[App_rpt-users] Simplex node with RPi and discriminator audio

[Marshall Oldham]

Keith,

 

I just had a chance to test out your configuration.  I happen to have all the hardware on hand. 

 

RPi 3 Model B with DMK URIxB connected to an Alinco DR-135 radio set for 9600 baud packet. (Discriminator Audio)

 

I was able to set the audio levels and CTCSS levels without any issues. I used a service monitor to do so.  

 

Receive and transmit audio sounded fine. 

 

CTCSS decode/encode on the radio also seems to work using the USBradio channel driver. 

 

DSP squelch works well. 

 

I ran several tests using 100.0 Hz for CTCSS decode on the receiver. 

 

There may be one slight issue, but if you are running simplex node at home, it may not really be an issue, just something for you to be aware of. 

 

Here are my findings:

 

88.5Hz = NO decode falsing

91.5Hz = decode falsing

94.8Hz = decode falsing

97.4Hz = decode falsing

 

103.5Hz = decode falsing

107.2Hz = decode falsing

1109Hz = = NO decode falsing

 

I hope this helps out. 

 

73

 

Marshall - ke6pcv 

 

 

 

From: App_rpt-users [mailto:app_rpt-users-bounces at lists.allstarlink.org] On Behalf Of Keith Williamson
Sent: Sunday, May 05, 2019 11:37 AM
To: Users of Asterisk app_rpt
Subject: [App_rpt-users] Simplex node with RPi and discriminator audio

 

I'm wondering if this is a realistic configuration for a simplex node:

 

RPi3 with DMK URI connected to the 9600 audio in and out signals of an Alinco DR-135T. I want to be able to use CTCSS so that random signals don't get bridged to connected nodes. 

 

My concern is that with the above configuration, the CTCSS decode in the radio is bypassed. Consequently, CTCSS decode needs to be done via usbradio since simpleusb does not have this capability. However, I keep hearing that usbradio is not handled well with an RPi and yields less than ideal audio quality. 

 

So all of the above implies that I either use a higher performance node PC or continue to use the RPi, switch to the 2400 audio in and out signals (so that the Alinco can handle the CTCSS) and use simpleusb. 

 

Opinions?

 

Thanks,

 

Keith

KF7DRV

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