Several weeks ago, we posted a message seeking information about time sources. There were many helpful and educational responses. An excerpt from one of the responses is included below. We have been following up with regard to how SDR capabilities might be used for obtaining time using SDR dongles as well as using the time source product referenced in that response. Our SDR investigation has yielded many sources of information, but not a source dedicated to CentOS support for SDR products. Is there a CentOS subgroup and mail list directly involved with SDR device or system support? The SDR information resulting from our search has many references to ADS-B and the P3. It is almost like one absolutely must have a P3 to make use of SDR products. One thing that we did not find was any reference at all to SDR products and software for monitoring the frequencies used by recreational Remote Controlled Aircraft. Thanks again for all the helpful system time responses.