First ROS contact on 500 kHz

On Friday April 30, Graham G0NBD and Gary G4WGT achieved the first contact on 500 kHz using the data mode ROS.

The contact between Graham G0NBD and Gary G4WGT took place on April 30 over a 30 mile path. Initially they used ROS 500/16 mode and then the ROS "eme" mode. During the contact power was reduced from 3 watts output to 30 mW. The antennas were 35ft top loaded whips.

Practical Amateur antennas for this band are very inefficient due to the wavelengths involved. It can require 50+ watts transmitter output just to get 100 mW ERP. Efficient weak signal modes such as ROS can help extend the range that is achieved.

Later in the evening, Jim M0BMU called Graham G0NBD using ROS 500/8 over a distance of 200 miles. they had a 30 minute contact with 100% copy.

Download the latest version of ROS from
http://rosmodem.wordpress.com/

To use ROS you just need your HF radio, a PC and a sound card interface. Information on sound card Interfacing can be found at
http://www.southgatearc.org/articles/g0ftd/
data_dummy_interface.htm

and

http://www.southgatearc.org/news/september2007/
psk31_soundcard_interface.htm