NOTES ON USING ROS
Some may know , some may not , listed are some points that may be useful , as the operation is not quite as expected , when used to digipan etc
The ROS digital mode package contains three separate data transmission systems, all the modes are â€˜liveâ€™ keyboard modes , the baud rate / bandwidth determining the performance ,ie, maximum from wide/slow minimum narrow / fast . There is NO requirement for time locking of the pc , tx/rx must be the same mode , usb is the norm
All the modes are single tone MFSK and may be transmitted via non linear systems
EME , centre frequency 1500 Hz 50 hz b/wâ€“ fixed b/w & speed
HF centre frequency 1500 Hz 2.0 K and 1 Khz 500 Hz mode , 4,8,16 baud
MF centre frequency 1500 Hz fixed 98 Hz B/W , 7 & 1 Baud
Why define a frequency, ? , Operating frequency 70.074.0 USB dial
To receive a ros transmission , the initial synchronisation frame of the transmission â€˜mustâ€™ be received , with out this the software will not lock . It is â€˜notâ€™ possible to causally intercept a ros transmission , the receiving station must be available and within the AFC range at the start of the transmission for the syc process to start , unlike conventional rtty or psk etc.
As it is possible for reception to take place at a signal level below the audible threshold or visibility on spec-lab , interception is only practically possible in such cases by prior tx/rx frequency alignment.
All of the data systems are suitable for use , the eme mode has a wide afc range , where as the HF and MF modes afc lock are much less , the MF mode is so called as it was coded to fit the 100hz data bandwidth of the EU 500K permits, MF-7 offers significant advantage over psk31. A 1 Khz audio test tone is available with in the set up menu
The AFC function serves only to allow the RX to lock to the transmission and displays the offset in Hz , it will â€˜notâ€™ follow a drifting signal . The TX frequency is fixed and there is no provision for NET as in the more usual spectrum/waterfall tuned packages .
For monitoring purposes, it is possible to run more than one session of ROS , set to different modes / bandwidth , i.e. ROS HF 2.2 K all speeds and ROS HF 500 all speeds , while maintaining the same usb dial set.