Jim Hawkins WOR Transmitter Tour

Looking up one of WOR's three
681' towers. Overall height above
ground is 689'.


Thanks to Kerry Richards, Chief Engineer and Thomas R. Ray III, Corporate Director of Engineering Buckley Broadcasting/WOR Radio for the grand tour and technical information. My thanks also go to Geoff Mendenhall, VP of Advanced Product Development at Harris Broadcast Communications HQ.


WOR is New York's First Digital AM Radio Station. Transmission of digital signal on WOR began At 9:00AM, October 11, 2002. Please go the WOR-HD site for further information.

Some History

On Wednesday, 2/22/22 a De Forest transmitter was fired up on the sixth floor of Bamberger's Department Store at 131 Market St. in Newark, NJ by Orville Orvis and Jack Poppele on a frequency of 833.3kHz with a power of 500W. The first thing that aired was Al Jolson's record, "April Showers." Louis Bamberger tried to get an assigned call of WLB, however, the call had just been assigned to another station. As it turned out, the station was assigned reissued ship's call, WOR. (S.S. California, owned by Orient Lines) The OR in WOR was taken from Orient or Orient Radio.

WOR was the first New York station to carry programming of the Columbia Broadcasting System, premiering on September 18, 1927.

In the mid 1930s a new 50,000 watt transmitter site was built alongside the Arthur Kill in Carteret, NJ, where it remained until 1968. It was moved to its present location in Lyndhurst, N.J.

Reference: "The Airwaves of New York" 1998 Bill Jaker, Frank Sulek and Peter Kanze

Location Marker

Accessed times since February 2, 2003

WOR Announcement of increase to 50,000 Watts

My own memories of WOR

As a kid, WOR was THE place to tune for school closings announced by John Gambling on a snowy day. When it snowed, my siblings and I would listen to Mr. Gambling as he read school after school. It was like winning a day-off lottery. I also remember John Gambling Sr. with a live band in the studio.

There was and still is Joe Franklin, who has been with WOR since I can remember. To me, Joe Franklin is not only the nostalgia king, he is the king of the idea of nostalgia radio and the pioneer of television talk shows.

Ah, then there was Jean Shepherd, an unbelievable master of story-telling. He was also a radio amateur ham (K2ORS). Some of his stories were about adventures with ham radio. He was the only radio personality that I can remember who talked about the transmitter that he was broadcasting from on WOR. He was also the author of his own Christmas Story, which is aired on television every year.

Visit the official WOR 710 web site for its current, diverse programming.


WOR pre 1932 Control and
Transmitting room

Source: Belden Photographers of Newark
Supplied by Tom Ray - WOR

WOR Tower 1924 on top of
Bamberger Station in
Newark, NJ.
Note transmitter
house, shown in image above,
appears bottom center in this

Source: Radio News, January 1932
Note: This photo was printed reversed
in the magazine so that the
"Bambergers" and "WOR" sign would
read forward!

WOR Site as it appeared at Carteret, NJ in 1935. The two Blaw-Knox towers
were 350' high. This system was an array of three vertical antennas consisting of the towers and the center wire suspended by
the wire between the towers. The Carteret location was chosen to be in line with NY City, Trenton and Philadelpha. The three verticals were in phase to create lobes in the the direction of those cities. The weak end signals, were in the direction of the nearby NJ shore on the southeast side and the northwest PA mountains in the low populated Pocono area. See below.

Source of photo: "electronics" September 1935
Source of information: "Commnication & Broadcast Engineering" February 1935

While at Carteret, the WOR transmitter was in line
with New York, Philadelphia and Trenton and
it's directional lobes were aligned to those cities.

Source: "Commnication & Broadcast Engineering"
February 1935

Amplifier Tubes
Source: "electronics"
September 1935
Mercury Vapor Rectifiers
Source: "electronics"
September 1935

These photos were used in am Isolantite Ceramic Insulator advertisement
which used WOR AM. The advertisement says that the photos are
from a recently built Western Electric Transmitter. The tower photo
was from the same advertisement, which appeared on Pg. 45 of "electronics"
September 1935. There waas no indication as to what part of the transmitter
the amplifier section was in, but it is obvious that they are high power, water
cooled tubes. (All images were computer enhanced.)

WOR AM Lyndhurst, NJ 2003

WOR Transmitter Building
visible from the NJ TPK
just before Exit 16

Auxiliary equipment racks
contain satellite receivers,
analog and digital audio
processing and IBOC

Many paths from the studios at 1440 Broadway. Input feeds rack, including satellite
telephone line.

Digital (top) and analog processors
Optimod 6200 (top) and 9200.
The digital processor feeds the IBOC
Ibiquity IBOC Exciter..

The IBOC software runs on a Linux OS platform. The unit can be controlled remotely via dial-in modem. It also has a TCP/IP port. The IBOC exciter box has a GPS receiver to synchronize all IBOC transmitters for quick tuning and lock-in from one HD station to another.


Left: Continental 317C-1 on left, Harris DX-50 Main
transmitter at the far end and RF Switching cabinet on
the right.
Right: View from opposite end showing RF Switching
and auxiliary equipment racks behind it.

The Continental 317C-1 is a Doherty linear tube transmitter.
It serves as a standby transmitter and is used once per week
for the Joe Franklin show on Sunday morning, midnight to 5:00 AM.
Joe Franklin not only still has his radio show, but his own restaurant
and, in a way, his own transmitter!

Door open on 317C-1 Driver cabinet
reveals 3CX3000As.

IBOC interface to Harris DX-50

IBOC Junction Box
Click to see connection

IBOC Junction Box on top
of the Harris DX-50

Exciter (blue) relay to switch from internal
to IBOC is mounted between the two

The IBOC system is connected into the Harris DX-50 with fail-safe mechanisms installed. The connection from the internal exciter to the first driver was replaced by a relay, which switches to the IBOC exciter. The Audio is also switched from pure analog processor the output of the IBOC exciter. If the IBOC system fails, it is detected and the relay switches from the IBOC exciter to the internal RF and the analog processor.

RF Switching Cabinet and Phasor

RF output switching cabinet connecting with
the phasor behind it.

Inside the RF switching cabinet.
It feeds the three towers, switches between the
two transmitters and switches the dummy load.
It allows single tower operation with any of the
three towers. Switching to low power
non-directional allows maintenance on other
towers and the phasor. It controls the common
point input to the phasor and
the 3 outputs of the phasor.

The phasor front panel.

Inside the phasor looking in through the back
door. The IBOC carriers could be
heard "ringing" the coils as a hissing sound
along with the analog audio in this cabinet.

New coils were installed in 1998.


The tower array is in a dogleg (weak triangular)
configuration. Each tower has detuning skirts for
1010 (upper) and 1190 KHz. Click on the images
for a better view of the skirts. At the bases are
detuning networks for 1010, 1190 and 620 KHz.

Tower base showing Austin
transformer, "Johnny Balls"
to divert lightning strikes.

IBOC Analog/Digital Receiver

Kerry demonstrated the WOR-HD with this receiver to me. First he tuned in some other AM stations, which, of course sounded like the usual narrow bandwidth AM. Then he tuned in WOR. Initially it sounded like the other stations, but within about 2 seconds it opened up with a very clear, High Fidelity sound. The transition sounded as if the radio had been in a box and the lid had been taken off. I was told that with the initial IBOC exciter software the sound was good, but, with each new exciter software update, the audio has continued to improve. One cannot make a final judgment as this system is continuing to evolve and improve.

IBOC Mask and WOR Spectrum

The IBOC AM Hybrid signal consists of

  • a 5KHz wide analog signal for current standard reception
  • Primary digital carrier regions (64 QAM) (C1 and C3), which contain the core, monophonic audio signal. These carriers are added in the audio modulating signal.
  • Secondary (16 QAM) and Tertiary (QPSK) regions (C2) contain enhanced stereo and higher spectral content audio and ancillary data.

In the IBOC AM all digital mode,
the analog signal is removed and replaced by the region for the primary digital carriers, which are transmitted at a higher level than in the hybrid mode, providing a more powerful digital service. The upper +5kHz to +10kHz becomes the region for the secondary digital carriers. The lower -5kHz to -10kHz becomes the region for the tertiary digital carriers.

The WOR-HD spectrum shows the carrier in the center, the two "valleys" on either side are the secondary digital regions and the first set of peaks show the primary digital carrier regions. The red outline show the NRSC Mask, which bounds the legal limits of the overall hybrid signal.

Some Technologies Used in IBOC

  • Lucent Perceptual Audio Coding (PAC) - A method of compression that takes advantage of masking of certain sounds in human hearing perception. iBiquity uses Lucent's version.
  • COFDM - Coded Orthogonal Frequency Division Multiplexing
  • QAM - Quadrature Amplitude Modulation
  • FFT - Fast Fourier Transform: Signal processing is performed in the frequency domain
  • REED-SOLOMON encoded audio data for forward error correction
  • TRELLIS ENCODER distributes the information over all the carriers like white noise.
  • QPSK - Quadrature Phase Shift Keying, applied to the carrier for tertiary region.

Emergency Generator

300KW 3 phase
440V Generator.

New York IBOC Pioneers

Kerry Richards, Chief Engineer (Left) and
Thomas R. Ray, III, CSRE, and
Corporate Director of Engineering

Read Tom's article in Radio World

The Signal Chain

as described by Tom Ray
Emphasis and formatting added by Jim Hawkins

The audio comes from 1440 Broadway via one of 5 paths:

  1. A non data compressed stereo digital signal on an Intraplex T1 system which is sent to and from Lyndhurst on a Harris Aurora 5.8GHz spread spectrum radio. The return path carries 10 channels of satellite audio, plus a bi-directional NY phone extension plus 5 channels of data for satellite control, newsroom data, satellite cues. And a link for transmitter control and telemetry. Plus a 10BaseT [Twisted Pair Ethernet] port with a connection to WOR's LAN.
  2. A digital 950MHz Moseley STL (stereo).
  3. A mono 950MHz Moseley STL (mono).
  4. An 8KHz equalized phone line.
  5. An ISDN codec.

These 5 sources (plus 2 hours of the Best of WOR on DAT in the event we need to abandon ship at 1440) go into a Broadcast Tools passive 6 channel audio switcher which is connected to the remote control. Output of the switcher goes to a Distribution Amplifier. DA outputs go to:

  1. Analog input of 9200 Optimod
  2. Input of 9100 Optimod
  3. Analog to Digital converter for HD Radio

If the main transmitter is operating in analog mode, the audio chain is:

  • 9200 Optimod feeds main as primary source, 9100 feeds main as secondary source
  • 9100 feeds Aux as primary source, 9200 feeds Aux as secondary source.

This switching is remote controllable.

The input of the 9200 is locked to the AES input for from the A/D (more on this below). If the AES stream fails, the 9200 will automatically revert to analog input.

With the main in digital mode, the aux chain does not change.

The chain for the main TX is as follows:

(Audio Engineering Society) stream from the A/D converter goes to the EAU (Exciter Auxiliary Unit). The EAU controls certain aspects of the exciter's operation, and also acts as a distribution amplifier for the AES stream. One AES output of the EAU goes to the AES input of the 9200, which will process the analog audio. One output of the AES output of the EAU goes to the AES input of the 6200, which processes the audio for the digital channel.

The AES output of the 9200 feeds the input of the exciter for the analog channel. The AES output of the 6200 feeds the input of the exciter for the digital channel. So we have two different processors; one to feed each channel.

It takes 8.5 seconds for the digital channel to be built and transmitted, and for the data correction information to pass to the radio. The exciter delays the analog channel by the same 8.5 seconds so that the radio will seamlessly blend between the analog and digital channels.

The exciter produces two outputs. The RF output (called PHASE) is an RF signal at 710kHz which is phase modulated by the tertiary set of IBOC carriers.

The audio output (called MAGNITUDE) contains the analog audio (bandwidth limited to 5kHz) and the primary and secondary IBOC carriers. The tertiary carriers are phase modulated and placed under the audio. The primary and secondary carriers are actually amplitude modulated, and are part of the audio.

The analog audio modulation is set, with IBOC carriers off, to -98%/+120%. This modulation does not change. The primary and secondary carriers then modulate the transmitter to produce sidebands where the primary IBOC carriers are -28dB referenced to carrier level [-28 dBc], while the secondary IBOC carriers are -38dB referenced to carrier [-38 dBc]. Total digital carrier power is approximately 1500 Watts for a 50KW station.

If you keep in mind that the AM signal as we typically know it (the modulated envelope) is actually a phenomenon of the modulation vectors interacting with the sidebands and the carrier, it appears that the AM carrier actually disappears at -100% modulation. In fact, the carrier never pinches off or diminishes in amplitude and is a constant (as proven on a spectrum analyzer), and the IBOC sidebands are in addition to the analog modulation. This may appear to a conventional AM detector as overmodulation in the negative direction, but this is not the case. Basically, we are adding 1500Watts to the sideband power on WOR.

-Thomas Ray

© 2003 by James P. Hawkins