[Scan-DC] Analog/Digital (cellphones/radios)

Tue Feb 26 09:55:28 EST 2008

" An effective personnel locator device would have been more useful than a
radio in this
situation."

I feel there is an easy solution to that. If you ever used a Motorola
Console some have the option to enable/disable Radio Check ect.
Well make an option to send a signal to the radio where it will now send a
loud alert tone out of the speaker along with the radio going between
conventional and trunk and when in conventional it will xmit a short blip
and you can have a signal meter on a special radio to track it down like a
lojack

It's all a matter of everyone getting all there ducks in a row and come out
with the ULTIMATE public safety radio.

JOHN

-----Original Message-----
From: Charley Armstrong [mailto:armstrong.c at verizon.net] 
Sent: Tuesday, February 26, 2008 8:40 AM
To: 'John Bacon'; Scan-DC at mailman.qth.net
Subject: RE: [Scan-DC] Analog/Digital (cellphones/radios)

Jumping back in.  At least in the case in Loudon County, the FF was able to
communicate clearly over his radio that he was trapped/lost inside. Like
almost all accidents, there were multiple causal factors that contributed to
his death, however malfunctioning radios was not one of them.  It turns out
the search and rescue was performed on a house that had already been
evacuated, with no backup line, on a very windy morning, in a heavily
involved house.  The FF was a rookie who got separated from his partner
while performing unsupported s&r, and got lost in a bedroom in heavy smoke
and fire conditions.  This was a residence on maybe a 1/2 acre lot - you
don't absolutely need radios to attack a fire in a house.  An effective
personnel locator device would have been more useful than a radio in this
situation. 

As for all or nothing, I agree that digital radios enforce channel
discipline - they won't allow you to step on other's transmissions.  When
you hear a system busy, that doesn't mean that every transmission is
blocked.  It means that you are trying to transmit when someone else "owns"
the channel. Their message gets through, you have to wait your turn. Your
idea about users being automatically switched to another TG if there is a
busy is similar to what is implemented now.  When a user presses his
emergency button, that radio is automatically given priority over all others
(by shifting it to another TG.)  Until that radio is reset, it continues to
have priority.

One design issue with digital trunking systems is how many frequencies pairs
are needed to cover your jurisdiction.  That number varies depending
geographic size, the number of users, your population, the types of users on
the system, and available pairs.  When the system is programmed, certain
priorities are assigned.  One priority might be to allocate enough resources
(frequency pairs) to ensure police coverage throughout the jurisdiction.  So
out of a 16 channel system, say eight channels are reserved for police use
only.  That leaves the remaining eight to be shared by fire and other users.
Now throw in a major fire where there might be 30 or 40 radios working that
incident.  An emergency occurs, and everyone wants to help.  They all try to
transmit at once.  There are simply not enough resources to support that.
And I guarantee you that 30 or 40 analog radios trying to transmit at once
nets the same result - important messages not getting through.

CA
Annapolis

-----Original Message-----
From: scan-dc-bounces at mailman.qth.net
[mailto:scan-dc-bounces at mailman.qth.net] On Behalf Of John Bacon
Sent: Tuesday, February 26, 2008 6:26 AM
To: 'David Lloyd'; Scan-DC at mailman.qth.net
Subject: RE: [Scan-DC] Analog/Digital (cellphones/radios)

Well I would like to get in on this. DIGITAL is kind of useless it is only
saving bandwidth.

Not the problem you have with digital is an ALL OR NOTHING reception. Now
when you have DIGITAL TRUNKING (ASTRO) it gets worse because if a user is
already using the channel (TG) you get the busy/locked tone, and that is not
what a firefighter needs when they are trapped.

If Motorola was SMART they would make a firmware upgrade to program some
radios to automatically change to the next unused TG not in use so that a
transmission can be heard by someone (hopefully dispatch)

Again the real use for Digital aka. P25 APCO25... is bandwidth.

Now as someone said about water in the MICs well an easy fix to that is a
thin plastic film over the element to your voice is still audible and
provides protection to the equipment. 

John

-----Original Message-----
From: scan-dc-bounces at mailman.qth.net
[mailto:scan-dc-bounces at mailman.qth.net] On Behalf Of David Lloyd
Sent: Monday, February 25, 2008 10:45 PM
To: Scan-DC at mailman.qth.net
Subject: [Scan-DC] Analog/Digital (cellphones/radios)

The recent discussion on analog/digital communications really has me
thinking.   Why DIGITAL?  Maybe I'm naive, but I REALLY haven't ever been
impressed with digital.  I bought a Uniden 396T scanner a year ago - I still
don't know how it works.. and I'm a nerd!! The only benefit I see with
digital is that you can do more with less.

The reason why I bring this up is that I spent an afternoon reading the
Loudoun County firefighter Line of Duty Death report and was I was really
disturbed with all the squawks and beeps and unintelligible audio on the
radio.  In my years in the fire department, I experienced the switch between
analog radios that worked great (okay, decent - there were still coverage
problems), to digital that worked terribly for the aforementioned reasons.
(Everytime I got on an elevator I got "BEEEEEEEEEP" no signal!)   I guess
this why more towers are necessary (ie: DC) and why MoCo is now using
repeaters on vehicles.   It's been a few years since I have been in the
service--I'm wondering if that changed anything.

Just for grins, I took my radio to Skyline Drive two years ago.  The
Montgomery County digital signal - D E A D.    The 154 UHF was perfect.

Sorry if this seems more like a rant than a question, I guess it's just my
fustration with the whole Public Safety initiative in the Washington area to
"improve things".. but it's certainly making things more difficult for all
parties invovled.  Just my observations,  being old-fashioned and hating
the digital transmissions.. what next? Computer voice dispatching?

David

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