[Home](/)/[Resources](/resources)/FCC KDB Guide FCCKDBequipment authorization # FCC KDB (Knowledge Database): How to Use It for Equipment Authorization The FCC's rules in 47 CFR often leave gaps when applied to specific product configurations. The Knowledge Database (KDB) fills those gaps with official FCC guidance that carries regulatory authority. Test labs and TCBs use KDB documents routinely — not knowing the applicable KDB publications for your product can lead to incomplete testing and rejected certification applications. Copy Link[Share on WhatsApp](https://wa.me/?text=https%3A%2F%2Fkrono-labs.com%2Fguides%2Ffcc-kdb-guide) [Check my FCC requirements](/platform/new) What the KDB is ## The Knowledge Database and its role in FCC compliance The FCC Knowledge Database is a publicly accessible repository of guidance documents maintained by the FCC's Office of Engineering and Technology (OET). KDB publications address specific compliance questions — test procedures, configuration requirements, labelling, product family rules, and policy interpretations — that are not fully resolved by the FCC rules themselves. KDB documents are not rules — they cannot be found in the Code of Federal Regulations. But they carry practical regulatory authority because TCBs are required to follow KDB guidance in their certification reviews. A certification application that conflicts with applicable KDB guidance will be questioned or rejected by the TCB during its review process. KDB publications are identified by five-digit numbers and may be approved Q&As, approved test procedures, or approved policies. The KDB is searchable by keyword and by applicable CFR rule section. Search the KDB before finalizing your compliance strategy for any FCC-authorized product — particularly for RF exposure, 5 GHz DFS testing, Bluetooth/Wi-Fi coexistence, and certification of product families. Key KDB publications ## The most important KDB documents for electronics hardware KDB 447498: RF Exposure Requirements for Mobile and Portable Devices. Covers the detailed procedures for evaluating SAR and maximum permissible exposure (MPE) compliance. Mandatory reading for any device used within 20 cm of the human body. KDB 784748: 5 GHz DFS Testing Requirements. Specifies the detailed test procedures for dynamic frequency selection compliance required for Wi-Fi devices operating in the 5.25-5.35 GHz and 5.47-5.725 GHz bands. DFS testing is complex and lab-intensive — misunderstanding the KDB requirements leads to expensive test failures. KDB 996369: Software Security for Software Defined Radios. Addresses security requirements for devices where software can be updated to change radio parameters — increasingly relevant for any connected hardware with OTA update capability. KDB 594280: Classification of FCC ID and Device Type for Modular Approval covers when a radio module's certification transfers to the host product vs. when the host must be independently certified. KDB 953509: Permissive Change Classification defines the criteria for Class I and Class II permissive changes. How to use the KDB ## Practical steps for applying KDB guidance in your program Start with your applicable FCC CFR sections. If your product has Bluetooth, Part 15 Subpart C applies. If it has 5 GHz Wi-Fi, 15.407 applies specifically. Search the KDB for each applicable CFR section — the KDB search interface allows filtering by rule section. Review the most recent version of each applicable KDB document as they are revised periodically. Share relevant KDB documents with your test lab at project initiation. Test labs should already know the applicable KDB publications, but explicitly referencing them confirms alignment on scope and avoids mid-project surprises. Reference applicable KDB publications in your test report — most FCC test reports explicitly list them alongside the CFR sections to show the complete compliance basis. TCBs expect to see this reference in the documentation they review. If no applicable KDB document exists for your specific configuration — a novel product type or unusual combination of radios — you may need to submit a KDB inquiry to the FCC before testing begins. The FCC publishes responses to KDB inquiries that become new KDB guidance. ## Learn this properly, not just for one product In-depth courses and books that teach the process — not a one-off answer you'll need to look up again next time. [Start the course — $149](/courses/02-fcc-authorization-for-hardware-startups)See your free roadmap [Prefer to read? Get the book — $24.99](/books/02-fcc-authorization-for-hardware-startups) ## Frequently asked questions ### Is following the KDB legally required? KDB publications are not regulations — they cannot be found in the CFR. However, TCBs are required to follow KDB guidance in their certification reviews, and the FCC's enforcement positions align with KDB interpretations. In practice, not following applicable KDB guidance means your certification application will be questioned or rejected, making KDB compliance functionally mandatory for FCC equipment authorization. ### How do I find which KDB documents apply to my product? Access the KDB at fcc.gov/kdb. Use the search function with the applicable CFR section (e.g., 15.247 for Bluetooth/Wi-Fi), filtering for Approved Q&As and Approved Test Procedures. Your test laboratory will also typically identify applicable KDB publications as part of project pre-planning. For 5 GHz DFS products and SAR-required products, explicitly verify KDB coverage before testing begins. ### What is a KDB inquiry? A KDB inquiry is a formal request to the FCC for guidance on a specific compliance question not addressed by existing KDB publications. Inquiries are submitted through the FCC's KDB system and reviewed by OET staff. The FCC publishes its responses as new KDB guidance documents. The process takes weeks to months, so submit early if a novel compliance question is anticipated. ### Do UK or EU regulatory frameworks have an equivalent to the FCC KDB? Not directly. EU harmonised standards under RED provide the technical requirements, and ETSI publishes guidance documents for wireless testing. The European Commission does not maintain a single KDB-style Q&A database. In the UK, OFCOM publishes technical interface requirements and the Radio Equipment Regulations guidance, but these are less granular than the FCC's KDB. 🇺🇸 US roadmap for your product Every standard, document, and test that applies — free, no account required. See your free roadmap[ Want an expert to take your product through 🇺🇸 US compliance for you? One consultant from Krono's compliance team takes your product from requirements to legal sale, with a fixed quote before any work starts. See compliance services](/services) Learn this properly In-depth course that teaches the full process, not just this one answer. [Start the course — $149](/courses/02-fcc-authorization-for-hardware-startups)[Prefer to read? Get the book — $24.99](/books/02-fcc-authorization-for-hardware-startups) Related guides * [FCC TCB Certification ProcessFCC Certification through an accredited Telecommunications Certification Body (TCB) is mandatory for all intentional radiators.](/guides/fcc-tcb-process) * [FCC SDoC Supplier's DeclarationFCC SDoC explained: which devices qualify, required content, responsible party obligations, record-keeping, and when Certificat…](/guides/fcc-sdoc-supplier-declaration) * [FCC Part 15 Class A vs Class BFCC Part 15 Class A vs Class B explained: how to classify your digital device, emission limits, residential vs commercial use, …](/guides/fcc-part-15-class-a-vs-b) * [OTA Testing for Wireless DevicesOver-the-air (OTA) testing measures the actual radiated performance of a wireless product in a controlled environment, accounti…](/guides/ota-testing-wireless) * [How to Work with a Test LabTest lab engagement strategy significantly affects CE, FCC, and global certification timelines and costs.](/guides/test-lab-engagement-guide) * [FCC CBRS and Shared SpectrumCitizens Broadband Radio Service at 3.5 GHz: FCC Part 96 equipment authorization, SAS registration and CBSD categories, PAL vs GAA access, OnGo certification, and private LTE/5G use cases for hardware companies.](/guides/us-fcc-spectrum-cbrs) Educational resource only. KDB publications are revised periodically. Always check for the current version of applicable KDB documents at fcc.gov/kdb before finalizing your test plan.