Motorola ASTRO25 - Optimize your audio settings

[Mars]

[Note: This post updated Feb. 18 2012]

Essentials: Audio Configuration

It often surprises me how many administrators and engineers overlook the most important factor besides RF coverage, in a communications system: AUDIO QUALITY.

In Motorola ASTRO, ASTRO25 and APX products, Motorola has implemented many adjustments which can be made to optimize audio quality for specific applications.

All current ASTRO25 and APX subscriber equipment ships with default settings which enable the Audio Gain Control (aka Subscriber AGC) with specific gain settings of 0dB output gain and 6dB total gain. Standard Noise Suppression attenuation is also enabled.

Many system administrators and engineers do not understand what these settings do or how they work. They sometimes even confuse Audio Gain Control with RF AGC, which is utilized in high-RF environments to combat against front-end desense. It's hard to believe anyone involved in maintenance/programming/configuration of a public-safety TRS could be that daft, but unfortunately there are people out there running these systems who have no business being employed in their capacities.

Have you ever experimented with the AGC settings or Noise Suppression Attenuation settings? Do you fully understand the benefits of implementation and the capabilities? Read on.


The Basics

First, it's critical you understand what TOTAL and OUTPUT gain actually represent:

TOTAL: Affects audio going IN to the DSP, before processing.

OUTPUT: Affects audio coming OUT of the DSP, after processing.

For most applications, the default Motorola CPS settings of AGC with 0dB OUTPUT and +6dB TOTAL, with Standard Noise Suppression Attenuation will work just fine. But there is significant room for improvement!


Average User

[These comments added 02/18/2012]

Due to the way the DSP works, it may be beneficial to increase the TOTAL (input) gain of the AGC settings, so that Noise Suppression Attenuation filters are activated more rapidly. The theory for this is explained further in this post. See notes below.

These settings seem to work great for most noise environments -- even FIREGROUND usage:

Analog/Digital AGC: Enabled
Output: -3dB
Total: +12dB
Noise Suppression Attenuation: Advanced


Extremely High Noise Environments

In a high-noise environment, you don't want to have high-gain transmit-audio on the INPUT (TOTAL) of the DSP. Knock the noise down before it's processed. Use 0db or negative values, depending on how loud the audio environment is. Compensate for the low input (TOTAL) gain by increasing the OUTPUT gain. You may have to use a OUTPUT setting as high as +9-12dB. Conduct tests to see what works best for your specific application. Have your users speak very close to the mics of their radios/speaker-mics; this will speed up the activation of the Noise Suppression Attenuation filter.

Different operating environments require different audio settings.

During testing, I found it was necessary to implement drastically different settings for bicycle/motorcycle portable use, in contrast to a portable being used by a pedestrian/person-on-foot. This was due to background/wind noise, operating/speaker-mic position and speech amplitude of the user.

Police/paramedic bicycle-patrol units should have their own, dedicated portables with optimized settings for their application. For bicycle use, I recommend trying -3dB OUTPUT gain, +12dB TOTAL gain, with Advanced Noise Suppression Attenuation enabled.

For analog or digital AERONAUTICAL operation (police helicopter/boom mics), I recommend these custom settings which work very well:

Analog/Digital AGC: Enabled
OUTPUT: +12dB
TOTAL: -6dB
Advanced Noise Suppression Attenuation Enabled

This significantly knocks down the audio-input levels, but compensates by increasing the amplitude of the audio after it has been processed by the DSP. The ANS filter will knock down a majority of any background noise present in the audio.


Linear Gain vs. AGC

AGC is superior. AGC decreases distortion, ensures constant audio levels from quiet-talkers, and pads-down users who swallow their mics. Linear Audio on a two-way radio system sounds like garbage.

It is true Motorola recommends AGC be disabled if using the SNS/ANS filters, however given the actual real-world use/frequency of activation of the filters, it is not reasonable to give up the benefits of AGC for slightly quicker SNS/ANS trigger times. AGC can actually cause the SNS/ANS triggers to react sooner, by supplying a higher-amplitude of input audio at the DSP. This has been verified in real-world testing.

Quick Fact: When either the Standard Noise Suppression or Advanced Noise Suppression Attenuation filters are triggered, AGC is automatically disabled by the DSP so it's able to process the audio without fluctuating levels.

(Background noise/patterns must reach a certain amplitude on the input of the DSP for the SNS/ANS filters to be triggered. Once triggered, the filters remain active until the background noise is either no longer present, or falls below the trigger level. At that point AGC is restored and the filters become inactive. AGC is automatically disabled so the DSP/filters see a constant input level during processing. Otherwise the DSP filtering would turn on/off/on/off/on/off as AGC reacts to the audio input-levels. i.e. ineffective filter.)

Early ASTRO systems (IMBE and VSELP codecs) did not support AGC. Those systems sounded terrible. Early IMBE systems were referred to as "DSP 6" (refering DSP firmare version 6, in ASTRO Spectra, XTS3000 and ASTRO Sabers). They were/are painful to listen to. Motorola later issued Host/DSP firmware updates for subscriber equipment which supported much-improved audio configuration and mid-range audio characteristics.


More on Noise Suppression Attenuation

Before I expand on this, it's important to note only 8MB radios with firmware of R12.xx.xx or greater (May 2008) support Advanced Noise Suppression Attenuation. Only Standard Noise Suppression Attenuation is supported on 4MB radios due to flash-memory size limitations. (8MB radios support both filters.)

Here's what Motorola says about the Noise Suppression settings in CPS:

Attenuation Level

(Radio Wide,Tx Audio Control Per Mode)

Selects the Attenuation Level for the Noise Suppression Feature.

• Noise Suppression works best when the AGC (Automatic Gain Control) fields are disabled.
• When the AGC fields are disabled, enabling the Digital/Analog Balance field will help to reduce acoustical feedback.

When the Noise Suppression field is enabled:

Standard: Provides a moderate amount of noise reduction to transmitted audio. The radio's DSP (Digital Signal Processor) removes some of the noise that is present in the background, before audio is transmitted. This setting should be used in areas where there is a reasonable level of background noise.

Advanced: Provides a high level of noise reduction to transmitted audio. The radio's DSP (Digital Signal Processor) is much more aggressive in removing noise that is present in the background, before audio is transmitted. This should be used in areas where there is a high level of background noise.

This setting may also cause some degradation of audio when no background noise exists.

----------------------

Quick Fact: Noise Suppression (NS) attenuation algorithms are NOT ACTIVE during normal, low-noise transmissions, regardless of what's implied above. No adverse affects in low-noise environments were noted in any tests I conducted.

Motorola has done an excellent job at refining the Advanced Noise Suppression filter since the initial release in R12 firmware. (Standard NS was already implemented in older firmware).

Most non-radio-savvy-users (i.e. public-safety personnel) are prone to speaking at great distances from the microphone, or not directing their mouths toward the microphones/speaker-mics. No matter how much training you give them, this will always be an issue. So you must compensate by allowing for more gain on the input of the DSP (aka TOTAL gain) than what would be ideal. This will slightly increase background noise, but it's not the end of the world. It's still important to educate users on proper radio operation to maximize the performance.

Having slightly higher TOTAL gain will actually benefit users of SCBAs in tactical fireground operations, whose audio tends to be lower.

Suggestion: On the topic of fireground communications, be sure to check out the PASS FILTER option in the Conventional Personality tab in ASTRO25 CPS. This is a firmware >R15.xx.xx feature.


Motorola's Bad Advice

A number of years back, Motorola released configuration settings which supposedly decrease acoustical audio feedback. Many of their users had complained of this disruptive and confusing (digital echo) problem. Here it is:

View attachment NoiseShield Settings.pdf

I don't feel Motorola did much testing to achieve those results: knock down treble, and decrease gain.

Many aspects of the ASTRO25-series DSP code/capabilities have changed since the time of this "fix".

Here's what I feel is wrong/sub-optimal with those settings:

• The document fails to mention DSP firmware R12 or greater is required for the Advanced Noise Suppression to function. >R12 is MANDATORY. R12 was released in May 2008. Only Standard NS supported in <R12.

• The ANS filter is designed to cut down on high-amplitude, high-frequency/pattern noise, in the upper part of the audio spectrum. The attack point is the INPUT (aka TOTAL gain) of the DSP. Motorola's document calls for attenuated treble settings (to help combat high-frequency acoustical feedback). Attenuating the received, high-end audio spectrum after-the-fact (DSP OUTPUT) does not accomplish much. Received-audio sounds distorted/muffled and unnatural;

• AGC isn't used. AGC is extremely effective, if used in combination with optimized OUTPUT/TOTAL gain settings;

• Motorola's document calls for -9dB of attenuation (speaker-mic) and -3dB for internal mic. This only succeeds in making the mic less sensitive while not addressing the need for AGC. AGC ensures consistent audio levels. Not to mention 4MB radios don't support (by way of firmware) the ANS filter. So it's a useless implementation.

My Own Thoughts

Enable Advanced Noise Suppression on all radios. This won't bite you in the ass. I promise. I've done hours and hours of digital testing. Analog was also fine. It only kicks-in when the threshold is reached. The filter is not constantly active. It will not degrade normal audio. Conduct your own tests if in doubt.

Consider tweaking the treble settings in CPS for both analog and digital audio. This should especially be considered if using a speaker-microphone, as they tend to add extra treble to received audio, due to sub-par speakers. To combat this, attenuate the treble. Try -10 to start.

Update radio firmware to current, stable versions. This can't be overstated enough!

Any comments or feedback is always welcome!

 

[Magnus]

The importance of these settings cannot be stressed enough. Too many times no thought is put into how these settings affect a system. And As Mars stated, take a few units and give them out to various different roles and do some tests, a detective is going to have different needs than a Firefighter or garbage truck driver or heli pilot. The environment these radios are used in needs to be taken into consideration. I can't count the number of times we have seen complaints about audio quality only to find the end user has been given something that does not fit their needs, causing them to use it improperly.

 

[Mars]

After conducting further testing, I'm going to have to revise the advice I gave on this topic.

Although the theory appears correct, it appears the TOTAL gain (input to DSP) plays a much larger role in activating the Noise Suppression Attenuation (Standard and Advanced) than I previously noted.

The background noise environment I conducted my original testing in, was extremely loud by means of motors, wind and piercing/drilling sounds. Perhaps attenuating the TOTAL (input) gain of the mic in those settings helped combat noises the DSP could not cope with.

These settings seem to be quite effective at rapidly activating ANS: (Due to increased amplitude at the DSP input)

Analog/Digital AGC: Enabled
Output: -3dB
Total: +12dB
Noise Suppression Attenuation: Advanced

Please post your results. I may even do up some audio samples and post them to this thread in the coming days.

[ Audio file for this specific setting is not yet available ]

 

[Mars]

Attached is an audio test (conducted in analog mode), which demonstrates the difference between:

XTS2500
AGC: Disabled
Advanced Noise Suppression: Disabled

AND

XTS2500
AGC: Enabled
OUTPUT: +12dB
TOTAL: -6dB
Advanced Noise Suppression: Enabled

Please make sure your speakers aren't cranked; the first sample without the proper audio configuration settings is extremely loud.

I recommend these audio settings for EXTREMELY loud environments, such as a helicopter, or a fireground scene-commander.

 

[kf4lhp]

OK, time for a follow-up question - Digital / Analog Balance. The help file isn't very clear, but I'm assuming this has to do with a mixed-mode channel and wouldn't really have any impact on a channel that's analog-only or digital-only? Looking to make some changes with a few agencies going forward.

 

[trbo90]

Ok... After spending a while looking through the APX Software, I am unable to locate the "Advanced Noise Suppression Attenuation" Fields. The Noise Reduction Fields are under Profiles Fields? Am I missing it? Thank you to all, great topic.

 

[Mars]

That's because the APX is part of the APX-family of radios, not the ASTRO25-family. This HOWTO applies to ASTRO25-family radios, as the topic would suggest.

 

[Pezking]

In Motorola ASTRO, ASTRO25 and APX products, Motorola has implemented many adjustments which can be made to optimize audio quality for specific applications.

All current ASTRO25 and APX subscriber equipment ships with default settings which enable the Audio Gain Control (aka Subscriber AGC) with specific gain settings of 0dB output gain and 6dB total gain. Standard Noise Suppression attenuation is also enabled.

This statement here makes it sound like the context of the post applies to all Astro radios.

 

[Mars]

The context does apply to all ASTRO radios. This particular thread applies to ASTRO25 radios.

Where the **** is Motorola? Why are they not helping their users or writing their own guides on optimizing the audio on their high-end radios?

 

[trbo90]

I stand corrected. Although I do know the Thread Topic was in reference to Astro25 series, I figured the Statement about all current Astro25 / APX shipping with the default settings applied to APX as well. Thank you again to you guys, great info here.

 

[Mars]

trbo90: I'll be more than happy to prepare a APX audio optimization guide, sometime after the 20th. I'm taking some time off (or trying to...$%@$) from the forum to concentrate on some other projects and commitments.

The APX has been somewhat more difficult to "optimize" however, as there are quite a few more audio/noise-attenuation options. There are even some customized DSP strings -- which look like raw hex code, and make no sense to me. There's also the "Extreme One-sided Noise Reduction" flashport feature, which can be purchased separately. I have tested it and it works great -- but audio (during normal operation) sounds really crappy.

The APX requires careful testing and documentation. Motorola needs to step up and write some guides for this -- their most expensive and powerful radio. I'm not an engineer and do not have access to laboratory test equipment to run proper comparisons or analyze the differences between various settings.

I have tweaked my own APX to work well in certain audio environments, but the results are quite subjective.

Two things I will say about the APX:

- RX audio is VERY shrill/high-end, even with the treble adjustment set at extreme negative levels;
- If using surveillance gear -- especially an ear air-tube/coil thing, you definitely want to INCREASE the treble as the output sounds quite bassy with default settings. (This is where the PROFILE menu/feature comes in very handy...you can also limit the MAX Volume setting so as not to deafen yourself!)

Yes, I have replaced my speaker. I thought I had issues or something. Nope; it's just very shrill audio.

I much prefer the XTS5000 over the APX. My APX doesn't include basic features such as QCII, which we use for dispatching/paging. The TRS is for response. I've whined about lack of QCII support in the APX in quite a few other threads, so I'll stop now.

APX needs some further development and documentation. Moto needs to step up their game once the engineering group is back from their summer holidays.

 

[trbo90]

Mars,

That is awesome. I have been playing around with these audio settings myself. Will keep you posted on my findings.

trbo90

 

[JMR061]

Mars....have you reviewed the Motorola presentations on the XTS and APX noise suppression setting what are your feelings on that?

 

[Mars]

I'm too busy (this afternoon) to discuss the settings in detail, but for now I have made Motorola's own videos/recommendations available for others who wish to hear Motorola's views on how the radios should be set up.

Also, I wish to apologize to Motorola for the criticism I made in July 2012, in regards to them not helping the customers with these settings. The videos above were produced in Oct. 2011. They are not accessible via the Motorola public website, but they were circulated via MOL. Apparently some people at Motorola do care -- it's just unfortunate these videos are not more accessible.

 

[JMR061]

I can't wait to hear you opinion. Seems you have spent a lot of time playing with and researching these settings. We just went to a P25 Tait system here but I am a true Motorola guy and I want to get the radios set up as best I can on the subscriber side for those I program for.

Thanks

Jason

 

[motorola_otaku]

Motorola APX Settings

Excellent description of how all the different settings work, though the recommended settings don't help me - the consistent complaint I get on all of my Astro, Astro25, and APX radios is that I'm too quiet.

I find it interesting that they recommend disabling AGC. Why even include it in the first place if fixed gain does a better job?

 

[PJH]

I started a thread about my XE RSM and with that mic, I got some complaints with the default profile settings, and was worse for the 1-sided setting. The only mic that seems to work great under default was the 4104 display RSM. I'd be interested in seeing where the sweet spot for radio only, standard RSM, XE RSM and XE extreme would be. A profile for each (or a good default) would be awesome.

 

[Mars]

I picked up my "Seth" APX at Dayton in 2011. It had the old settings in it. Once I plugged in the new values, it sounded a bazillion times better.

Doing a firmware update to the APX with latest CPS does NOT install these new settings; you have to manually do it...even though the latest APX Depot codeplugs (or so I'm told) come with these new settings, as default.

Just a quick note: You may wish to scroll down to the last post in that thread and download the APX codeplug I posted. It may be easier to open two sessions of APX CPS and compare codeplugs. Copy/pasting values across codeplugs is also easier. The formatting of the board adds a space in long segments of code -- which unfortunately has happened in some of the posts in the thread. A space will screw you up if you don't fix it after pasting

 

[radionut]

Hi, great thread. I have a further question about these settings. This thread covers optimizing an entire system that uses one voice format, and doesn't seem to cover both. I've used the settings above on full digital systems, and I like the results. I have a system, however, that uses analog and digital channels, although each channel is dedicated either analog or digital and does not use both. The problem I have is not necessarily the user's noise level, but rather the overall noise level of the channel its self. What I mean is, the digital "response" channels sound great, but the analog "events" channels are way too loud. I need to find settings that compensate for both and meet in the middle. Anyone have a similar problem and can post the setting they use? Thanks

 

[robb]

thanks this helped alot just doin theses settings
Analog/Digital AGC: Enabled
Output: -3dB
Total: +12dB