It is my oun definition. It is different from that of usual proffesional. All is made by the same crystals 10.645MHz. I tryed the following 6 types. Figure indicate the definition of this page.
Settlement is as follows.
The more element of crystal makes the more better shape factor. The bigger capacitor makes the narrower bandwidth. Input impedance of this type of crystal filter is anyway some ten ohms. Impedance is changed in the band. Minimum impedance happens on the center of bandwidth.