Built-in linearity testing arrangement for an FM radio system
US4365346A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 2, 1981 |
| Grant date | Dec 21, 1982 |
| Priority date | — |
| Expiry date | Mar 2, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B17/10
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
The baseband input to a frequency modulation radio transmitter is switchably connectable to a square wave generator, the amplitude of the square wave output being adjusted to provide a predetermined deviation of the FM radio transmitter. The output frequency of a pilot oscillator is also applied to the baseband input and is subjected to amplitude modulation because of non-linearities which exist in the system and which adversely affect the signal during transmission through the system. At the receiving end of the radio system, the receiver output contains a signal comprising the pilot frequency and a superimposed amplitude modulated signal, and this signal is applied to a product detector. The output of the product detector is a pulsating DC signal comprising a basic DC component, which is representative of the amplitude of the pilot frequency, and an AC component, which is representative of the system non-linearity. The pulsating DC signal is applied to one terminal of a capacitor. The AC component appears at the other terminal and is rectified and integrated to obtain a DC signal, the amplitude of which is proportional to the slope component in the system non-linearity. This DC s…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.