Re: LF: RE: Who's playing on 503.7

[Andy Talbot <andy.g4jnt@googlemail.com>]

continued ...

 

The black trace gives it away.  If there is extended  QRM that spans  the noise measurement period (which is the WHOLE minute before) and the 5s Tx period it will show up on both.   The different system of noise measurement explains why the (no QRMed) green and blue traces are not sitting on top of teh black trace.   Ideally, with no signal there, they should.

Andy  G4JNT
www.g4jnt.com

2009/3/17 Andy Talbot <andy.g4jnt@googlemail.com>

I filled in a couple at 1800, deliberately, by flicking the test switch on my beacon Tx.   But there are too many peaks on the green annd blue traces to not suspect someone else is firing up a Tx.

 

Its not a case of false decodes - there's not such thing as a 'decode' with this monitoring S/W.   All it does is to measure the signal power over precisely  this time slot, using a synchronised FFT with a bin size of 0.2Hz, which after windowing gives about 0.4Hz noise bandwidth.  So any QRM would have to be quite strong to make a significant impact, and persist over 5 seconds.   Short spikes get  averaged out to not-a-lot.

 

Did the messages about the modified beacon timing software get though this reflector - don't appear to see them in the in box?

 

If not,  http://www.g4jnt.com/beacons.htm at the bottom look for PCBCN

Directly, http://www.g4jnt.com/PCBCN.zip

 

Andy  G4JNT
www.g4jnt.com

2009/3/17 Gary - G4WGT <g4wgt@tiscali.co.uk>

Hi Andy, LF,

 

I have not detected anything here other than your Tx.

 

I was going to e-mail anyway because I have some false decodes on the 5 & 6 minute slots, see list below. These coincide with high bursts of noise which I experience here from time to time. Is there an issue with the decode software being “foxed” by high noise level?

 

Gary – G4WGT.

 

15:45  40.35  25.76  -240.0  0.0

15:46  41.05  25.76  -240.0  1499.5

15:47  39.52  25.76  -240.0  0.0

16:00  41.70  25.75  -240.0  1499.5

16:01  41.62  25.75  -240.0  1510.6

16:02  31.49  25.75  -240.0  0.0

16:15  40.10  25.47  -240.0  0.0

16:16  30.16  25.47  -240.0  0.0

16:17  29.17  25.47  -240.0  0.0

16:30  37.85  28.93  -240.0  0.0

16:31  41.80  28.93  -240.0  0.0

16:32  36.23  28.93  -240.0  0.0

16:45  40.98  25.80  -240.0  1499.6

16:46  29.45  25.80  -240.0  0.0

16:47  30.17  25.80  -240.0  0.0

17:00  35.23  25.58  -240.0  0.0

17:01  28.35  25.58  -240.0  0.0

17:02  35.28  25.58  -240.0  0.0

17:15  45.32  25.10  -240.0  1499.4

17:16  30.14  25.10  -240.0  0.0

17:17  27.57  25.10  -240.0  0.0

17:30  51.09  25.30  -240.0  1499.5

17:31  53.16  25.30  -240.0  1499.6

17:32  30.18  25.30  -240.0  0.0

17:45  47.93  25.21  -240.0  1499.5

17:46  48.63  25.21  -240.0  1499.5

17:47  49.12  25.21  -240.0  1499.5

18:00  38.75  34.29  -240.0  0.0

18:01  32.01  34.29  -240.0  0.0

18:02  28.89  34.29  -240.0  0.0

18:15  51.36  26.01  -240.0  1499.6

18:16  38.85  26.01  -240.0  0.0

18:17  40.74  26.01  -240.0  0.0

18:30  43.06  24.96  -240.0  1499.5

18:31  29.24  24.96  -240.0  0.0

18:32  29.61  24.96  -240.0  0.0

18:45  36.98  26.26  -240.0  0.0

18:46  34.87  26.26  -240.0  0.0

18:47  36.14  26.26  -240.0  0.0

19:00  50.09  26.57  -240.0  1499.7

19:01  42.04  26.57  -240.0  1518.0

19:02  28.58  26.57  -240.0  0.0

 

 

 

---

From: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Andy Talbot
Sent: 17 March 2009 19:48
To: rsgb_lf_group@blacksheep.org
Subject: LF: Who's playing on 503.7

 

OK, Who is it?

We can see you

There's activity in the 5 and 6 minutes slots.

 

 

Andy  G4JNT
www.g4jnt.com