PSN-L Email List Message

Subject: Re: predictions and arrivals
From: ChrisAtUpw@.......
Date: Fri, 15 Sep 2000 18:42:16 EDT

Hello John Tacinelli,

    Have you now cured your local interference problem from radio station 
K0LM on 1.52 MHz? A short report saying how you achieved it could be useful 
to other members. Are you completely immune now?

> On another subject, I have gotten several very strange arrivals lately. The 
> other night, I got three arrivals each about the same size at around 2am.  
> They were a few minutes apart. They start as a fairly large arrival then 
> decrease monotonically over about 1 minute. It looks like something jostled 
> the instrument but when that actually happens the response is very 
> Also, every time this happens, the waves are the same size. They don't seem 
> to be related to any earthquake. I have occasionally gotten them during the 
> day as well.

    Do they correlate with anything in your building? If they are roughly the 
same size, this suggests a repeated action by some source. Like the 
ventilation system switching, or open windows when there is a wind, or a 
night watch patrol slamming doors? Are any very heavy objects moved about / 
dropped? Rubbish skips? Can you use the signals to switch on a tape recorder 
+ mike? A sound recording might suggest a possible source. A piezo sounder 
disk with a nut glued to the centre makes a good cheap acceleration / noise 
sensor. I use a BF244A FET with a 10 M input resistance and choose an emitter 
resistor to give about 0.1 to 0.5 mA to suit the input circuit of the 
recorder, with a 100 mu F capacitor across it.

    Do you have any rats, mice, bats, birds about? It is quite surprising 
what you see if you connect an Infra Red Camera + recorder to a PIR heat 
detector trigger. I had a problem with rats coming through the hole in a wall 
from next door. The Council 'Rodent Operative' was not very interested, so I 
fixed up a PIR trigger + counter. I clocked 25 the first night and 39 the 
second. He visited me on the third day and put down seed/poison bait. The 
count dropped to near zero and then went up to several hundred. I used an IR 
camera and found tiny voles about half the size of a small finger jumping 
onto the plastic dish, grabbing a mouthful of seeds and leaping off again. 
Their prominent eyes glowed bright in the IR. It was marginally more 
entertaining than the TV. They are apparently immune to the rat poison and 
acted like they hadn't had a feast like this in years! 

    Insects in general and spiders in particular can cause problems. Shell 
sell Vapona 'insect strips'. You just hang a strip of orange plastic about 
the size of a large chocolate bar inside your enclosure and the dichlorvos 
slowly evaporates. You can also probably still get camphor and maybe BHC 
'mothballs'. Nocturnal insects that you normally don't see pose the greatest 
> I am thinking it might be an explosion somewhere, such as a 
> quarry. Has anyone ever recorded anything like that?

    Explosions at 2 am don't sound very likely. Quarrying and building 
demolition tend to take place during daylight / working hours. Check if there 
is any mineral extraction near you. Coal, Iron, etc.? It doesn't have to be 
explosions. Underground roof falls in mines can produce large seismic signals.

    Do you have a railroad with goods trains anywhere near you?  Or site 
which handles heavy road vehicles and has an uneven / potholed road? I used 
to get woken up by car transporters hitting a depressed manhole cover in the 
road outside.


    Chris Chapman

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Larry Cochrane <cochrane@..............>