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QO 100
Es'hail-2 (QO-100) never rises and never sets: the dish stays put, there is no Doppler, and the whole job is landing in the right spot inside the 500 kHz of the narrowband transponder. SatMe's QO-100 geostationary page (⋮ menu) helps you aim the dish, describe your converters, calibrate on the beacon and stay inside the band plan.
Sky frequencies, steps, beacon and centre, and what the hardware sees.
Built and bench-tested piece by piece; the whole chain (converters, crossed pair, fixed aim, beacon lock) has not yet been proven end to end with a real station.
Under Initial setup:
- Dish aiming: azimuth, elevation and Skew (LNB) computed from your position for a satellite at 25.9° east. Once found, this aim never moves again.
- Aiming by the Sun: the satellite is invisible, so the Sun gives the direction without a compass — the time when the shadow of a vertical stick points the right way, and the days when the Sun passes in front of the satellite (reception collapses for a few minutes: not a fault).
Each site has its own converters, and each oscillator its own error. Describe them once per station under Station chain:
| Item | Example |
|---|---|
| Downconverter (LNB) | 10,489 MHz comes down to 739 or 489 MHz depending on its oscillator; a 10,057.5 MHz LNB brings QO-100 down to 432 MHz |
| Upconverter (transverter) | a 2400 driven from 432 has a 1968 MHz oscillator |
| Station rig | the same setting as Rig (CAT) |
Next to each choice, SatMe shows the frequency the rig would display for where you are. Direct (no converter) removes it. The converters also appear, read-only, in Settings › Converters. On SatMe-PC they live in a per-band table (SDR dongle, the rig's receive and transmit), with the dongle's calibration: see SatMe-PC's QO-100 cockpit.
Listen to the same signal on a reference (a GPSDO-locked WebSDR) and on your rig, and copy both frequencies: the difference is the oscillator, nothing to compute. The result is stored in the chain. Each Receiving device (rig, dongle) can carry its own frequency error too.
- Downlink (sky) and Uplink show the sky frequencies; the buttons step by ±10 kHz, ±1 kHz, ±100 Hz, or jump to the Middle beacon or the Centre.
- The Transponder ruler draws the 500 kHz band plan (CW beacons, CW, digital, SSB, broadcast, emergency, mixed, multimedia beacon): drag a finger across it to move. Each segment says what is allowed, and transmitting is refused on the beacons and outside the transponder.
- What the hardware sees: the radio and the dongle work at intermediate frequency; Apply to the radio and Apply to the dongle send it to them.
- Memories: store the spots you use (beacons, CW, digital, SSB…).
- Sweep the whole of QO-100 leaves the transponder to listen elsewhere; in transmit, the edge guard no longer applies.
A downconverter's oscillator drifts, especially from cold. With the SDR dongle, SatMe looks for the middle beacon and shows its frequency error; Calibrate on the beacon writes the error into the calibration and every frequency falls back into place at once. Without a dongle, tune the beacon, read the frequency actually heard and type it under Beacon calibration.
An LNB without an external reference moves with temperature, sometimes by a few hertz per second, sometimes in jumps of ±25 Hz within a second; FT8's tones are 6.25 Hz apart. The beacon calibration now follows a real drift more closely, and the FT8 decoder finds and takes out a slot's shared drift. SatMe-PC adds a beacon lock that takes the jumps out of the whole transponder (see SatMe-PC › A drifting LNB).
This mitigates, it does not solve: the real answer is an LNB held by a reference — for instance a Twin LNB whose PLL takes 25 MHz from a GPSDO (see LNB and GPSDO reference). The calibration then stays useful for the fixed offset.
Upcoming, after 20.83. The QO-100 screen → DATV wide band (MiniTiouner on a SatMe-Node): the phone drives the MiniTiouner of a SatMe-Node set by the dish (its address and code, Associer) and shows the picture through its own decoder, with the lock, the MER and the constellation.
- Stations on the wide band (off by default): QO-100's public spectrum from the ground station (BATC), received over the Internet while the screen is open — nothing is sent there; the stations on the air, named once received, to receive with a touch.
- The phone takes from the node its calibrated oscillator, its input and the LNB supply in use: changing station no longer cuts the LNB the node feeds (likewise from SatMe-PC, which finds a receiving node by itself).
- The picture full screen, in landscape, with a touch.
The same node seen from SatMe-PC (health, board roles, restarting or switching off the Pi): SatMe-PC › SatMe-Node.
- An uplink oscillator that has not been measured is flagged: check what the rig shows before transmitting.
- The wideband (DATV) transponder is listed for reference only.
See also: Rig control (CAT) · Extensions