Crystal Filter Design Software
There have been articles on how to design crystal filters in magazines for years. The difficulty always centered around measuring and selecting crystals and then designing the circuit. There are several programs which can help design a crystal filter but I generally use the free AADE Filter Design program at http://www.aade.com/filter.htm which designs several types of crystal ladder filters. All the programs I have seen require the crystals to have identical parameters. The measurement of the crystal parameters has been automated in the software for the AIM 4170 VNA (also in the AIM 4170 UHF and VNA 2180). Using a small fixture with socket pins, crystals can be measured with precision at a rate of 2 to 3 per minute. Other VNA's could have the ability to automatically measure crystals but I do not know of any which have the necessary software. The table below shows the file created by the AIM 4170. Notice that all the relevant crystal parameters are included. I generally match crystals first on Fs, Fp, and Q.
Active Filter Design Software
2 Million+ Photoshop Actions, Add-Ons, and Design Resources With Unlimited Downloads. Download thousands of stunning Photoshop actions and add-ons with an Envato Elements membership. It starts at $16 per month, and gives you unlimited access to a growing library of over 2,000,000 actions, presets, design templates, themes, photos, and more. It features a 4-pole 24 db/octave filter, 2 ADSR envelopes, 4 low frequency oscillators, a flexible modulation matrix and a built-in stereo delay/flanger effect. Each LFO can modulate the rate of it's adjacent LFO in addition to it's assigned destination in the matrix, thus allowing for many unusual modulation possibilites: PC Downloads: Click here.