COMBINED DEVICE TO FEED AND COMPACT PRESET DOSES OF GROUND COFFEE OR OTHER SIMILAR SUBSTANCES. Field of the art The present invention concerns the technology of the packaging machines for pads made out of filtering paper. International Classification B65b. State of the art Filtering paper pads to package doses of ground products with heterogeneous granularity are well known. All the known machines have specific problems as far as the control of the pad's shape and of the presence of product's resides at the edges of the pad, and also for the regulation of the degree of compactness of the resulting pads. The problem to be solved is in fact to obtain flawless pads with respect to the shape and to presence the product's residues at the edges of the pad. The combined device introduced by this invention solves the problems mentioned above, and it is also affordable in its practical realization. In particular, the combined device features a monobloc structure resulting from the combination of the measuring and the compacting equipment. Such solution ensures the highest reliability during the industrial application, even under high production demands. Description The invention is now disclosed with reference to the schematic figures of the drawings, attached as an unrestrictive example. Figure 1 represents, in vertical section, the rest phase of a combined device (D) provided with two equipments (A, B) to feed and compact preset doses of ground coffee (C) onto the underneath polygonal conveyer (P). Said conveyer features a series of equidistant shaped concavities (5) upon which a film of filtering paper (Fl) has been placed. Figure 2 represents the beginning of a phase of the feeding operation of the granular product (C). One should notice the presence of the engine (M) that performs the controlled and regulated rotation of the feeding screw (1) in vertical upright position (A). It should also be noticed that the moving liner (3) upon the filtering paper (Fl) is meant to avoid the spilling of the product (C). Figure 3 represents the completion of the gravity-based feeding process. The screw (1) is still and the entire preset dose of product ( C) has fallen into the cavity underneath (5), covered with filtering paper (Fl). Figure 4 represents the intervention of the sliding and turning compacting piston (2) inside the moving liner (6). It should be noticed that the position of the piston (2) and of the relative liner (6) is inclined with respect to the vertical axis, but it results perpendicular to the underneath lying concavity (5) present on the polygonal conveyer (P). Figure 5 shows the compacting of the product into a symmetric pad ( C). It can be noticed the presence of arrows that indicate the rotation and translation of the compacting piston (2) that, while compressing the granular product (C ), defines the roundness of its upper surface giving it more geometric stability during the following packaging phase. The figure 5bis shows the compacting phase of the product into an asymmetric compacted pad (C), with the piston (2') having the lower surface coplanar. In the figures 7 and 7bis one can notice that, upon completion of the compacting operations, the conveyer proceeds angularly by one step, and the combined device (A, B) resumes the initial position as showed in figure 1. In the figures each single detail is marked as follows: 1 is a measuring screw for the measuring and the regulation of the quantity of product to be introduced and compacted into each pad. 2 indicates the head of a rotating and translating compacting piston to compact symmetrical pads. 2' indicates the flat head of a piston to compact asymmetrical pads. 3 indicates the lower edge of the sliding liner (6). 4 indicates an interchangeable die provided with concavities geometrically congruent to the configurations of the pads. 5 indicates the concavities matching with the format of the pads. 6 indicates the moving liner within which the rotating and translating compacting piston slides. A indicates the upright measuring equipment. B indicates the oblique compacting equipment. C indicates the product packaged into symmetrically shaped compact pads. C indicates the product packaged into asymmetrically shaped compact pads. D indicates the structure of the combined devices consisting of the equipments (A5 B). Fl indicates the film of filtering paper. M indicates the time-switched engine. The clearness of the figures highlights the simplicity of the device that is the object of the present invention, and highlights the compactness of the monobloc structure (D) in which are combined both the operating devices (A, B) that act in conjunction for the measuring and the compacting of the preset doses of product in symmetric and asymmetric pads of filtering paper. The invention of course allows for several variations of practical realization both for overall dimensioning and structural proportioning, and also for the technological choices of the materials employed during the production process. It is evident that the diameter, the depth and the degree of compactness of the pads will adjust the production demands. The inventive core of the present invention consists therefore in the combination within a single monobloc structure (D) of two operating equipments (A, B) that act in conjunction to package compacted filtering pads, and upon its disclosure any average technician will be able to realize it without any inventive effort.