HN50

June 21, 2020

@Tomatobro glad it is running, look forward to seeing the outputs.

@7170 thanks for your comments. In terms of the ADS1115 I am certainly not against the idea of going to a higher resolution, at this stage I am trying to keep down the number of extra add-ons while I learn more about Arduino. 10 bit is giving reasonable results and I think that the MKR 1010 can be increased to 12 bit. But I did make the change you suggested of taking an average of 1000 readings so am looking forwards to seeing how that affects things.

My progress...

In terms of data not too much has happened in the last fortnight, though late on the 13th the signal starts to jump about as I assume they were testing/fixing (???) something at the transmitter. Anyway, the radio appears to be working as expected which is giving me increasing confidence. GIF for teh last fortnight;

The signal on the 13th looks like;

Which does make me wonder if the funny readings I got way back at the beginning were something happening at the transmitter rather than within my setup. The average data looks like the following. Nothing especially amazing but the data continues to settle down;

It occurs to me that I should average by month as the diurnal profile will alter as the day length changes.

Coding today has gone well, the chassis I built works when powered from the laptop and before powering it from the power regulator on the chassis I checked that what was coming was indeed 5V as I didn't want to fry the Arduino. It was, so I tried to get it logging powered by the supplied by the radio.

It did nothing.

The Arduino powered up but no logging was attempted. After scratching my head I found the offending code.

    while (!Serial) {
      ; // wait for serial port to connect. Needed for native USB
    }

I added that to get the Arduino to wait until the Serial port was connected so I could see the comments I added to check which parts of the code have been executed in the setup function. Unfortunately when running from VIN/ground pins the serial port will never connect anyway so it was going into an endless loop. I made a hasty tweak logging now occurs under battery power. It is not waking up from sleep yet (need to work out why) but I am keen to get the MKR logging data properly so will look at this during the week. The linear regulators get warm but nothing too bad and I will just bear this in mind at the moment, I used them as I already have them in and did not want to buy more parts than I have to. Otherwise i can look out for a bit of copper or aluminium for a heat sink.

And just as importantly, the RTC is now set to GMT!

So all in all not bad, I just need to work out why the wake from sleep is not working. But another week or two and I think I can start looking at connecting it to my WiFi and looking into Azure IoT...

Thanks for reading.

June 20, 2020

Hi,

Sorry for the delay, did you get to the bottom of the problem? Do you think it is radio interference or a problem within the microcontroller?

My progress...

It has been a bit of a busy fortnight with work so I have not been able to do too much on this, I have several weeks of data to analyse and will do that tomorrow. However today I sat down with some stuff I had ordered and soldered the chassis for the MKR 1010 to plug into. Have not tried it yet so will do that tomorrow as well.

I left the board bare on the left in case I need to play around with the voltage divider. Top right is the regulated power supply that drops first to 9V and then to 5V before being fed into the Arduino.

It looks like it should work but I will reserve judgement until I switch it on..!

Thanks for reading.

June 7, 2020

1 hour ago, Tomatobro said:

All my laptops are tied up analysing and logging the daytime meteor shower (Arietids) at the moment but as soon as one becomes free will take a look at my SID data for comparison.

You have quite a few things on the go! I have added my data for this last week below.

VLF_T2_20200606.TXT

June 6, 2020

Well, I have checked the data for the last week and not a whole lot has happened - below is the weekly GIF.

And in the average for all time the numbers continue to settle down.

This week I have been focusing on getting the MKR running as a 1:1 copy of the bare bones Arduinos that I can't currently reprogram, and can say that I now have it running on the breadboard.

It is doing pretty much what I want it to, I just need to get it to go into sleep mode but all in all I am quite pleased. So while the Sun may have been quiet this week things have been busy on the programming side. I have also posted my code as well at the bottom.

I will order some more stripboard so I can solder up a chassis and also a plastic project box for it all to sit in. I am chosing plastic as if it is metal I am not sure the WiFi signal will be shielded.

Not a bad week though.

Thanks for reading.

Dave

#include <DS3231.h> //v1.0.2 https://github.com/NorthernWidget/DS3231
#include <Wire.h>
#include <SD.h> //SD card library
//#include <LowPower.h> // https://github.com/rocketscream/Low-Power

DS3231 Clock;
bool Century = false;
bool h12;
bool PMT;

#define ALRM1_MATCH_EVERY_SEC 0b1111 // once a second
#define ALRM1_MATCH_SEC 0b1110 // when seconds match
//#define ALRM1_MATCH_MIN_SEC 0b1100 // when minutes and seconds match
//#define ALRM1_MATCH_HR_MIN_SEC 0b1000 // when hours, minutes, and seconds match
byte ALRM1_SET = ALRM1_MATCH_SEC;

//Variables for SD card START
Sd2Card card;
// set up variables using the SD utility library functions:
const byte chipSelect = 6;
//CS pin for SD card
String logFile = "VLF_MKR.txt";
//Variable to hold filename to be created/written to
//Variables for SD card END

//Variables for voltage calculation START
byte interruptPin = 7;
//float value = 0.0;
int var;
int loops = 10;
float voltage;
const float referenceVoltage = 1;
//Variables for voltage calculation END

//Variables for RTC START
//bool showRTCFlags = true;
bool showRTCFlags = false;

volatile bool alarmflag = false;
byte timeComponent;
//Variables for RTC END

void setup() {
// Start the I2C interface
Wire.begin();
// Start the serial interface
Serial.begin(9600);

while (!Serial) {
; // wait for serial port to connect. Needed for native USB
}

Serial.println("Turn off alarm 1 & 2...");
Clock.turnOffAlarm(1);
Clock.turnOffAlarm(2);

Serial.println("Set alarm clock time...");
Clock.setA1Time(0, 0, 0, 1, ALRM1_SET, true, false, false);

Serial.println(F("Turn on alarm 1..."));
Clock.turnOnAlarm(1);

Serial.println(F("Attaching pin interrupt..."));
// Attach interrupt
pinMode (interruptPin, INPUT_PULLUP);
digitalWrite(interruptPin, HIGH);
attachInterrupt (digitalPinToInterrupt (interruptPin), clockTrigger, FALLING);
Serial.print(F("Pin interrupt on "));
Serial.print(interruptPin);
Serial.println(F("..."));

Serial.println(F("Initialize SD card..."));
// see if the card is present and can be initialized:
if (!SD.begin(chipSelect))
{
    Serial.println(F("Card failed..."));
    // don't do anything more:
    return;
}
Serial.println(F("SD card initialized..."));

if (SD.exists(logFile))
{
    Serial.println(logFile + F(" found..."));
}
else
{
    Serial.println(logFile + " !found, creating...");
    File dataFile = SD.open(logFile, FILE_WRITE);
    dataFile.println(F("D,T,V,K"));
    Serial.println(logFile + F(" created..."));
    dataFile.close();
}

analogReference(AR_INTERNAL1V0);
//Set to use internal 1V reference voltage - so that the 8 bit
//range is measured over a smaller range
}

void loop() {
voltage = 0;
var = 0;
while (var < loops) {
    voltage = voltage + analogRead(A4);
    delay(5);
    var++;
}
voltage = voltage / loops;

voltage = voltage * referenceVoltage / 1023;

float temperature;
temperature = 273.15 + Clock.getTemperature(); //((Clock.getTemperature()) / 4);

if (alarmflag == true) {
    File dataFile = SD.open(logFile, FILE_WRITE);
    if (dataFile) {
      if (showRTCFlags) {
        Serial.println(F("AlarmFlag is true"));
      }

      printString("20", dataFile);
      timeComponent = Clock.getYear();
      printByte(timeComponent, dataFile);
      printString("/", dataFile);
      timeComponent = Clock.getMonth(Century);
      printByte(timeComponent, dataFile);
      printString("/", dataFile);
      timeComponent = Clock.getDate();
      printByte(timeComponent, dataFile);
      printString(",", dataFile);
      timeComponent = Clock.getHour(h12, PMT);
      printByte(timeComponent, dataFile);
      printString(":", dataFile);
      timeComponent = Clock.getMinute();
      printByte(timeComponent, dataFile);
      printString(",", dataFile);
      printFloat(voltage, 4, dataFile);
      printString(",", dataFile);
      printFloat(temperature, 2, dataFile);
      Serial.println("");
      dataFile.println("");

      alarmflag = false;
      dataFile.close();
    }
}
if (Clock.checkIfAlarm(1)) {
    if (showRTCFlags) {
      Serial.println(F("checkIfAlarm(1) is true"));
    }
}
}

void clockTrigger()
{
alarmflag = true;
}

//Only use these when SD card is initialised
//and has been started ready for writing...
void printByte(byte value, File dataFile)
{
if (value < 10) {
Serial.print("0");
dataFile.print("0");
}
Serial.print(value);
dataFile.print(value);
}

void printString(String value, File dataFile)
{
Serial.print(value);
dataFile.print(value);
}

void printFloat(float value, byte places, File dataFile)
{
Serial.print(value, places);
dataFile.print(value, places);
}
//Only use these when SD card is initialised
//and has been started ready for writing...

June 3, 2020

5 hours ago, Tomatobro said:

I am up and running!

Two challenges, the first was...

...about 15 mins to do this on this size of memory chip.

That is looking good, I look forward to comparing data.

I am slowly rewriting my code so that the MKR 1010 will do what my existing Arduino does. Had a few issues over weekend so not quite as far along as I had hoped. Once that is running again I will look to get using the WiFi.

May 30, 2020

2 hours ago, Tomatobro said:

Nice plot. Very inconsiderate of them to switch off when a SID occurs!

I am waiting for a UKRAA antenna tuning unit to calibrate my new antenna. This one has been made according to the instructions in the construction PDF. If I cannot wait I will go into the "stores" and see if I can find some temporary capacitors to get it up and running.

After a couple of hours of battle with LibreOffice Calc I have charted my data against the GOES x-ray flux data for the same time, and the results are below.

As I had thought the M-class (biggest since Oct 2020 https://www.swpc.noaa.gov/news/first-m-class-flare-observed-years) fell slap in the middle of the routine maintenance window and so was undetected. Ain't that the way?

However the following C-class flare did cause a SID as the signal strength for DH038 dropped appreciably and gradually recovered. The data from both datasets correlates spot on.

Throughout the afternoon and evening there were further events but I can't correlate them in the same way so I guess these events led to the ionosphere being disturbed and causing the signal from DHO38 to jump about.

So whilst I missed the big fish I did indeed detect a following flare. I am very pleased, we can turn the internet off now.

I will have a think this afternoon about what I do next whilst I enjoy the sun, data attached if it helps anyone.

Thanks for reading.

Dave

VLF_T2_20200530.TXT

May 30, 2020

1 hour ago, Tomatobro said:

Nice plot. Very inconsiderate of them to switch off when a SID occurs!

I am waiting for a UKRAA antenna tuning unit to calibrate my new antenna. This one has been made according to the instructions in the construction PDF. If I cannot wait I will go into the "stores" and see if I can find some temporary capacitors to get it up and running.

Thanks! Doing battle with LibreOffice at moment to brink them together. Hopefully will have a chart out soon.

May 29, 2020

12 hours ago, Tomatobro said:

I missed the flare due to non availability of the kit. It will be interesting to see if you captured it

Hi,

I will analyse properly tomorrow (I took some screenshots of the GOES data so will tie up times), but at first glance it does look like there has been some activity detected today. My times are BST rather than UTC so I think the peak at 07:00 UTC has fallen into the 08:00 - 09:00 maintenance window, and I think the downward spike was the transmitter going offline. However the GOES spike at 11:45 UTC corresponds with a sudden drop in signal in my plot at about 10:45 BST.

So I think I have detected a flare.

I will look again later when my brain is more awake as there are a few features to correlate, and it would help if I converted my times to UTC.... Interestingly they are negative which suggests to me that the changes in the ionosphere make the ground wave and skywave further out of phase (?).

Dave

May 29, 2020

6 hours ago, Tomatobro said:

I missed the flare due to non availability of the kit. It will be interesting to see if you captured it

!!!

Thanks for the heads up.

Things are looking quite lively still, I will leave it until late tonight or tomorrow and pull out the data.

Fingers crossed...

Dave

May 25, 2020

1 hour ago, Tomatobro said:

I have found that feeding the receiver with the right signal the outputs are correct. I based my antenna design on a website that on reflection seems to be specific to using the sound card rather than the UKRAA receiver. I have ordered some 24 awg wire and will rewind the antenna.

The antenna as it stands responds well to the noise generated by the notebook screen. Those bumps in the graph are the notebook waking and turning on the screen when I go look for the current signal data.

Hi,

Glad it looks like the radio is okay.

I am in the midst of 'Arduino Can't Find Drivers Part 746'. I think though that I might have got to the bottom of it, I am writing it here as much for my reference as anyone else's!

When CHRG light stars flashing and IDE can't find COM port, unplug Arduino MKR 1010
Restart laptop
Unplug I2C modules (in this case the RTC), also unplugged the SD card even though not I2C (I found a posting in https://forum.arduino.cc/index.php?topic=567417.0 that gave me an idea)
When laptop restarted plug in Arduino
CHRG light may flash but should hopefully go out after a couple of seconds, in Device Manager should see Arduino MKR WiFi 1010 under a COM port
Try uploading a sketch
Plug in I2C RTC and SD card
Should now upload code successfully in IDE
Universe is in balance again

That is a rather long way of saying turn it off and on again. I like Arduino a lot but I find I can burn up hours trying to resolve these issues.

And now on to what I actually wanted to do today...

!

May 24, 2020

Just now, Tomatobro said:

Yesterday was the first real test of my newly constructed UKRAA receiver. Its clearly not working properly based on yesterday's and today's log so will pull it out and take another look at it.

Sorry to hear that, hope you get it working.

May 24, 2020

Weekly update...

I pulled out the data and passed it through my trusty LibreOffice spreadsheet and generated the following GIF (I won't post each individual day but will do if asked).

The data looks okay and the unit is running as I would have hoped, but yes, quite an uneventful week. If we are at a deep solar minimum then I guess we have a few years to get this all perfected! I also recalculated the all time averages as well and has hoped the averages are stabilising with continued normal functioning.

@Tomatobro - I looked at 22/05/2020 to compare to what you had recorded. The whole day looks like;

I see a drop at about 15:00 (my RTC is running on BST at the moment), so I zoomed in further.

I must admit I am not sure I see the same output, there is a dip in signal but I don't see that high/low output you were getting. Do you have a plot for 23/05/2020 (mine is pasted below)? There seems to be several on/off events in the evening so would be good to see if you detected these.

In terms of development, I have been looking at getting a MKR 1010 prototype running on a breadboard.

I have got it writing to the SD card but one thing I have found is that the DS3232.h library I had been using is not compatible with the MKR 1010, I think there are some reserved keywords in there that clash and error when you compile. I found this posting https://forum.arduino.cc/index.php?topic=626051.0 which refers to a particular v 1.0.3 version of an alternative RTC library to use so I downloaded that. The keywords are different so I have spent today getting to grips with setting the time and using the alarm functions.

Pretty poor photo but that is just a sketch that shows the time and various alarm settings.

So I think the next step will be to get the various bits (RTC/SD card/low power) all working together on the breadboard prototype. I also need to check the voltage divider as I am not sure there is a setting to put the internal voltage reference to 1.1V in the MKR 1010 so the divider will need to drop the radio 5V to 3.3V instead. I am not too concerned as I can set the ADC to 12 bit.

Anyway, things to do in the coming days.

Thanks for reading.

May 22, 2020

1 hour ago, Tomatobro said:

This is a recording of a few hours worth of data taken today using my UKRAA receiver. It seemed to make sense for a while but not from 15:40 onwards. It looks normal enough at the start then it seems they had a problem and shut it down for maintenance. At the restart it looks normal then it was reduced to half power then shut down again and so on. Looking at your 05/07 graph I can see a similar pattern

Hi,

I will try and get the data out the SD card tomorrow, I am hoping to see a similar pattern.
Dave

May 17, 2020

Double clicking the reset button when connecting the MKR1010 to the laptop via USB seems to help the drivers get set correctly.

Beats me but there we are.

May 17, 2020

Hi,

I like it, I am trying to visualize it - that is pretty small, isn't it? Do you have a block diagram of how your setup will work?

Well, a bit of a mixed bag in terms of progress this week. Firstly, the good, my data capture is going on well. The overall signal strength seems down as compared to earlier weeks, however the results seem to be stable.

There do not seems to be have many maintenance shutoffs either. Weekly animation is below.

Another week and has passed and my rig seems stable, the logger and radio are working, and I am getting a steady profile. I am interested as to why the overall signal is weaker as compared to the late in April, so I wonder if the transmitter is operating at reduced power? I also checked the GOES X-ray flux data for the last 7 days but nothing bigger than A class has happened.

I have also produced an average plot by hour of all data logged so far which is starting to show that certainly the mean is gradually settling down to resemble a quiet day as extreme data becomes less significant.

And now the bad.

1) I still can't push code out to the barebones Arduinos I have built, I keep getting an 'avrdude not in sync error'. This seems to be a little cryptic to work out what is going on. I have;

> Bought a new usb to serial chip in case this was the cause - it isn't as I still get the same problem

> Run the logger under external power to see if it is working or the Atmega328p chip is fried. It works and happily logs, so that isn't the cause.

> Reburnt bootloader to chip to see if that had corrupted. I could do this successfully however I still can't upload my code to the chip.

So still a problem that I can't push out updates..! :BangHead:

2) After spending a lot of yesterday and today on the above, I have been experimenting with getting the MKR1010 working if I can't now upload code to the Atmega328p models. I have it writing to an SD card and have been trying to get it working with an RTC. There is one built into the MKR1010 however it needs to be set via a WiFi connection and has no battery backup. In initial experiments I have found that if you have a sketch that sets the clock via the internet and then upload the logger sketch the RTC starts up at the last time the previous sketch ran and does not increment between. There may be settings that deal with this, I am still investigating how it works but I do not want it to be constantly connected to the internet in case I need this to be battery powered. I am also seeing if I can use the DS3231 RTC as I like it being battery backed up and has several alarms built in to it. So while I have not got round to building anything I am at least investigating what the MKR 1010 can do.

That all sounds good, the bad part in the above is in the last hour my laptop has started refusing to detect the MKR1010 at all. I think the drivers became corrupted so now I can't upload to code to the new Arduino either. :BangHead:

Three steps forward and three back this week, those emoticons are rather apt.

Thanks for reading.

May 10, 2020

On 09/05/2020 at 13:42, Tomatobro said:

Spectrum lab's txt file is quite extensive so I copy it into Libre office calc, select the column of data of interest and paste it into a new spreadsheet. I then strip out the decimal and export as a text file.

Using TeraTerm I send this file to my hardware that writes it to an EEPROM and then read it back to MakerPlot doing any data processing necessary.

I take a snapshot of the MakerPlot graph for later reference.

The hardware will allow direct recording so if I build a UKRAA radio I can dispense with the laptop . I will have to rebuild the hardware using a more powerful processor as the one I am using at the moment has 1k of memory and its about all used in the above process.

Sample Graph attached

Hi,

That is interesting, if you get rid of the laptop what is the unit a custom built computer/microcontroller? I ask that as I see you mention EEPROM which is available on the Arduino. You only get 100k (I think) writes Arduino though which would get used pretty quick with the loop that is triggered every minute. How many writes to do get before it corrupts?

Well, here is the Sunday post.

As I ever I resisted the temptation to hoick out the card before today. I copied over the data into LibreOffice Calc and analyzed it.

The good;

>>> Orienting the antenna did not seem to make too much difference. I realised that I was already nearly pointing in the right direction.

>>> I don't think the significantly higher temperatures this week affected the radio

The bad (well, not sure, I don't think I have any control over it but it becomes clear from the plots). There is a time jump in the first screenshot as I had it switched off for a few hours doing work on it.

'Something' happened on the 04/05/2020. Prior to that the signal strength of the transmitter was of a range I had seen before, however after the maintenance window on Star Wars Day (May 4th, boom boom) the signal strength of the transmitter has been significantly down all week up to and including today.

I have not made changes to the radio's tuning and the fact that this behaviour takes place after the switch on on the 4th makes me wonder if the transmitter is running at a much lower power..? I suppose I will get an idea when I pull out the data next Sunday. So I won't worry too much at this stage as my setup still seems to be working.

GIF for the week.

I have also started looking at the Arduino MKR1010, I have played around with some of the sketches and have got it logging details of WiFi connections available around my house. I think there will be a bit of a learning curve with it as I have not quite been able to get some of the WiFi enabled projects working, though they do focus on it being used as a server and as a data logger I think it would be a client.

In addition there will be some rewriting as it has its own RTC built in and I am not sure if the DS3231 is compatible (the library for this is filed under 'Incompatible' in the Arduino IDE when you select MKR1010). Plus it runs on 3.3V not 5V so the chassis I plug it in to will need to be quite different to the YABBA ones I have built, but I had expected that.

The biggest problem I have is that after installing the MKR1010 software I don't seem to be able to program my YABBA boards any more, I get a program error when I upload to the board(!!!). I was going to reset the RTC to be on GMT (I realise mine is set to BST) today but at the moment I can't. Let's hope my setup is reliable as I can't currently make changes..!

Anyway, let's see how things go. If I can't program my existing boards then I have to migrate fully to MKR1010 and done with. I guess I had better get investigating it...

Thanks for reading.

May 4, 2020

21 hours ago, Tomatobro said:

The shutdown looks similar to yours

Hi,

Thanks for posting your output, that does look rather similar. When I first saw the 02/05/2020 plot it did make me wonder if there was a problem with my setup but it appears that it is a real result.

Dave

May 3, 2020

3 hours ago, Tomatobro said:

I am fortunate that I have access to an expensive fluke multimeter and a frequency generator.

I will post some screen shots later on. I think that Spectrum lab offered a range of "standard" vlf frequencies and 23.4 is the only one I am currently logging ( and noise floor level) as all the others either give no signal or are seriously affected by local interference such as our induction hob and gas boiler.

I am reasonably confident that I am recording DHO38 because rotating the antenna gives me a peak signal when pointing towards the station in Germany and I am seeing the early morning maintenance shutdown sessions. I can see a problem trying to extract small signal changes from the data as the noise span covers some 3db (at least). I am taking 1 reading every 30 seconds as a plot. Perhaps averaging over (say) 5 readings might help but I have not looked at this yet.

Hopefully my signal maintenance dips will match up with your UKRAA receiver data

Regards

Hi,

I could quite happily own a Fluke multimeter..!
I posted my data for the last week so would be interested to see how it compares, not least as there were some strange readings yesterday morning around the maintenance window.

Dave

May 3, 2020

I was going to do some work on this yesterday however I found as the weather was unexpectedly better than I had thought it would be I spent it in the garden in the veg beds. By that I mean I was working on them, not lying in them.

Today I worked out the bearing from my house to Rhauderfehn in Germany and it comes out at ~64 degrees, so once I start logging later I will re-orient the antenna. At present the antenna is not in this orientation, however it does put (I think) a lot of noise from the house into the null zone. So I am interested to see what the trade off will be - next Sunday I will pull out the data and have a look.

Earlier I cut the power and hopped into the roof to pull out the SD card. Among other things I wanted to check was that the change to the voltage divider had not caused any problems, I don't know why that would be an issue but as I had made a hardware change I did want to confirm all is okay.

The general trend looks okay, I can see the diurnal pattern, the daily maintenance period is there, the readings taken have have not berserk and the Arduino has been logging the temperature recorded by the RTC as well.

By day it looks like the following;

And in GIF:

My setup is still returning the diurnal profile. Some funny stuff happened 02/05/2020 between 0800 and 1000 but I wonder if that was due to work at the antenna(?). Otherwise though the numbers logged look as expected, and I am gaining confidence that my setup is stable.

I had a look at the GOES data - there was an event on 01/05/2020 at about 14:30 however I still think that this lower/mid B class is below what the radio can detect.

For the first time I have temperature from the RTC being logged as well (red line). I am interested in this as the tuning guide says that temperature increases can push the radio into oscillation (page 16, #12) and my radio is up in the roof where things can get quite warm in the summer (touching 40 Celsius!). I don't think though at this stage I have enough data to give any meaningful results so I am going to use it for reference over the coming summer.

Anyway, in all I am pleased with what has been logged this week and am thinking about what I will do next. I would still like to have the option to run from battery with power being supplied by the Arduino and the radio being turned on when needed. I looked around and found the ready-built MOSFET switch unit using an IRF520 transistor. Even more useful I found a website that as well as advertising the module for sale also gives a schematic of it;

https://protosupplies.com/product/irf520-n-ch-mosfet-module/

Turns out I have all the bits. Handy!

I am increasingly aware that needing to go up the ladder to get an SD card interrupts logging and, while fine for testing, isn't really conducive to real time SID monitoring. Earlier this week a page arrived with an Arduino MKR wifi 1010 arrived.

I think I will try and work on the switching and initial MKR 1010 investigations in parallel.

Thanks for reading - data is attached.

Dave

VLF_T2_20200503.TXT

May 3, 2020

On 29/04/2020 at 11:21, Tomatobro said:

Just out of interest I measured my loop antenna response to input frequency and the peak response is at 25.596 Khz. looks like I would need an ATU if I go the UKRAA receiver route. Blue is frequency steps from 20 to 40 Khz in 1 khz increments and red is ac millivolts change rms

Update. The antenna required 600pf to bring its peak to 23.4 khz. Its now located in the quietest place I could find, Spectrum lab is sorted. I am getting the early morning maintenance cut offs so just need a SID to verify the system.

Hi,

Thanks for the post. One thing I quite like about this work is that it generates data for analysis . Out of interest what are you using to measure your loop antenna response? Am I right thinking you have an A/C multimeter capable of going down to milivolts?

Having tuned the antenna to 23.4kHz are you finding that the other transmitters are now attenuated or have you got SpectrumLab just logging DHO38?

Dave

April 26, 2020

Today’s work;

I have built a 1:1 copy of the chassis so I can undertake further development and still leave my production set up logging in the roof. They look and work exactly the same, which is good!

On checking through my components box I found I don’t have any 10nF capacitors (might have to check again as I don’t quite believe that) however I did find some discussion about the voltage divider and if your total resistance is 10k ohms or less you don’t need a decoupling capacitor. So I recalculated and used a 5.6k and two 2.2k ohms in series to drop to 1.1V.

I also updated the code to log the temperature measured by the RTC. I converted it to Kelvin as, ummm, I could .

It is all running again in the roof so I will leave it to see what comes back later in the week.

Thanks for reading.

April 26, 2020

3 hours ago, Tomatobro said:

Thanks for posting your latest data.

Its interesting that out of 5 laptops of varying vintage...

Hi,

That MakerPlot looks interesting as you could hook up several Arduinos to feed in to it.
I would like to go down the cloud route myself as I love the idea of building a sensor (battery or mains powered) that just fires its data off to an internet connection and all the processing and analysis happens online. The Arduino store page for the MKR 1010 has links to several articles that discuss this plus it has some encryption built into the board from the outset.

How do you find SpectrumLab? People seem to get good results but I found it a bit frustrating and looked at other means of detecting SIDs, which brought me to this method.

Dave

April 26, 2020

And this is a GIF for the week.

April 26, 2020

On 20/04/2020 at 19:41, Tomatobro said:

SID or Induction hob at 16:50 (UTC)?

Hi,

Sorry, with one thing and another this week I didn't get round to replying. I had a look on the NOAA website the other day and took a screenshot. They didn't flag any events for the same time, so it might be some local interference.

I resisted the temptation to pull the data out the SD card this last week and let the thing run continuously to see if I get any odd behaviour again. Last night after 6 days I decided to look at the data. The pattern for the week looks like;

Which looked promising. I looked at what happened after I had switched off the radio for an hour and restarted it on the 19th...

The high voltage readings had dropped off afterwards, so I think the restart helped. So I conclude it is probably better to turn everything off before I switch the SD card!

Individually the days looked like;

What I am pleased about is how samey they look with a remarkably consistent daily plot. Yes, there is some noise in the plots themselves but that does not seem to swamp the overall daily pattern.

I had a look at the NOAA data for the same period (https://www.swpc.noaa.gov/) and it looks like there may have been an even on 23/04/2020 however it does not correspond with anything I can see in my plot for that time. So I think if that is one I didn't detect it. Having said that the plot puts it in the smallest 'A' class - if it it had been an 'X' class I would be more disappointed!

I also calculated an average daily curve for all my data as well. The gradual accumulation of data means it is starting to look more like a normal daily plot as bad data is beginning to represent a smaller percentage of the total.

That plot does not show much, I just like it. For the first few days of data the average daily curve looked nuts.

I am still interested to see how running it all under battery power helps so the additional chassis I build today will have space for a TIP120 transistor to act as a switch. I also have a pack of 12 NiMH AA cells that I will solder into a single pack but that will have to be another weekend. Likewise, I don't forever want to be writing the data to an SD card so in spare moments I have been looking at the Arduino MKR WiFi 1010. Further down the line I would like to write data to a database (nicely dovetails with my day job!) but for the moment I want to get to grips with the basics; I have found the jump from kitchen table prototype to reliable sensor is a big one.

Today's tasks;

Add a decoupling capacitor to the voltage divider to see if that helps smooth things a little
Build second chassis that is 1:1 copy of existing one
Change code to log temperature measured by RTC as well

Also when I get it running again tonight I will make sure the radio and Arduino are out of the plane of the greatest sensitivity of the radio. I don't know if that will help but it is worth a try.

Thanks for reading.

April 19, 2020

38 minutes ago, Tomatobro said:

I have constructed a "SID" antenna and have been using the sound card input as a first look at recording "SIDS" but Speclab just locked up and I lost my first days data. I think there is a BMP image somewhere on the hard drive so will post it here if its recoverable.

As I understand it we are looking for a sudden drop in signal strength with a slow recovery?

Hi,

That is annoying, have you been logging to a .csv as well?

I think the change can be an abrupt decrease or increase, but both will be followed by a gradual recovery.

Dave

Sign In

Profiles

Forums

Gallery

Events

Blogs

Posts posted by HN50

Important Information