Hi LF folks,
SID effects are mainly caused by solar EM radiation
and D region effects by hard X-rays. So they travel
with about the same speed than visible light does.
SID's are labelled according to observation method
involved. SWF's are observed on low HF measurements.
Of those SID's of interest to LF community SPA
(Sudden Phase Anomaly) is normally obscure for us.
SES (Sudden Enhancement of Signal) is known to
VLF people but can be detected on LF quite often.
A good part of LF group consists of veterans, so
most of you know all this better than I know...
I need some advice, please: Have been trying to
record LF signal levels with ESH2 DC rec output
connected to Pica ADC on LPT1. Funny things happen:
- Using Pica DOS software results of abt 20 dB less
(extra) noise level than Pica Windows software.
Don't remember any explanations for that...
Sort of analogous to using Gram (Windows)
or Specgram (DOS) on audio scanning via SB.
Can only use Specgram on freqs lower than 500 kHz.
The ESH2 -> LPT1 cable is too long (3 m) and is a
normal thin 50 ohm coax. Any advice how to cut at
least some of the noise? Any optical isolators for DC?
73 de Vaino, OH2LX
----- LAWRENCE MAYHEAD wrote:
---------------------------------------------------------
Extract from Daily Telegraph today:-
"A recent Sun flare that has caused a radio blackout has prompted
scientists to warn that the Earth will be most at risk from the effects of
space weather later this year.....Just after the latest flare the Solar and
Heliospheric Observatory recorded the dramatic ejection of
material......The Flare on February 5,caused a radio blackout for about an
hour.In extreme cases,such storms can induce currents in the Earth and
oceans that can interfere with or even damage power transmission
equipment.Solar forcaster Essi Ellis said that disruptions will become more
common as the solar cycle picks up with a peak expected in mid-2000".
So can we assume that the exceptional conditions reported by Larry Kaiser
were related to this Flare on 5 feb.if so there is a delay of one week
between the event and the change in propagation! is this unique or has it
been observed before?Usually SIDs appear to be associated with increased D
layer absorbtion and consequent radio blackouts.Perhaps there is another
mechanism in the recovery of the ionosphere from such an event which
results in the dramatic improvement in propagation noted by Larry.There
must be something about all this in the literature?and it would certainly
help to know how long after a flare some changes can be expected.At any
rate from the forecasts our best chances are yet to come in mid -2000,so
keep up the good work,Larry and all. 73s Laurie. .
----------------------------------------------------------
V.K.Lehtoranta, OH2LX, POBox 50, FIN-05401 Jokela, Finland
------ Tel: +358-9-4173965 ---- Fax: +358-9-4173961 ------
E-mail: [email protected] - alias: [email protected] & [email protected]
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