Abstract: A signal generating device and method of control thereof for producing a desired output frequency, the generator having coarse and fine tuning controls capable of producing frequency changes over a limited range, wherein the output of the device is combined in a mixing device with a multi-component reference signal produced from an oscillatory generator circuit, a beat signal is detected by processing circuitry as the frequency controls are adjusted and the values of the frequencies of the control signals occurring on such detection are stored, and using a look-up table or algorithm the value of a correction signal is determined which, when combined with the stored values, will cause the output frequency of the device to be adjusted to the desired value via the fine tuner.

Abstract: A microwave attenuator consists of a plurality of variable attenuation PIN diodes connected in a serial path. At least one of the diodes forms part of a feed-back loop so that the attenuation level it provides can be adjusted to correspond with a reference signal. The effective level of the reference signal is modified in accordance with correction factors, by means of which non-linearities in the performance of the remaining diodes can be compensated.

Abstract: An anti-rattle element for a curtain of a closure, the curtain having a corrugated surface and, adjacent to its edges, either a strap riveted to crests of each corrugation or bridges extending across the troughs of the corrugations. The strap or bridges form detent surfaces engageable by a resilient latching tongue protruding rearwardly from a body of the anti-rattle element. The tongue has a tip that engages either the bridge or the strap to hold the anti-rattle element to the curtain. The body of the element also has first and second abutment side faces and a rear face having a recess therein which embraces a portion of an edge margin of the curtain. The anti-rattle element is connected to the curtain in such manner that its abutment faces are disposed respectively on opposite sides of the curtain and face outwardly therefrom.