The AM Forum
March 28, 2024, 12:43:50 PM *
Welcome, Guest. Please login or register.

Login with username, password and session length
 
   Home   Help Calendar Links Staff List Gallery Login Register  
Pages: [1]   Go Down
  Print  
Author Topic: ICOM IC-756 Pro III Performance on AM  (Read 52181 times)
0 Members and 1 Guest are viewing this topic.
W1AEX
Un-smug-a-licious
Contributing
Member
*
Offline Offline

Posts: 1488


Apache Labs SDR


WWW
« on: January 26, 2009, 08:41:49 PM »

Updated 6-26-2010:  The link below has a few simple ideas about working around the aggressive ALC problem and the hard-coded DSP limitations of the 756 Pro III without any internal modifications to the rig itself. If you currently use your 756 Pro series rig for digital communications through one of the common computer interfaces, some easy improvements in AM performance can be made by using "real-time" computer processed audio that is generated by the free Voice Shaper software and then ported out from the computer sound card into the audio port in the back of the Pro III. This is pretty much a zero-effort-project if your digital interface is already installed! A number of mp3 files are included at the link to give some idea of how the Pro III behaves while transmitting in the AM mode with different EQ and compression settings.

Two small audio samples are included here to help show the difference between the stock AM audio and the processed audio with the internal ALC defeated. These were created by using the line output of an FRG-7700 receiver, connected to the line input of one of the station computers, to record the Pro III with Adobe Audition as it sounds on the air. This is a project in progress, but it seems worth a little effort given the large number of 756 series rigs out there, and the excellent AM receivers they have.

http://www.w1aex.com/756AM/756AM.html

* Sample Pro III running stock in the AM mode.mp3 (78.75 KB - downloaded 1116 times.)
* Sample Pro III with external ALC and processed audio.mp3 (128.16 KB - downloaded 1112 times.)
Logged

One thing I'm certain of is that there is too much certainty in the world.
W2BX
Member

Offline Offline

Posts: 29



« Reply #1 on: April 09, 2020, 08:36:27 AM »

Updated 6-26-2010:  The link below has a few simple ideas about working around the aggressive ALC problem and the hard-coded DSP limitations of the 756 Pro III without any internal modifications to the rig itself. If you currently use your 756 Pro series rig for digital communications through one of the common computer interfaces, some easy improvements in AM performance can be made by using "real-time" computer processed audio that is generated by the free Voice Shaper software and then ported out from the computer sound card into the audio port in the back of the Pro III. This is pretty much a zero-effort-project if your digital interface is already installed! A number of mp3 files are included at the link to give some idea of how the Pro III behaves while transmitting in the AM mode with different EQ and compression settings.

Two small audio samples are included here to help show the difference between the stock AM audio and the processed audio with the internal ALC defeated. These were created by using the line output of an FRG-7700 receiver, connected to the line input of one of the station computers, to record the Pro III with Adobe Audition as it sounds on the air. This is a project in progress, but it seems worth a little effort given the large number of 756 series rigs out there, and the excellent AM receivers they have.

http://www.w1aex.com/756AM/756AM.html

I assume you can run an external analog audio chain into that same audio port on the rear panel. I have a Pro III ,think ill give it a try.  Cool
Logged
W1AEX
Un-smug-a-licious
Contributing
Member
*
Offline Offline

Posts: 1488


Apache Labs SDR


WWW
« Reply #2 on: October 26, 2020, 01:22:02 PM »

Yes, you can certainly do that. I ran audio right into the little interface that I used for the digital modes. The tight bandwidth constraint in the PRO III firmware was still present of course but it was passable as long as the heavy-handed ALC was defeated with the little battery trick.

73,  Rob W1AEX


* soundcard.jpg (31.58 KB, 729x553 - viewed 800 times.)
Logged

One thing I'm certain of is that there is too much certainty in the world.
Pages: [1]   Go Up
  Print  
 
Jump to:  

AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
 AMfone © 2001-2015
Powered by SMF 1.1.21 | SMF © 2015, Simple Machines
Page created in 0.05 seconds with 18 queries.