Rf Roofing Filter

The narrow band sdr receiver removes strong out of band signals by using a superheterodyne method with narrow band roofing filters which significantly attenuates unwanted out of band frequency components and the wanted signals within the passband are converted to digital by a high resolution 18 bit a d converter and sent to an fpga field programmable gate array for signal processing.

Rf roofing filter. Used sinclair bandpass filter low power n connectors 720 980mhz. Inrad roofing filters for the ft dx5000. Rugged radios audio choke electric static clamp on rf noise reducer filter. Here s what the plot looked like.

Agc rf or af chain overload shack noise etc. The goal of a roofing filter is to limit the passband of the first intermediate frequency if stage. It is usually found after the first receiver mixer. Reducing the bandwidth at this point in the radio helps to keep strong off frequency signals out of the second mixer where they can cause intermodulation.

Transmission is not changed as it does not pass through the roofing filter. The cut off frequency of the filter is defined as the point at which the output level from the filter falls to 50 3 db of the in band level assuming a constant input level. The narrow band sdr receiver removes strong out of band signals by using a superheterodyne method with narrow band roofing filters which significantly attenuates unwanted out of band frequency components and the wanted signals within the passband are converted to digital by a high resolution 18 bit a d converter and sent to an fpga field programmable gate array for signal processing. Based on an idea from daniel sandu yo3gjc inrad has taken their stock series of 9mhz filters and fitted them to a daughter card allowing drop in use in the yaesu ft dx5000 series rigs.

The roofing filter mod inserts a narrow band crystal filter between the rf assembly and the if board. A roofing filter is a type of filter used in a hf radio receiver. The 3 khz roofing filter for ssb and 600 hz cw filter have excellent shape factors which produce outstanding out of band attenuation characteristics. O needs vhf roofing filters wide cheap or narrow expensive o excellent image rejection o close in dr varies down conversion architecture 9 mhz typical 1 st if o performance near if is not uniform o image rejection near ham bands requires design attention o needs only hf roofing filters narrow cheap.

Rf filter characteristics a filter allows signals through in what is termed the pass band. Anritsu ma410a low pass filter. Bench results and observations. Third generation rf preselector rf vc tune.

This is the band of frequencies below the cut off frequency for the filter.