nope far from it, shropshire west midlands.

Radio waves bounce off the Ionosphere hence its height depends on whether they reach you or miss you.



if someone suggests that to me on a job ill faint.

agreed but i do get the french lady at night on 612kHz all the way to shropshire.

However i query my router with routerstats every 5 seconds and the change would not be so sudden as it obviously is. I doubt my issue is anything with the expected drop in snr at night, this is certainly noise caused by a device.

Edited by deleted (Sun 26-Dec-10 00:54:58)

you will need to raise it with your provider and get an sfi job booked.

mention to the engineer you know what you are on about and ask him to raise it with rein department. its a very difficult process though, sometimes taking weeks to track down a source.

In reply to a post by andyboygsi:

Radio waves bounce off the Ionosphere hence its height depends on whether they reach you or miss you.



if someone suggests that to me on a job ill faint.

Ah, so you don�t believe that radio waves bounce of the earth's ionosphere How do you think terrestrial RF transmissions get around the world, and why do some broadcast stations change their frequencies dependant on the time of day.

Remembering that ADSL2+ uses the frequency range 100Khz to 2.2Mhz, any radio frequency transmission within those frequencies that arrives at your router input affects the ADSL2+ signal. One of the worst in the UK is the Droitwich transmitter on 1.5 MHz (199 metres), 612 KHz is 489.5Metres.

When you listen to the French Lady the signal is probably varying in strength, because the Ionosphere layers are changing all the time.

Perhaps this might help

When a radio wave reaches the ionosphere, the electric field in the wave forces the electrons in the ionosphere into oscillation at the same frequency as the radio wave. Some of the radio-frequency energy is given up to this resonant oscillation. The oscillating electrons will then either be lost to recombination or will re-radiate the original wave energy. Total refraction can occur when the collision frequency of the ionosphere is less than the radio frequency, and if the electron density in the ionosphere is great enough.

The critical frequency is the limiting frequency at or below which a radio wave is reflected by an ionospheric layer at vertical incidence. If the transmitted frequency is higher than the plasma frequency of the ionosphere, then the electrons cannot respond fast enough, and they are not able to re-radiate the signal. It is calculated as shown below:


where N = electron density per cm3 and fcritical is in MHz.

The Maximum Usable Frequency (MUF) is defined as the upper frequency limit that can be used for transmission between two points at a specified time.


where � = angle of attack, the angle of the wave relative to the horizon, and sin is the sine function.

The cutoff frequency is the frequency below which a radio wave fails to penetrate a layer of the ionosphere at the incidence angle required for transmission between two specified points by refraction from the layer.

Also this might help

Radio frequencies and their primary mode of propagation
Band Frequency Wavelength Propagation via

VLF Very Low Frequency 3�30 kHz 100�10 km Guided between the earth and the ionosphere.

LF Low Frequency 30�300 kHz 10�1 km Guided between the earth and the D layer of the ionosphere.

Surface waves.

MF Medium Frequency 300�3000 kHz 1000�100 m Surface waves. E, F layer ionospheric refraction at night, when D layer absorption weakens. (ADSL2+ uses upto 2.2MHz)

HF High Frequency (Short Wave) 3�30 MHz 100�10 m E layer ionospheric refraction.
F1, F2 layer ionospheric refraction.

VHF Very High Frequency 30�300 MHz 10�1 m Infrequent E ionospheric refraction. Extremely rare F1, F2 layer ionospheric refraction during high sunspot activity up to 80 MHz. Generally direct wave. Sometimes tropospheric ducting.

UHF Ultra High Frequency 300�3000 MHz 100�10 cm Direct wave. Sometimes tropospheric ducting.

SHF Super High Frequency 3�30 GHz 10�1 cm Direct wave.

EHF Extremely High Frequency 30�300 GHz 10�1 mm Direct wave limited by absorption.

Edited by deleted (Sun 26-Dec-10 10:40:32)

meh, happened again today but times have changed.

Was happening from 22:30 to 12 and now its gone again, most certainly not just the usual snr drop at the evenings. I live in a detatched house by about 2 meters. The next door neighbour is the obvious one and then the house next to him which is a set of 3 semi (which he is the one end) has moved out, the other is occupied.

fed overhead or underground

underground at my property.

this has probably been asked, what real world effect is it having on your connection?

Just the drop in speed, other than that its the same (but annoying)