DFW Daylight Savings Time Transition and ATSC

March 2018

The Daylight Savings Time transition is scheduled for 11 March this but several stations are not off to a good start. (Because the month is not included in the time for the transition it is vital that stations begin the process no sooner than 12 February.) Two full power stations that should know better never bothered to transition out of DST last fall. (KDFW - RF35 and KDFI - RF36, the local FOX affiliate and its sister station.)

8 February

One station began the transition yesterday at 10PM:

KODF (RF 27)KODF DST change information

Much too early so any receiver using that data will be displaying incorrect times on 11 Feb. KODF is a low power station and given a pass by the FCC on some regulations including those that require accurate time keeping. But they ought to at least make an effort. (Note also that even without the DST problem their transmitted time is nearly two hours fast. And drifting.)

10 February

Several more stations join the too damn early group today:

KERA (RF 14)KERA DST change information

KPXD (RF 42)KPXD DST change information

WFAA (RF 8)WFAA DST change information

All full power stations that should know better. You would think they don't read the ATSC specifications.

11 February

Many more joined the rush to be wrong today:

KTVT (RF 19)KTVT DST change information

KUVN (RF 23)KUVN DST change information

KTXA (RF 29)KTXA DST change information

KMPX (RF 30)KMPX dst change information

KDAF (RF 32)KDAF DST change information

KXTX (RF 40)KXTX DST change information

KXAS (RF 41)KXAS DST change information

KDTN (RF 43)KDTN DST change information

KTXD (RF 46)KTXD DST change information

KSTR (RF 48)KSTR DST change information

KXTX and KDTN took an unusual position by sending 1 as DS_day_of_month. It is like they know today is the wrong day to start the process and can't stop it. But they can fudge the data. (KAZD has been sending a 1 as well for quite some time but they left the hour of the change as zero.)

It took a while but once my DVR noticed all of these stations saying that today was the change, it satisfied its majority vote algorithm (or whatever it uses) and gave in. It is displaying time one hour fast until Monday. Any repeating recording events today will happen at the wrong time.

I really wish that the FCC was interested in enforcing compliance with their regulations. They used to have at least a little interest, but not now.

12 February

Today is the day that they should begin the transition but only two got it right:

KFWD (RF 9)KFWD DST change information

KJJM (RF 34)KJJM DST change information

KDTN began the transition yesterday using a bogus day of month and today they switched to the correct day.

KDTN (RF 43)KDTN DST change information

1 March

A late arrival to the party today:

KDTX (RF 45)KDTX DST change information

This is another full power station that ought to know better.

11 March

I usually haven't had a lot of data to report on the day of the transition but there was enough strange things going on to make it worthwhile. The way that it is supposed to work is that once all of the broadcast area completes the transition, DS_status is changed to in DST (1) and the other two values go back to zero. Since DFW is nowhere near a time zone boundary, that means it happens at 2AM CST. A few stations managed to do that: KERA, KFWD, WFAA, and KPXD. (All times in the following plots are in CST.)

KERA (RF 14)KERA DST change information

A few stations waited till later: KTVT, KUVN, KTXA, KMPX, KDAF, KJJM, KXAS, KDTN, KTXD, and KSTR. KXTX was notable in this group because they had been transmitting a day for the transition of the 1st for the last month. Yet somehow their hardware did it today.

KTVT (RF 19)KTVT DST change information

At least being late wouldn't result in any receivers displaying incorrect times.

Then there are the stations that couldn't come close to getting this bit right.

KODF decided 12:30AM was the time for it:

KODF (RF 27)KODF DST change information

KDTX was just too wierd. They changed all of the DST data to zero (standard time and out of transition) at 8PM yesterday. Then at 2AM they changed DS_status to 1 or in DST. I suspect that it required manual intervention to screw it up that badly.

KDTX (RF 45)KDTX DST change information


Two stations never switched out of DST last fall. (KDFW and KDFI) Exactly one station managed to complete the transition as required by the standard (ATSC A/65 Annex A): KPXD. A really poor showing for broadcast engineering.

ATSC Monitoring