Average Co-Inventor Count = 4.00
ph-index = 2
The patent ph-index is calculated by counting the number of publications for which an author has been cited by other authors at least that same number of times.
Company Filing History:
1. Hitachi Telecom Technologies, Ltd (4 from 61 patents)
4 patents:
1. 7532606 - DTMF signal transmission method and communication apparatus
2. 7062033 - DTMF signal transmission method and communication apparatus
3. 7050570 - DTMF signal transmission method and communication apparatus
4. 6700973 - System for transmitting DTMF signal and communication equipment thereof