Please explain in the area below why an STA is necessary:
Dexcom, Inc. is seeking this Special Temporary Authority from the FCC for use of a medical device transmitter in a clinical investigation. This clinical investigation will be conducted under FDA’s Investigational Device Exemption requirements (21 CFR 812) and will have an approved Institutional Review Board study protocol. The clinical study will collect sensor signals from an experimental continuous glucose monitoring (CGM) system which is being developed to help detect episodes of hypo/hyperglycemia for the management of diabetes. The component of the experimental CGM system which requires this Special Temporary Authority is the wearable transmitter which is pre-connected to the glucose sensor and attached to the patient’s skin via an adhesive patch.
The wearable transmitter is a Bluetooth Low Energy (BLE) device which acquires the sensor signal, logs the sensor data and uploads the data at the end of the trial. The wearable transmitter is also designed to communicate the sensor signal every five minutes via BLE to a compatible display device i.e. smart phone. Dexcom conducts immunity testing to verify the wearable transmitter meets requirements for a Home Healthcare Environment and the requirements of the FCC for an intentional and unintentional radiator device prior to conducting a clinical investigation. As a result, Dexcom evaluated the wearable transmitter according to Electromagnetic Compatibility (EMC) requirements as defined by IEC 60601-1-2:2014 Clause 7.3 under the requirements for Group 1, Level B. The device met these EMC test requirements. In addition, Dexcom evaluated the wearable transmitter to FCC Part 15 Subpart C Section 15.247. The device met the requirements for Peak Output Power (Part 15 Subpart C §15.247(b)(3)), Minimum 6 dB RF Bandwidth (Part 15 Subpart C §15.247(a)(2)), Band-edge Compliance of RF Conducted Emissions (Part 15 Subpart C §15.247(d)), and Power Spectral Density for Digitally Modulated Device (Part 15 Subpart C §15.247(e)). The wearable transmitter was also tested according to Radiated Spurious Emissions (Part 15 Subpart C §15.247(d)), however the device under test failed at 7319.25 MHz and 7440.75 MHz which is in the frequency band for “SPACE RESEARCH (Earth-to-space)” and “SATELLITE MOBILE” as the device frequencies were above FCC limits intended for Mobile and Fixed Satellites (Federal use only). As a result, Dexcom is seeking this Special Temporary Authority to operate the transmitter given the noted failures in spurious emissions.
The particulars of operation for these frequencies which require this Special Temporary Authority are summarized in the next section of this request. The transmitter passed all FCC requirements for the remaining frequencies of operation in the BLE(ISM) Amateur Band (2.4 GHz and 2.4835 GHz) and therefore no Special Temporary Authority is necessary for these remaining frequencies of operation. Dexcom conducted further analysis of these failures and determined that there is no potential risk to the subject or “SPACE RESEARCH” and “SATELLITE MOBILE” communication channel for the following reasons:
1. The study design only requires the subject’s data be downloaded via BLE communication in a clinic environment one time at the end of the trial session;
2. Transmission and reception of these satellite systems is via parabolic dishes and are typically 3m-8m in diameter, receiving antenna are highly selective and positioned directly at the satellite when receiving;
3. The wearable transmitter’s signal cannot affect the high-power output of these satellite transmitters (Note: Satellite transmitters typical output power 10W vs. wearable output power of 1mW, a factor of 40dB);
4. The wearable transmitter would need to be precisely aligned to the satellite receiver’s electronics which would require that the subject be positioned inside of the dish in order to possibly interfere;
5. All investigational devices will be tracked, dispositioned, returned to Dexcom and disposed according to Good Clinical Practice guidelines at the end of the clinical trial;
6. The wearable transmitter passed CISPR 11 required in 60601-1-2 emissions testing.
In summary, there is no potential risk to subjects due to the device under test’s failure to Radiated Spurious Emissions at the third harmonic of the fundamental 2.4GHz signal (as indicated by passing the 60601-1-2 emissions testing) and there is an extremely low potential to interfere with reception for Federal Fixed/Mobile Satellites. As a result, Dexcom would like to request this Special Temporary Authority to conduct this limited clinical investigation (under 6 months) to continue developmental efforts on the next generation continuous glucose monitoring system.