From: "Kent Hastings" <kent_hastings@qmail2.aero.org>
Date: Wed, 25 Aug 93 14:32:41 PDT
To: cypherpunks@toad.com
Subject: Julieboard DDS
Message-ID: <199308252128.AA16005@aerospace.aero.org>
MIME-Version: 1.0
Content-Type: text/plain


                      Julieboard DDS
Remember my constant whining about the lack of suitable hardware for
spread-spectrum radio? No more!

The August 1993 issue of 73 Amateur Radio Today
contains an article and schematic for: JULIEBOARD. Woo hoo!
 
Ahem. The Julieboard is a Direct Digital Synthesis (DDS) circuit built
around the 28-pin DIP Harris HSP45102 DDS chip. A software controller
program is shown using GWBASIC. Here is a summary of features:
 
"0 to 16 MHz coverage (*Note: can be used to modulate UHF/Microwave*)
 0.007 Hz frequency resolution
 Virtually instantaneous switching time
 No drift/no calibration
 Excellent spectral quality
 Simple interface via PC printer port"
 
The following is music to my eyes (Wha?...Dhoh!):
"...there is no reason why an appropriately programmed single chip
 microcomputer (such as a Motorola '68705 or Intel '8051) couldn't
 replace the PC for those who object to having to drag around a
 large, bulky *Homer-mungous* PC just to drive a tiny little board.
 With a single chip microcomputer, an entire HF rig could be made
 to fit into a shirt-pocket-sized package!"

A circuit board can be obtained for $25 U.S. from:

Bruce Hodgkinson, VE3JIL
Box 232
Pakenham, Ontario, CANADA K0A 2X0
Phone: (613) 624-5247

A wired and tested 33-MHz chip system can be obtained from stock or 
within a week for $120+$5.00 S&H. A wired and tested 40-MHz chip 
system waits up to 8 weeks for availability of chips, and costs
$135+$5.00 S&H. Bruce told me that the 33-MHz chips he tested
worked fine at 40-MHz. It seems Harris is very conservative in 
their chip ratings.

Of course, nobody would use these DDS boards for direct-sequence, 
frequency-hopping, time-hopping, plus chaos-transmitted-reference
hybrid spread-spectrum transmitters to achieve signal hiding and
interference rejection. Nope. Last thing on MY mind.
 
Haa ha ha ha... eat flaming death statist scum! You are all doomed!
 
Kent aka WA6ZFY - <jkhastings@aol.com>