
                       =======================

                       EMBAYCOM & SIMPLE MODEM

                       =======================


The purpose of embaycom is very simple. It is an
emulator prog that allows you to run Baycom software, but with just a
hamcom/JVFax 741 opamp interface, instead of a baycom board.

The practical upshot of this is severalfold:-

        1>  The terminal unit costs pence to build, rather than 30 - 50 as
            a Baycom board does.

        2>  There are two emulation drivers available, on for HF and one for
            VHF.

        3>  It means that you can play fax/sstv/amtor/cw/rtty/hf&vhf packet
            without altering any leads or connetors. (Just run hamcom jvfax
            or baycom and the embaycom driver)

This is the actual circ for the TU, you will see that it is slightly modified
from the original hamcom design, but is still essentially a junk box project.




                      S I M P L E   M O D E M

     for BAUDAUT, AMTOR, PACTOR, SSTV, FAX, HF/VHF PACKET
                              BY RT4UZ


                                  Computer RS-232
                    COM1                                  COM2
                25-Pin  9-Pin                         25-Pin  9-Pin
                 20     4   DTR   >> DCD  8     1

                  5     8   CTS   >Ŀ
                                    
                  8     1   DCD   >Ŀ
                                            
                  4     7   RTS   >> RI  22     9
                                             
                                             
  Transceiver                                
                                             
        100 nF       A741 (or similar)      
                           Ĵ<> DTR 20     4
                    3 \ 7              
   >ĴĴ+\     Ĵ>  
                       \ 6             
   AF IN                  >> DSR  6     6
                     2   /               
   >Ŀ          Ĵ-/      Ĵ<Ŀ 
                     / 4              
                    Ĵ>> RTS  4     7
        100k    100k   +          
                   +            
                     1F     1F   > GND  7     5
               16V 16V     
     PTT >Ŀ                     
                                          
                      \    Ŀ     SW1 "HAMCOM"
                       Ĵ    Ĵ<Ŀ ٳ
                      /           \  
                             3k          "BAYCOM"
                    
                          Ŀ   Ŀ
        100nF    Ĵ91 kĴ10 k> TXD  2     3
           10k        
   MIC <Ĵ>           
                     
                         
       <Ŀ         1nF    30nF
                       





    SW1 used to switch between STANDARD HAMCOM mode
   for MIX v2.5, JVFAX v5.1, HAMCOM v2.1, TV2 v1.0 etc and
   EMULATE BAYCOM mode for BAYCOM v1.50, PCTOR v2.06.

   ..........................................................

   EMULATE BAYCOM mode requires additional small program EMBAYCOM.EXE
   and two COM-ports.



   ################################################################



Instructions:
=============

1. Copy files em1200 and em300 
   into Baycom directory.
2. Create file embay.bat:
	@echo off
	l2
	scc
	off
3. Run BAYCOM by giving command
   em1200m2.com... (for 1200 baud)
or EM300M.COM ....   (900-1100hz)
or em300m3.COM....  (1400-1600hz)

You don't need EMBAYCOM.EXE.

If any question arise address  UA9AJ or UZ4FXT
(authors of the programs) or RV6LHB (it is me).


                 ######################################


I'd like to pass on a few tips and tricks: and if YOU know of any that are
not mentioned here, PLEASE pass them on.......

First of all, the interface. I have found that the component values shown 
in the circuit digram that was supplied with the files works OK, but my own  
epxperience has shown that the filter could be a little better for use with 
SSTV and FAX, where the highest frequency used is somewhat higher than the
packet tones. I have settled for the values shown in the original HamComm
doc file, and find them satisfactory. It is also good practice to use a 
ten-turns potentiometer for adjusting the output from the interface: it  
can be quite tricky to get the correct deviation using an ordinary low-cost
pot.

The next thing we come to is EMM386.EXE..............
If you have this installed on your computer disable it NOW !! It really 
screws up the timing no end, and makes it well-nigh impossible to connect
to another station: they just can't decode your werd s ϒO ώOp  Oσ O K0'@    @^p 9 	 9 q9N  B	 9@ 		@	0	q	0	0@1	 3bvbR' @	<$+"| p
biky+C	K){Ck@y[){#c0AhUIccI@` D\@BbJX&&@o<OM0C.BAP6 I' all qn y_B40 C>A )1
dD&d܅?&4 H	5	,` c0l 4=>Aw 37 ||/χ t9`=dY,

 3@``@F%I`*&0@$<㑂tp8[ ,678& @ $AT file to start EM1200M2: it'll then start Baycom
for you.

I've been using the system for a couple of weeks now, and I'm having no real 
problems.......except for the fact that my local digipeater on 70cms refuses
to hear me! I can connect to every station that I hear, EXCEPT this one. 
I have no idea what the cause can be, because when my signal was measured it 
looked 100% OK ....... weird !

Anyway, that's about it - and don't forget: if YOU have any tips to pass
on I'd be DELIGHTED to hear from you.

Credits: Nick - RT4UZ  for a really smart piece of programming,
         Norm - VK5ZAH for a neat layout for the HamComm interface
         Lars - DB9BJ  for not believing what he saw (Hi Lars !)
         Timo - PE1NTP for real-time measurements of signal quality 

         

               #########################################



All the best & Good Luck