Is WTIC 's IBOC Gone for Good?

WTIC's IBOC'd signal extended from 1065 to 1095 kHz!

Living 13 miles line-of-sight of WTIC’s 50,000-watt transmitter site on 1080 kHz makes DXing on 1070 and 1090 kHz very difficult especially since WTIC uses IBOC (In-band on-channel), a hybrid method of transmitting digital radio and analog radio broadcast signals simultaneously on the same frequency. 

With IBOC on, I can’t hear a thing but IBOC on 1070 and only 50,000-watt WBAL manages to break through on 1090.

Good news is that it seems that WTIC is no longer using IBOC. It has been off for weeks (maybe months) and I hope it is not coming back. 

Hurrah!

WTIC's IBOC and WWCO's absence

Before turning in last night, I tuned the AM band to hear what I could hear and came up with a couple of surprises.

WTIC on 1080 kHz, 50,000 watts, 13 miles line-of-sight from my home, seems to have turned off its IBOC, which made reception on 1070 and 1090 kHz difficult, if not impossible. I noticed this when I turned to 1070 and could actually hear stations without having to use my receiver's filters to tune out WTIC's IBOC. I checked again this morning and the IBOC was still off, but it had returned when I checked again this afternoon. It was nice while it lasted.

Tuning further up the band, I noticed that 1240 kHz was absent WWCO's signal (1000 watts, 7 miles from my home). I cannot receive anything but WWCO on 1240 when it is on the air, but last night, there was a cacophony of stations on 1240 typical for a graveyard channel.

I decided to forgo sleep and take advantage of this rare opportunity and try to identify something. Briefly, WFTN popped up for identification – a new one for the log. (WFTN transmits 1000 watts from Franklin, New Hampshire, 142 miles to the north-northeast.)

I hung around for about 15 minutes more until WWCO came back to life and dominated 1240.

Receiver: ICOM IC-R8600, Antenna: 128-ft Loop on Ground (LoG)

WTIC's IBOC'd signal extends from 1065 to 1095 kHz!

WCSZ Logged

Got the word Friday that WCSZ on 1070 kHz in Sans Souci, South Carolina, 693 miles to the southwest, would be running test transmissions at 0400 UTC Saturday.

I live line-of-sight of WTIC’s 1080 kHz, 50,000 watt transmitter. That’s bad enough, but WTIC also uses IBOC, which interferes with signals on 1070 and 1090, so I had my doubts about hearing WCSZ, but since my bedtime these days is about 0400 UTC, I planned to listen anyway.

The ELAD FDM-S2 SDR receiver was my receptor of choice. I tuned it to 1070 and switched to USB because the WTIC IBOC runs strongest between 1064.6 and 1070 (see figure), then drops in strength above 1070. I also narrowed the bandwidth down to 2800 Hz (represented by the vertical red bar in the figure).

At 0400 UTC, I heard station audio way down in the mud – so far down in the mud that there was no way I could identify it. But at 0404, clear as a bell, I heard Morse code: V V V DE WCSZ WCSZ WCSZ.

With that, I shut down the station, entered WCSZ in the log and went to bed.

WCSZ may have been transmitting either 25 or 50 kW for the test when I heard it.

Also, it is interesting that at the time, 50 kW WBAL (254 miles to the southwest) was stronger than 50 kW WTIC (12 miles to the north-northeast).

IC-R8600's Digital Twin Passband Tuning

There is a handful of nearby AM radio stations that are very strong here and sometimes make it difficult to hear stations on adjacent frequencies, for example, WPRX on 1120 kHz running 1000 watts 2 miles away, WNTY on 990 kHz running 2500 watts 5 miles away and WLAT on 910 kHz running 5000 watts 8 miles away. But by far, the worst is WTIC on 1080 running 50,000 watts line-of-sight 16 miles away. Its 50 kilowatts are bad enough, but it also uses IBOC, which dumps hash on 1070 and 1090 that is 20 over 9.

Despite the hash, I have managed to bag seven stations on 1070 by rotating my radios and/or antennas to null WTIC's signal.

I wondered if my new whiz-bang ICOM IC-R8600 could handle WTIC's IBOC hash. Studying the IC-R8600 manual, I thought that the radio's "Digital Twin PBT" might solve the problem.

"The Digital Twin PBT (Passband Tuning) electronically narrows the IF passband width by over wrapping the passband frequency ranges of 2 PBT filters (PBT1 and PBT2), to reject interference."

So I saddled up to the radio last night around 2330 local time, powered up the IC-R8600 and found Radio Havana loud and clear on 530 kHz, so conditions were very good and WTIC's IBOC hash would be very strong. Tuning to 1070, all I could hear was the IBOC hash.

I selected the Twin PBT option and began adjusting the two PBT filters (see figure above). In less than a minute, the IBOC hash gave way to The Eagles singing "Already Gone" on CHOK in Sarnia, Ontario!

Twin PBT did the trick!

Two New Ones

Monday evening, I finally identified the Spanish language station on 920 kc: WURA transmitting 7 kW from Quantico, Virginia, 310 miles to my southwest. The station was very weak, but solid until sunset when it switches to 750 watts and lets WHJJ and CKNX vie for 920.

At 1056 UTC Saturday, I caught the station id of WKMB transmitting 250 watts from Stirling, New Hersey, 100 miles to my southwest. This was a nice catch because it was on the often difficult 1070 kc... difficult due to the IBOC QRM from the 50-kW WTIC on 1080 kc, 15 miles to my northeast.

Both new ones were captured using the Elecraft KX3 with the Terk Advantage antenna.