sounds excellent to the end-users and uses very little bandwidth in comparison to analog to do so.

Vendor Marketing

Beyond the technical advantages digital brings, radio manufacturers also need to push for new and improved systems to be profitable. Nobody wants to implement an archaic trunked analog system when they can have a crystal clear digital trunked system! When organizations upgrade their radio system, it’s usually combined with a new dispatch system or mobile terminals and so on – it’s an investment.

Encryption

This is a touchy subject. There are perceptions that organizations switch to digital primarily for encryption capabilities, this may be a bit of an overstatement. True, encryption can be a very big selling point for organizations but combinations of who is using the system and technical requirements just discussed are generally considered. When digital radio is used, encryption is much easier to implement and the loss of quality is fairly limited - in comparison to legacy analog systems. If you’re in an area where encryption is used in either analog or digital modes – you’re out of luck. Attempting to decrypt transmissions is illegal in Canada, not to mention close to impossible for even the advanced user.

So. You tune in on your analog scanner and hear odd sounds. How do you know what kind of scanner to get or if they’re digital at all?

Let’s discuss what exactly “digital radio” is. It’s really nothing too exciting. Instead of analog voice being transferred, digital modulation and streaming occurs instead. If you’ve ever used online radio stations that stream music, the method of hearing the music is exactly the same as radio – the transfer realm is just different. If you’re a Windows or Mac user, you should be familiar with audio files (e.g .wav/.aiff). If not, they play audio that has been stored on your hard drive.
For example, depending on the format of the file – you must use what is called a codec. A codec in short, describes to a player what do with the data. When you use a sound recorder application on your computer and record your voice, a codec is taking your voice and storing that information in that specified digital format. It’s also known as encoding.

For example, using a “.wav” file in Windows; you can record your voice using a codec called GSM. If you’ve ever used a Rogers or Fido cell phone – when you speak into the phone – your phone is constantly taking your voice and using the GSM codec to send the data stream to the cell tower. The same is true with non-cellular networks and computer applications. Again, the transfer realm is what differs.

Now, if one was to send you a file that used the GSM codec – and you don’t have it installed – guess what? You cannot decode the file! The same is true in radio applications. When a person talks into a radio there is a device called a vocoder that takes their voice and converts it into a digital data stream that can be decoded in real-time by a receiver. Various vendors use open or proprietary voice codecs to encode speech and stream it over the air. If you don’t have the proper radio with the right codec installed, you will not be able to properly encode it, just like our audio file situation.

One drawback to digital radio is that you may need multiple types of equipment to partake in a transmission. The good news is - there aren’t too many digital formats that have been widely used yet. The technology is still evolving and being implemented.

So. Now you understand the meat about digital voice itself – let’s discuss the popular formats out there:

Motorola IMBE

This digital format is also commonly known as “APCO25” or “P25” or “DIGITAL” or “P25 CAI”. For the most part, this slang all refers to this type of digital format. It’s fairly popular and, it’s the only form of digital voice on the market that is scanner compatible. It can be used in conjunction of a trunked system or conventional simplex/repeater operation.

Currently there are six scanners that support this digital format:

- Radio Shack Pro-96
- Uniden Bearcat 250D (with card) or 296D
- Uniden Bearcat 785D (with card) or 796D
- Uniden Bearcat 396DT (pending release)

See the other sections of the FAQ regarding differences with the scanners on digitally trunked systems.

Motorola VSELP

This digital format pre-dates Motorola’s IMBE format. It was short lived, but has been implemented throughout various places in North America. Any transmissions that use VSELP cannot be monitored unless you have a system radio. An off-topic note, VSELP is used on iDEN phones/radios. For the most part, it’s an obsolete format in real two-way radios.

MA/Com ProVoice

This is the current digital format that is pushed by MA/COM. It’s prominently used on EDACS systems, but can be conventionally as well. The format is quite similar to IMBE, but differs with some features such as error correction. Monitoring transmissions is possible, but requires the use of system hardware. Despite rumors, MA/COM has stated numerous time it would never license their proprietary codec to scanner vendors. This means, there most likely will not be a scanner introduced that allows you monitor such transmissions.

GE/Ericsson AEGIS

This digital format was the second generation digital voice developed by GE/Ericsson. It’s since been replaced by ProVoice. AEGIS transmissions cannot be monitored with a scanner, however, the good news is - few agencies still use AEGIS.

--

Keep in mind, there are numerous other types of digital formats that will be introduced for amateurs and non-public safety operations in the next few years.

And, that’s about it. Enjoy.

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Post by Wardriver » Fri Jan 21, 2005 4:28 am

Thanks Bob.
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Post by mr.syntrx » Fri Jan 21, 2005 4:55 am

Alinco's digital audio sounds like shit. ASTRO all the way!

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Post by KF4ZTO » Fri Jan 21, 2005 4:43 pm

Yeah, but how much does a DECENT digital rig cost?

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Post by KC8RYW » Fri Jan 21, 2005 4:57 pm

KF4ZTO wrote:Yeah, but how much does a DECENT digital rig cost?

More then I can make a night on the corner, that's for sure.

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Post by KF4ZTO » Fri Jan 21, 2005 6:08 pm

hahahaha, good one. but that's still not a number

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Post by kv5e » Fri Jan 21, 2005 6:09 pm

Icom - IC-2200H is 219.95 VHF 65 watt transceiver
Icom - UT-118 is 189.95 DStar CAI card

This is the basic DStar configuration for 2 meters.

There is not likely to be a lot of other hams on the Dstar CAI yet, but you can find a "bud" who wants to play around and both make the jump.

The IC-V82 will be out soon at less than the IC-2200H if you want to add the UT-118 card to that and have a hand held setup.

Motorola AstroSabers are more money for P25 and you should get a programming set up for these as they are not programmable except by the radio service software. You may find a AS for under $500 but you have to know what you are buying.

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Post by mr.syntrx » Fri Jan 21, 2005 9:43 pm

kv5e wrote:Motorola AstroSabers are more money for P25 and you should get a programming set up for these as they are not programmable except by the radio service software. You may find a AS for under $500 but you have to know what you are buying.

kv5e


And Shaun's newbie guide to ASTRO portable radios is the document that everyone unfamiliar with /\/\ gear who wants to go P25 should read.

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Post by KF4ZTO » Sat Jan 22, 2005 10:41 am

k thanks

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Post by KF5DDE » Sat Feb 12, 2005 2:59 am

[quote="Wardriver"]

All this talk of ASTRO has me convinced, I need to learn more about this

digital world you guys are on.[/quote

I agree i need to do the same
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Post by VE6HBD » Sat Feb 12, 2005 3:14 pm

bobsflying wrote:I'm usually found on the ScanOnt group that Bryan owns...


Just as an aside.... I don't run Scanont.... I'm just a moderator.... Steve runs it..... Don't wanna get Steve mad at me (grin)

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Post by KC8RYW » Sat Feb 12, 2005 3:16 pm

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Post by KI4IHC » Wed Jun 08, 2005 2:46 pm

The thing that really intrests me about D-Star (and other digital modes) is the possibility of high speed data - i.e. - the ability for me to access my home network from my car while I'm waiting for a traffic light to change.

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Post by mr.syntrx » Thu Jun 09, 2005 2:38 am

You will have to be careful about encryption if you do that, because the law still says that's a no-no on the ham bands. Youl would have to force your machines to use clear passwords on SMB/CIFS shares, and stuff like that.

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Post by KI4IHC » Thu Jun 09, 2005 3:08 am

mr.syntrx wrote:You will have to be careful about encryption if you do that, because the law still says that's a no-no on the ham bands. Youl would have to force your machines to use clear passwords on SMB/CIFS shares, and stuff like that.


Yeah, that's a pretty big drawback, but it still seems cool.

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