[App_rpt-users] CM119 USB interface

[Mark DuMoulin]

Kevin,

I downloaded ASL 1.01 and had the same issue as with the RC.19
When I try to use it asterisk fails claiming to not find the chan.

I'll put it back in and try again to give you feedback.

Tnx!
Mark

-----Original Message-----
From: Kevin Custer [mailto:kuggie at kuggie.com] 
Sent: Tuesday, January 01, 2019 12:23 PM
To: Users of Asterisk app_rpt; Mark DuMoulin
Subject: Re: [App_rpt-users] CM119 USB interface

Howdy Mark,

This particular group is for supporting the "official" AllStarLink distribution of Asterisk and app_rpt called ASL1.01, and legacy distributions like ACID and DIAL.  As such, we don't generally get into the discussions and support for HamVoIP.  Those folks have their own support system.  However, I'll attempt to answer your questions. HamVoIP doesn't recommend the use of usbradio, however it's fully supported in ASL 1.01.  My suggestion is you download ASL 1.01 and give it a try.
<https://wiki.allstarlink.org/wiki/Main_Page>

USBradio is one of the features that I really like about AllStarLink. When fed with discriminator audio, the software will determine the noise squelch and CTCSS detection, eliminating the need for hardware modifications and obtaining the right logic signals for COS and CTCSS (sometimes not as easy as one would like).  Then, feeding the FM modulator directly with audio that's been filtered, pre-emphasized and limited, makes all transmitters sound the same no matter who made them. The noise squelch detection is as close to a Motorola M6709 as you can get.  That's often thought of as the high water mark in noise squelch circuitry.  The CTCSS detection is as good as any COM-SPEC product of past or present, also thought of as the best in the industry.

Since we're on the subject of usbradio, there's something else that I should mention.

Since 2008, a C-Media integrated circuit of some kind has been used as the heart of most radio to computer audio interfacing in AllStar Link. The CM108, CM119 and CM119A are used in most of the adapters to date. Some manufacturers have settled on the new CM119B chipset.  In my opinion, the adapters based on this chipset shouldn't be used with usbradio. Why? All of these components are similar, except the CM119B. The "B"component includes a few changes which are significantly different. These differences may not allow the CM119B to operate correctly with AllStar.  The two big differences are the lack of crystal stability, and a new "feature' called Pop Filtering on the MIC input. In review of the spec sheet for the CM119B in comparison with its prior counterparts, the pop filter rolls off the low end frequency response. This slope might be enough to cause unreliable detection of CTCSS when using the usbradio channel driver, especially on lower tone frequencies.  I'm also concerned that without the crystal time base, the RC stability of the CM119B will result in unreliable CTCSS detection caused by frequency drift. This is especially true in systems where the audio adapter is subjected to wide ambient temperature changes, as found in shelters that are not environmentally controlled.  In addition, there are audio scaling differences between the prior chipsets, and the CM119B.  The scaling differences are currently being worked out in software.

In conclusion, the CM119B may be fine when used with the simpleusb channel driver, but there are lots of people that rely on the DSP of app_rpt for software noise squelch and CTCSS detection. I recently purchased several hundred CM119A components directly from C-Media. That's what I will continue to supply in my radio adapter offerings, as we know it works in every distribution, no matter if it's simpleusb or usbradio.

Kevin W3KKC

On 1/1/2019 9:19 AM, Mark DuMoulin wrote:
> Kevin,Brian;
>
> I have been trying to set up use of radiousb instead of simpleusb. I see here Brian is doing that with the issues he is having.
> I can't get nearly that far.
> I am running hamvoip rc19 on some and recently downloaded stretch.
> In both cases I set the usbradio module to load however I cannot get the driver to work and keep getting asterisk failures.
> Additionally the menus set up by the programmer show only simpleusb-radio-tune not radio-tune-menu.
> Is there another image or procedure I need to run to get this started?
>
> Tnx,
> Mark
> WB2ERS