M. Lindgren October 5, 2001 CMS EMU Meeting -1 ALCT-TMB Cable Comparisons l 2 companies expressed interest in supplying a cheaper cable than the Amphenol Skewclear. äTYCO – sent two pieces of cable to UCLA ä3M – Had meeting with them, and they apparently decided that they were uninterested l TYCO cables äSumitomo, 12 meter, halogen, 30 gauge individual pairs äMadison, 10.5 Meter, halogen free, 28(?) gauge individual pairs. - No individual pair shielding on either cable, just an overall one.

M. Lindgren October 5, 2001 CMS EMU Meeting -2 Cable tests l Initial tests used OSU cable tester, and both cables passed walking ones and zero’s tests, and also a pseudorandom one at 80 Mhz. Could not look at signals with a scope as board was too noisy. l Built a small board with just 2 lvds drivers to look at individual signals for skew and rise time, etc. l Also had one FAST site Skewclear cable(failed the first tester) for comparison.

M. Lindgren October 5, 2001 CMS EMU Meeting -3 Skewclear – LVDS signals l LVDS driven down on pair and terminated into 100 Ohms. l Signal measured using FET probe and Tek scope

M. Lindgren October 5, 2001 CMS EMU Meeting -4 Madison – LVDS signals l Same driver into the Madison cable l Signal shape and attenuation is similar to Skewclear

M. Lindgren October 5, 2001 CMS EMU Meeting -5 Sumitomo – LVDS signals l Same driver into Sumitomo cable l Much worse than the other two

M. Lindgren October 5, 2001 CMS EMU Meeting -6 Skewclear – Pair to pair l Used two drivers, then compared arrival times at termination resistors l Largest difference measured was.3 ns l Actual skew probably less, as were close to limit of ability to measure on scope

M. Lindgren October 5, 2001 CMS EMU Meeting -7 Skewclear – Pair to Pair Skew Pair # ns

M. Lindgren October 5, 2001 CMS EMU Meeting -8 Madison – pair to pair l This is one of the better pairs. l Max difference between any two pairs was 1.1 ns

M. Lindgren October 5, 2001 CMS EMU Meeting -9 Madison – pair to pair skew Pair # ns

M. Lindgren October 5, 2001 CMS EMU Meeting -10 Sumitomo – pair to pair l Sumitomo cable skew was about the same as the Madison, max difference between pairs was 1.2 ns

M. Lindgren October 5, 2001 CMS EMU Meeting -11 Sumitomo – Pair to Pair Skew ns Pair #

M. Lindgren October 5, 2001 CMS EMU Meeting -12 Skew within pairs l Skewclear was hard to measure, as it was again vary small compared to the other two. l Madison maximum skew within a pair was.9 ns

M. Lindgren October 5, 2001 CMS EMU Meeting -13 Mad. – Skew within pairs Pair # ns

M. Lindgren October 5, 2001 CMS EMU Meeting -14 Conclusions l Neither cable met the spec that the maximum pair to pair skew be < 1 ns. l The Madison cable signal attenuation was much less than the Sumitomo, and the signal shape was comparable to the Skewclear. l The quoted price for long Madison cables from TYCO was $239/cable. If the Skewclear is much more expensive than this, we should have TYCO construct some actual cables using this cable and the proper connectors and backshells to evaluate at the FAST sites. l Otherwise, the Skewclear is clearly superior to the TYCO cables, and should be used if it can be purchased for about the same money.