Practical OTRSP

Do you also feel that the newer TCVR, tak tým menej je prepojiteľný s niečím iným? Predstavte si, že si kúpite TCVR a po čase k nemu tranzistorový zosilňovač. Ten ale potrebuje prepínať dolnopriepustné filtre… a čo teraz? Ak na to výrobca TCVR-a pamätal, tak ho dokážete prepojiť tak, aby sa prepínanie realizovalo automaticky. Ďalšou možnosťou je zdieľanie CAT dát. Treťou možnosťou je, že zosilňovač si odmeria frekvenciu z vysielaného signálu a prepne dolnopriepustné filtre..Ale je to zlé riešenie pretože prepínanie prebieha už počas vysielania. Posledná možnosť je, že operátor prepne dolnopriepustné filtre ručne.

The situation will get even more complicated if we have multiple antennas on some bands. Another switch. In addition to obvious discomfort, there is also a chance that some switch will not be in the correct position during transmission and may damage the equipment.

Imagine switching to a different band and the correct antenna automatically switches. That on vkv zadáte „DL“ alebo „JO50“ a hneď sa prepne pevne nasmerovaná yagi antenna in this direction? And conversely, if I type '9A', will it switch to the other - rotatable - antenna?

Imagine low-pass filters in the amplifier are switched automatically even when the TCVR does not have a band output. Imagine the correct transvertor….

Solution: OTRSP. What is it?

OTRSP is a simple serial (RS-232 / USB-serial) protocol that allows contest logger or other program to control:

• Two-radio switch (switching RX/TX between two transceivers)
• SO2R controllers
• Antenna switches
• Footswitch / PTT routery
• CW/FSK/PTT matrix
• Headphone / audio switch control

There are many possibilities and it sounds complicated. However, in practice, it is simple. How to do it?

Practical example of OTRSP with N1MM+

First, we will need an OTRSP decoder. It is possible to implement it with minimal costs using Arduino Nano a kódom K7MDL, ktorý nájdete napríklad na https://github.com/ok1cdj/OTRSP_BAND_DECODER . Don't be misled by the name "BAND DECODER".

It will provide conversion to BCD code. This gives us the direct ability to control 4 switches or with a BCD decoder, we get 8 (DEC decoder) up to 16 outputs. An example of a simple switch with a board with 4 relays

Such modules are available for example through Techfun https://techfun.sk/product/4-channel-relay-with-jumper-hl

These relays are not intended for switching RF signal. They are suitable for switching a special RF switch or controlling an amplifier.

For 16 outputs, another decoder is needed, for example https://remoteqth.com/bcd-to-16.php

Po pripojení Arduina k PC spustíme N1MM+. Cez položku Config v menu prejdeme na možnosť Configure Ports, Mode Control, Winkey etc. V novom okne na záložke Hardware Select the COM port that was created by connecting Arduino to PC and select the OTRSP protocol on it.

Na záložke Antennas we can define a switching table. The example shows an example of two antennas in the 144 MHz band. The first one is for azimuth 230 to 300 degrees (called West) and the second one is for azimuth 50 to 130 degrees (called East). At the same time, there is an option activated that automatically selects the antenna for the station in that direction.

First TIP

Doesn't suit at the moment as it defines automatic switching? Use ALT+F9 for manual switching.

Second TIP

If we also enter the name of the connected rotator in the table, it is possible to control it directly from N1MM+, where the command for rotation will go to the respective rotator even if multiple rotators are connected.

Third TIP

Ak Vám nevyhovuje N1MM+, tak skúste DXLog či Logger32 a Other, ktoré podporujú OTRSP

Conclusion

Therefore, OTRSP is not just for SO2R, but a practically useful thing for many radio amateurs. One possible disadvantage is that switching requires a PC with a log. However, this may not be a disadvantage - PC is now a standard hamshack.

Warning: If the PC is not connected or there is a loss of communication with the PC - the Arduino switch does not work! LED indicators on relay boards can be used to check functionality.