Cable TV: Strong Pager Signals cause interference to Cable Channels.

Cable TV: Strong Pager Signals cause interference to Cable Channels.

Post by Jason » Fri, 18 Jun 1999 04:00:00

The source of the herringbone pattern interference is caused
by high power transmitters that broadcast pager signals.

I used to have the same problem with (cable) channel 19,
which has a frequency range from 150-156 MHZ.

I realized that the interfering signal was originating from
 Outside  of the cable system.  I purchased a scanner radio,
and searched between 150-156 MHz and found a
Extremely powerful pager signal broadcasting at 152.540 MHz.

The Cable Ch. 19 Video Carrier is at 151.250 MHz,
and the pattern of the interference matched the pager tones.

What are the frequencies for cable channel 68?

Are there any pager frequencies near Ch. 68?

Locate the pager transmitters in your area, click here:
http://gullfoss.fcc.gov:8080/cgi-bin/ws.exe/beta/genmen/state_county.hts

Enter your state and county, search the paging and radiotelephone
service, click on WTB Paging Database.
---


> A cable person came last night and said he had no idea
> why I had a Herringbone on the upper channels-he checked
> the pole and put on a new splitter-he also disconnected
> the neighbors cable at the pole to see if anything changed.  

> He said he would turn it over to maintenance.

> he also said I had an ac hum and when the ground was removed the
> hum disappeared-so I left it off.  He said he would order me an
> electric isolator for the pole.

> He said the herringbone on 68 the MSG channel could never be
> repaired because there was usually a station that bleeded
> through.

> Can anybody help?

--------
 
 
 

Cable TV: Strong Pager Signals cause interference to Cable Channels.

Post by Stev » Sat, 19 Jun 1999 04:00:00


Nope, Thats called ingress. Close but no cigar!

> The source of the herringbone pattern interference is caused
> by high power transmitters that broadcast pager signals.

> I used to have the same problem with (cable) channel 19,
> which has a frequency range from 150-156 MHZ.

> I realized that the interfering signal was originating from
>  Outside  of the cable system.  I purchased a scanner radio,
> and searched between 150-156 MHz and found a
> Extremely powerful pager signal broadcasting at 152.540 MHz.

> The Cable Ch. 19 Video Carrier is at 151.250 MHz,
> and the pattern of the interference matched the pager tones.

> What are the frequencies for cable channel 68?

> Are there any pager frequencies near Ch. 68?

> Locate the pager transmitters in your area, click here:
> http://gullfoss.fcc.gov:8080/cgi-bin/ws.exe/beta/genmen/state_county.hts

> Enter your state and county, search the paging and radiotelephone
> service, click on WTB Paging Database.
> ---


> > A cable person came last night and said he had no idea
> > why I had a Herringbone on the upper channels-he checked
> > the pole and put on a new splitter-he also disconnected
> > the neighbors cable at the pole to see if anything changed.

> > He said he would turn it over to maintenance.

> > he also said I had an ac hum and when the ground was removed the
> > hum disappeared-so I left it off.  He said he would order me an
> > electric isolator for the pole.

> > He said the herringbone on 68 the MSG channel could never be
> > repaired because there was usually a station that bleeded
> > through.

> > Can anybody help?
> --------

 
 
 

Cable TV: Strong Pager Signals cause interference to Cable Channels.

Post by F Barry Mulliga » Sat, 19 Jun 1999 04:00:00


Quote:> What are the frequencies for cable channel 68?
> Are there any pager frequencies near Ch. 68?

    Cable channel 68 runs from 484 to 490 MHz, with the video carrier at
485.250. This overlaps the broadcast TV channel 16 at 482-488 MHz. If an
external signal is leaking into the cable system it may be a broadcaster
or a mobile radio service. 482-488 MHz is allocated for Land Mobile use
in the Boston, Dallas/Ft. Worth, Detroit, and San Franciso/Oakland areas.

From the  FAF - Frequently Asked Frequencies
      on  ftp://oak.oakland.edu
      as  /pub/hamradio/docs/misc/scanner.faf

Television                                                  [73.603]

        Ch      Range       Video      Audio

         2     54 -  60     55.250     59.750
         3     60 -  66     61.250     65.750
         4     66 -  72     67.250     71.750
         5     76 -  82     77.250     81.750
         6     82 -  88     83.250     87.750
         7    174 - 180    175.250    179.750
         8    180 - 186    181.250    185.750
         9    186 - 192    187.250    191.750
        10    192 - 198    193.250    197.750
        11    198 - 204    199.250    203.750
        12    204 - 210    205.250    209.750
        13    210 - 216    211.250    215.750
        14    470 - 476    471.250    475.750   }
        15    476 - 482    477.250    481.750   } Range for Ch. N
        ..    ... - ...    .......    .......   }   Low  = 386 + 6*N
        68    794 - 800    795.250    799.750   }   High = 392 + 6*N
        69    800 - 806    801.250    805.750   }

        Note the gaps between chs 4/5, 6/7, and 13/14.
        Freqs in the 470-512 MHz range (Ch 14-20) may be assigned to
    Public Service mobile use in major metro areas.  No transmitters
    are allowed on 608-614 MHz (Ch 37).
        Each TV channel is 6 MHz wide. The video carrier is 1.25 MHz
    above the start of the range. The audio carrier is 0.25 MHz below
    the end of the range. Television audio is wideband FM.
        Some TV stations may be offset +/- 10 kHz.

    Cable TV  (IRC)                                         [76.605]
                                                        [EIA IS-132]
                   Ch         MHz
                 2 - 13     54 - 216     (same as broadcast VHF)
                14 - 22    120 - 174     Mid band     Ch. A-I
                23 - 36    216 - 300     Super band       J-W
                37 - 53    300 - 402     Hyper band       AA-QQ
                54 - 64    402 - 468       "    "
                65 - 94    468 - 648    (Ultra band)
                95 - 99     90 - 120     Low band         A5-A1
               100 -125    648 - 804    (Ultra band)

 
 
 

Cable TV: Strong Pager Signals cause interference to Cable Channels.

Post by someb.. » Sat, 19 Jun 1999 04:00:00

The frequency range for channel 68 (EIA) is 486-492 MHz.  The
interference you see on channel 68 is, most likely, caused by a UHF TV
station broadcasting on channel 16 or 17.  UHF off-air frequencies are
2 MHz off of the cable designated (EIA) frequencies.  This means that
one UHF station can interfere with two cable channels.  

Hope this helps.

TB


>The source of the herringbone pattern interference is caused
>by high power transmitters that broadcast pager signals.

>I used to have the same problem with (cable) channel 19,
>which has a frequency range from 150-156 MHZ.

>I realized that the interfering signal was originating from
> Outside  of the cable system.  I purchased a scanner radio,
>and searched between 150-156 MHz and found a
>Extremely powerful pager signal broadcasting at 152.540 MHz.

>The Cable Ch. 19 Video Carrier is at 151.250 MHz,
>and the pattern of the interference matched the pager tones.

>What are the frequencies for cable channel 68?

>Are there any pager frequencies near Ch. 68?

>Locate the pager transmitters in your area, click here:
>http://gullfoss.fcc.gov:8080/cgi-bin/ws.exe/beta/genmen/state_county.hts

>Enter your state and county, search the paging and radiotelephone
>service, click on WTB Paging Database.
>---


>> A cable person came last night and said he had no idea
>> why I had a Herringbone on the upper channels-he checked
>> the pole and put on a new splitter-he also disconnected
>> the neighbors cable at the pole to see if anything changed.  

>> He said he would turn it over to maintenance.

>> he also said I had an ac hum and when the ground was removed the
>> hum disappeared-so I left it off.  He said he would order me an
>> electric isolator for the pole.

>> He said the herringbone on 68 the MSG channel could never be
>> repaired because there was usually a station that bleeded
>> through.

>> Can anybody help?
>--------