Abstract: A multiple conversion receiver system capable of avoiding receiver spurs by combined switching of multiple local oscillator frequencies, including combinations of high-side and low-side injection and IF shifting.

Abstract: A combined signal level meter and leakage detector having a built-in antenna for the leakage detector, and dual clock frequency control of the microcontroller along with bandwidth switching for greater sensitivity in leakage detection mode. A data logging function is also provided. Control circuitry is also provided for avoiding receiver spurs by combined switching of multiple local oscillator frequencies, including combinations of high-side and low-side injection and IF shifting.

Abstract: A communication circuit comprises a plurality of sources of program material, and a plurality of modulators for supplying a plurality of carrier frequency signals. Each modulator is modulated by a respective one of the sources of program material. Each of the program material sources is coupled to a respective modulator. The program material-modulated carrier frequencies are coupled in the circuit. Terminal apparatus is provided for demodulating at least one of the program material-modulated carrier frequency signals. The terminal apparatus includes automatic gain control (AGC) circuitry having an AGC bandwidth. The terminal apparatus is coupled to the circuit. One of the program material-modulated carrier frequencies is coupled in the circuit through a variable attenuator having an attenuator control signal input, a program material-modulated carrier frequency input, and a variably attenuated program material-modulated carrier frequency output.

Abstract: A combined signal level meter and leakage detector having a built-in antenna for the leakage detector, and dual clock frequency control of the microcontroller along with bandwidth switching for greater sensitivity in leakage detection mode. A data logging function is also provided. Control circuitry is also provided for avoiding receiver spurs by combined switching of multiple local oscillator frequencies, including combinations of high-side and low-side injection and IF shifting.

Abstract: A test instrument for measuring hum and other AM distortion components on active audio carriers such as in a cable television distribution system. The instrument has an RF tuner capable of tuning to the audio carrier frequency for a selected channel, and also has three IF amplifier stages including a third stage with a 280 KHz bandwidth, which is sufficiently narrow to reject the video signal when the tuner is tuned to the audio carrier frequency. An AM detector detects amplitude variations in the FM signal, and the AM detector output signal is filtered alternatively in a 400 Hz lowpass filter or a bandpass filter to facilitate measurement of the level of different forms of distortion. The center frequency of the bandpass filter is capable of being set to the AC power line frequency or twice the line frequency. The bandwidth of the bandpass filter is limited to about 2-3 Hz to minimize the effect of amplitude variations other than hum in the FM audio signal.