Digital data transmission system having frequency or phase modulated data carrying signals to provide supervisory channel
US4393279A · kind A · utility
5Cited by
4References
16Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jun 8, 1981 |
| Grant date | Jul 12, 1983 |
| Priority date | — |
| Expiry date | Jun 8, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L7/027
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A supervisory channel is provided on a digital transmission system by frequency modulation of the data signal transmitted along a transmission link which includes repeaters. The frequency modulation can be carried out using an elastic store. Each repeater includes means for demodulating the frequency modulation so that each repeater can be addressed and interrogated. Each repeater can also phase modulate the data signals on the return link to a terminal station so that signals indicative of an interrogated condition can be transmitted to the terminal station.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.