whether a digital signal is encrypted or not does affect the range. encrypted radio signals are decoded once they are obtained and in the radio's memory. the only performance issue (if it does make a difference) is that encryption uses more processor cycles, at least it does with a computer server.
Will scanners/scanning keep upgrading or die off in 5 years
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That was true with older platforms like Aegis, where audio was digitized and encrypted, then sent over an analog radio path. That's not how P25 encryption is applied.
Transparency in government does not require unencrypted radio communications. One popular argument against encryption states that the public loses oversight over government when police communications are encrypted, but encryption doesn't alter the facts that police communications are discoverable as evidence in court, and it's the grand jury that acts as civilian oversight over local government. Grand Juries can easily subpoena decrypted recordings to provide that necessary oversight.
That's a common complaint. I look at it like this... (in much simplified terms)
Nyquist theorem states that in order to accurately sample an analog signal and digitize it, the sample rate must be twice the highest frequency to be sampled. I don't know, offhand, the sample rate used, but as an example for discussion, telephone transmission uses an 8 KHz sample rate to represent a 4 KHz audio channel. With 8 bit encoding, this results in a 64 kb data rate.
For P25, that raw sample produces a continuously changing digital word that, if it were to be directly modulated to RF, the bandwidth would be VERY very wide, in comparison to allowable channel bandwidths.
So, it undergoes compression via mathematical algorithms that essentially rebuilds the audio from an abbreviated digital instruction set, as opposed to transmitting a full digitized version of the audio.
A lot of fidelity gets lost in the process, because you've taken raw data that runs in several tens of KHz, and reduced it to 12.5 or 6.25 KHz occupied bandwidth. The algorithms are very good, and the complex modulation schemes used to apply it to RF are impressive, but what seems to be lost is voice recognition. It comes out sounding rather generic. Human speech is quite complex, communicating things via inflection and accentuating certain sounds, that simply doesn't translate to highly compressed digital audio. Therefore, it stands to reason, information contained in the original audio is lost in the process.
I've also noted in some tests I've observed that a rapid talker can seemingly "out talk" the algorithms, and the end result is received audio that sounds clear and noise free, but you have to ask for a retransmission because you just didn't understand it. It's an effect that's hard to describe and harder to quantify, but it's the only way I can explain what I've heard on strong, noise free signals, where asking the sender to talk just a bit slower makes a world of difference in intelligibility.
In a fire situation, add a high back ground noise level competing with the voice for the limited number of bits available for transmission, and intelligibility suffers even more.
I'm not at all surprised that the fire service frequently rejects P25 for fireground channels.
Problem with digital is you either have good signal or nothing. With analog when the signal degrades you get static but can still hear the trasnmission. But with digital it just cuts out.
I saw a video where a fire chief was talking about them being on a digital system but it performed poorly so they switched back to analog. I will see if I can dig up the video and post it.
But there is a difference between a digital system versus encryption over analog. But I am sure some of the same principles apply as far as signal quality. I would think a poor analog signal with encryption would start to get hard for the radios to decode back to voice.
Anyone remember when cell phones first went digital? Coverage was horrible and people were always dropping calls.
I saw a video where a fire chief was talking about them being on a digital system but it performed poorly so they switched back to analog. I will see if I can dig up the video and post it.
But there is a difference between a digital system versus encryption over analog. But I am sure some of the same principles apply as far as signal quality. I would think a poor analog signal with encryption would start to get hard for the radios to decode back to voice.
Anyone remember when cell phones first went digital? Coverage was horrible and people were always dropping calls.
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But if you can't monitor encrypted communications, then how do discover a crime was committed to begin with?
In my area, it's common to not only use P25, but it's used on a trunk system which adds to the issues. After all, what does NFPA know recommending analog simplex? And yes, there are many buildings that are dead spots. The 911 center's answer? Use talk-around and keep a unit outside who can relay.
bryan_herbert
Member
I remember some 30-years-ago when trunked radio systems and MDTs were supposedly going to kill scanning.
The only real threat is when people stop being curious. When people stop being curious they stop experimenting. When people stop experimenting, the hobby stops advancing.
Never stop being curious. Never stop experimenting.
The only real threat is when people stop being curious. When people stop being curious they stop experimenting. When people stop experimenting, the hobby stops advancing.
Never stop being curious. Never stop experimenting.
Being curious and experimenting, while good, will not solve the encryption dilemma. As I said above, encryption is not a technical issue to overcome - it is a legal one.
The real reason trunking didn't stop scanning is because someone found a way around the patents used. This will not be possible with encryption.
NXDN can be overcome. DMR can be overcome. Fusion can be overcome. D-Star can be overcome. Open Sky might be able to be overcome (if encryption is not a standard feature). Encryption cannot be legally overcome without a reversal of the ECPA (which I wholly support). But, I don't expect to see it in the next 40 years.
The victims come forward and report it.
Not if they're dead!
That's a job for the next of kin, not some guy living in his mothers basement with a scanner.
Well I'm not a kid, living in my mother's basement. I'm a 64 year old responsible citizen, and tax payer, in the community. I feel it's my right to monitor, and observe, the response, and actions of my police, fire, and EMS services.
It's not a constitutionally protected right to listen to those agency's private radio traffic. It's just a fun hobby, nothing more. And it certainly doesn't make us all government watchdogs who will save the world from tyranny.
Well of course it's not in the Constitution, public service radio communications didn't exist back then.
They are servants of the tax payers, paid for by the tax payers. Why should their radio traffic be private?
Because sometimes it needs to be.
Public oversight of government does not necessarily include real time scrutiny of internal communications.The argument that scanner listeners keep police honest is weak. Whats to keep crooked cops off their cellphones? If there are legal questions, tapes and transcripts are pulled and presented in court.
It's a hobby. You're not going to make the world safe for democracy. :roll:
TPC2075
Member
Scanners/Scanner will be around for many years.
I have been Monitoring for many many years even before our radio's were able to Scan.
I started Listening to the tube type radios and then started listening to the tunable type radios when they
were sold in the stores then when the first Scanner came out ,i bought my first program able scanner the i
owned was a BearCat 210 ,i think it was a 10 channel desktop/mobile type then i bought a BC210XL am
not sure of the model anymore i know it was a BearCat 210 x something though.I am using a BCD436HP &
BCD396XT and a Pro96 and BC785 xlt 500 Channel Scanner i am also monitoring with a Home Patrol one
that i bought a few years a go when it was first sold. these Scanners perform very well ,i have not had any
problems with any of these devices that i own.
my Radio Shop or Shack has all of these Devices working as well as a iMac ,Printer etc. all operational !
though out the day/night.
So "yes" i do believe that this Hobby will be around for many many more years, i think there will always be
some thing to monitor ,well until i die ,i will still be out here scanning and monitoring all maybe even "you"!!
TPC2075 have a great day ! and don't worry "Just" have fun and Monitor.
Rory S.
I have been Monitoring for many many years even before our radio's were able to Scan.
I started Listening to the tube type radios and then started listening to the tunable type radios when they
were sold in the stores then when the first Scanner came out ,i bought my first program able scanner the i
owned was a BearCat 210 ,i think it was a 10 channel desktop/mobile type then i bought a BC210XL am
not sure of the model anymore i know it was a BearCat 210 x something though.I am using a BCD436HP &
BCD396XT and a Pro96 and BC785 xlt 500 Channel Scanner i am also monitoring with a Home Patrol one
that i bought a few years a go when it was first sold. these Scanners perform very well ,i have not had any
problems with any of these devices that i own.
my Radio Shop or Shack has all of these Devices working as well as a iMac ,Printer etc. all operational !
though out the day/night.
So "yes" i do believe that this Hobby will be around for many many more years, i think there will always be
some thing to monitor ,well until i die ,i will still be out here scanning and monitoring all maybe even "you"!!
TPC2075 have a great day ! and don't worry "Just" have fun and Monitor.
Rory S.
There are people, and there are sheeple.
And there are delusional optimists.
It appears that some in this thread represent the government and some represent the rest of us.
TPC2075
Member
I am here because it is my hobby and i am not worried for i will not live forever "but" i will scan and monitor
everything there is to monitor and enjoy without disagreeing with anybody for it is Still just my hobby while
i am here and still a live.so far so good ! and yes there are those delusional optimists out there or even out
Here "but" once again i monitor my little scanning devices because i can and it interests me like others
while i am able too.i may own a peace of your big rock. lol lol "and" i really do not care.for i am dying of a
type of Cancer and i am quite sure you like most people here really aren't interested in my issues.
and no matter what our government does or doesn't do i really do not care anymore for i really do not
have anything to lose at this point ! so have a great life .
TPC2075
RAS
everything there is to monitor and enjoy without disagreeing with anybody for it is Still just my hobby while
i am here and still a live.so far so good ! and yes there are those delusional optimists out there or even out
Here "but" once again i monitor my little scanning devices because i can and it interests me like others
while i am able too.i may own a peace of your big rock. lol lol "and" i really do not care.for i am dying of a
type of Cancer and i am quite sure you like most people here really aren't interested in my issues.
and no matter what our government does or doesn't do i really do not care anymore for i really do not
have anything to lose at this point ! so have a great life .
TPC2075
RAS
Or don't represent anyone, and just deal with facts.
I get the emotional attachment to the hobby, I really do. But the fact is, there is no inherent right to listen to communications not intended for you, and having the ability to listen isn't going to keep the police honest.
It'll take a whole hell of a lot more than that.
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