11. A specific frequency is removed using a notch filter . 12. An example is a UREI 562 Feedback Suppressor and the Ashly SC-68 Parametric Notch Filter . 13. Depending on the values you choose, it could be a bandpass filter or a notch filter . 14. A notch filter , usually a simple LC circuit, is used to remove a specific interfering frequency. 15. Analog technology allowed cable providers to offer standardized subscription packages using low-pass filters and notch filters . 16. An audio notch filter removes the 2, 175 Hz low-level tone from the actual transmit audio. 17. Thus, the early color TVs used only notch filters , which cut the luminance off at 3.5 MHz. 18. If that doesn't work, you'll have to escalate with a tunable notch filter , which can selectively block interference. 19. A good ground filter / notch filter will prevent a feedback loop up case ground which causes false alarms. 20. However, they were expensive and only high-end models used them, while most color sets continued to use notch filters .
