IARU report on the recent meeting of ITU-R WP5A, the lead group responsible for developing the Conference Preparatory Meeting report about the WRC23 agenda item on the 23cm band.

The latest meeting of ITU-R WP5A concluded on June 2, 2022. The IARU was represented by Ole Garpstad (LA2RR – ITU Lead) and Barry Lewis (G4SJH – WRC23 AI9.1b Lead).

ITU-R WP5A is the study group at ITU which deals in part with topics related to the amateur and amateur satellite services. It is the lead group responsible for developing the Conference Preparatory Meeting (CPM) report on agenda item 9.1(b).

This Agenda Item provides for a “Review of the amateur service and the amateur-satellite service allocations in the frequency band 1240‑1300 MHz to determine if additional measures are required to ensure protection of the radionavigation-satellite (space-to-Earth) service operating in the same band in accordance with Resolution 774 (WRC‑19);” The CPM Report will form the basis for consideration of this issue at WRC-23 next year.

At the conclusion of the recent WP5A meeting a draft recommendation was prepared which will provide guidelines to administrations to ensure the protection of the RNSS primary allocation from the secondary amateur and amateur satellite services.

The draft recommendation will be the most important element of the WP5A work going forward for the amateur and amateur satellite services in the 23cm band. The working document contains a number of proposals for severe limitations on amateur usage of the band including transmitter power constraints. Very low power levels are proposed for large portions of the band (100% in one case). Proposals also identify possible frequency band usage limitations for broadband applications (e.g. ATV), narrowband applications and amateur satellite services in 1260-1270 MHz.

A full report of the WP5A meeting can be found here.
https://www.iaru.org/wp-content/uploads/2022/06/Report-from-WP5A_June-2022-FINAL.pdf

None of these proposals are adopted at this time and work will continue at the next meeting of WP5A to rationalise the variations proposed by national telecom-administrations.

The IARU will work to minimise the constraints on amateur radio activities and continue to seek amendments to the draft recommendations through the ITU process, but as a secondary user, radio amateurs should understand the need to protect the Radionavigation Satellite Service (RNSS) in many consumer and industry applications (like autonomous vehicles) that will lead to some restrictions on our use of the 23 cm band.

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/

During the period October 20-29, 2021, the IARU continued to engage in the preparatory work for WRC-23 agenda item 9.1b in ITU‑R Working Party 4C (WP4C).

The IARU Region 1 reports says:

The working party is considering simulations provided by two administrations to estimate the interfered area that might exist around a 23cm band amateur service transmitter. A number of amateur station configurations are under consideration identified as “Home Station 1”, “Home Station 2” and “Permanent Station” (e.g. Repeater station) based on characteristics developed and contributed by the IARU. Both narrowband and wideband emissions are considered. Two further scenarios are included in which “Home Station 1” operates with antenna uptilt as an amateur satellite uplink station and in which “Home Station 2” operates with antenna uptilt as an E‑M-E station.

The IARU representatives contributed to an off-line email discussion to ensure the amateur station parameters used are more representative than those that had been proposed in the original contribution papers. The studies were revised based on these negotiations during the meeting and are reflected in the draft working document. The interim results show interference distances of up to several km depending on the antenna and power level assumed. Work on these studies will continue into the next meeting.

Other measurements campaigns are investigating the effect of offsetting the transmission frequency of various amateur signals with respect to the centre frequency of the RNSS signal and the impact of the RNSS receiver bandwidth.

The IARU is working to ensure the amateur services are realistically represented in the studies as they move forward and remain consistent with the information developed in WP5A. It remains vital that national amateur communities present their views on the importance of this band to their national regulators in a consolidated and consistent manner.

The work on this topic will continue throughout the year both in ITU‑R and in the regional telecommunications organisations and the IARU is committed to ensure every group hears the amateur position on this important microwave band.

The summary report from the WP4C meeting can be found here

Click to access Report-from-WP4C_Oct-2021.pdf

The parallel work in CEPT SE40 is tracking the activity in the ITU‑R and is at a similar stage of development. This is also within the purview of the R1 SRLC.

Source IARU Region 1 https://iaru-r1.org/