To: All Michigan Army MARS Members

Subject: Digital Tips, Traps and Tweaks #2

Frank Wegori/AAR5NG MI – 5 OCT 2006

AAR5NG@sbcglobal.net

INTRO

This article and the ones that will follow relate to digital mode operations.  They are developed from a variety of sources and will likely appear on a bi-weekly basis.  The goal here is to provide information that can be useful to members already working digital and to those thinking about trying a digital mode 

for the first time.

TODAY'S TOPIC:  How to determine your RX calibration settings

1. The importance of calibrating your sound card absolutely cannot be overstated. If others in the net are consistently showing 100% solid copy, while you are seeing occasional random character substitution or gibberish for the same message, your sound card calibration settings may be the culprit.

Note: Changing the calibration values within a given program, will only affect that particular program. It does not make an actual change to your sound card. So, you must manually set the calibration values for each different program.

2. There are two RX calibration values associated with the sound card, i.e., RX SAMPLE RATE and RX CLOCK ADJUSTMENT (ppm).

3. If you are using MixW, the calibration procedure using WWV is spelled out in the manual. When properly completed, the values will be stored

under Configure/Sound Device Settings.

4. If you are using the IZ8BLY MT63 Terminal Program instead, connect

to: http://mmhamsoft.amateur-radio.ca/ and select MMSSTV from the

scroll-down menu on the left. Download and install the program. Tune your radio to the strongest WWV signal.

5. Click on:

Options/Setup MMSSTV/Misc/Adj. Allow the WWV vertical signal to begin scrolling down. Place your cursor at the bottom of the WWV signal and click. Then place the cursor at the top of the signal and click. The end results displayed will be the RX calibration values for RX SAMPLE RATE and RX CLOCK ADJ. Write these values down.

6. Next, launch the IZ8BLY MT63 Terminal Program. Click on:

File/Preferences/PTT Port. Enter the RX SAMPLE RATE (including any

decimal value) derived from the MMSSTV calibration procedure, into

terminal Program’s RX Sample Rate window and click OK to save. This program does not currently require the entry of an RX Clock Adjustment value, but others may.

7. How to determine your TX calibration setting will be covered in a

future article.

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