Digital vs. analog

Status
Not open for further replies.

dkw19388

Newbie
Premium Subscriber
Joined
Jun 16, 2020
Messages
2
Location
Appleton, WI
What is the big difference between Digital signals and analog? I'm just new to this, and was told all the police, etc. are going digital.

Don Winrich
 

ofd8001

Member
Premium Subscriber
Joined
Feb 6, 2004
Messages
7,104
Location
Louisville, KY
Sort of like how televisions went from analog to digital a number of years ago. Supposedly a little higher definition product, more flexibility, decrease of band usage as frequencies were getting less available and so on. Same thing for cellular phones which first started out as analog then went to digital.

While there are some who will disagree, I believe the audio is more clear on digital - less scratchy. Another benefit to digital is that it remains clear right up to the edge of coverage before falling off. With analog, there is a lot of noise in the signal before it goes away.

Truth be told, I'm sure there were some financial incentives or benefits to radio manufacturers to delve into this and not necessarily because they were nice guys.
 

Ubbe

Member
Joined
Sep 8, 2006
Messages
5,514
Location
Stockholm, Sweden
Converting speech to digitial data makes it possible to compress the data and encrypt it very easily and have conversations taking up less frequency space. When it is in digital form you can use network equipment like routers and network switches. But it is alway worse audio quality when using digital data in radio systems. There's nothing yet that can replace clean analog speech in a radio system. Analog processing are much more forgiving to low audio or overlodulated speech, where digital converted speech are much more dependent of exactly correct audio levels or it will sound like trash.

Digital=more efficient use of the resources available to the cost of unintelligible speech and the risk of a small error creating a total blackout in the system.

/Ubbe
 

Kaleier1

Member
Joined
Dec 27, 2019
Messages
227
Welcome to the forums Don.

One type of digital, DMR (Digital Mobile Radio) allows two conversations on the same frequency (or repeater) at the same time by taking two audio streams and transmitting them in alternating 30 ms signals. They are called time slot 1 and times slot 2 or TS1 and TS2 for short. When one time slot is transmitting the other one is not.

Plus since you are only transmitting every 30 ms with a 30 ms pause in between you will have a longer battery life because you aren't transmitting continuously.
 
Last edited:

a29zuk

Member
Joined
Mar 6, 2005
Messages
765
Location
SE Michigan
I've used Motorola HT1000 analog transceivers and the Motorola digital equivalent transceivers as they transitioned from analog to digital over the years at my place of employment.

With all of the digital processing the batteries on the digital radios never lasts a whole shift. Everyone gets frustrated because it hard to find a fully charged battery in the chargers. Even after the boss orders new batteries.

On the analog radios you could put a fresh battery on your transceiver at the start of your shift and you were good to go.

Also, working in noisy locations(foundry, stamping plants, etc.), the analog receiver conversations are a lot easier to understand. Digital receivers are awful in a noisy location as the processing is always trying to adjust when someone is speaking making for a lot of garbled audio.

Jim
 

MTS2000des

Member
Joined
Jul 12, 2008
Messages
3,605
Location
Cobb County, GA Stadium Crime Zone
I've used Motorola HT1000 analog transceivers and the Motorola digital equivalent transceivers as they transitioned from analog to digital over the years at my place of employment.

With all of the digital processing the batteries on the digital radios never lasts a whole shift. Everyone gets frustrated because it hard to find a fully charged battery in the chargers. Even after the boss orders new batteries.

On the analog radios you could put a fresh battery on your transceiver at the start of your shift and you were good to go.

Also, working in noisy locations(foundry, stamping plants, etc.), the analog receiver conversations are a lot easier to understand. Digital receivers are awful in a noisy location as the processing is always trying to adjust when someone is speaking making for a lot of garbled audio.

Jim
The HT1000 had 640 BYTES of RAM. One single DSP chip handled all audio processing (and all was done digitally including CTCSS/DCS/MDC/QC/Single tone) and a single audio IC handled both main and ancillary accessory audio. These were cutting edge radios when they rolled out when Bill Clinton first took office in 1992.

An APX8000 has 2GB of RAM, a multi-core CPU, an array of support chips for things like WiFi, Bluetooth, multiple displays, sensors, and a can transmit on all four RF LMR bands. It can handle all analog FM, P25 phase 1/2, multiple encryption algos with no add on hardware boards needed.

The APX NEXT is a full blown Android phone with an APX LMR smashed together like a Wendy's 3/4lb triple.

Comparing the two: they're both radios. That's about it. I would say we've come along way.
 

a29zuk

Member
Joined
Mar 6, 2005
Messages
765
Location
SE Michigan
I agree that the transceivers have come a long way. We just don't need all of that. A lot of those capabilities are not used. I blame our company for buying the system. But you know how sweetheart deals go.
It's frustrating trying to troubleshoot a production line with another tradesperson and the battery goes dead on your radio. Not to mention someone that has a medical emergency in a basement or on a deck four levels up.
For our needs, give us good reliable communication that works well in a noisy environment. The digital radio sounds great when someone in a nice quiet office calls for you.

Jim
 

mmckenna

I ♥ Ø
Joined
Jul 27, 2005
Messages
14,684
Location
SNCZCA01DS0
For our needs, give us good reliable communication that works well in a noisy environment. The digital radio sounds great when someone in a nice quiet office calls for you.
This isn't an analog versus digital issue.
It's a radio programming issue.

High background noise isn't a new thing. Fire fighters have been challenged with this for a long time. Early vocoders outright sucked eggs when it came to figuring out what was voice and what wasn't. The noise picked up by a firefighter standing next to the pump panel, under a screaming fire alarm annunciator, or next to a guy with a chain saw venting a structure fire was a real issue.

Fire fighters died due to this issue, people were sued. Finally the big radio "M"anufacturers realized that they couldn't not deal with this. Noise suppression systems were designed and included in new radios. Equalizers on both transmitted and received audio were added, multiport mics were added, noise cancellation became the "thing".

This is easily demonstrated with any digital radio sold in the last 8-10 years.

If your radios are not handling the background noise, then that needs to be fixed by the vendor. Radios need to be programmed properly for their intended environment. If someone in your company is just ordering radios online without the dealer understanding the environment they will be used in, then there's a big issue. If employees using radios in high noise environments do not have the proper accessories, then there's another big issue.
Users not understanding how to properly use the radio or radio accessories, then that's something that needs to be addressed.

If radios are running through batteries before the shift is over, then there could be a number of issues:
Improperly sized batteries.
Someone has cranked the radios up to high power
Improper chargers
Failing batteries.
No battery maintenance program.

Again, none of this is a "digital" issue. It's an issue between the company and the dealer.
 

a29zuk

Member
Joined
Mar 6, 2005
Messages
765
Location
SE Michigan
The radios are only about 5 years old. When we complained about the audio they did send the vendor in and they made their adjustments on every radio. It didn't help. I will agree with you that they more than likely are not adjusted correctly. There were a few adjustments that we had access to in the menus and we tried some different combinations to no avail. We ended up putting them back to the original settings. There were also some menus that we didn't have access to.

There were no receive accessories with the radio as we didn't expect any or need any with the older analog radios.

As for the batteries, new chargers and batteries were supplied with the new system. We just expect them to supply the correct equipment for us. Whether they were the right batteries and chargers, I don't know. They weren't worth a crap from the get-go.

I transferred out of that location about 6 months ago and don't remember the Motorola model number. They haven't assigned me a radio at the new location.

This is probably more of a simple radio vs a complex radio issue. On the older 900mhz analog radios they would program the new radios channel ID's and it was ready to go.

And yes, I do remember the firefighters complaining as our state started going digital in the early 2000's.


Jim
 
Last edited:

mmckenna

I ♥ Ø
Joined
Jul 27, 2005
Messages
14,684
Location
SNCZCA01DS0
The radios are only about 5 years old. When we complained about the audio they did send the vendor in and they made their adjustments on every radio. It didn't help. I will agree with you that they more than likely are not adjusted correctly. There were a few adjustments that we had access to in the menus and we tried some different combinations to no avail. We ended up putting them back to the original settings. There were also some menus that we didn't have access to.
They need to find a more responsive shop.

There were no receive accessories with the radio as we didn't expect any or need any with the older analog radios.
Well, that's because the analogs were working in that environment, and the digitals can also, but it requires a shop that is willing to support it's customers after the sale is complete.
A good speaker mic or even headset can help a lot.

As for the batteries, new chargers and batteries were supplied with the new system. We just expect them to supply the correct equipment for us. Whether they were the right batteries and chargers, I don't know. They weren't worth a crap from the get-go.
Yeah, not surprising. The proper accessories can get expensive, and it's often the first place that gets cut.
Depending on how heavily the radios get used, they may need to have higher capacity batteries.
Turning down RF power to the minimum amount necessary will also extend battery life.
Using proper audio accessories allows running the radios at a lower volume that will help extend battery run time.
1 hour chargers should be there to allow batteries to be cycled through faster. If someone bought the desktop trickle chargers to save a few bucks, there's your issue.
I usually strongly recommend that each radio gets two batteries and a rapid charger. That can add to the costs of the system quickly, but in any sort of critical application, the radios are only as good as the battery pack.

I transferred out of that location about 6 months ago and don't remember the Motorola model number. They haven't assigned me a radio at the new location.
Ah, got it. I had issues for years with Motorola shops. There are some good ones out there, but I seemed to always get the ones that were more focused on sales than service. It's not a good place to be/

This is probably more of a simple radio vs a complex radio issue. On the older 900mhz analog radios they would program the new radios channel ID's and it was ready to go.
A bad shop or a bad tech can screw up a perfectly good radio system.

Analog worked well since it pretty much passed whatever it heard. Human ears are good at picking voices out of crappy audio. When they started using digital, they didn't get things right, and it caused a lot of issues. Took a lot of work to get things right. Now most digital radios can do a pretty good job of getting human voices out of and into loud environments with a pretty high level of fidelity. But like I said, it does take a tech that knows what they are doing.

It sucks when the end user gets stuck with this sort of stuff.
 

a29zuk

Member
Joined
Mar 6, 2005
Messages
765
Location
SE Michigan
They need to find a more responsive shop.



Well, that's because the analogs were working in that environment, and the digitals can also, but it requires a shop that is willing to support it's customers after the sale is complete.
A good speaker mic or even headset can help a lot.



Yeah, not surprising. The proper accessories can get expensive, and it's often the first place that gets cut.
Depending on how heavily the radios get used, they may need to have higher capacity batteries.
Turning down RF power to the minimum amount necessary will also extend battery life.
Using proper audio accessories allows running the radios at a lower volume that will help extend battery run time.
1 hour chargers should be there to allow batteries to be cycled through faster. If someone bought the desktop trickle chargers to save a few bucks, there's your issue.
I usually strongly recommend that each radio gets two batteries and a rapid charger. That can add to the costs of the system quickly, but in any sort of critical application, the radios are only as good as the battery pack.



Ah, got it. I had issues for years with Motorola shops. There are some good ones out there, but I seemed to always get the ones that were more focused on sales than service. It's not a good place to be/



A bad shop or a bad tech can screw up a perfectly good radio system.

Analog worked well since it pretty much passed whatever it heard. Human ears are good at picking voices out of crappy audio. When they started using digital, they didn't get things right, and it caused a lot of issues. Took a lot of work to get things right. Now most digital radios can do a pretty good job of getting human voices out of and into loud environments with a pretty high level of fidelity. But like I said, it does take a tech that knows what they are doing.

It sucks when the end user gets stuck with this sort of stuff.
Our immediate bosses agreed with us and wanted to get the situation improved. It's a big corporation and they didn't have any luck going up the corporate latter. $$$ are the number 1 spotlight and they could care less if we got frustrated. It's the same with the software used to troubleshoot the machinery. It's all geared for the engineers so they can just cut and paste but takes us more time to find simple inputs and outputs. Down time costs $$$.

I have no idea what Motorola shop they used to supply and service the radios. They didn't do a good job upgrading the radios when they made their service call.

We did have the desktop chargers so that was the problem. The office personnel got the individual chargers. This is good to know so I can complain in the future if the same problem comes up again at my new location.

Using the different Motorolas over the years, their main asset was the loud audio they provided in noisy locations. If they would have had the new digital radios adjusted correctly they would have worked well.


Jim
 
Last edited:

Ubbe

Member
Joined
Sep 8, 2006
Messages
5,514
Location
Stockholm, Sweden
There'no noise supression function in any radio that doesn't also manhandle the speech audio, removing parts of it it thinks are noise. You can adjust all parameters in both radio and system until the cows come home and it doesn't help getting the audio any better in a noisy enviroment. In a non noisy envirement it works better, because there's no noise to filter, but then you do not need the noise filters anyhow.

Disabling all voice "enhancing" features turns out to work best at the end and let the human ear be the noise filter. What you must never do in a digital system are to have too much audio in any stage so it turns into a square wave without any treble. But using all of the systems audio dynamics are also important to get as high audio definition and resolution as possible, so it will be a balancing act.

/Ubbe
 
Status
Not open for further replies.
Top