I use a Motorola Oncore module with software called SynTac which runs on PC and has time optimization. How are you applying the 1 us time tag to the data? Or do you rather need an accurate frequency? Don -- Dr. Don Latham AJ7LL 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com