### ATSC: MGT tables_defined

Posted:

**Tue Jan 31, 2017 10:34 am**I'm working my way through our annual PSIP checklist.. We've changed encoders/muxes since last time & I'm having a bit of trouble reconciling what's going on here. I have a theory on what they're looking at but I'm interested what you all think...

"The tables_defined field in the MGT must be 3 + highest numbered EIT."

Our tables_defined field is 50. Our highest numbered EIT is 23 - since they start at 0 that means we're transmitting 24 EITs. We are also transmitting 24 ETTs. And a TVCT and RRT. If I add 24 EITs, 24 ETTs, one TVCT, and one RRT I get 50. There's nothing else in the MGT. I have no idea where they're getting "3+" from.

If I spy on the competition...

WTVF: 4 EITs, 4 ETTs, RRT, TVCT = 10. tables_defined field: 11.

WKRN: same as WTVF

WZTV: 4 EITs, 4 ETTs, RRT, TVCT = 10. tables_defined field: 10.

WNPX: 8 EITs, 8 ETTs, RRT, TVCT = 18. tables_defined field: 18.

WNPT: 16 EITs, 16 ETTs, RRT, TVCT = 34. tables_defined field: 35.

I don't see any way to directly change tables_defined & I'm not getting anything from the mux/PSIP manufacturer.

Does my reasoning make sense?

"The tables_defined field in the MGT must be 3 + highest numbered EIT."

Our tables_defined field is 50. Our highest numbered EIT is 23 - since they start at 0 that means we're transmitting 24 EITs. We are also transmitting 24 ETTs. And a TVCT and RRT. If I add 24 EITs, 24 ETTs, one TVCT, and one RRT I get 50. There's nothing else in the MGT. I have no idea where they're getting "3+" from.

If I spy on the competition...

WTVF: 4 EITs, 4 ETTs, RRT, TVCT = 10. tables_defined field: 11.

WKRN: same as WTVF

WZTV: 4 EITs, 4 ETTs, RRT, TVCT = 10. tables_defined field: 10.

WNPX: 8 EITs, 8 ETTs, RRT, TVCT = 18. tables_defined field: 18.

WNPT: 16 EITs, 16 ETTs, RRT, TVCT = 34. tables_defined field: 35.

I don't see any way to directly change tables_defined & I'm not getting anything from the mux/PSIP manufacturer.

Does my reasoning make sense?