Running RTTY & CW on the KD1JV ATS-3 transceiver
						   by William K. Mabry, N4QA
					       Initial writing: 10 December 2004
						       Updated: 19 August   2005


					         *This is a work-in-progress*

	The Appalachian Trail Sprint-III, aka ATS-3, is a four-band, DDS-based CW transceiver kit, designed and produced 
	by Steven Weber, KD1JV, of Berlin, New Hampshire. His webpage describing the kit is:

	http://www.qsl.net/kd1jv/ATS3.HTM
	
	I have built an ATS-3 and am making modifications to the rig which will facilitate its operation in RTTY mode,
	to augment its CW capability.
	I am also writing the code for my new Windows app, 'DDS_RTTY for the ATS-3' which must be run concurrently with
	the Windows RTTY app, 'MMTTY' ver1.65B, by Makoto Mori, JE3HHT, or with another, similarly-acting RTTY app.
	
	This project is not meant to be used with a stock ATS-3. Rather, the project's implementation requires making
	permanent modifications to a stock ATS-3. While most ATS-3 owners will not likely wish to 'chop' their rigs,
	I will assist, in any way I can, anyone wanting to duplicate this project.
	
	The very first thing I did was to isolate from ground, via Dremel Tool with tiny saw bit, printed wiring board,
	'U6', pad 9. This had to be done before the AD9834 DDS chip was soldered to the board at 'U6', and was done in
	order that modification hardware would be able to manipulate the logic level of DDS pin 9(FSELECT) between
	logic one (5 VDC) and logic zero (0 VDC), as required.
	
	Next, I ordered 5 Volt parts to replace 3.3 Volt parts at 'U11' and 'REF OSC'.
	The replacement parts, from Mouser, are:
	
	628-812C50AU      for 'U11'
	695-CSX750FCC-40  for 'REF OSC'
	
	There are several stock ATS-3 kit parts which are not used in this project:
	
	Most notably, the Texas Instruments MSP430-F1121A MPU at 'U10'.
	The 3.3 Volt parts at 'U11' and 'REF OSC', mentioned previously.
	The crystal at 'X6'.
	Pushbutton switches at 'S1' through 'S4'.
	Capacitors at 'C47' through 'C52'.
	Transistor at 'Q6'.
	Possibly others.
	
	How the DDS_RTTY_ATS-3  project software/hardware combination works:
	
	Frequency data are stored to the ATS-3's onboard Direct Digital Synthesis chip via Printer port pins 1(FSYNC),
	4(SDATA) and 5(SCLK).

	The mode-select output bit appears at printer port, pin 3 and drives the control input of the 'Mode Switch',
	which is a Pericom PI5C3303TX bus switch.
	
	1) CW mode:
	This is the ATS-3's native mode of operation and is selected by clicking on 'CW' in the DDS_RTTY_ATS-3  window.
	The ATS-3 may then be keyed with external keyer output connected to printer port pin 10.
	Transmit frequency data are stored in the DDS' FREQ1REG and receiver local oscillator frequency data are stored
	in the DDS' FREQ0REG.
	
	2) RTTY mode:
	This is the mode which I've added to the ATS-3 and is selected by clicking on 'RTTY' in the DDS_RTTY_ATS-3 window.
	
	For transmitting RTTY, the DDS_RTTY_ATS-3 software stores mark and space frequency data within the ATS-3's onboard
	DDS'  FREQ1REG and FREQ0REG, respectively. The MMTTY software causes the DDS to toggle between these two
	frequencies, during transmit intervals, via the hardware interface between the DE9 serial port, pin 3(TXD) and
	the DDS chip, pin 9(FSELECT).
	
	For receiving RTTY, the DDS_RTTY_ATS-3 software does not disturb the transmit mark frequency data in the DDS'
	FREQ1REG, but restores the ATS-3's normal receiver local oscillator frequency data to the DDS' FREQ0REG.
		   		
	Accordingly, in RTTY mode, the DDS_RTTY_ATS-3  software receives the 'T/R' data bit from the MMTTY software,
	via the	hardware interface between the DE9 serial port, pin 7(RTS) and the DB25 printer port, pin 10(nAck) and,
	from this data bit, determines whether to store transmitter space frequency data or receiver local oscillator
	frequency data within the DDS' FREQ0REG.
			
	More to follow...

	I have no connection with any above-mentioned vendor.