Tweaking station
#1
Hello,

A few days ago I finished the build of a system RED. Initial hardware and software went smoothly and so far there is no indication that the receiver is not doing what it is supposed to do.

However, a receiving station is only working when all parameter are set to the right values so I started looking around in all data that is available.

When I first set up the station I noticed it went into INTERFERENCE and I have responded by lowering the gain as my ferried rods (the antenna) are located indoor as the amplifier is easier to access when needed.

Yesterday, August 29, the station ran for several hours and in one case a signal was used to locate a thunder. As thunder levels were low in a 500 km range of the southern part of the Netherlands, it seems normal behaviour as you can not expect the same performance from an indoor antenna as from one on an outdoor, suburban, located antenna.

However, today, there were some thunders within acceptable range and I saw relative close stations (40-50 km) receiving strokes. I decided to look at the Live signals that are visible by accessing the controller via IP.

I noticed "strange" behaviour of signals displayed as they looked like an almost perfect sinus and random noise should not look like that. I have attached 3 pictures showing the signals and when I manually turn the antenna I can "beam" the signal or not. Actually I was expecting that the "noise" on channel 1A would disappear and appear on channel 1B when moving the antenna around.

I this behaviour I can expect in a high noise urban environment and will it disappear when my antenna will be located in a 20 meter high tower? Is this an example of the feared robotic lawnmower?

I must admit that I have not used yet a high quality shielded CAT5 cable but a normal 3 meter long "of the shelf" CAT5 cable.

Anyone have had seem during setting up his station?

Regards,

Frank Veldhuijsen
[station 1152]


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#2
Self oscillation - how close are the antennas to the cat5 cable

Please show a picture of the antennas and sorroundings
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#3
I have been looking into the signals I might expect from a RED system that is running as it should be. As I'm a newbie on Blitzorting I don't know enough yet how signals should look from a well tweaked system.

The self oscillation, as suggested by Richo Andersen, was already ruled out before sending my initial post. With more than 30 years experience as a hardcore builder of antenna's, transceivers, receivers and high power RF-amplifiers I do have experience tracing self oscillation in build configurations. It was clear that what I was seeing was man made noise / interference.

After a days rest I realised that I did not have enough background to analyse the live signals I was seeing when accessing the system through IP. Understanding what I was seeing should be the solution. So I started if I could find examples of live signals from a working RED system as there are none given in the manual. On www.wxforum.net I found a topic on Interference and Noise with some screen captures from interfering signals and they gave very good information how signals should look or should not look like. And.. the pattern what I had seen and interpreted as not good was there too.

It became clear to me that the system is way more sensitive than I expected. Moving the antenna through the house it's easy to get it into interference mode by getting close to the TV and other electronic stuff. The signal I was seeing comes from my neighbour and it switches on and off with his laptop computer. I'm convinced that his laptop will not be a problem any more when my antenna is looked outdoor about 20 meters over ground level.

It might be interesting for others to have a look at the examples of signals. When I look at the station list I see many stations sending quite large numbers of signals but with zero efficiency and that can be an indication that the system is not correctly set-up and might have man made noise and trigger signals that are not thunder related.

The URL for it is: http://www.wxforum.net/index.php?topic=20439.0

In the next week the weather in the southern part of the Netherlands will get better and the antenna will be placed in my antenna tower. I'm curious if all man made noise will be at an acceptable level and that the nearby solar panels (50-80 meters distance) will not cause to much trouble. On VHF I can hear them switching on and off when the sun rises and sets.

For those who are curious how I build the outdoor antenna I have made two pictures showing a solid but easy to build housing.

Regards,

Frank Veldhuijsen
[station 1152]


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#4
As the weather improved it was time to get the antenna outdoor. For testing I'm using an old telescopic aircolift from which the platform is removed. Just 3 meters high but very handy for testing antenna's.

The quality of the received signal improved at lot, even when the antenna is still surrounded by houses. But now received thunder strikes are clearly visible and the ground and sky waves are recognized. The returning pattern still shows interference, most likely nearby solar panels but that has to be investigated in the near future.

Next step will be adjusting the amplifier to the best gain level and then the antenna will be placed in my antenna tower at 20 meters groundlevel.

Regards,

Frank Veldhuijsen
[station 1152]


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#5
PA4EME: I see that you have connected the antenna to channel B. Waveform colors - blue and purple. Normally it should be connected to channel A - this is a recommendation.
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#6
(2014-08-30, 19:24)PA4EME Wrote: I noticed "strange" behaviour of signals displayed as they looked like an almost perfect sinus and random noise should not look like that. I have attached 3 pictures showing the signals and when I manually turn the antenna I can "beam" the signal or not. Actually I was expecting that the "noise" on channel 1A would disappear and appear on channel 1B when moving the antenna around.

Why do your images show no gain settings? There is just a column of dashes under the word "Gain" - here is what mine looks like at the moment:

   
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#7
The antenna has moved from the temporary tower into a low position in my main antenna tower.

While setting up in the garden I connected indeed the wrong channel so corrected that.

The remark about "why don't you have the gain settings listed" is more concerning. I was not aware that these are visible in the list so I started to have a look. Gain setting on the amplifier board is "working" as the 4 yellow leds will change their status when I turn the potentiometer. That was already verified at initial set up.

I noticed that on the controllerpages is listed what I'm using: FW 7.4 * PCB 10.4/Unknown. I did not paid attention to that yet but as the controller should recognize the used type of amplifier, it seems that something is not in order yet.

On the statuspage there is written for the amplifiers: Amplifier 1 - PCB Unknown - FW 1.7

Looking on the schematic, the Atmega8 should indentify the type of amplifier to the controller at PD5, PD6, PB6 and PB7. I assume the Atmega8 was already flashed when it arrived in the building kit.

As it is already dark I will not get the antenna/amplifier tonight but will have a look what is happening. It seems that the gain is working because I was able to get the system overloaded when I used max gain settings. Maybe someone else has seen same issue and is able to give any hints.

Regards,

Frank Veldhuijsen
[station 1152]
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#8
(2014-09-03, 19:33)PA4EME Wrote: Gain setting on the amplifier board is "working" as the 4 yellow leds will change their status when I turn the potentiometer. That was already verified at initial set up.

When connected to the controller, the potentiometer on the amplifier should not work - the green remote control LED should be lit on the amplifier and the gain is set via the controller. The yellow LEDs on the amp seem to blink from time to time (I think this is when the gain gets changed in auto mode?), but are normally off. The potentiometer should only work when the amplifier is disconencted from the controller and powered from the local USB on the amp.

It looks like your controller can read the amplifier firmware version (I guess this comes from the ATmega8), but the ATmega8 seems not to be able to detect the amplifier board type. I don't have the schematics in front of me to see how that bit works, but would suggest you look closely at the amplifier board build.
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