GRI 7950
Identity
GRI 7950 matches the Russian Far East Chayka/Loran-C chain centered on Aleksandrovsk, Sakhalin. Japanese hydrographic publications list the Russian Chain with master Aleksandrovsk and secondaries at Petropavlovsk, Ussuriisk, and Okhotsk; the provided M/W/X placemark coordinates closely match ITU-listed transmitter positions for Aleksandrovsk, Petropavlovsk, and Ussuriysk, and the Z placemark is consistent with the Okhotsk locality named in the same official chain list. ([www1.kaiho.mlit.go.jp](https://www1.kaiho.mlit.go.jp/shoshi/tsuiho/pdf/301/301-2021-07.pdf))
Configuration
This record fits the post-2013 public configuration of the chain. In 2013 the Japan Coast Guard announced abolition of Tokachibuto Loran-C station in Hokkaido, which had served as the 7950-Y secondary of the Russian chain; later Japanese hydrographic publications list only W/X/Z secondaries, matching the four placemarks in this record. ([www1.kaiho.mlit.go.jp](https://www1.kaiho.mlit.go.jp/KAN3/tuho/2013/pdffile/201305.pdf))
Technical profile
Authoritative technical tables identify the Aleksandrovsk master and the Petropavlovsk/Ussuriysk secondaries as 100 kHz, omnidirectional long-range radionavigation transmitters. In the ITU-R TF.768-4 historical listing, the published M/W/X entries each show 700 kW carrier power, confirming that GRI 7950 was built as a high-power terrestrial PNT chain rather than a local beacon network. ([itu.int](https://www.itu.int/dms_pubrec/itu-r/rec/tf/R-REC-TF.768-4-200105-S%21%21PDF-E.pdf))
Geographic relevance
The verified nodes place chain elements on western Sakhalin, Kamchatka, Primorye, and the Okhotsk coast. That layout would support low-frequency maritime navigation geometry across the Sea of Okhotsk and adjacent Russian Far East/Northwest Pacific approaches; this coverage point is an inference from the station distribution, not a current official coverage plot located in this review. ([www1.kaiho.mlit.go.jp](https://www1.kaiho.mlit.go.jp/shoshi/tsuiho/pdf/301/301-2021-07.pdf))
Status
Public status reporting is mixed. A Japan Coast Guard supplement available in this review specifically notes that Ussuriisk was not in service officially, while a later JCG publication still lists Ussuriisk as part of the Russian chain; as of March 12, 2026, open sources reviewed verify the chain identity and site composition more confidently than they verify full operational status of every GRI 7950 leg. ([www1.kaiho.mlit.go.jp](https://www1.kaiho.mlit.go.jp/shoshi/tsuiho/pdf/304/304-2020-02.pdf))