Digital fireground radios a no go.

[KA5PIU]

Hello.

The Second round of tests are in, and digital again flunked the tests.
Motorola is in the lead in pushing for digital but due to the troubles with the Motorola system on 9/11 in NYC congress has instructed the FCC to prove to congress that digital is needed.
One of the things that did happen due to 9/11 is that mutual aid is a 25KHz analog conventional scheme, digital is not permitted and all public safety radios must be able to do mutual aid, in effect mandating analog conventional as a feature.
So, P-25 radios systems will be mixed use.
Motorola wanted to add proprietary features to their public safety offerings, something the FCC had at first approved but congress has since prohibited this.
Mutual aid frequencies are not police frequencies, they are mutual aid frequencies, congress has made this clear.
There is little on the web on this at the moment, I attended a CAP meeting where this was all brought up in a video conference.
All of CAP has migrated to P-25 on the new radios and are to already have discontinued the older equipment however due to the requirement to retain analog the older equipment, provided that it is still on the approved list, may still be used as secondary radios.
The 390MHz operations may now be 50 watts.
There were issues with garage door openers and the like and thus the government decided to limit the introduction of 390MHz for a while.
As of April we now are to operate at full power, up to 50 watts.
Repeaters may be as much as 1250 watts.
This is a P-25 and Analog mixed use system.

[n2ize]

The law does not require that services go digital. They can remain on analogue. The only requirement is that they reduce (narrow) their occupied bandwidth from 25 kc to 12.5 kc. Numerous services have already narrowed their bandwidth but at the same time have decided to remain analog. Most modern radios, even many ham radios are already capable of being switched to narrow band FM.

Now, if I were in charge I would have mandated that all public services be narrow band digital and encrypted. I'm pretty tough when it comes to stuff like that.

[KA5PIU]

The law does not require that services go digital. They can remain on analogue. The only requirement is that they reduce (narrow) their occupied bandwidth from 25 kc to 12.5 kc. Numerous services have already narrowed their bandwidth but at the same time have decided to remain analog. Most modern radios, even many ham radios are already capable of being switched to narrow band FM.

Now, if I were in charge I would have mandated that all public services be narrow band digital and encrypted. I'm pretty tough when it comes to stuff like that.

Hello.

Correct, as it is now the FCC can not mandate digital.
But like you, they wanted to require digital.
Narrow banding is also a requirement but what is the point?
Fact of the matter is this.
The FCC really screwed up when they let Nextel run in the same frequency range as public service.
Now they have to reband everything, so the FCC is now involved in some more unneeded spectrum games.
The opening of 700MHz should have been public safety only, not an effort to find another place for Nextel.
The cellular common carriers have proven that frequency reuse works, and works well.
Fact of the matter is that the cellular carriers have more subscribers in any major city than all of the public service radios of the entire nation, combined.
The trouble the cellular carriers have is not one of spectrum, but where to put the antennas.
They have hundreds of them in any major city, some on towers, some on buildings, some inside buildings.
That is the challenge the cellular industry faces now.

[NQ6U]

http://i815.photobucket.com/albums/zz79/gyrogeerloose/pickle-stains.jpg

[n2ize]

Hello.

Correct, as it is now the FCC can not mandate digital.
But like you, they wanted to require digital.
Narrow banding is also a requirement but what is the point?
Fact of the matter is this.
The FCC really screwed up when they let Nextel run in the same frequency range as public service.
Now they have to reband everything, so the FCC is now involved in some more unneeded spectrum games.
The opening of 700MHz should have been public safety only, not an effort to find another place for Nextel.
The cellular common carriers have proven that frequency reuse works, and works well.
Fact of the matter is that the cellular carriers have more subscribers in any major city than all of the public service radios of the entire nation, combined.
The trouble the cellular carriers have is not one of spectrum, but where to put the antennas.
They have hundreds of them in any major city, some on towers, some on buildings, some inside buildings.
That is the challenge the cellular industry faces now.

Part of the point is to enable more services onto a single band. Think of the "band" as a total area of x units. Now think of each station as a blob that takes up 25 units of that area. Eventually you can only squeeze in so many 25 unit blobs. Now, require that every blob must decrease in size by 1/2 or 12.5 units. Now you have more free area to work with and you can fit more blobs within that given x units of area.

The whole idea was to make more space available, to be able to fit more stations within a fixed amount of bandwidth. The only real downside is

1) That it requires funds to upgrade or modify existing equipment at a time when municipalities are already strapped for cash.

2) incompatibility issues with some wideband devices. Older wideband scanners, and equipment without adjustable filters might receive two stations at once or might experience interference effects. In many cases the easiest cure is to upgrade to newer narrowband capable equipment. Of course this translates to money. Most modern radios are already narrowband capable.

[KA5PIU]

Hello.

Yes, but the real way to fit more blobs in a given area is to have the blobs cover a much smaller area and have a hundred or so use the same layer.
That is how cellular works, frequency reuse.
Think about this for a moment, when Analog cellular hit there were only 832 channels split between 2 carriers.
Yet within 5 years the average carrier had around 7000 calls going at any one time in a given metro area.
Now the traffic density is around 40 thousand at any time and going up.
And that is just the voice calls, data density is even higher.
CDMA provides the highest density of all, up to 14 subscribers per 15kHz equal spectrum.
So, if one were to allocate a CDMA system that could support 50 users in a given area with 15kHz analog channels it could serve 700 users.
But if we were to split the area up into just 5 cells in a given area we could get 3500.
Lets say that we are only 50% efficient in the system, mobiles moving into other cells, etc.
We still have 1750 users, far greater than the 50 analog users.
Now, lets say we split the analog 50 channels with cellular into 5 cells and assume 50% efficient.
That is 125 users, more than double the number of users,
One single cell tower can provide 5 cells, just one.
Assume that there are 10 towers in one given metro area and you take that figure and move the decimal point over.
On analog we have 1250 users, digital 17500 users, and we still are only doing 50%.
Most cellular systems approach 90% efficiency.
The smallest PCS bands could only do around 50 analog users if used in a non cellular application.
http://en.wikipedia.org/wiki/Cellular_frequencies#Frequency_bands_used_in_the_U nited_States
Yet the low cost PCS carriers manage to squeeze 80 to 100 thousand subscribers into that small a spectrum.
Call quality suffers, that is a given, and when call volumes are high coverage is spotty in places.
But Cricket and Pocket along with MetroPCS and the like do just that, and provide the lowest cost cellular service in the nation on an unlimited basis.
They also do not cover anything but the metro areas, there is no effort whatsoever to cover anything but the metro areas.
They are proof that it can be done.

[W7XF]

That's all good, but the push now is NOT for CDMA/TDMA (Sprint and Verizon),
but the push is for cellular carriers to transition to GSM (AT&T and T Mobile), as
GSM is becoming the global standard for cellular. That way,
one can get off the plane wherever in the world and turn on
their cell and it will work.

Oh, BTW, WART

[KA5PIU]

Hello.

Actually there is a push for GSM in CDMA.
http://www.phonescoop.com/news/item.php?n=7817
But even GSM is going CDMA, as in W-CDMA.
T-Mobile runs W-CDMA on its 2100MHz system.

[W4RLR]

Want to read about a world class cluster fsck? Just look up the Florida statewide encrypted radio system sole sourced by Harris. A lot of state and county users are balking at the price tag. Our sheriff has said thanks, but no thanks to hand held radios that cost $4500 a piece.

[KA5PIU]

Hello.

Bexar county has much the same system, ProVoice, that replaced Motrorola type II.
The Fire services decided to go 800 MHz for dispatch and VHF conventional FM for everything else, in effect new radios but the old system.
The overall cost was $1600 per VHF P-25 narrow band compliant, complete with mobile charger and 25 watt RF amp in the Jerk and run configuration.
$4900 for the 800MHz radio and VA, no amplifier but a good external antenna.
Where the 800MHz system has spotty coverage one can use the VHF radios and have coverage.
There are only a few channels on the VHF system so it is not used by the higher ups, Fireground and the like only and fire alarm.
For every Harris radio there are at least 5 VHF radios.
CAP can intercommunicate directly with the fire services on VHF, police require a patch or switch to 800 mutual aid direct and the use of a talkie that can not be charged in the aircraft.

[KA5PIU]

Want to read about a world class cluster fsck? Just look up the Florida statewide encrypted radio system sole sourced by Harris. A lot of state and county users are balking at the price tag. Our sheriff has said thanks, but no thanks to hand held radios that cost $4500 a piece.

Hello.

After looking at the costs I see no major issue, they are in line with Motorola.
http://www.pspc.harris.com/media/Portable_Radio_Configurations_tcm27-13538.pdf
Florida wanted a secure system, scanner proof, ProVoice delivers even without encryption.
Encryption on the EDACS system is by far the best non feds system right now.
Expensive? you bet! but it delivers on the promise of security.

[W4RLR]

Hello.

After looking at the costs I see no major issue, they are in line with Motorola.
http://www.pspc.harris.com/media/Portable_Radio_Configurations_tcm27-13538.pdf
Florida wanted a secure system, scanner proof, ProVoice delivers even without encryption.
Encryption on the EDACS system is by far the best non feds system right now.
Expensive? you bet! but it delivers on the promise of security.

Security...it makes me wonder when the powers that be issued an encrypted radio to the amateur radio room at the EOC. The statewide satphone hookup also terminates in the amateur radio room. Yes, we hams thought that was a hoot, the governor calls and it has to go through a ham to get to anyone in charge...