Note C – Patents

The Company’s intangible assets at December 31, 2022 include patents with estimated remaining economic useful lives ranging from 0.50 to 16.50 years. For all periods presented, all the Company’s patents were subject to amortization. The gross carrying amounts and accumulated amortization related to acquired intangible assets as of December 31, 2022 and 2021 were as follows:

Amortization expense for the years ended December 31, 2022 and 2021 was $316,000 and $295,000, respectively. Future amortization of current intangible assets, net is as follows:

Two patents within the Cox Patent Portfolio expire in July 2023 and November 2023, and the balance of the patents within such portfolio have expired. The expiration dates of patents within the Company’s M2M/IoT Patent Portfolio range from September 2033 to May 2034. The expiration dates within the Company’s HFT Patent Portfolio range from October 31, 2039 to November 1, 2039. All of the patents within the Company’s Mirror Worlds Patent Portfolio expired and the Remote Power Patent expired.