P4-A NB Transponder Bandplan and Operating Guidelines

P4-A NB Transponder Bandplan and Operating Guidelines

Oktober 19, 2018 Aus Von Peter Gülzow


Of all leisure activities, only licensed radio amateurs have the valuable privilege of experimental use of frequencies.

In addition to its rights to use frequency bands, the amateur radio service also has the privilege and obligation (for “self regulation”) to independently design the intended use of the allocated areas with radio applications (operating modes and band plans). This also includes the coordination of radio operation facilities such as beacons, relays and satellites.

AMSAT is indeed not in a position to play “Police”, we can only give recommendations and advice.

However, every radio amateur should be encouraged to help and advice others lacking technical experience. This should indeed be done in a friendly manner, not as a sheriff.


This document is being used as a guideline for the first AMSAT P4-A transponder on Qatar-OSCAR 100 (QO-100, Es’hail-2), the first geostationary amateur radio transponder. It will enable potential users to be informed about the plans and operating procedures that should be adopted. This document might be updated regularly to take into account the operational experience.

Frequency Chart

This chart shows the two transponders, their passbands and uplink and downlink polarisations. Note that, unlike the linear transponders on most other amateur satellites, these transponders are not inverting.

The two amateur band transponders on Es’hail-2 are a hosted payload being provided by the Qatar Satellite Company – Es’hailSat and the Qatar Amateur Radio Society (QARS) in co-operation with AMSAT-DL. It is vital that operators respect this facility and refrain from any activity that might cause offense, or which is outside the terms of their amateur radio licence.

QO-100 NB-Transponder Operating Guidelines and Bandplan

The narrowband transponder is intended for conventional analogue and narrowband digital signals.

No transmissions should be made beyond the nominal edges of the transponder passbands. In particular, no operation should take place below the lower beacon nor above the upper beacon.

No uplinks should result in downlink signals that are stronger than these beacons. In the event that such signals are detected, they will be marked by a “LEILA” siren. When they have been marked by “LEILA”, operators should immediately reduce their uplink power (ERP).

No FM transmissions should be made to Es’hail-2 as these would use excessive power and bandwidth.

Although there is no formal bandplan, the following details are provided for initial guidance.

Uplink [MHz] Downlink [MHz] available Bandwith [kHz] Notes
10489,550 – 10489,555 do not transmit Lower Beacon, 400 Bit/s BPSK or CW
2400,055 – 2400,100 10489,555 – 10489,600 45 CW Only
2400,100 – 2400,120 10489,600 – 10489,620 20 narrowband digimodes (500 Hz max. BW)
2400,120 – 2400,140 10489,620 – 10489,640 20 digimodes (2700 Hz max. BW)
2400,140 – 2400,190 10489,640 – 10489,690 50 mixed modes  (2700 Hz max. BW)
2400,190 – 2400,295 10489,690 – 10489,795 105 SSB only
10489,795 – 10489,800 do not transmit Upper Beacon, 400 Bit/s BPSK or CW



  • Amateur Radio is a self-regulating radio service, so please respect some rules when you are operating within the amateur satellite service, i.e. over a satellite transponder:
  • Not stronger than the Beacon, keep your signal below Beacon level.
  • No FM mode or any other modulation exceeding 2700 Hz bandwidth is allowed on the NB transponder.
  • No digital FM modes like C4FM, DSTAR and others, same rule as above!
  • No transmission below the lower CW beacon: the Amateur Satellites Service operate exclusively on a secondary basis in the band 2400-2450 MHz.  You are responsibly for you own transmissions!
  • No transmission above the upper PSK beacon.
  • Please keep the “guardband” around the CW & PSK beacon free.of transmissions. If you transmit on 10489,795 MHz in USB, your spectrum will be up to .798 MHz and interfere with the PSK beacon.
  • The NB transponder is a bent-pipe transponder and non-inverting.
  • Uplink polarisation is RHCP (right-hand circular polarization).
  • Downlink polarisation for the NB transponder is  V (vertical linear polarization).
  • Excessive signals might trigger LEILA warnings to remind you to reduce uplink power.
  • Full-Duplex operation is mandatory (you must be able to monitor your own downlink while transmitting!)
  • The Upper Beacon is modulated in 400 bit/s BPSK (similar to the P3-satellites).
  • The beacons are generated by the groundstation and will carry additional operational or maintenance information.
  • Remote operation over Internet (Gateway traffic) is undesirable and only permitted during disaster communication.


Coverage Map

This map shows the coverage expected using the global beams on the spacecraft. For broadcast satellites it is usual to show the coverage down to 5 degrees elevation, but it is expected that well sited locations may provide access beyond that shown. The actual limits and power/dish sizes required will not be known until after commissioning.

Here is another map shopwing the maximum possible visibility area at 0° elevation angle:


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