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# sandbox: Journal 129 has gone to press and is due for publication in March 2025 CREG Journal 129 (0-24) This issue has a cover date of March 2025 and was published on 1 March 2025. Front Cover (1) Through-the-Ice Radiolocation and Communication from a Glacial Cave on Spitsbergen Photo: / Stone Aerospace Contents (2) List of contents and masthead information. News and Notes (2) Spring 2025 Field Meeting, Editorial Team, Hidden Earth. Lessons Learned in a Rainfall and Stream Depth Monitoring Project (3-5) & outline some of the practicalities and issues encountered in monitoring rainfall and stream depth in Ogof Ffynnon Ddu. It is hoped that, in discussing the things they found out in running these projects, the wider cave science community can have some ideas of what to avoid and some things to adopt. While they talk about rain and depth gauges, any issues will apply equally to other sensors and "gizmos". Introduction to the Radio Spectrum (6-7) Understanding the radio spectrum, and how different bands have different characteristics, is key to knowing which bands are suitable for various caving applications. provides a guide and also clears up some incorrect but common terminology. This article is #10 in our Fundamentals series. We Hear (8) reports: Self-guiding Show Cave Visitors, Sodium-ion Batteries Offer Charging in Seconds and 3D Surveying with iPad Pro. Through-the-Ice Radiolocation and Communication from a Glacial Cave on Spitsbergen (9-12) describes through-the-ice radiolocation and communication experiments from a cave in a glacier above Longyearbyen, the world's northernmost town, on the island of Spitsbergen. Practical Use of GIS in Cave Exploration (13-16) Geographic Information Systems are becoming commonplace and finding application in discovering new cave entrances. presents examples of using GIS to find new entrances by analysing satellite and orthophoto images. A Simple DSP-based Radiolocation Receiver (17-20) Most published designs of radiolocation receivers have been exclusively hardware-based. Here, , N4ADP, provides details of his DSP-based design, which limits the complexity of the hardware and so is easy to build. Building Blocks (21) The Inductor, a lesser known, but important electrical component - by . Searching for Muons in Caves (22-24) and from Brno University of Technology, from the Czech Academy of Sciences, and from Northumbria University describe their search for muons beneath the Earth's surface.