Sound Card Packet  with AGWPE

Translations of this site
Most recent AGWPE version is:  2013.415  15 Apr 2013

Computer requirements
Packet Engine Pro

Configure AGWPE
Download and Install
Basic AGWPE Setup
2 Radio Setup
2 Card Setup

Sound Device Setup
Basic Device Settings
Rename Sound Device
Additional Settings
Using the Tuning Aid

Program Behavior

AGWPE Features
AGWPE on a Network
Baud Rates & Modes
Remote Control
TCP/IP Over Radio
Tips and Tricks
Traffic Parameters

Compatible Programs:
Setup Help

Radio Interface
Getting Started
Kits and Pre-assembled
USB SignaLink
Receive Audio Cable
Transmit Audio Cable
PTT (TX Control) Cable
2 Radio Modification

About Packet
Packet Overview
Exchange Modes
What To Do with Packet
Common Frequencies
Frame Headers
Further Reading

Sound Card Tuning  Aid

The Sound Card Tuning Aid screen is accessible from the AGWPE menu and can be used to "see" the quality of received signals and, for HF packet particularly, help in tuning the radio to the correct frequency. At least one oscilloscope will appear on the left side of the screen. A second scope below the first only appears if you have selected Dual Port use of the sound card on the Properties screen.

This page describes the Tuning Aid and gives some examples of good and bad signals as seen on the tuning aid's oscilloscope.

The first screen shot below shows the Tuning Aid page with the sine wave view selected. Only one oscilloscope is visible since the sound card is running in Single Port mode. In Dual Port mode, another scope would appear beneath the first. Note the sine wave in the scope. This is what a quiet 1200 baud packet channel looks like. The only undulation in the wave is due to noise. It verifies that the audio connections to the sound card and radio are working.

<-- Click for larger image

In contrast, if the sine wave was perfectly flat (or nearly so), as below, then you know you have no audio input from the sound card, either because of a problem with the audio feed from the radio or incorrect sound card volume settings (source or volume):

<-- Click for larger image

Oscilloscope Styles

There are four (4) display styles available for the Oscilloscope. The first two are generally the most useful.

1. Sine Wave

-- shows strength of the signal (audio volume) and the quality of the signal. A signal with good strength will have waves that fill about 1/2 of the screen (relative distance between the peaks and valleys of the wave). You can use the Volume Control settings for RX audio to adjust them.

Signal samples for 1200 baud:


Sample of a good signal;
packet decoded.


Too weak or distant;
packet was not decoded


Collision of packets;
packet was not decoded


This is from a Yaesu FT209 transceiver with "bass boost" activated. The boost creates incorrect pre-emphasis: the low tone is emphasized, not the high tone. These packets can only be decoded about 80% of the time. The sending station must turn off the radio's bass boost option to correct this.


  Below, a  9600 baud signal sample:

This is a generally good signal that was decoded, but you can see small sparks caused by some "bug" at either the transmitting station or the receiving radio or sound card.

2. Waterfall

This is a frequency spectrum display that shows activity in the audio pass band over the last few seconds. Received signals create color streaks which will 'fall' down the display as time progresses. Relative signal strength is indicated by the colors, which are -- weakest to strongest -- blue, green, yellow, red. Black indicates no signal.

The waterfall should be centered between the two vertical white lines. For AFSK (UHF/VHF), it should center automatically. For HF operations (FSK), adjust the radio's receive frequency to center the waterfall. Centering is critical for accurate decoding of HF packets. The strongest signal (yellow/red color streak) must lie between those two lines, as this next screen shot illustrates:


The screen shot below shows an HF radio that needs tuning. The yellow area showing packet activity is below the tuned frequency marked by the two vertical lines:


This sample below is a waterfall display showing two 1200 baud packets. The packets have black areas to their left and right of the two vertical white lines.

The upper packet has fair modulation and was decoded. Also, note in the black area above the packet that there are small green vertical lines. This is the result of TXDelay, i.e. a short interval of carrier with no modulation.

The bottom packet has very low modulation (little color; similar to a carrier with no modulation), but the packet was still decoded.

3. Eye

 - is really a scatter diagram. The closer together the scattered points, the better the signal.

4. Frequency

 - a real-time display of where signals are being heard along a frequency scale. The TWO white vertical lines are centered around the dialed frequency, and the majority of signal peaks and valleys should fall between the left line (lower tone) and the right line (upper tone). If they don't, you'll need to change the radio's dialed frequency to center the signal between the white lines.

Set Volume Button

Pressing this button takes you to the Sound Card Volume Settings window where you can adjust TX audio levels, RX audio levels, and the RX input source jack.

Last Updated:

by Ralph Milnes NM5RM


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