Severe OTA Interference From New Digital Services Tower - Page 9 - Canadian TV, Computing and Home Theatre Forums

LinkBack Thread Tools Search this Thread Display Modes

post #121 of 149 (permalink) Old 2011-03-23, 11:31 AM
Join Date: Apr 2003
Location: Gatineau and Ottawa
Posts: 11,088
I am surprised you have not been presented with a non-disclosure or asked to not discuss this issue until it is resolved.

I assume this will be working its way back up Rogers hierarchy and you will receive instructions shortly.
Jake is offline  
Sponsored Links
post #122 of 149 (permalink) Old 2011-03-23, 12:00 PM
Join Date: Jul 2005
Location: Craig Henry (Greenbank/Hunt Club), Nepean, ON
Posts: 3,184
I don't think there is, in legal terms, a consideration offerred as part of the NDA. (In other words, no money is changing hands, so why should a complainant sign a non-disclosure. In any case, Rogers didn't really "disclose" anything that Gerry didn't know already.)
tvlurker is offline  
post #123 of 149 (permalink) Old 2011-03-23, 12:32 PM
Join Date: Apr 2003
Location: Gatineau and Ottawa
Posts: 11,088
I understand Gerry is under no obligation. But if I were Rogers I would see a potential RF issue with future roll-outs. They have an interest in seeing that happens without a lot of nimby lobbying. No offence Gerry. I am on your side. But if they can pressure politicians to stop bulldozers or wifi they can stop an antenna from going up.
Jake is offline  
post #124 of 149 (permalink) Old 2011-03-23, 03:09 PM Thread Starter
Join Date: Nov 2007
Location: Ottawa - Lees Ave
Posts: 325
I dont want this running away with the NIMBY crowd, because a lot of what they say is junk science. Most of the towers you see going up have a lot of vertical clearance and reasonable tilt angles. The situation here is different. No walls to block or attenuate the signals. Residential area. Lots of KW of ERP. Less than 70 meters away.
GerryB is offline  
post #125 of 149 (permalink) Old 2011-03-23, 05:31 PM
Join Date: Apr 2004
Location: derry + winston Mississauga
Posts: 1,577
With the kind of power their using why would they point antenna down when the signal from these cell panels could reach atleast 20km range.Ask them to try adjusting the tilt to straight out or no tilt.

Attic CM 4248 at Buffalo,M4 at Buffalo.VHF yagis at Toronto .
rob50312 is online now  
post #126 of 149 (permalink) Old 2011-03-23, 05:38 PM
Join Date: Jan 2009
Location: Kitchener, ON
Posts: 4,985
Down tilt from horizontal is necessary for urban cellular installations to reduce interference with other cell sites using the same spectrum.

DMX 68' tower, HyGain HAM 5 rotator, Antennas Direct DB8e & C5, Channel Master 7777 preamp, Siemens surge protection. TiVo Roamio DVR
Jase88 is offline  
post #127 of 149 (permalink) Old 2011-03-23, 07:14 PM
Join Date: Apr 2004
Location: derry + winston Mississauga
Posts: 1,577
It seems they are planning a much larger coverage area with this UHF spectrum application and thus the higher power levels.

Attic CM 4248 at Buffalo,M4 at Buffalo.VHF yagis at Toronto .
rob50312 is online now  
post #128 of 149 (permalink) Old 2012-02-22, 02:13 PM
Join Date: Feb 2012
Posts: 2
Some news from the UK

Not sure if this applies but as i saw it and looked here was surprised that I've heard little on the problem
derfinlondon is offline  
post #129 of 149 (permalink) Old 2012-02-23, 07:01 PM
Join Date: Nov 2008
Location: San Diego, CA
Posts: 3,176
Here's applicable LTE output power "limits" paragraphs from FCC Rules Sec 27.50:

a) Fixed and base stations: 1000 watts (60 dBm) EIRP, reducing to 65 watts
for 4500-ft HAAT (Height of Above Average Terrain)

b) Control stations and mobile stations: 30 watts (44.8 dBm) EIRP

c) Fixed stations: 30 watts (44.8 dBm) EIRP

d) Portable stations (hand-held devices): 3 watts (34.8 dBm) EIRP

e) Fixed and base stations: 50,000 Watts (77 dBm) EIRP, subject to sec 27.55 constraints:

Remainder of FCC Sec 27 Rules can be found here:

LTE in the 700+ MHz Band just fired up last year in a few major cities and it was
announced that more (incl. San Diego) were being fired up this year, although
where and when wasn't disclosed. So it will probably take most of this year before
a large number of users have 4G LTE devices and are actually using the new system:

I'm still looking for interference analyzes and actual test reports, other than the
WSD adjacent-channel tests conducted by the FCC OET, CRC and others: [See DTV and WSD Test REPORTS]
Note that WSD EMI test found leakage into a NEWLY installed CATV system. [Three CRC Reports attached to the FCC Filing]
Note that WSD analyzes still apply for LTE interference to DTV, except the Next-next-next-etc
Adjacent Channel EMI is now of primary concern (e.g. N+1, N+2...N+7...N+14, N+15, etc).

Note that in the Super-Heterodyne STB/DTVs tested by the FCC-OET (see links above),
inadequate Image Rejection resulted in most (2005-2006) units under test being MUCH
more susceptible to EMI when it was 7 or 14-15 HIGHER than the desired channel. This
is easier to see on pg71 (of 145) in the CRC Report attached to MSTV's FCC Filing
(see link above). It is important to recognize that this means that a UHF DTV channel
will be MUCH MORE susceptible to EMI when it is about 42 MHz and 87 MHz higher than
the desired UHF channel frequency----smack in the middle of the LTE TRANSMIT BAND. [Image Rejection Explanation]

So far, Charles Rhodes articles have concentrated on interference from DTV to LTE Devices,
not just adjacent channel (solved by on-going effort to vacate Ch51) but also third-order
Intermod products falling into the LTE User Device's RF input that may or may not be
filtered enough to prevent problems operating LTE devices anywhere "near" a DTV Tower:

Impact of LTE to CATV, esp Cable Modems:

In Europe, LTE has been active in their 800+ MHz Band for quite a while, so in
the fol. reports, shift all frequencies down by about 100 MHz to see what would
happen wrt North America's 700+ MHz Band.
U.K.'s OFCOM sponsored an LTE interference to DTT test, measuring "typical" levels
that would cause interference to OTA, CATV and even SAT (coax carries TV freqs):

In addition to finding that Super-Het. type DVB-T tuners are ALSO more susceptible
when the EMI is 7 Euro-Channels higher than the desired DTV channel, the first UK report
also tested so-called "Silicon" tuners [i.e. Double Conversion, such as from Microtune],
finding that although they did NOT have the Image Rejection susceptibility (as expected),
the susceptibility on other frequencies was about 10-20 dB WORSE than Super-Het. tuners
[no doubt due to the lack of an input tuned filter]. Unfortunately, they did not recognize
the importance of this HUGE difference, which widens the susceptibility bandwidth.

Yup, TV viewers sitting around their living room and also using their 4G LTE devices
could disrupt TV viewing if they were really close (and with one DTV, further away).
This was "cured" by adding an "LTE Band Pass Filter" which provided more or less
20 dB of Loss on the subject test frequencies. Signals leaking into the cable system
via a leaky cable was also found in one particular TV device, cured with a new cable.

With the EIRP level noted above, nearby Cell Phone Towers are going to be a problem.
AND, I have yet to see an analysis for dozens to 100's of bar patrons interfering
with the big screen DTV hung on the walls.....Nor effect of 100's to 1000's of other
4G LTE signals coming into a roof-top antenna from the extended neighborhood,
esp. in crowded metropolitan situation (1000 mobile phones is a 30 dB increase in EMI).

Studies for the Netherlands:
And one for Germany & Austria (with imperfect translations):

Here is a LTE-DTT Interference Overview from Rohde+Schwarz:

Latest update re Telco responsibiity to FIX THESE PROBLEMS in Europe:

I'm surprised the FCC, et. al. have kept this dirty little secret for such a long time.....
holl_ands is online now  
post #130 of 149 (permalink) Old 2012-02-23, 09:04 PM
Join Date: Nov 2008
Location: San Diego, CA
Posts: 3,176
FYI: I posted an assessment of candidate "LTE Low Pass Filters", finding Pico Digital's
LPF-700 to be the least effective, easily surpassed by Tin-Lee's LP7-700:

But due to slow frequency roll-off, it isn't optimized for use as an "LTE Low Pass Filter"
for AT&T's lower part of the 700 MHz Band, for uplink: 704 - 716 MHz, but would
suppress AT&T's data to users downlink: 734 - 746 MHz (Band 17):

Note that Verizon's 4G LTE frequency assignments are higher, with data to users,
downlink: 746 - 757 MHz and uplink: 776 - 787 MHz (Band 13):,2817,2388526,00.asp

Lower Block D (old Ch55): 716 - 722 MHz was until recently occupied by Qualcomm's
MediaFlo one-way transmitters, which were operating at 50 kW EIRP in our area.
FCC recently approved the sale to AT&T, but plans have not yet been fully revealed for
this UNPAIRED allocation (hence more suited for one-way broadcasts), other than for
additional capacity to users. LTE-Advanced (2014?) supports an auxiliary transmitter:

Lower Block E (old Ch56): 722-728 MHz appears to be sparsely populated (update needed).
Qualcomm bought a small number of UNPAIRED licenses in major metro areas and Frontier
bought a few locations:

LTE (Band 14) can occupy even higher frequencies: downlink: 758 - 768 MHz and
uplink: 788 - 798 MHz.

So an LTE LPF could be effective against some LTE Cell Tower transmissions, but
would be hit or miss against AT&T's uplink transmissions from user devices co-located
with your DTV....and the 1000's if not 10,000's of OTHER LTE device signals being
received by a roof-top YMMV....a lot....

I would expect that LTE LPF's specifically designed for North America's 700 MHz Band
should be coming to market in the near future....

SO....does this mean that I might have a problem since I'm in "AT&T Territory" (with a
major Cell Tower mountain only a couple miles away) and my son MIGHT have an easier
to solve (or NO) problem since he's in "Verizon Territory"????? [At least until they cross-mingle....]

While I'm not all that concerned with 1000 Watt EIRP (and under) Base Stations if they
are on nearby mountain tops, I would be very concerned if they were located on top of
convenient apartment and other hi-rise buildings. And those 50-kW monsters should
be confined to existing transmitter farms....still looking for a GOOD Cell Tower Locator
website that includes LTE operating frequencies....
holl_ands is online now  
post #131 of 149 (permalink) Old 2012-02-24, 06:18 AM
Join Date: Nov 2008
Location: San Diego, CA
Posts: 3,176
LTE Details for the Ubber-Geek:
Also known as Evolved UTRA (E-UTRA) and E-UTRAN. [UMTS LTE Intro] [LTE-Advanced Upgrade]

LTE Specifications:

Note that the LTE 3GPP Base Equipment Spec: TS-36.104 V10.5.0 (36104-a50.doc)
specifies +24 dBm max for one Base Station transmitter port and +20m dB max for
one Home Station transmitter port, both with +/- 2 dB tolerance for "normal" conditions
and +/- 2.5 dB tolerance under "extreme" conditions. When two or four transmit
ports are active at the same time (e.g. for Dual and Quad Transmit Diversity), the
output power is derated by -3 dB and -6 dB respectively to maintain the same average.
Antenna arrays (like DTV Transmitters) are use to provide Antenna Gain to reach the
desired EIRP.

LTE 3Gpp TS-36.101 V10.5.0 User Equipment Spec stipulates +23 dBm (+/- 2 dB)
Transmit Power with a 0 dBi Antenna Gain for Mobile User Devices, hence +23 dBm EIRP.

For convenience, I posted charts from FCC-OET 2005/2006 STB/DTV EMI Susceptibility
Test Report and U.K. OFCOM Cobham LTE Interference into DTT Test Results here:
holl_ands is online now  
post #132 of 149 (permalink) Old 2012-02-25, 02:17 PM
Join Date: Nov 2008
Location: San Diego, CA
Posts: 3,176
Verizon's 4G LTE (750+ MHz) Coverage Query by Address:
Nearly ALL of L.A., Riverside, Orange and San Diego Counties are covered.
Very detailed coverage with lots of small dead spots, so appears to be accurate,
derived from an actual propagation prediction program.
Zoom out to see Regional and National Coverage....mostly around large cities.

PS: Apparently NO COVERAGE for Camp Pendleton and busy I5 that runs through it.
Or maybe the prediction program overlooked it because of no street addresses.....
That's going to make it more difficult for families headed to Disneyland to keep
their kids entertained or business executives make updates to their presentations
while they zip through at 80+ mph....

AT&T's 4G LTE (700+ MHz) Coverage Query by Address:
Nearly ALL of L.A., Riverside, Orange, and San Diego Counties are allegedly covered,
although AT&T said that they only started San Diego service last month and won't be
FINISHED for "several more months".
But it doesn't show the many dead spots that users report, so it might be an
"artist's broad-brush mis-conception" other AT&T "coverage" maps....
Zoom out to see Regional and National Coverage....mostly around large cities, or use:

Canadian LTE Overview (from Rogers Comm. Inc.):

In Canada, the lower 700 MHz Band has not (yet) been auctioned off, although
there are trials underway in Ottawa.....networks MAY fire up late this year...prob 2013:
Note LTE will also be in AWS Band(s), which are much, much higher freqs...
holl_ands is online now  
post #133 of 149 (permalink) Old 2012-03-03, 04:07 PM Thread Starter
Join Date: Nov 2007
Location: Ottawa - Lees Ave
Posts: 325
The LTE at 700 is gone for now, but I guess I shouldn't be surprised to find out that theyve put up a few more transmitters in the 2100 MHz band pointed straight into my window, according to the Spectrum Direct service provided by Industry Canada. I added up the power and converted it to EIRP -- works out to about 15,000 watts in my direction alone. I have that nice buffer of 70 meters from the antenna though. Once they hit that magic 50,000 watts I'll have to get serious again - thanks for that Holl ands.

I forgot entirely about the letter they sent me back in May of last year. It goes something like this:

May 3, 2011
To Whom it may concern:

RCI conducted a visit to the Citadel Apartments located at 169 Lees Avenue, Ottawa on March 22, 2011. The purpose of the visit was to respond to a request concerning possible interference from Rogers' radio-frequency communication equipment into home electronics belonging to a tenant of the building, Mr Gerry B.

Observations confirmed that an electronic keyboard was producing audio noise while RCI's 700 MHz and 850 MHz radio transmitters were in operation. No degradation to the keyboard was observed while the radio transmitters were out of service. Degradation to the picture of a television receiver was also observed while Rogers' 700 MHz transmitter was in operation. A spectrum scan from 500 MHz to 3600 MHz confirmed that no significant contributions from other external sources were observed. It should be noted that the 700 MHz transmitter is currently operating under an experimental license granted by Industry Canada, which will expire on June 15, 2011.

Spectrum analyzer observations were performed using a Rhode & Schwarz FSH4 spectrum analyzer and a Rhode & Schwarz HE300 directional antenna. Rogers 700 MHz LTE carrier, 2100 MHz LTE carrier, 850 MHz UMTS carrier and 1900 MHz UMTS carrier were all visible. All carriers were clearly observed to drop when the transmitters were taken out of service. The observations confirmed that the Rogers carriers were present in their proper locations and that no spurious noise or other intrusions from the Rogers transmitters were seen at signal levels as low as -100 dBm, with the test equipment used.

Rogers confirms that no evidence was seen to suggest that Rogers transmitters were creating out of band emissions that would create interference into home electronic devices. Rogers also confirms there is an interaction between the Rogers transmitters and the affected electronics. The physical proximity of the Rogers antennas, the output power from the transmitters, the close proximity in frequency of the television receiver frequencies, are likely resulting in the desensitization of the television receiver, which does not have sufficient filtering capability to remove teh out of band signal. Since Rogers' equipment is not transmitting out of band and is operating according to Industry Canada license requirements, the resolution would therefore reside with Mr. B, the operator of the home electronics.

With regards to the degradation of the television, Rogers confirms that the experimental 700 MHz license under use will cease prior to June 15th, 2011, after which time Mr. B should not experience noticeable degradation as a result of Rogers' equipment. The electronic keyboard appears to be affected by both the 700 MHz carrier and the 850 MHz carrier. As noted, the interference from the 700 MHz system will cease on June 15th. Possible solutions to the interference from the 850 MHz carrier were considered in order to assist with the resolution of the issue, including the relocation of the antenna. This was determined to not be possible without impacting customer service since the coverage of the cell would be impaired.

Going forward, Rogers is agreeable to working with Mr. B to provide technical assistance and advice for helping him resolve his issues.


GerryB is offline  
post #134 of 149 (permalink) Old 2012-03-05, 09:42 AM
Join Date: Apr 2006
Location: Ottawa (Stittsville), ON, OTA (DB4e & VHF-HI folded dipole, AP-2870 pre-amp in Attic), MythTV HTPC
Posts: 6,248
Interesting letter Gerry. So they are basically admitting that they are causing problems, but they are within regulated limits so they aren't legally responsible, but out of good will are willing to help.

If they start transmitting again, I suspect they would be willing to buy a custom filter for you. Not sure if there is much they can do about your keyboard though (maybe buy you a new one that won't be affected, if one can be found).

Link to my TVFool results is in my profile Homepage URL. I suggest others do the same.
roger1818 is offline  
post #135 of 149 (permalink) Old 2013-10-08, 03:14 AM
Join Date: Nov 2008
Location: San Diego, CA
Posts: 3,176

Last year, 717-728 MHz was allocated as a DOWNLINK (Tower Broadcast) Supplemental Data Link (SDL), which should be available "soon" [likely already in selected "test" areas]. It will increase data rates in new HSDPA capable devices. SDL will become the PRIMARY interference source from 4G/LTE towers....and will be difficult to attenuate with a simple Low Pass Filter:

4G/LTE in 716 - 728 MHz presumably in upcoming Release 11 (see Slide 50):
holl_ands is online now  

Quick Reply

Register Now

In order to be able to post messages on the Canadian TV, Computing and Home Theatre Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Thread Tools Search this Thread
Show Printable Version Show Printable Version
Email this Page Email this Page
Search this Thread:

Advanced Search
Display Modes
Linear Mode Linear Mode

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome