By Moe Wheatley,AE4JY and Pieter Ibelings,N4IP
This project began as one of those "Here's a neat chip, what can we do with it?" conversations and grew from there. The heart of the beacon is a relatively new Direct Digital Synthesis(DDS) chip from Analog Devices. The original idea was to use some of the unique features of this DDS chip to implement a simple FSK441 Meteor Scatter beacon. From there it turned into a much more capable and "versatile" signal source.
The VersaBeacon is a frequency agile, modulation agile RF source using a DDS chip and minimal support circuitry. It covers a frequency span of .1MHz to 150MHz in 1 Hz steps and provides a variety of modulations including OOK CW, FSK CW, FM CW, FSK441, PSK31, RTTY, and other modes that can be created using phase or frequency modulation.
Stored messages can be sent using any of the modulation modes on any frequency continuously or at specified timed intervals. Most modes can also be sent live by sending text using the RS232 serial port and a simple terminal program running on a PC or laptop.
Using the A/D inputs of the Beacon, telemetry data can also be inserted into canned messages such as temperature or battery voltage.
The Beacons firmware or message data is easily updated or customized by downloading new code using the RS232 port.
The beacon's primary components consist of a DDS chip, a PIC processor chip, a 4Mbit FLASH memory chip, and a clock calendar alarm chip.
A small PIC microcontroller is used to control the DDS chip over a 3 wire serial port.
The PIC only has 16Kbytes of internal memory so an external 4Mbit serial flash chip is used to provide a lot more storage saving the PIC memory for actual program use.
A 16 position rotary switch can be used to select various program settings.
The PCB is 2.95" by 4.72"(Fits into a Hammond 1455K1202 extruded case)