23cm band and Sat-Nav Coexistence: Preliminary Studies considered in ITU‑R WP4C

Dur­ing the peri­od 5–13 July 2021, the prepara­to­ry work for WRC-23 agen­da item 9.1b con­tin­ued in ITU‑R Work­ing Par­ty 4C (WP4C). (See Region 1 Feb 23rd news item for fur­ther back­ground). The IARU mem­ber rep­re­sen­ta­tives from Aus­tralia, Brazil, Cana­da, Ger­many, Japan, Nor­way, UK and USA, par­tic­i­pat­ed in the meet­ing and deliv­ered addi­tion­al infor­ma­tion on ama­teur activ­i­ties in this key microwave band. 

Pre­lim­i­nary stud­ies came from France based on the ongo­ing CEPT work to pro­vide ini­tial esti­mates of sep­a­ra­tion dis­tances required between RNSS GALILEO receivers and a sam­ple of ama­teur emis­sions. The Euro­pean Com­mis­sion GALILEO team pro­vid­ed a set of obser­va­tions per­tain­ing to a RNSS inter­fer­ence event in north­ern Italy.

Glob­al IARU Band Plans and RNSS sys­tem fre­quen­cy band overlaps

The work con­tributed by France, although need­ing refine­ment, is going in a good direc­tion, using ITU‑R rec­om­mend­ed prop­a­ga­tion mod­els and assump­tions based on oper­at­ing sce­nar­ios pro­vid­ed by the ama­teur com­mu­ni­ty. Fur­ther work is need­ed to take account of the large dis­par­i­ty between the RNSS ser­vice receiv­er band­widths and the fre­quen­cy band off­sets of the ama­teur appli­ca­tions based on the mea­sure­ments car­ried out by Germany.

One exam­ple result from a pre­lim­i­nary sim­u­la­tion run

The RNSS com­mu­ni­ty have updat­ed their RNSS receiv­er pro­tec­tion cri­te­ria with an update to ITU‑R Rec­om­men­da­tion M.1902 that now includes para­me­ters rel­e­vant to the GALILEO E6 sig­nal block. How­ev­er these cri­te­ria only dis­tin­guish between a nar­row band and wide band inter­fer­er lev­el at the receiv­er and take no account of off­set fre­quen­cy in the receiv­er band­width or any time variance.

The IARU is work­ing to ensure the ama­teur ser­vices are real­is­ti­cal­ly rep­re­sent­ed in the stud­ies as they move for­ward. 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 will con­tin­ue through­out the year and beyond 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.

Click for the sum­ma­ry report from the WP4C meet­ing.

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