Sound Card Interfacing

There are many sound card interfaces out on the market today and most should be able to be utilized with RoMac 10 Band Equalizer & Receive Filtering software.

There are a few terms that one should become familiar with before we delve into the nitty-gritty of hooking up an interface for use with the Equalizer software.

First lets tackle the serial port.  There are two signals on the serial port that we are interested in.  One of these signals is referred to as "RTS".  This signal normally originates from the computer (software) to the radio, and when sent, places the radio in the transmit mode.  If your present sound card interface and software places your transceiver in the transmit mode, so far so good.

The other signal on the serial port that is needed to utilize all features of the Equalizer software is the "CTS" signal. This signal normally originates from the sound card interface to the computer. This signal tells the software that the transceiver is in the transmit mode. Again most sound card interface units that utilize the "RTS" signal to place the transceiver into transmit, will supply this signal, when the PTT switch is activated (closed).

If your present sound card interface works with some kind of digital mode software, you may be assured that the Equalizer software will work correctly in both transmit and receive.

I believe that all the commercially made sound card interface units route the sound cards "line out (speakers)" and "line in" audio paths correctly. After all if they didn't, they wouldn't work with all the digital software on today's market.

Some of the higher end sound card interface units also take care of routing the microphone audio correctly. If your interface unit has the capability of routing your microphone audio to the "microphone in" on the sound card you're all set, although I prefer to wire the microphone directly to the sound card in order to avoid any frequency restricting transformers that may be in line when using an interface unit.

If your sound card interface doesn't have this capability, simply cable the microphone directly to the sound cards "microphone input" (use stereo jack, ground to sleeve, hot side to tip, leave the ring not connected. Balance microphones should be wired hot to tip, and minus and shield to sleeve, and ring left unconnected. See FAQ #13 for microphone wiring issues) and leave all other cabling as outlined in the sound cards interface units documentation. 

 Click here  for a simple to build interface unit that supports all modes of the RoMac 10 Band EQ and Receive Filtering. 

Please note that some interface face units use an inexpensive audio isolation transformer that may have an effect on the audio pass band.  In those cases you are better off connecting your microphone directly to the sound card. Cabling your microphone directly to you sound card and using a ferrite core (type-43), may also help reduce any RF on your audio. See FAQ #3 for more information.

The RoMac 10 band Equalizer and Receive Filtering software has five different modes of operation. The table below outlines the serial port requirement  for each, and which features of the software may be utilized. The software utilizes the "microphone in" for transmit audio and the "line in" for receive audio. The sound cards "line out" (speakers) is utilized for either audio to the transmitter  for the transmit EQ, or to the speakers for receive filtering. See FAQ #18 for more information....