DFW Daylight Savings Time Transition and ATSC

November 2017

The Fall DST change is on 5 November this year. Three stations are sending a DS_status of 0 or not in daylight savings time and have been for some time. (RF10, RF20, and RF25)

RF20 (KBOP) did something quite odd on 4 October. They changed DS_status to 1 like it should have been all along but in the process mangled the time data they were sending. It went from about 19 seconds fast to 3621 seconds slow. In addition they changed the GPS offset from 15 to 0. The correct value is currently 18. But almost no one gets that correct.

5 October

Nine stations changed their DST data today. Which means that any receiver depending on them will display the wrong time today.

Each plot shows the values for DS_status (1 means in daylight savings time), DS_day_of_month, and DS_hour for the previous day and current (at time plot was made) day.

KTVT (RF 19)KTVT DST change information

KUVN (RF 23)KUVN DST change information

KODF (RF 27)KODF DST change information

KTXA (RF 29)KTXA DST change information

KMPX (RF 30)KMPX dst change information

KDAF (RF 32)KDAF DST change information

KAZD (RF 39)KAZD DST change information

KTXD (RF 46)KTXD DST change information

KSTR (RF 48)KSTR DST change information

Two other stations changed today but are using an incorrect date of the 29th. They may or may not change that to the correct date later.

KXTX (RF 40)KXTX DST change information

KDTN (RF 43)KDTN DST change information

6 October

Today is the day that stations should be starting the process but no one did.

7 October

A day later than they should have, a few more stations begin the transition.

WFAA (RF 8)WFAA DST change information

KERA (RF 14)KERA DST change information

KPXD (RF 42)KPXD DST change information

8 October

One of the stations (KDTN, RF43) that started sending the wrong date on the 5th changed that to the correct value today.

9 October

Three more stations start the transition. Better late than early.

KFWD (RF 9)KFWD DST change information

KBOP (RF 20)KBOP DST change information

KJJM (RF 34)KJJM DST change information

5 November

The standard requires that stations change the dst_status bit after all parts of their broadcast area have completed the transition. Since the DFW market is firmly in the middle of the central time zone, it has only one time zone so everyone should have done this at 2AM CDT. Many did not.

One completed the transistion before2AM!

(All times in these plots are DST.)

KODF (RF 27)KODF DST change information

A few did it at 2AM as expected: KERA, KBOP, KPXD, WFAA, and KFWD. The rest (at least those that had set a non-zero day and hour) did it withing a few hours.

It still surprises me that so many stations are incapable of following a simple process. Particularly surprising is that one major network affilicate (KXAS) did absolutely nothing. Maybe they will notice the problem before the next transition starts.

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