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DRM Interference from DW/BBC Broadcast Relay in Sines/Portugal

Discussion in 'Amateur Radio News' started by DL5RBW, Jan 17, 2009.

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  1. DL5RBW

    DL5RBW Guest

    For over a year now the Deutsche Welle/BBC transmissions from the Sines/Portugal Relay are interfering with amateurradio communications on 14 MHz. The transmission starts 0803z until 1400z on 13810 kHz and continues from 1400z to 1600z on 13590 kHz. The beam is 30 degrees which means Central Europe with a power of 90 kW. If you tune to these frequencies you will hear a "diesel engine" like noise. By the way its only the Sines Relay Station that causes the problem therefore its not a DRM problem (DRM is NOT necessarily QRM!) but a transmitter adjustment problem.

    Many people are not aware of this interference and take it as an atmospheric, military or local man made noise. The interference is wideband (up to 14400 kHz) and sounds like rainstatic. It reaches up to S9 at times with the antenna pointed towards Portugal which for Central Europe means QTF 245 degrees. People with a spectrum analyzer will notice a wideband increase of the noise level on 14 MHz of 5 to 10 dB!! But more impressive is the crackling noise that one can hear with every receiver (transceiver). If you have a 2 receiver radio or 2 separate receivers you may follow the QSB on the BC transmitting frequency and the crackling noise on a clear frequency somewhere in the 20 m band.

    Discussions with the DW and the authorities didn´t result in any improvement so the only way it seems is a combined effort in writing as many complaints as possible to the DW.

    From the schedule above one can see that the problem seriously degrades communications for the time with the best propagation in that direction.

    Lets not get the Broadcasters away with something like this but help to keep the bands as clean as possible by filing a complaint TODAY:

    More info and where to direct your complaint:

    http://www.dw-world.de/dw/article/0,,1777509,00.html

    Here is the announcement of the cooperation with BBC beginning 2009:

    http://mt-shortwave.blogspot.com/2008/11/test-begin-for-bbcdw-drm-service-to.html


    Thanks for your cooperation!

    73s Roger, DL5RBW
     
  2. CT4RK

    CT4RK Ham Member QRZ Page

    Dear friends

    THis is the most strange fact that I seen. I believe that any strange fenomena existe but why I canot listen any noise in Sines during the transmission...I`m hight RF technician in the DW station in Sines, and I`m the first interested to keep our QRG clean, and for this, I was make a exaustive investigation, aroun the station, in the antenna field, and in the transmitter, to try find something wrong, but canot find nothing. I was caloborate with ANACOM, the portuguese autority, and during 2 days we are make a lot of measurements in the transmitter and around the antenna fields, and canot find noise in the 20m band....this was make some times in front to the cortain antenna, at about less than 1 km!!!!...Incluse, I have able to make 20m QSOs, in my car, using a IC706 and an Hustler antenna, inside of the antenna field. Also in my mobil station, a canot listen noise from DRM, also in the neighbors of the antenna, field (about 2,5 km away in the beam), with a field strenght of 7V/m.

    Please do not clame war, I was made a exaustive work about this, but what can I do more, if I canot find this noise in the station or in my QTH in Sines? Help me to find wath is wrong. I have the shape from spectrum analizer that show the noise -90dBs down relative to pick power on the output of the transmitter. On the air measurements, with the spectrum analyzer, with a SSB transceiver setings, (RBW 3KHz and VBW 1KHz) show a 20m clean band.
    Maybe an intermodulation product with other strong transmission...I canot find explanation for this!!!!

    Any question please contact me by email radiofarol@gmail.com

    73 from CT4RK
    Carlos Mourato
    Sines
     
  3. KL7AJ

    KL7AJ Premium Subscriber QRZ Page

    I agree this could be an intermod situation, or even the Luxembourg effect...mixing in the ionosphere with another station. It's unlikely that a DRM signal would be THAT broadbanded, since that would result in considerable power and signal loss ON frequency. Broadcast stations have a vested interest in clean operation...it's incredibly EXPENSIVE to put any R.F. out where it won't do any good.

    It's possible there is some jamming going on...I've been hearing powerful white noise jamming just above 4MHz for the past couple of months....shades of the Cold War era stuff.

    I haven't heard the 20 meter interference up here (yet). This sort of situation calls for some systematic DFing, at the very least. Then with some real data, we can approach the powers that be.

    Eric
     
  4. KA5S

    KA5S Ham Member QRZ Page

    I'd suspect rusty bolt effect. That has to be hunted down in the high RF field area around the antennas, as it does not exist in RF going to them.


    Cortland
    KA5S
     
  5. CT4RK

    CT4RK Ham Member QRZ Page

    Hi all my friends

    Thanks for alll your help. You can shure that me, CT4RK, are the most interested in keep our QRG clean. I`m an active amateur radio and I like very much the HF operation, and I`m active member against BPL/BLC tecnology. Not only me, but also CT1ADT, another active Ham radio working in the station and is a denfensor of HF spectrum.

    Our transmitters in the DW station, are "stat of art" TX, with the most advanced thomcast DRM system, and all the DRM transmitters are full automatic tuned, and most of time fine retuned by me, and continuously monitorized by an advanced monitor receiver, with a spectrum analyzer incorporated, that permite monitoring continuously in the comand room the transmission. Our transmitters (DRM is send by all our transmitters and not by only one) contrary to what DL5RBW said, are perfectly tuned, and in acordance with the ITU RR. This is confirmed by ANACOM the portuguese autority for comunications, that was make an extensive work, with me, to confirm that ABSOLUTE NO QRM are outside of ITU mask.
    In my Station, in Sines, I have a lot of TRX. The most used is FT1000 MP MKV, but I was try find the noise with all of them, and canot listen nothing.
    The in frequency signal, (13810 KHz and 13590 KHz) are above 59+50, my QTH are only 10 km away from the Station.
    During time, I was tell to the amateur in the station area, for monitoring the 20 m and try finding any QRM from DRM (CT1ADT, CT1EOM, CT1UW, CT2GQL etc), and they can`t listen any QRM during the DRM transmission on 13 MHz band.

    By the way I ask for calm to DL5RBW, tell him that the DW STATION in Sines are runing without any problem, ( I can send you the spectrum analyzer picture during my work around this problem), and with the help of all our friends, we can find an explanation for this fenomena. Maybe this is a real "in field" , very interesting exercice for amateur radio investigation. For mi, I`m 100% available for try finding an explanation.

    Thanks again for your help

    73 from CT4RK
    Sines Portugal
     
  6. K4KYV

    K4KYV Premium Subscriber Volunteer Moderator QRZ Page

    We have a similar problem in the US during prime evening hours on 75m. The DW station transmitting on 3995 completely wipes out a swath between 3990 and 4000 kHz with what sounds like white noise. There is a weaker one lower in frequency that takes out a swath between 3960 and 70. I have heard a couple of these on 40m as well.
     
  7. KA5S

    KA5S Ham Member QRZ Page

    That is the permitted bandwidth for the DRM signal; it is on a frequency that in Europe is allotted to broadcasting.

    The problem reported here is that the DRM signal is heard interfering well away from its occupied bandwidth. This can be transmit intermod, rusty bolt effect, or even receiver intermod. IMO, any decent roofing filter should deal with the latter in this case.

    Cortland
    KA5S
     
  8. NV8X

    NV8X Ham Member QRZ Page

    intermod

    I hope it is not 146.610 repeater causing the problem it has southwest Ohio screwed up now with interference.
    nv8x
     
  9. DL5RBW

    DL5RBW Guest

    Hi Carlos and all,

    thanks for your effort in tracking down the signal. I talked with Jürgen (DL4??) at DW headquarters in Germany on the phone a couple of times and he could not find any problems either.

    Anyhow this is an ongoing issue for over a year now and I involved a number of amateur radio operators all over Germany including the DARC monitoring station to make sure its not a local problem with my station. All of the people involved are affected by this noise too so a local effect on my side can be excluded.

    Don´t get me wrong I dont want to start a war its just that I (and the amateur radio in general) cannot accept an interference thats covering 400 and more kHz. Of course the interference is down about 70 dBs however as the DRM signal is 50 to 60 mV!!(@50 Ohm) it means that the interference is still peaking S9.

    As pointed out by someone else if you do consider how much power is "wasted" in the interference at this level and this bandwidth it would be more useful to put this energy in the signal ON the spot.

    You can see the report of the DARC monitoring station here right at the bottom (Notice board)

    http://www.iarums-r1.org/iarums/latest.pdf

    While I am writing this I am talking to local ham who complains about the noise which rendered DX contacts he wanted to make impossible.

    Anyway we can discuss offline and maybe I can help you to track the source of interference although its strange that the interference is not detectable at the Sines site and causing trouble here Central Europe. 90 kW of DRM power is not enough to create nonlinear effects in the ionosphere and if rusty bolts for example would be the source it would be detectable at the transmitter site as well.

    As I am in the High Power Broadcast Business myself I have some experience so the most obvious problems have been checked out.

    73s Roger, DL5RBW
     
  10. G0IFI

    G0IFI Ham Member QRZ Page

    I can't reproduce the problem here in Southwest England with any receiver/antenna combination, so the probability is quite high of some 'luxemburg' mixing effect local to the QTH of dl5rbw. Both 13.590 and 13.810 TXs are extremely strong here every day, but the transmission looks very clean when the IF stages of my RX are viewed on a scope.

    I really hope the guys in your QTH can find the answer, losing the use of the 20m band isn't something you can afford.
     
    Last edited: Feb 9, 2009
  11. M0BCT

    M0BCT Ham Member QRZ Page

    At Last I've found someone else who is also receiving this QRM in the 20m band. I had begun to wonder if there was something wrong with my tranceiver or the inrad roofing filter.
    I live in Suffolk on the East coast of the UK and have been getting this Qrm for a while now. It is not a problem when beaming out to the East or west But very strong when beaming long path ZL North Island or to South America etc, which is 230 deg from here, and passes clean through Portugal. I have experimented with one receiver tuned to 13.810Mhz, and another receiver listening within the 20m band, and the Qrm will "switch" off at exactly the same time as the DRM transmission. Approximately 14:00hrs gmt. Now I will freely admit that I'm not a radio engineer type but do enjoy the hobby and this qrm is a problem. It does seem odd how some seem to suffer and some do not. For the record I use an FT1000MP mk5 Field fitted with the Inrad roofing filter.
    I shall watch this thread with interest, and would be interested to hear of any other groups or forums discussing this issue.

    Vy 73
    Martin
    M0BCT
     
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