Feds pushing Project 25

[ElroyJetson]

The problem with interoperability is obvious...we're dealing with FOUR different bands,
or actually, FIVE, if you consider that the UHF band goes as low as 383 MHz and as high as
520 MHz and no radio currently on the market handles that full range by itself. Only the
700/800 bands are close enough together that one radio can cover both, at least until
someone makes another multi-band radio option.

And even if everyone is on the same band, there's still unique system data. Unless you're
already part of a multi-site, wide area system, you're going to have separate personalities
for any other radio system. Do you have enough radio memory to handle a large number
of systems? Is it very user-friendly to have to contend with that many radio systems that
you have to choose from? Who gets to use ALL these systems? Who's got that authority
and who's going to manage ALL the required system and encryption keys for ALL those
systems and keep them ALL updated for ALL concerned?


It's a pretty hairy situation at best. But at least, with P25 interoperability, the situation
is less hairy than it was.

If I did join the standards group, I'd recommend setting up a nationwide network of
VHF repeaters. Set a PL tone, go analog, clear voice, and stay that way. Keep it simple.

All this digital technology has dramatically raised the cost of radio equipment and systems
but it hasn't made it WORK BETTER.


Elroy

 

[16b]

Wow.
I guess you better join the standards group and let them all know they are waisting their time!:roll: :roll:

If the people in the "standards group" think that developing an open digital communications standard and making everyone in the U.S. use it is all it takes for "interoperability," then they *are* wasting their time. I'm glad we have P25. I'm glad that people are using it. But...

I'm not going to repeat what Elroy said; he nailed it. There are already P25 systems on VHF, UHF, 700MHz, and 800MHz. How is this interoperable? It's the *band* that presents the biggest problem.

 

[N_Jay]

If the people in the "standards group" think that developing an open digital communications standard and making everyone in the U.S. use it is all it takes for "interoperability," then they *are* wasting their time. I'm glad we have P25. I'm glad that people are using it. But...

I'm not going to repeat what Elroy said; he nailed it. There are already P25 systems on VHF, UHF, 700MHz, and 800MHz. How is this interoperable? It's the *band* that presents the biggest problem.

Maybe you need to look at all the goals for P25 and not just Interoperability.

 

[randyf]

apco-25

up here in ontario canada the goverment pushed the apco-25 radio system , so all emergency sevices could inter- comunicate, after two years of listening i have yet to here this happen everything is still relayed through the respective dispatchers, nothing really changed other then analog scanners have become almost scrap if one would want to here police and ambulance , most rural fire departments are still analog

 

[N_Jay]

up here in ontario canada the goverment pushed the apco-25 radio system , so all emergency sevices could inter- comunicate, after two years of listening i have yet to here this happen everything is still relayed through the respective dispatchers, nothing really changed other then analog scanners have become almost scrap if one would want to here police and ambulance , most rural fire departments are still analog

You can't fix an operational problem with technology, but technology can cause a lot of operational problems.

Sometimes you have to build the inter-operational hardware before you can even open the inter-operational discussion.

 

[ElroyJetson]

I see the whole thing as an excessive and unnecessary application of technology with the result NOT being a better radio system.

Digital costs more to achieve results equivalent to analog. I don't see that as a winning situation.

I despise the post-9/11 paranoia in the name of "homeland security" and "anti-terrorism"
that is giving our governing bodies a "good" excuse to make their communications virtually
impossible for the pepole to listen to. When a government expands secrecy, expect it to
expand tyranny as well.

You might call me paranoid, but really I'm just a little bit skeptical of motives.


Elroy

 

[N_Jay]

I see the whole thing as an excessive and unnecessary application of technology with the result NOT being a better radio system.

I am sure you do.

Digital costs more to achieve results equivalent to analog. I don't see that as a winning situation.

However, in every other market the move from analog to digital has reduced costs.
I think we may be hitting tho cross over point very soon here also.

I despise the post-9/11 paranoia in the name of "homeland security" and "anti-terrorism" that is giving our governing bodies a "good" excuse to make their communications virtually impossible for the people to listen to.

Yes, but P25 development predates 9/11 by about a decade, and the move to digital radio started about a decade before that. And if you count digital features carried on analog channels you can go back another decade or more.
So it would seem history has punched a big hole in your paranoid delusion.

When a government expands secrecy, expect it to
expand tyranny as well.

You might call me paranoid, but really I'm just a little bit skeptical of motives.

No, I think you have crossed the line beyond just skeptical.

 

[WayneH]

Digital costs more to achieve results equivalent to analog. I don't see that as a winning situation.

Please tell me why you feel this is true. It better not be the whole analog goes farther than digital argument, which is not true.

 

[flecom]

isnt conventional FM the ultimate "interop" technology... i mean they are all on different bands/frequencies anyway, adding a layer of complexity with P25 (IMBE) is just extra crap that some people wont have...

 

[MOTOROLANUT]

p25

Its all about $$$$$$$$$..

 

[flecom]

However, in every other market the move from analog to digital has reduced costs.
I think we may be hitting tho cross over point very soon here also.

the problem here is that while P25 is an "open standard" IMBE is not an open-source vocoder, so no matter what, you still have to pay for that little IC that turns the digital into analog and back again... and those chips are very expensive (and licencing) which is why those P25 scanners cost so much...

so until DVSI decides to stop being a bunch of greedy bastards, or they go with an open source vocoder (which mind you there are some excellent open-source vocoders, some with arguably better quality than IMBE) its still going to be more expensive to go digital, becuase its still analog audio to RF and back...

 

[N_Jay]

isnt conventional FM the ultimate "interop" technology... i mean they are all on different bands/frequencies anyway, adding a layer of complexity with P25 (IMBE) is just extra crap that some people wont have...

Except for the range loss due to narrow-banding,
AND,
The lack of any standardized features (beyond coded squelch)
AND,
Any progress towards network interoperability,
AND,
Any secure system standards,
AND,
Any unit ID scheme,
AND,
Any messaging/data scheme.

Yes, but other than that and a few other things.

Wait, lets go back to AM, that is "interoperable",
No, No, the answer is CW . . . .

Yeahhhh, "CW", That's the ticket!:roll: :roll:

 

[N_Jay]

the problem here is that while P25 is an "open standard" IMBE is not an open-source vocoder, so no matter what, you still have to pay for that little IC that turns the digital into analog and back again... and those chips are very expensive (and licencing) which is why those P25 scanners cost so much...

so until DVSI decides to stop being a bunch of greedy bastards, or they go with an open source vocoder (which mind you there are some excellent open-source vocoders, some with arguably better quality than IMBE) its still going to be more expensive to go digital, becuase its still analog audio to RF and back...

Well then I guess you should join the Standards committee and cast your vote!

 

[flecom]

Well then I guess you should join the Standards committee and cast your vote!

woah who pooped in your wheaties?

i suppose your on the Standards committee also correct?

i think P25 is great, but realistically, the bigger problem is the fact most systems are on different bands, the radios have to be pre-programmed for the other systems (which some system operators wont even let other agencies do to begin with), people like motorola adding their own "features" and a bunch of other logistical issues...

so there will never really be a truly "interoperable" system unless we get self programming radios that do DC-light

 

[N_Jay]

i suppose your on the Standards committee also correct?

Nope, not me, but I am not the one complaining on there decisions.

i think P25 is great, but realistically, the bigger problem is the fact most systems are on different bands,

Yep, but the existence of other issues is a bad reason to not fix what you can.

so there will never really be a truly "interoperable" system unless we get self programming radios that do DC-light

Nope, GOOD PLANNING and the PROPER application of technology can do much for "True Interoperability"!

 

[DaveNF2G]

Not to mention adding more expense to the whole communications function by layering managers to plan out how to control interoperable systems, a function that most PS agencies don't need now. Project 25 started as a way to make digital radios affordable by promoting competition between brands and breaking the old single vendor stovepipe market. Then 9/11 happened and "interoperability" took over. Should be a new Project.

 

[zerg901]

N Jay - what exactly has P25 fixed? How is P25 better than analog overall?

I can tell you how P25 is worse than analog : rapid drop off at edge of coverage area - total loss of signal during doubling - cannot carry pager tones - dies due to loud background noise - watery audio - makes scanners cost 5X more .

Peter Sz

 

[N_Jay]

N Jay - what exactly has P25 fixed? How is P25 better than analog overall?

In no particular order

Better coverage at 12.5 kHz bandwidth
Potential to move to 6.25 kHz without coverage feature for clarity loss
Less noise in fringe coverage
Standardized "advance conventional" (for lack of a better term) feature set
Standardized "public safety grade" trunking
Standardized secure with advanced features (OTAR, etc)
Standardized inter-trunked system interface
Other standardized system interface points (in process)

I can tell you how P25 is worse than analog

OK

rapid drop off at edge of coverage area

Yes, but the edge is further out that with analog, so this is a false problem.

total loss of signal during doubling

At times, and being investigated. Can happen with analog also.

cannot carry pager tones

Has other signalling,
I would anticipate paging type operation to be addressed in the future.

dies due to loud background noise

Being addressed, Can happen with analog also.

watery audio

Typically a symptom of other system issues or poor coverage.
Not a problem in a properly designed current generation system.

makes scanners cost 5X more

Who cares!:twisted:
Well, really, it doesn't. How much was a top of the line trunking
scanner when it was first released (in current $$)?
Does add some costs, but so has every new feature.

 

[zerg901]

N Jay - thanks for your reply.

I dont think that digital has greater range than analog.

I think that your comments about digital scanner prices are unlogical .

I think you are talking more about (proposed) 'system architecture' than over the air transmissions (CAI).

Could you explain your comment about 6 Khz channels? I think you are saying that P25 can migrate easily to 6 Khz channels.

Peter Sz

 

[N_Jay]

I dont think that digital has greater range than analog.

I don't "THINK" so either; I know so! :twisted: :lol: :twisted:
Especially at 12.5 kHZ

I think that your comments about digital scanner prices are unlogical.

Why?

I think you are talking more about (proposed) 'system architecture' than over the air transmissions (CAI).

I am talking about the entirety of the standard. Why would you not consider the whole standard when you consider you need the lower layers to make the high layers practical.

Could you explain your comment about 6 kHz channels? I think you are saying that P25 can migrate easily to 6 kHz channels.

P25 includes a 6.25 FDMA standard, that has not been implemented by the vendors for a variety of technical reasons, but is there and could provide 6.25 kHz operation with range equivalent or better then today's 25 kHz.
These is currently in finalization a 2 slot TDMA standard that will provide 6.25 kHz equivalent operating.

"Easy" is always a judgement call. Certainly easier than without a standard!!