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AMSAT-UK

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EASAT-2 and HADES Update

Posted: 18 Jan 2022 07:56 AM PST https://amsat-uk.org/2022/01/18/easat-2-and-hades-update/


AMSAT-EA Mission Manager Felix EA4GQS provides an update on the status of
the EASAT-2 and HADES satellites launched on January 13.

On the AMSAT Bulletin Board he writes:

We confirm the reception of both EASAT-2 and HADES, as well as the decoding
of telemetry and the FM recorded voice beacon with the callsign AM5SAT of
the first one. EASAT-2 appears to be working well except for the deployment
of the antennas, something that apparently has not yet occurred and causes
weak signals. However, the AMSAT-EA team confirms that, based on the
reception of FSK, CW, the FM voice beacon and the telemetry data that has
been decoded, it can be said that the satellite is working perfectly. In
the event of low battery or system malfunction, the on-board computer would
not transmit CW messages or the voice beacon-callsign, as it would be in a
safe state with only fast and slow telemetry transmissions.

These signals that have been able to confirm the operation of both
satellites were received by Dr. Daniel Estévez EA4GPZ at 18:07 UTC on Saturday, January 15, using two antennas from the Allen Telescope Array.
The TLEs used were obtained from the radio amateur community, with Doppler observations from the Delfi-PQ satellite, deployed together with EASAT-2
and Hades.

TLEs used were these ones:

https://github.com/AMSAT-EA/easat2-tle-lottery/blob/main/satnogs-2022-01-16-DELFI-PQ.tle

Daniel EA4GPZ performed a preliminary analysis using just one polarization
of one of the satellite dishes. EASAT-2 has been detected with a relatively strong signal, close to the Delfi-PQ signal, obtaining said recorded voice
FM beacon transmissions and FSK, FSK-CW at 50 baud.

The CW beacon clearly shows the message: VVV AM5SAT SOL Y PLAYA, which is
one of several that both satellites emit, although the callsign AM5SAT
confirms that it is EASAT-2.

In the recording made by Daniel EA4GPZ there is also a faint trace
confirmed to be from Hades and stronger packets probably from the IRIS-A satellite.

HADES, like EASAT-2, is transmitting weak signals, weaker than the ones of EASAT-2, most likely because the on-board computer has not yet managed to deploy the antennas either, although it will continue trying regularly. The reason the signals are suspected to be weaker at Hades is that the antennas
are more tightly folded than those of EASAT-2. In any case, this is great
news, since the transmission pattern confirms the proper functioning of the satellite. In the observations you can see the FSK tones with a deviation
of about 5 kHz interspersed with the FM carrier corresponding to the voice beacon of the satellite, which has callsign AM6SAT. The AMSAT-EA team is working to try to decode the telemetry signals and obtain more detailed information on the state of the satellite.

We kindly ask you, if you have very high gain antennas, to try to receive
them, specially Hades. If we could decode telemetry it would be very
helpful for us.

Until antennas are deployed it will be very difficult to use their
repeaters or to receive any SSTV camera images from Hades, but we hope that this will happen sooner or later, at least because even if the computer
doesnt succeed applying heat to the resistor where the thread is attached,
with time, the thread should break due to the space environment conditions.

Details of the decoded telemetry and voice, as well as more details in:

https://www.amsat-ea.org/ (Texts are in Spanish)

And in the following Twitter threads:

EASAT-2 transmissions:

https://twitter.com/ea4gpz/status/1482457631566487553

EASAT-2 decodings by Gabriel Otero:

https://twitter.com/gaoterop/status/1482758196037050382

HADES transmissions:

https://twitter.com/ea4gpz/status/1482696274797338625

Thanks a lot and 73,

Felix EA4GQS AMSAT EA Mission manager


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IARU-R1: 23cm Band and RNSS - Compromises need to be found

Posted: 17 Jan 2022 10:48 AM PST https://amsat-uk.org/2022/01/17/iaru-r1-23cm-band-and-rnss-compromises-need-to-be-found/

RNSS Credit IARU Region 1

The Chair of IARU Region 1 Spectrum Affairs, Barry Lewis G4SJH, reports on
the work being done in defending the interests of the Amateur Services in
the 1240-1300 MHz band.

On the IARU Region 1 site he writes:

As we head into 2022 the ITU‑R and CEPT work considering the 23cm band and coexistence with the RNSS systems (GALILEO, COMPASS, GLONASS, GPS…) will continue so where have we got to and where is it heading?

The IARU has provided extensive information regarding the amateur and
amateur satellite service applications in the band 1240 – 1300MHz as well as operational characteristics and data indicating the density of active transmitting stations and the busiest periods when these are most likely to
be operational. Using this data, one CEPT administration has provided an extensive set of propagation model predictions for a number of amateur operating scenario assumptions (including satellite working and EME
operation) that predict an “interfered area” over which an amateur transmissions may be received by a RNSS receiver at levels exceeding a
defined protection level. Another ITU‑R member administration contributed a smaller set of predictions using the same model. The received RNSS
interference level that the RNSS can tolerate (receiver protection level)
is based on ITU‑R recommended criteria and depends on whether narrowband or wideband interfering signals are being transmitted.

The propagation model predicts that an interfered area can extend out to several tens of km (depending on the scenario) but at the extremes of the
area, the time probability of exceeding the protection level is very low
(1%) and for only 50% of locations. The model can only assume a full power continuous transmission.

In addition much attention has been paid to documenting an interference
case recorded in Italy between an Italian 23cm band repeater and GALILEO receivers at the nearby European Commission Joint Research Centre in Ispra where work is undertaken to develop and test GALILEO system applications.
The impact of traffic through this very local repeater (12.5km distant) on three different GALILEO receivers has been documented. This work suggests
that whilst RNSS receiver bandwidth can have a part to play in enabling coexistence, beyond that nothing has been reported that could help develop
any coexistence criteria. Nothing is reported about the mode of failure in
the receivers beyond degradation on C/N.

This one case is often cited as the “proof” that interference can occur.

At present the conclusions from this work are being developed (in ITU‑R and CEPT) and IARU work continues to ensure these results are put into a real
world context to understand what they imply with respect to successful coexistence.

Amateur transmissions virtually anywhere in the band will be co-frequency
with the RNSS receivers from one system or another. It is therefore obvious that any RNSS receiver will be open to any co-frequency amateur
transmission and amateur operators have no way of knowing where or when a
RNSS service user is active. Therefore IARU has expressed a view that for successful coexistence guidance to be developed, some compromises will need
be necessary.

As we move through the work in 2022 we need these compromises will become apparent so that the amateur community can know how to respond
appropriately in a way that can allow our diverse set of applications to continue to develop whilst minimising any potential disruption to RNSS services. It is anticipated that the international views on the ITU‑R
studies will need to stabilise by the middle of this this year in order to
meet the timetable for the WRC-23 preparatory work. These views will likely propose technical and operational measures to be applied to the amateur and amateur satellite services that could be formalised in the Radio
Regulations.

As the study activities work towards conclusions it is vital that the
national societies engage with their national amateur radio regulators to ensure they understand and hear about the importance of this band for the amateur radio community.

Source IARU-R1

https://www.iaru-r1.org/2022/23cm-band-and-rnss-compromises-need-to-be-found/

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