449 UK simple irritating noise?

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Andy
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449 UK simple irritating noise?

Post by Andy » 27 Nov 2019, 11:23

I used to listen quite a lot to the 449 MHz simple channels, but over the last few years there an annoying fast chuffing sound spoiling all the channels. It makes listening almost impossible. I suppose it's data of some description...? {bnghd}
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Re: 449 UK simple irritating noise?

Post by thelad » 27 Nov 2019, 17:20

Yep more and more DMR handys around now.
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Re: 449 UK simple irritating noise?

Post by 26mb04 » 01 Dec 2019, 01:49

It's digital.... You'll need an SDR to listen to it, unless you have access to a DMR radio and know the colour code etc. Some DMR radios have promiscuous mode which allow you to listen to the frequency regardless of what the talkgroup settings etc are. SDRs are available on the net for very little money, and the software is free (I used to use gqrx).

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Re: 449 UK simple irritating noise?

Post by Goffy » 01 Dec 2019, 06:36

Andys description of the noise doesnt sound like DMR. I've heard a similar chuffing sound elsewhere but not on 449,

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Re: 449 UK simple irritating noise?

Post by thelad » 01 Dec 2019, 08:31

http://www.w2sjw.com/radio_sounds.html

Section 3 on the link may help ID it.
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Re: 449 UK simple irritating noise?

Post by jhampton2000 » 01 Dec 2019, 14:46

DMR Simplex (or input to a repeater) sounds like a fast chuffing noise. DMR Repeater sounds like a buzzing noise. Quite common to have DMR simplex on Simple UK Light frequencies.

Setting a CTCSS or DCS tone (if used, and if your receiver has this feature) may help you continue to listen to analogue.

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Re: 449 UK simple irritating noise?

Post by Mikel » 01 Dec 2019, 17:21

Yeah, it's DMR simplex as you say, and becoming more frequent around here as well - very irritating!
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Re: 449 UK simple irritating noise?

Post by Andy » 01 Dec 2019, 17:30

Yup, it sounds just like FDMA DMR in that link. Thanks. Bloody annoying though.
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Re: 449 UK simple irritating noise?

Post by 26mb04 » 01 Dec 2019, 19:44

I could be wrong, but I think the site you linked to isn't quite accurate. The bit in Section 3 says DMR is TDMA when used through a repeater, and FDMA when used simplex. This is incorrect, simplex mode still uses TDMA. FDMA is used by dPMR, which is not DMR. The link marked FDMA mode is actually TDMA, but only 1 timeslot instead of 2.

The SigID wiki has a page on DMR here

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Re: 449 UK simple irritating noise?

Post by thelad » 02 Dec 2019, 06:18

26mb04 wrote:
01 Dec 2019, 19:44
I could be wrong, but I think the site you linked to isn't quite accurate. The bit in Section 3 says DMR is TDMA when used through a repeater, and FDMA when used simplex. This is incorrect, simplex mode still uses TDMA. FDMA is used by dPMR, which is not DMR. The link marked FDMA mode is actually TDMA, but only 1 timeslot instead of 2.

The SigID wiki has a page on DMR here
Yes i spotted that myself.
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Re: 449 UK simple irritating noise?

Post by Goffy » 02 Dec 2019, 10:30

Ah of course. I had forgotten that simplex dmr sounds very different to the saw type sound of a dmr repeater.

Slight hihack here. The example of an idling channel on the sigid wiki sounds like what I've heard on my local hospitals frequency. I'm not what an idling channel is. Voice or data?

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Re: 449 UK simple irritating noise?

Post by Cornelius » 02 Dec 2019, 11:55

449 MHz Simple - is that UK-only frequencies? Like we here in Norway (and Sweden) have 444 MHz?

Or are you talking about 446 MHz? :)

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Re: 449 UK simple irritating noise?

Post by thelad » 02 Dec 2019, 12:29

Cornelius wrote:
02 Dec 2019, 11:55
449 MHz Simple - is that UK-only frequencies? Like we here in Norway (and Sweden) have 444 MHz?

Or are you talking about 446 MHz? :)
Here in the uk "449 Simple" or "Simple Light" are a handful of frequencies both Uhf and Vhf that Ofcom provide the use of for a fee of £75 for 5 years. You can only use a handheld up to a max of 5W, alot of UK Supermarkets and Businesses use them.
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Baofeng BF-888
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Baofeng UVB5
Zastone D900
Icom IC-R6

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Re: 449 UK simple irritating noise?

Post by Cornelius » 02 Dec 2019, 17:15

thelad wrote:
02 Dec 2019, 12:29
Cornelius wrote:
02 Dec 2019, 11:55
449 MHz Simple - is that UK-only frequencies? Like we here in Norway (and Sweden) have 444 MHz?

Or are you talking about 446 MHz? :)
Here in the uk "449 Simple" or "Simple Light" are a handful of frequencies both Uhf and Vhf that Ofcom provide the use of for a fee of £75 for 5 years. You can only use a handheld up to a max of 5W, alot of UK Supermarkets and Businesses use them.
Ok, don't have that here exactly, but anyone can lease a frequency on Vhf or Uhf on a yearly basis, priced per unit in use (currently around £30 i think); handheld are max 5W, and base/car stations max 25W - repeaters are also allowed (priced higher per unit).
Though, not many private persons lease their own frequency here, mostly because many people here are active hunters, and they have their own frequencies on Vhf through their hunting-teams... :)

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Re: 449 UK simple irritating noise?

Post by 26mb04 » 02 Dec 2019, 17:56

Goffy wrote:
02 Dec 2019, 10:30
Ah of course. I had forgotten that simplex dmr sounds very different to the saw type sound of a dmr repeater.

Slight hihack here. The example of an idling channel on the sigid wiki sounds like what I've heard on my local hospitals frequency. I'm not what an idling channel is. Voice or data?
Idling noise could just be residual data being sent across a repeater output (status requests, GPS data, random telemetry etc) in which case a DMR (voice) radio would be silent despite there being data on the channel. It could also be synchronisation packets, one of the drawbacks with DMR over dPMR is that DMR users MUST be synchronised with each other and the repeater (if used) or the whole thing falls apart.

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