usermod is a software for creating user defined mappings for smiq and exporting user defined baseband filters into smiq. it consists of two parts: usermapping and userfilter.
usermapping allows to create different user modulation mappings as frequency shift keying (fsk), phase shift keying (psk) and quadrature amplitude modulation (qam). so new standards and customer specific mappings can be implemented in smiq.
any i/q value or amplitude/phase can be set. the mapping is displayed in the constellation diagram. herein the i/q values can be changed by dragging the mapping points with the pc mouse.
after processing the constellation diagram and setting various parameters, e.g. differential coding, psk rotation, etc. the mapping can be stored on the pc or transferred to smiq via the iec/ieee bus. the new modulation mode can be set in smiq in the same way as the predefined modulation modes. up to 4 user mappings can be made available simultaneously in smiq.
with userfilter customer specific baseband filter coefficients, calculated by a filter design program (e.g. matlab) can be read from a file into the program. after loading the coefficients, the filter is displayed in the time and frequency domains. the filter can be transferred to smiq via iec/ieee bus and set in the same way as predefined filters. up to 4 user filters can be made available simultaneously in smiq.
the online help menu of the program includes detailed examples and gives information on the system requirements.