================================================================ D A S (DTMF ACCESSORY SQUELCH) APPLICATION NOTE 1 OPERATING WITH FEWER CONTROLS AND INDICATORS 951105/Iss-1 ================================================================ Paul Newland, ad7i Post Office Box 205 Holmdel, NJ 07733 ad7i@tapr.org ---------------------------------------------------------- | Copyright (c) 1995 by Paul Newland, P.E. | | All Rights Reserved. This guide may be reproduced | | by radio amateurs for their own personal use, provided | | this copyright notice is included in any reproduction. | ---------------------------------------------------------- ******************************************************************* * NOTES * * * * SPECIAL TYPESETTING FUNCTIONS (I.E., FOOTNOTES, ITALICS, * * ETC.) ARE MARKED WITHIN THE TEXT USING A DOUBLE SLASH (LIKE * * THIS //). * * * ******************************************************************* INTRODUCTION ------------------------------------ DAS (DTMF Accessory Squelch) acts like a switch connected in series between the speaker output of your VHF or UHF transceiver and an external speaker. DAS will monitor a radio channel for you, with the speaker switch open so the speaker remains silent, until someone sends one of the DTMF sequences you have selected. When DAS hears your your personal Touch-Tone ID sequence on the radio channel it will light a LED, sound an buzzer and close the series speaker switch so that you can hear the audio of the calling station. An introductory discussion of DAS was published in //QST//, December, 1995, pages 25-31. The "DAS Configuration Reference Guide", available from the TAPR FTP file server as well as the ARRL BBS//1, provides a more complete description of each programming option, the purpose of the option and how the various options may interact. This document, DAS Application Note 1, "Operating with Fewer Controls and Indicators", describes how to do just that for DAS DAS-AN1: OP W/FEWER CON & IND -2- 951105/Iss-1 SELCAL operation, without significantly reducing functionality. Most users don't need all the switches and LEDs that DAS provides. Some users may not want any of those things. This may be due to panel space limitations or just the desire that the operator face less stuff. This application note describes how to get by with less in the area of DAS controls and indicators. DELETING THE MONITOR SWITCH ------------------------------------ There's a simple work-around to avoid using (or even providing) the monitor switch. Consider using the MICUP signal for monitor control. Have two hangers -- one connected to MICUP and the other not connected to anything. When the microphone is in the MICUP hanger DAS will be in the normal SELCAL mode with the speaker quiet. When the microphone is in the other hanger (or in your hand) DAS will be in the monitor mode. It's that simple. DELETING THE CLR SWITCH ------------------------------------ As with the monitor switch, there's a simple work-around to avoid using (or even providing) the CLR switch. CLR is only used to enter/exit the CONFIG mode and to clear the LEDs and relays. For configuration, you don't need the CLR switch -- you can simply press a clip lead to the correct contacts on TB1 in order to enter the CONFIG mode. To exit the CONFIG mode issue the DTMF command "*0#". That will get you out of the CONFIG mode just the same as pressing CLR. To clear the LEDs and the relays, you can configure DAS to treat every occurrence of the microphone leaving the MICUP hanger as a brief press of the CLR switch. This function is active whenever the MICUP IS CLR option is set to ACTIVE. To ACTIVATE this feature enter the CONFIG mode and issue the command *4161#. After the command accepted flash code is displayed issue the command "*0#" to leave the CONFIG mode. With DAS so configured, when you want to clear the LEDs or relays just take the microphone out of the MICUP hanger. That will be just like pressing and releasing the CLR switch. USING JUST ONE LED ------------------------------------ You may not have noticed but the various detected SELCAL events (Personal, Group, LiTZ) are represented by different LED flash codes. If the user doesn't need to easily and uniquely differentiate between all the various detected events, consider connecting all the LED driver outputs together to drive just one LED, instead of four separate LEDs. DAS-AN1: OP W/FEWER CON & IND -3- 951105/Iss-1 DOING WITHOUT LEDS ------------------------------------ If you don't care that you received a SELCAL call while you were out of the room (or car) you don't need to use any LEDs with your DAS unit. In this case, if you hear audio from the speaker you know that either (a) you left DAS in the monitor mode (the microphone out of the MICUP hanger or monitor switch set to MON) and/or (b) your DAS unit detected one of the DTMF sequences that you configured into the system. If that's all you need to know, you don't need LEDs. One or two LEDs might be helpful during configuration, but they are not essential. NOTES ------------------------------------ 1. TAPR FTP File Server ftp.tapr.org, look in /tapr/das. TAPR on the Web at "http://www.tapr.org". ARRL BBS, +1 860 594 0306, 8-N-1, look in the FILES area, search on DAS. ---ooOoo---