Pros & Cons of Digital vs Analog

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WX9RLT

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Can you provide information on the Pros and Cons of Digital vs Analog

Basically the range, reliability, safety for 1st responders, etc...


I am trying to research this topic, and thought I would post this in hopes to get some answers from people who know scanners/radios :)


Thanks in advance
 

jonwienke

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Digital range and reliability is as good as, or better than analog if set up properly.

Digital is more secure, it allows encryption (very secure) vs scrambing (not secure) for sensitive communications. It also allows better per-radio tracking--the ID of everyone on the system is known, because every radio on the system has a unique ID. Unauthorized radios on the system can be remotely disabled, as can stolen radios.

It's more complicated to set up than analog, but there are many benefits.
 

jcm87jm

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Jonweinke makes a great case for digital, but there should be a cautionary note for agencies chomping at the bit to switch to digital. I've noticed (and this is my assumption as a guy who scans) that digital systems take years to perfect and have the bugs worked out. This became apparent in my County when the p25 system crashed during a fast moving brush fire. This left firefighters unable to communicate with each other for an extended period until they switched back to their analog fire ops channels which the county had been maintaining as interoperability patch repeaters for mutual aid with surrounding counties.
As a pro for digital, I've been on ride alongs with both fire and police and have noticed that digital does produce much cleaner and easier to understand transmissions, and prevents users from walking on each other inadvertently. The user will know this when their radio gives them the "bonk" tone.

Sent from my Western Electric 1500D using Tapatalk
 

troymail

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In addition to what has already been said - once you ear "tunes" to listening to what many say sounds like "robotic" digital voice, it tends to be better for communication. Analog is many times "scratchy" and tough to listen to.

Having said that, some (rightfully so) still argue that they'd rather have scratchy, broken analog voice than nothing at all.

As has been stated - many of these are complex (and can be very expensive to properly build out) systems. In critical mission applications (public safety - police, firefighting ,etc.), lives can be at risk if the communication fails due to poor coverage. There are many known cases where this has been learned the hard way. But improvements have been made over time.

Unfortunately, the (usually tax) dollars to install a system are not unlimited so the needs for a 100% system aren't always addressed. On the other hand, the cost to build, install, and maintain these systems aren't cheap - so you hear all the time they are built for "on street" coverage and/or 95% (I think I hear things like it will work 95% of the time in 95% of the intended coverage areas - hmmmm... 95 or 95 - that's 90% of the time). I am also aware of one case where, when going back and saying "what would it take to build a system originally intended for "on street" coverage to provide "in building" coverage?" and the answer given was something along the lines of "double" the original cost (and therefore complexity).
 

ofd8001

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As a former public safety responder having experience with both analog and digital systems, I can say digital is far and away better than analog. Better coverage and better voice quality.

My believe is that when communities saw problems with their new digital systems it's because of a couple things. One is they pinched their pennies a little too much. Another was they didn't devote enough time to system trial - spending a sufficient amount of time testing the new system before accepting and going "live".
 

jonwienke

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Jonweinke makes a great case for digital, but there should be a cautionary note for agencies chomping at the bit to switch to digital. I've noticed (and this is my assumption as a guy who scans) that digital systems take years to perfect and have the bugs worked out. This became apparent in my County when the p25 system crashed during a fast moving brush fire. This left firefighters unable to communicate with each other for an extended period until they switched back to their analog fire ops channels which the county had been maintaining as interoperability patch repeaters for mutual aid with surrounding counties.
This isn't so much a digital issue as a "have a backup" issue. If you're dependent on a repeater, you'll have issues if the repeater goes down, regardless of whether the repeater is digital or analog. You should always have simplex as a backup in the event of a repeater failure.
 

12dbsinad

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I use and listen to both. I am more of an analog type guy. To me, nothing sounds better than full quieting analog.

For an example, while packed up with full SCBA for my fire Dept I can understand analog much better thru my hood and competing background noise because of much better fidelity. Digital sounds more mono tone and I have to concentrate more on what is being said.

Again, that's just my opinion. Maybe it's my old ears.
 

pinballwiz86

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Digital voice quality is terrible sounding compared to analog. But, digital has so many high tech features that analog can only dream about! DES encryption, digital data, GPS, etc.

So...it's a trade-off. P25 really needs to be wider bandwidth. Then you'll have high fidelity audio! I blame the FCC mandating public safety having to move from FM to NFM.

Stupid.
 

WPXS472

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My experience working with digital is old. Back during another life, working at a Government installation, we moved from DVP, which was hated, to DES-XL. The audio quality was still awful. The security folks just flat out refused to use it. The folks who managed the ammunition and chemical weapons made the choice to lock their radios in encrypted mode and make everyone get used to it. I have to admit, they did. Once during an exercise, they were wearing gas masks and trying to communicate. I couldn't understand a word anyone was saying, but their coworkers sure did. So, it is a learning curve with digital. Most everyone is now used to cellphone quality audio now, so a digital radio doesn't sound all that bad anymore. I wouldn't believe it until I saw it, but we did a range test to prove that DES-XL didn't have a range penalty. Sure enough, when analog was just barely breaking squelch and so noisy you couldn't make out a word, digital still provided acceptable communication. Either way, digital radios are the future. With radios becoming ever more software defined, it is just easier to handle everything as data. I haven't seen an IF transformer or second L.O. crystal in a radio in many a year. I don't expect that to reverse course.
 

jim202

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One major issue that no one has mentioned so far about digital is that there is no warning that your at the end of the RF rope. When you hit the threshold of no more signal, it just stops working. In the analog system, the signal gets noisy and you can tell your at the edge of coverage.

There has been many cases where a digital system user has gone into a low signal area and then tried to use their portable radio. Guess what people, the radio didn't work when you needed it the most.

Another radio issue with a digital system is when using a simulcast system. When your in the overlap area between 2 towers, you might have issues trying to hear the signal if the radio system was not set up correctly with the timing between the towers. Setting the time delay between the towers is not a simple task. It takes a good amount of skill on the side of those people doing it. Poorly done you have a system that works and sounds like crap.

In an analog system, if a radio is slightly off frequency it really doesn't matter that much. In a digital system, if your radio is off frequency, it starts to effect the bit error rate in the data being sent and received. If the bit error rate gets too high, your going to have a problem with the recovered audio and maybe even the ability for the radio to be controlled by the system. Like being able to be told what channel or frequency to go to after leaving the control channel. You might not receive the go ahead signal to transmit after pressing the PTT button. All sorts of strange problems can happen.

Digital systems are nice to have all the abilities and features. But it brings with it all sorts of technical issues that require real good radio maintenance on the user equipment and the base stations. Even such a simple issue like a low battery voltage on a portable can cause problems on the digital system.
 

Ensnared

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Digital Preference

Digital Pros: If properly installed, I agree, conventional digital transmission seem to propagate for longer distances than analog. I don't know if this is associated with the design of my radio (436HP) or the use of repeaters. Each system is different. Also, I enjoy the absence of static associated with analog signals when longer distances are involved.

Digital Cons: The price of radio equipment would be at the top of my lists for cons. Also, linear simulcast distortion seems to be a great annoyance since I cannot currently afford a G5.

Analog Pros: Cheaper radio cost, generally speaking. Some analog radios are easier to operate in comparison to digital scanners. Also, voice quality is better in the presence of a strong signal, generally speaking.

Analog Con: Birdies. I cannot think of more cons. It is too early today.
 
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NC1

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A little more information is really needed.

Is this a rural, suburban, or urban area?

Is it flat, or are there big hills?

What size is the department?

What size area do you need to cover?

This is necessary to know before really giving an informed answer.
 

mmckenna

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Audio quality of digital has both improved as technology has progressed -and- has a whole lot to do with how the radios have been set up.

Example:
In my work truck I have a Kenwood NX-700 VHF radio running in analog 12.5KHz mode on our PD dispatch channel.

I also have a Kenwood NX-900 800MHz radio, running 12.5KHz NXDN on my trunked system.

Same external speakers. Same radio, save the frequency. Same dispatcher, same headset, same dispatch console.

The NXDN system sounds better than the VHF analog system. Again, same dispatcher, same mic.

It really does depend on how much effort goes into setting up the digital systems. In many cases it can be difficult to truly do a side by side comparison.
 

N9JIG

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Before I retired from the PD we had received APX7000's from the county that had both the P25 trunked system and our analog UHF channels. When we used the digital channels it took quite a bit of getting used to. Guys were used to the artifacts present in analog signals and it reminded you that you were using radio.

On the digital side there were many times I would hear a voice and look around the room to see who walked in. When the signal strength was good it was devoid of these artifacts and it sounded like they were in the room with you. On the other hand, like others have stated, with an analog radio you can still get a partial message thru in a weak signal area, the digital radios are all or nothing.

We went thru similar situations twice before. When we replaced our old GE MastR II repeaters and other infrastructure with Motorola Quantars the difference in voice quality was dramatic. The guys hated it, not so much that the voice quality was worse (which it was...) but that it was different.

A few years later came narrowbanding and the same thing happened. Voice quality suffered but the worse part was that it sounded different. Once they got used to it it seemed to sound better, even though there was no change.

One nice thing on digital is that ANI is sent with the signal and not as an audible data burst like MDC. When we changed the system to eliminate the repeater delay that masked the ANI so that the MDC was audible (and thus decodable on the mobiles and portables) the guys squawked for a week until they got used to it. Once they noticed that the were able to see what radio was talking they were much more tolerant of it.
 
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Analog versus digital…you really have to narrow it down and remember (this being the scanning discussion and all) that we are discussing FM based communications (not AM). As such, there are several things to remember about FM communications.
  1. There is no such thing as a negative SNR with as the FM capture effect doesn't allow for a signal to be below the noise floor and still recognizable and the Shannon-Hartley Theorem is based upon a log scale and doesn't allow for a SNR less than 1 (0 dB).
  2. The modulation index is essentially a measure of resolution and can give an idea of how reliable a signal will be.

Now remember, if we were talking about AM communications, the above would be a false assumption as you can't have a modulation index greater than 1 (without distortion) and you can make out an analog signal with a negative (in dB) SNR.

There is a fringe area with digital, most are just so used to analog noise, they don't recognize packet error as the digital noise equivalent.

The pros of digital:
  • More universal (voice, data, positioning, messaging, etc)
  • With more updated firmware algorithms, voice quality is improved (especially when comparing AMBE based radios to the older IMBE/VSLEP radios).
  • Generally outperforms 2.5 kHz narrowband operation. All current digital modulation modes in use have a higher modulation index compared to 2.5 kHz analog.

The cons of digital:
  • Expense. Digital systems are generally higher cost.
  • Some systems do not outperform 5 kHz (wideband) analog. For example, when comparing the modulation index of 5 kHz (~1.67) to P25 Phase 1 (~1.5) you get a .5 dB difference which results in a 5% loss of coverage when doing an in-band migration (which supports the reduced coverage claims of those who went from Smartnet II to Phase 1 trunking in-band).
  • Digital technology is always improving. A simple firmware update can make the difference between crappy audio and good audio.
 
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