• COM-5001 BER Measurement: the status indicates zero errors while the received data stream is known to have many errors. Why?
    • The BER measurement shown in status registers 1 through 4 is valid if and only if the module was able to synchronize with the 2047-bit reference pattern. The synchronization bit is located at register 5 bit 0. When the BER is too high or when no data is being transmitted, the synchronization bit is low and the BER measurement is not updated.
  • COM-1000 VHDL development platform: the .mcs FPGA configuration PROM file created from our own VHDL code does not seem to upload properly using the graphical user interface. Why?
    • The ComBlock Control Center graphical user interface accepts .mcs files with 16-bit hex format. Starting with the release of ISE 4.1 in early 2002, Xilinx ISE tools changed the default bit file format from 16-bit to 32-bit. To create 16-bit format bit files, select the format MCS-86 in the PROM formatter program and insert the following line in the autoexec.bat: SET XIL_PROM_MCS16=YES. More information on this topic can be found on the Xilinx web site.

      The following checks will confirm that the FPGA .mcs configuration file is properly loaded:
        - the DONE test point is high after FPGA configuration
        - firmware revision and option are displayed as readable charaters in the properties window of the ComBlock Control Center.
        - during firmware upload, 3 flash sectors (for XC2S200) or 4 flash sectors (for XC2S300E) are written to.
  • COM-8002 In the data acquisition mode, how to extract the 10-bit I and Q samples from the byte-wise data file?
  • How much of the 256 MB memory in the Com-8001/8002 modules is actually accessible?
    • The last 32 bytes of the memory are never accessible. Thus, at most 268,435,424 bytes may be stored. Partial samples may not be stored in the memory and therefore when using the 14-bit and 20-bit input/output option the accessible range is further reduced. If the 14-bit output/input width option is used then at most 268,435,412 bytes may be stored. If the 20-bit output/input width option is used then at most 268,435,420 bytes may be stored.

    Basic Settings
    End-to-end Tests
    Comblock Control Center (GUI)
    LAN / TCP-IP Networking
    Test modules. Signal generators.
    Firmware Configuration Management