[App_rpt-users] Strange oscillation

[Tony KT9AC]

  Shawn,
  I'm also running an M120 with URI and it works fine. Maybe try another 
mobile to see if you can duplicate the symptoms, or see if the power 
supply is bogging down when the M120 goes into transmit (i.e. voltage 
drops from the load).

  A 10-25W M120 should be run between that power range; a 25-40W in that 
range. My M120 is a 1-10W model and I keep it at 3W running just fine.

  Another tip: the URI and/or USB FOB handles PL encode/decode just fine 
but not DPL. If you want to use DPL, setup the radios to use the 'PL and 
COS' logic output and configure the interface to look for a 'carrier' 
signal only from the radio (in the rpt.conf file). So basically the 
radio does all the signal work and just tells the interface a signal is 
present, removing the need for DSP processing.

Tony

On 08/17/2010 09:57 PM, Shawn Hastwell wrote:
> On Tue, Aug 17, 2010 at 10:42 PM, Stephen Rodgers<sales at qrvc.com>  wrote:
>> kb8ude at gmail.com wrote:
>>> I am still testing my hardware here on a dummy load and having strange behavior.  First, my hardware:
>>>
>>> Dell P3 1.13GHz server, 1gb RAM, 36gb SCSI drive, installed via ACID CD.
>>> URI interface, output cable about 6 inches long, twisted but not shielded.
>>> Motorola Radius M120 UHF turned down to 20W.  Set as a simplex link and the channel is set to carrier squelch.
>>>
>>> Set my audio levels using a Motorola service monitor.
>>>
>>> Sometimes when the radio transmits I get clear voice.  Most of the time there is a noticeable low frequency oscillation on the signal and the audio is unreadable. Almost sounds like mid-rpm engine ignition noise if that helps paint a cleare picture of the sound.  RX seems good, I am listening using iaxrpt on the pc and can hear myself slightly delayed and clear.
>>>
>>> I tried a couple ferrites on both sides of the URI with no change.  I also noticed that sometimes the 'connected' announcement has a ripping or tearing sound to it as well as stuttered courtesy tones on occasion.  I am wondering if my server just isn't fast enough or if the URI needs a 2.0 USB port to plug into.
>>>
>>> Any thoughts folks?
>>>
>>> -Shawn
>>>
>>> Sent via BlackBerry from T-Mobile
>>> _______________________________________________
>>> App_rpt-users mailing list
>>> App_rpt-users at qrvc.com
>>> http://qrvc.com/mailman/listinfo/app_rpt-users
>>>
>> Slow PC: If you run the 'top' command from the linux shell command line, how much CPU is being consumed by asterisk?
>> More than 25% is asking for trouble. Try a faster pc and see if it clears up the problem.
>>
>> Audio oscillations: It's hard to say what might be wrong. This could be CPU speed related, interface adjustment related,
>> or a grounding/ground loop issue. It wouldn't hurt to look at the URI audio output with the scope in your service
>> monitor while it is oscillating.
>>
>> BTW: Ferrites are no good at reducing noise at audio frequencies.
>>
>> Steve
>> WA6ZFT
>>
> I am still getting used to the service monitor and how to do various
> things with it properly.  I will see what I can do in that regard.
>
> TXVoice and TXTone are at 300 and 175 respectively.
>
> I did a 'top' while there was audio activity connecting and
> disconnecting from the Echotest server.  It peaked near 22.3 and only
> one time at 24.8.
>
> I was thinking RF may have been affecting the URI, hence the ferrites.
>   I am not ruling out the radio as the cause directly though, I
> understand that some of these models will exhibit some erratic
> behavior when turned down too far based on the rated average power.  I
> am going to turn it back up to it's rated power and see what happens
> as well.
>
> -Shawn
> _______________________________________________
> App_rpt-users mailing list
> App_rpt-users at qrvc.com
> http://qrvc.com/mailman/listinfo/app_rpt-users
>