Over the period 9^th to 19^th May 2023, the preparatory work for WRC-23 agenda item 9.1b continued in ITU‑R Working Party 5A (WP5A). Two deliverables are under discussion:

1) Draft ITU‑R Report M.[AMATEUR_CHARACTERISTICS] – this reports on the specific 23cm band amateur and amateur satellite service technical parameters and operational characteristics used in the studies now published in ITU‑R Report M.2513 – 0.

2) Draft ITU‑R Recommendation M.[AS_GUIDANCE] – this will recommend guidance that national administrations can take to facilitate the protection of the radio navigation satellite service from harmful interference from amateur radio stations.

Ahead of this WP5A meeting the IARU global WRC-23 9.1b team led by G4SJH developed and submitted two contributions, one for each deliverable above. As usual, the IARU participated in the meeting to present the contributions and take part in the ongoing discussion and negotiations. The IARU contribution to the Guidance recommendation proposed specific limits for EME operation in the range 1296 – 1300 MHz. The proposal was largely adopted but only in the range 1298 – 1300 MHz. The IARU contribution to the “characteristics” report proposed an annex containing a Monte Carlo style study assessing the impact of a range of amateur transmissions on a population of RNSS receivers around the amateur station. Contributions were also provided by a number of national administrations and a summary report of the meeting can be downloaded here.

The development of the recommendation is proving challenging although many of the IARU proposals remain in the draft document for further discussion. Challenges are arising from other proposals that could be judged to go beyond the original mandate for the work. In addition some proposals for technical and operational measures seem impractical from both an administration and amateur station perspective.

The study proposed for the characteristics report was accepted for now but is to be liaised to WP4C for consideration and possible revision to Report ITU‑R M.2513.

Meanwhile in CEPT the work in project team SE40 continued during the same period (15 – 17^th May) with their development of an ECC Report on the same coexistence problem. IARU contributed the same Monte Carlo study to that group where it now sits in the draft deliverable.

In ITU_R the work on this topic will continue at the next ITU‑R WP5A meeting in September with some urgency to finalise both deliverables ahead of the WRC.

WRC23 – agenda item 9.1b

The IARU maintains the view that the likelihood of widespread and persistent interference from amateur radio activities to RNSS (e.g. Galileo) receivers in the 23cm band is minimal. The WRC-23 preparatory studies carried out in the ITU‑R study groups have only considered static one-to-one estimations using a minimum coupling loss approach. These studies do not consider the effect of an amateur transmitter on a population of RNSS receivers deployed around an amateur transmitting station.

Therefore IARU volunteers have carried out a “Monte Carlo” style study simulating scenarios assuming a fixed and mobile population of RNSS receivers deployed around an amateur station. A 100W amateur ‘home station’ and a 25W eirp ‘repeater station’ have been assumed.

The simulation results suggest that at most only around 1% of a population of fixed and mobile RNSS receivers randomly situated around a transmitting amateur station location would have a small chance of receiving a signal level above the RNSS protection threshold identified in the relevant ITU‑R Recommendations. In most scenarios, the percentage of RNSS receivers impacted by interference above the threshold within the “simulation area” is far less than 1%. Even in the densest areas of amateur station activity and with the lowest clutter model the percentages remain less than 5%.

See video representations of the simulation scenario here.

The study assumed that an amateur station is transmitting throughout the whole “Monte Carlo” trial period. However event data collected by the IARU shows that even in the busiest amateur communities the amount of time during which these sporadic transmissions are most likely to occur amounts to less than 2% of time over a one year period.

Therefore the IARU maintains its position that the potential for widespread and persistent interference between amateur radio transmissions and RNSS receivers is minimal.

The IARU paper is available for sharing and can be found here.

All the background information including links to the latest developments within the international regulatory committees can be found here.

As usual, IARU SRLC volunteers participated in the two most recent CEPT CPG project team meetings. Project team A (PTA) is developing the CEPT Briefs and European Common Positions on a number of WRC-23 agenda items of interest to the amateur community. In particular agenda item 1.12 on Space-borne Earth Exploration Satellite Service Radar Sounders in the 40 – 50MHz band and agenda item 9.1a spectrum proposals for Space Weather Sounders are being followed carefully. The project team is also considering proposals for future WRC agenda items (Agenda item 10).

A summary report is available here. 

CEPT CPG project team C (PTC) also met to consider a range of agenda items that includes preparation of the CEPT Brief for the 23cm/RNSS agenda item 9.1b. No major change occurred to the substance of this Brief or the proposed CEPT position.

As usual the IARU participated in the most recent CEPT SE40 meeting developing the ECC Report on 23cm band amateur and RNSS GALILEO coexistence. The meeting reviewed and accepted a major statistical study carried out by the IARU for inclusion in the developing draft work item deliverable. No other contributing parties have provided such a study and the results clearly underpin the IARU view that potential interference to a population of RNSS GALILEO users is unlikely on any large scale.

A SRLC summary report is available here and includes links to the relevant documents.

CEPT Short Range Device project team SE24 meeting #108 took place 9 — 11 January 2023. The IARU participated in the work of the group on several work items associated with Wireless Power Transfer (WPT) and Ultra-Wide Band (UWB) automotive radars. 

The impact and standardisation of WPT technologies is being carefully assessed across the lowest HF bands and the impact of the UWB technologies is relevant in the amateur service allocations in the mm-wave bands at 76 GHz, 122 GHz and 134 GHz. 

The IARU R1 continues to fully engage in the ongoing studies associated with WPT to ensure minimal impact to our lowest HF bands. The IARU made a contribution to ensure the amateur services voice was heard in the discussion to finalise draft ECC Report 351 on spectrum sharing studies on mm-wave UWB radar systems. Draft ECC reports 350 and 351 were finalised. A SRLC report can be found here.