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 Introduction to Sound Card Interface & Radio Modems:



SC1: Simple Sound Card Interface

SC2: Advanced, Sound Card & Echo Link Interface


 SC1: Simple Sound Card Interface


Previous SC1 Web Page is here..........

 NO LONGER AVAILABLE   Please consider SC2

For many radio amateurs, talking & chit-chatting on-the-air is of no interest. They rather like to "Silently" work on their bench with hobby projects & communicate with fellow amateur by way of a PC and a modem connected to wireless set.

There are lots of ideas & radio modems available to fill this requirements. I have gone thru this 15 years back when I first bought a Kentronics all mode TNC and later a 1200baud VHF TNC. 

Here I have presented two such "Modems" which are not really modems but give us the same results at a fraction of cost.

The first is called "Hamcom" a PC software (DOS) written by  . It has a very simple interface to PC com port containing a ua741 and few components. Most work of a "TNC" is done by the software.

You get a simple, economical & fast way to start digital communication on amateur bands with this kit & a free software. With Hamcom you can receive & transmit RTTY & CW.

Similarly, PC's soundcard is nothing more than a modem itself. Using soundcard capabilities for Digital Communication has attracted many hams to use a simple interface to isolate PC & Radio to achieve clean signals & reject noise and spurious frequencies.

Sound card Interface detailed below does this.

 Sound Card Interface for Amateur Radio Stations:
As discussed above, PC's sound card is nothing but a modem, a term defined as "modulator" and "Demodulator". In short, it converts digital zeros & ones to sound tones and again, sound tones to digital levels.

The soundcard interface detailed here is not different from many made by amateurs and available commercially.

SC1 is simple to construct and easy to use. On this interface, you have an RJ45 connector where you connect your microphone, PTT and Receive audio using a shielded cable.

SC1 is a passive interface. Means, it dosnt require any external power. 

Assembled SC1 Sound Card Interface:

Click the photo to enlarge


 Technical Details & Schematic:
Sound Card Interface Document
Schematic & Parts List


Component Data Sheets

 Project Component Datasheets




With sound Card Interface, you can use many software available either as a freeware or shareware. Please go thru following links & find one suitable to your communication requirements.
Collection of Digital Communication Software
More Digital Communication Software links
Look under "Digital Communication" and Packet, Amtor, CW, Pactor etc.


 Free Software Utilities Download
Wave Generator
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