QO-100/Es’hail

The QO-100/Es’hail example program can be used to transmit and receive signals to/from the Qatari Oscar 100 /Es’hail 2 geostationary satellite. If a LCD with four lines and 20 characters is connected the UTC, GPS data, call sign and locator and the TX/RX status are shown.

Generic block schematic showing how to use a RFzero for a QO-100 LNB-transverter-radio solution. The multipliers and band pass filters may not be needed in a specific implementation.

The configuration is done through the USB port.

The RFzero pin D16 detects if the radio in TX- or RX-mode. When in TX-mode the TX LED is lit.

When GPS signals are received the PPS LED flashes ones per second and when the status of the GPS signal is valid the Valid LED is lit.

OZ1BXM

Lars, OZ1BXM, is using his RFzero as a rock stable LNB GPSDO solution for his QO-100/Es’hail station.

The RFzero inside a box. Picture courtesy Lars, OZ1BXM.

You can see much more of the Rock Stable 10 GHz LNB solution here.

Local oscillators

The RFzero is used as a dual local oscillator for a LNB-transverter in combination with an IF-radio. The program is capable of generating one fixed frequency, e.g. for a fixed local oscillator for a LNB that typically uses 25 MHz, and a second frequency pair that can be used for transmit and receive local oscillators for mixers that are connected to the transceiver. None of the frequencies have to be related in any way and can be anywhere in the fundamental frequency range the Si5351A can generate. All the frequencies are GPS locked, if the GPS is valid, thus you will be spot on on both 2,4 GHz and 10 GHz.

To get two local oscillator signals you need to remove T1. Then either short the C40 to Z1 path, f0 will then be on the SMA connector, and mount a U.FL connector on CON5. Alternatively mount two U.FL connectors using the CON4, f0 will then be on the CON4 connector, and CON5 pads. The transmit/receive local oscillator frequencies are always found on CON5.

Whether the band pass filters and/or multipliers are needed depends on the actual implementation, e.g. many SDRs are able to receive directly on the LNB output frequency.

You may also use one of the harmonics from the RFzero as local oscillator.

Display

The display is a LCD (4×20) that shows the UTC, the transmit/receive status, GPS status, the number of satellites, the  HDOP, call sign and locator.

If you want to change what is shown on the display please edit the functions in the display.cpp file.

Configuration

The configuration of the program is done via the USB port, 9600 Baud, 8 bits, no parity and one stop bit, using a terminal program (e.g. Arduino IDE Serial Monitor, Termite Terminal (Windows), CuteCom (Linux) or Terminal (Mac OS)). Please connect the RFzero via a USB B cable to your computer and connect the terminal program to the right COM port in the terminal program. The RFzero identifies itself as an Arduino Zero (Windows Device Manager).

If you don’t see the RFzero> or RFzero config> prompts please press the enter key. When you want to execute a command you don’t have to enter the prompt but only the command and parameters after the >.

All input to the RFzero must be in lowercase.

To enter the configuration mode please enter   config   at the RFzero> prompt, i.e.

RFzero> config

To see the available commands please enter   ?   at the RFzero config> prompt, i.e.

RFzero config> ?

To leave the configuration mode please enter   exit   at the RFzero config> prompt, i.e.

RFzero config> exit

When in configuration mode, i.e. when you see the RFzero config> prompt, the most frequent commands are

rd cfg

to see the configuration that will be used after exiting the configuration mode.

wr call CALL

where CALL is your call sign shown on the display if any. Max length is ten characters.

wr loc LOCATOR

where LOCATOR is your locator shown on the display if any.

wr f0 FREQ MULTI

where FREQ is the fixed frequency in Hz, e.g. that is used for the LNB, and MULTI is the multiplication factor used. Set the multiplication to one (1) if no multiplier is used.

wr f1rx FREQ MULTI

where FREQ is the receive local oscillator frequency in Hz and MULTI is the multiplication factor used. Set the multiplication to one (1) if no multiplier is used.

wr f1tx FREQ MULTI

where FREQ is the transmit local oscillator frequency in Hz and MULTI is the multiplication factor used. Set the multiplication to one (1) if no multiplier is used.

More commands are available so please enter a question mark (?) at the RFzero config> prompt to see them.