Re: 23cm QRM


Dave - G4RQI
 

Hello…

If you don’t think it should be there why not just report it to ofcom? That’s what we did when we had problems in the 70cm band a couple of years ago. Ofcom came out and shut it down.

David


From: UKMicrowaves@groups.io <UKMicrowaves@groups.io> on behalf of ian hope (2E0IJH) <ian@...>
Sent: Saturday, February 26, 2022 9:33:22 PM
To: UKMicrowaves@groups.io <UKMicrowaves@groups.io>
Subject: Re: [UKMicrowaves] 23cm QRM
 
Not detectable in Gravesend across the Water from John Either, Is it a CCTV link? They can look similar to this? but strange part of band to find it
 
Ian
M5IJH
 
 
Sent: Saturday, February 26, 2022 at 8:59 PM
From: "John Lemay" <john@...>
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] 23cm QRM

Pete, Alwyn

 

Firstly the good news – it’s not detectable in Colchester. Good news for me anyway !

 

The spectrum bears some similarity to what I see from the nearby TV transmitter – multiplexed digital signals. See http://www.g4ztr.co.uk/amateur-radio/23cms/ and scroll down below the yagi pictures. Having observed the similar pattern it doesn’t make sense to me that it would appear on 23cms. So I may have offered a red herring.

 

I really must update my web pages ……….

 

John G4ZTR

 

 

 

From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Pete G4CLA via groups.io
Sent: 26 February 2022 20:03
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] 23cm QRM

 

Hi Alwyn,

 

It certainly seems to be coming from the Birmingham area. 

I don't have any expertise in the appropriate area of telecoms to offer a suggestion as to what the type of transmission it is. 

I wonder if others on some of the forums might know?

I thought Ben G4BXD might be able to help who lives SW of Birmingham I think and is QRV on 23cms?

 

Pete

 

On Sat, 26 Feb 2022 at 18:39, alwyn.seeds1 <a.seeds@...> wrote:

Dear All,

 

I have noticed a new QRM source on 23cm since the beginning of February.

 

It is present 24/7. It raises the noise floor at my site by 25 dB in 3 kHz bandwidth.

 

G4CLA, G0NZI, G8SEI and I have taken bearings on it and it seems to be located in Birmingham.

 

On J3E it sounds like hash/ ignition noise. It covers all of 1296MHz to 1298MHz and beyond.

 

Here is a spectrum analyser trace of it; 3 x 5MHz wide channels, the centre one overlapping the DX part of 23cm. (the peaks at the right of the scan are Clee Hill and other radars).

 

The centre frequency of the trace is 1295.33 MHz and span is 4 MHz/division. Vertical is 10 dB/division.

 

I checked the Ofcom frequency allocation table and can’t find anything like this listed.

 

1. Would anyone have a suggestion as to what it might be?

 

2. Are there any stations in the Birmingham area that could take bearings on it and report back, so that it can be located more accurately?

 

Thanks,

 

Alwyn G8DOH

 

 

 

 

 

 

_____________________________________________________

 

Alwyn Seeds, Director
SynOptika Ltd.,
114 Beaufort Street,
London,
SW3 6BU,
England.


SynOptika Ltd., Registered in England and Wales: No. 04606737
Registered Office: 114 Beaufort Street, London, SW3 6BU, United Kingdom.

_____________________________________________________

 

 

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