Method and apparatus for closed loop testing of first and second modulators and demodulators
US4039751A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 22, 1976 |
| Grant date | Aug 2, 1977 |
| Priority date | — |
| Expiry date | Mar 22, 1996 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L1/243
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A method and apparatus are disclosed for closed loop testing of first and second modulators and demodulators from the modulated signal side of the first modulator and first demodulator. During ordinary communication, the first modulator and second demodulator are connected in series and the first demodulator and the second modulator are connected in series. In response to each test initiate signal, a loop is established between the second modulator and the second demodulator on their modulated signal side. Upon reception of some test initiate signals, a loop is established between the first modulator and first demodulator on their demodulated side and they are disconnected from the second demodulator and second modulator. Thus, the first modulator and demodulator can be tested from their modulated signal side when a loop is established between them; and the first and second modulators and demodulators can be tested when a loop is established between the second modulator and demodulator but not between the first modulator and demodulator.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.