On the Internet since 1999 TV DX EXPO Photographs of real TV DX
Many Thanks to Raymie Humbert

The appearance of tiny text IDs beginning in 1999-2000 made IDing Mexico network relayers much easier. Unfortunately, location names on those IDs often did not match the official Mexico station list. Therefore, I called them "unofficial" stations. Fernando Garcia told me years ago that Televisa and Azteca commonly use fill-in transmitters on the same and other channels for TV stations. Nevertheless, a number of DXers and others told me I was wrong about those locations being transmitter sites.

Raymie Humbert has done much research and found answers to many questions about local TV in Mexico. His information is invaluable, and I greatly appreciate the job he has done for TVDXers. He also proved that Fernando and I were correct.

You can read Raymie's Mexico TV blog in the Chat Room forum (OPMA is Changing thread) at WTFDA Forums.

A Guide to Shadow Channels

by Raymie Humbert

1. What is a shadow channel?

A shadow channel, known legally as an "equipo complementario de zona de sombra," is a 
transmitter of another television station on the same or different channel as its parent station.
Shadow channels do not carry their own call signs and instead ID with the call sign of their
parent station.

The English term “shadow channel” is my own, playing not only off the description of these
stations as serving areas shadowed from their parent stations (zona de sombra) but also from
their incredibly elusive character.

2. Why do they exist?

Shadow channels exist for a variety of reasons:

• Mexico is a rugged country. Mountains often shield significant areas from television signals
they would receive if the land were flat. XEFB-59 Cerro de la Silla, Monterrey, serves areas
shielded from the XEFB-2 signal at Cerro El Mirador. The need for shadow channels is often
calculated by analyzing the station’s theoretical signal reach in flat terrain and comparing it to
the station's actual signal in real-world terrain. Shadows may also be used to provide improved 
reception in areas with weak signals.

• Television services often serve large areas. For instance, both Televisa and Azteca maintain
shadow channels at Saltillo, Coahuila, which is near Monterrey but has some of its own
stations. In some cases shadow channels significantly extend the service area of a station.
Another example are the Televisa stations on Altzomoni, State of Mexico. XHTM-10 has
repeaters in five different states, carrying its signal into Puebla, Tlaxcala, Hidalgo and Morelos

• Some stations are licensed with “principal service areas” of multiple major cities. This is the
case of Televisa Querétaro stations XEZ-3, XHZ-5 and XHQCZ-21. Each of those stations has a
shadow channel at Cerro Culiacán, serving Celaya, Guanajuato, which is listed in the stations’
concessions. XEZ and XHZ each have other shadow channels as well, including San Miguel de
Allende, Gto., and Cerro El Cimatario (Querétaro), Qro.

• A clause in Mexican television station concessions and permits encourages stations to open
shadow channels at underserved or underdeveloped areas (cobertura social).

• Municipalities in stations’ defined coverage areas not receiving adequate service can petition
broadcasters to add shadow channels to improve television services in their area.

3. What are shadows like technically?

It’s very hard to know. Getting an accurate ERP for a shadow channel is almost impossible. One
of the reasons I call them shadow channels is because most lists only show television stations
with concessions and permits; it’s the same reason that historically we’ve called them unofficial
stations. You have to go hunting to find proof of shadow channels, unlike American translators
that have their own call signs and licenses.

In analog, most shadows are on the same or adjacent channels as their parent station. XHAW
Monterrey has 14 shadow channels, almost all on channel 11, 12 or 13. The shadow channel for
XHQCZ-21 in Celaya is on 22. Not all shadow channels follow this behavior, and many VHF
stations have shadows on UHF. (There are even a couple that are the reverse, mostly inherited 
from changes in parent station, like XHCNL-2/3 and XHSTC-2 Concepción del Oro, Zac., once
tied to XHBQ.) In digital, almost all shadow channels will broadcast on the same frequency as
the parent station.

4. What about XHI Los Mochis? That’s a shadow channel, but it has local programming?

XHI Los Mochis is a real special case, 125 miles away from its parent in Ciudad Obregón,
Sonora (XHBS-4 is the reverse, licensed to Los Mochis with a shadow in Ciudad Obregón). XHI 
Los Mochis sometimes breaks from Ciudad Obregón in programming, both resulting from the
local-heavy programming of the Grupo Pacífico stations (which are local Televisa independents)
and also from the demise of Los Mochis local station XHCG in the late 1990s.

Another super-strange shadow is XEFB/XHCNL-2(-) Saltillo. It’s licensed as an XEFB shadow but
became an XHCNL relayer in 2006, when Televisa Monterrey’s local station moved from 2 to 34.
(Everything I’ve ever read about XEFB is written as if the station itself changed channels.)

Another notable (though not low-band) shadow with its own programs is XEQ-8 Cerro
Jocotitlán/Toluca, State of Mexico, which produces its own local programs as “Gala TV Estado
de México”.

5. What stations have low-band shadows?

These low-band shadows have been caught by DXers somewhat regularly. I’ve included coordinates
where I’m fairly sure of the location of the station; in some cases, there are full-licensed stations
transmitting from the same or similar locations, and in others, government documents give an
address or coordinates. This list isn’t complete.

An asterisk indicates that the site is an estimate based on the presence of other television and 
radio station(s) or TV and radio towers at similar coordinates.

Channel 2
XEZ-2 San Miguel de Allende, Gto. (IDs as San Miguel de Allende) [20.896549, -100.737931] 
XEZ-2 Cerro El Cimatario, Querétaro, Qro. (IDs as Querétaro) [20°31’45.06”, -100°21’42.59”] 
XHCNL-2(-) Saltillo, Coah. (licensed as a shadow of XEFB) [25.411516, -101.005474]*
XHCSA-2 Tuxtla Gutiérrez, Chis. (IDs as Tuxtla Gutiérrez)
XHI-2 Los Mochis, Sin. [Cerro de la Memoria, 25°48’32.00”, -108°58’04”]
XHHHN-2(-) Tehuacán, Pue. [18.459579, -97.427740]*
XHQ-2 Guamúchil, Sin.

Channel 3
XEZ-3 Celaya/Cerro Culiacán, Gto. [20°20’19.95”, -100°58’07.74”] 
XHCNL-3? (location unknown). Danny Oglethorpe and others have caught this station, but I cannot find an
XHCNL (or XEFB) shadow on channel 3.
XHKYU-3 Tizimin, Yuc. (found by Ed Phelps)

Channel 4
XHP-4 Tlaxcala, Tlax. [19.340437, -98.281080]*
XHP-4 Tehuacán, Pue. [18.459579, -97.427740]* (In practice, it is very hard to determine which is which.)
XHWX-4(-) Saltillo, Coah. [25°24’42.10”, -101°00’08.10”]

Channel 5
XHHLO-5 Tehuacán, Pue. [18.459579, -97.427740]*
XHZ-5 Celaya/Cerro Culiacán, Gto. [20°20’19.95”, -100°58’07.74”] 

Channel 6
XHAJ-6 Orizaba, Ver. (ERP 13.7 kW) [Cerro Macuilacatl, 18°55’46.1”, -97°06’33.15”]
XHDI-6 Col. Los Remedios, Dgo. [24°01'12.35", -104°40’56.28”] (originally thought to be at Cuauhtémoc)
XHDY-6 Tuxtla Gutiérrez, Chis. (ERP 1 kW) [16.774950, -93.125235] 
XHZ-6 San Miguel de Allende, Gto. [20.896549, -100.737931] 
XHZ-6 Cerro El Cimatario, Qro. [20°31’45.06”, -100°21’42.59”] 

6. I found a station whose text ID says something different from its city of license. Is this a
shadow channel?

Certain stations have unusual IDs that may seem like there are shadows involved or the call
signs don’t match up, but instead the transmitter location and community of license are
somewhat different:

XHCOL-3 Atenquique, Jal. (Colima, Col.). It’s not the only Colima station to be broadcasting 
from a transmitter site in Jalisco, either. 
XHURT-5 Cerro Burro, Mich. (Uruapan). Station has a directional antenna pattern aimed toward 
Uruapan and Morelia.
XHIH-5 Tehuantepec, Oax. (Palma Sola). The transmitter is 30 air miles from the city of license.
XHGZP-6 Torreón, Coah. The callsign seems to imply a city of license of Gómez Palacio, Dgo.
(this is also the case with the other Azteca station which is not on low-band). The transmitter,
however, is in Coahuila on Cerro Las Noas, one mile from the border with Durango. Torreón and 
Gómez Palacio form a two-state metro area. 


Written by Raymie Humbert for tvdxtips.com, 2014. Please credit when citing.

Most technical information provided is based on Mexican government documents including the
Infrastructure of TV Stations list from April 2014, the first to include coordinates for all fully
licensed stations. For some shadows, coordinates are estimates based on common transmitter 
Mexico TV DX Photos
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