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Several cables have been tested in 35 meter lengths using active equalization (MAX3800). Shown is a result for a Samtec 26 gauge cable typical eye diagram for equalized signals. This is very typical and doesn’t vary much from cable to cable in appearance. The amplitude is nearly identical for all equalized signals irrespective of the cable with only some smaller variations in jitter.


Typical eye diagram and measurement results for an active equalized twinax cable


Table: 35 meter Cables tested to date. At a Pre-emphasis of 17 none of the cables passed a BER test


All cables in the table above failed the BER test with multiple bit errors when measured up to 1013 bits or greater. Up to this time all signals were measured with a pre-emphasis of 17 as was done in this table. Following is a BER test made on 3 of the same cables as above; the difference is a PE of 21 was used. A PE of 21 generally provides a better eye diagram of highly attenuated signals than a PE of 17.


Note that 2 of the cables (Samtec and Leoni) would more than likely have passed a BER test which was stopped at 1013 bits.

Following are cable length measurements of 25 meters, 1.3 GHz,