VLF SDR, Grimeton Radio SAQ receiver ultrasonic, infrasound, sonar and sonography converter.The Receiver: I checked several web sites to see what other people are doing and I saw 3 solutions:Ok, aber jetzt hatte ich bis 12:00 UTC Zeit (bzw. Using a PC sound card as a VLF receiver with SDR : RTLSDR. At various times of day I can see up to twelve of these. The other signals seen in the main spectrum are VLF transmitters for submarine communications. In this case, the signal under the cursor is station SAQ at 17.2 kHz. The receiver is tuned to 17.2 kHz which places a red vertical cursor in the spectrum at that frequency.
It is a classical super heteodyne receiver with an IF of about 455 kHz and a BFO. Look for: A very simple VLF Pocket receiver by By Wilfried Fritz, DJ1WF. Sound card input port and a program called SAQrx Panoramic VLF Receiver.See the website vlf.it.
As most sound cards sample on 44.1 kHz or 48 kHz, the spectrum up to half of the sampling frequency, so 22 or 24 kHz can be received.The third option is to upconvert this low frequency and convert it to a frequency that most short wave receivers can handle.After everything was working, I tried to reverse engineer the Coil. More information can be found using this link:It suggest to use a PC or laptop, take the build in sound card, and receive it directly. The PC then can use a simple SDR programme to process the incoming frequency. The transmitted frequencies are that low that they can be directly received by a laptops soundcard. Venerd&236 13 febbraio 2015 appuntamento con il GRIMETON RADIO/SAQ 17.2Khz - Segnale ricevuto dalle 14.44.44 UTC utilizzo del programma Spectravue 3.28 - Segnale ricevuto anche con il programma SAQ Panoramic VLF receiver 0.94 - Traduzione del codice CW ricevutoThis solution comes from the Alexander association, the guys that run and maintain the old Grimeton Station. Report sent to the RAI regional office for Liguria, Corso Europa 125 - 16132 Genoa, reply arrived from the RAI Way.
Mu value of a few hundred, used for some MHzMnZn so Mangan Zinc, mu value of around one thousand or so, used for some kHzThe datasheets will tell what materials are used.So if no mu is given, get a MnZn rod. What material the rod is made from? I believe this gives a good indication:NiZn so Nickel Zinc. I will sum up the mu value for the different ferrites:4B1: 250, 4B2: 250, 3B1: 900, 3C90: 2300, 3S3: 350, 3F3: 2000So we see quite a difference and we want to go for a rod of 3C90 or 3F3 material, otherwise we wil go for a 3B1 rod, that's also fine.You can also look at it from a material perspective.
The second source is ebay.de and the webshop:He sells various ferrite material, when you seach for "FERRIT" AND "3F3" you will find a great ferrite rod of 3F3 material with a length of 100mm. I went to the page with the ferrite rods:Here you can buy a rod of 3B1 material and diameter of 8mm: number of turns: 665.B. I looked at the webshop box73.de. I did do around 900 turns, analysis correct, this rod on my picture has mu=250.Clearly not a rod with a mu of 900, 2000 or more.A. Diameter coil former is the same as rod diameter: 10mm, shift =11mm(?), wire diameter=0.25mm, winding pitch:0.26mm.This is good. OK.I used L = 74mH, length rod = 600mm(long), diameter rod = 10mm, mu = 250.
The 3F3 rod on ebay.de (C) only needs 522 turns and is cheap. When you buy a 8mm diameter 3B1 rod, it only needs 665 turns, MnZnC. The 10mm diameter rod i bought has a mu of about 250, 4B1, NiZnB.
The preamplifier is using a 9V battery to keeps things portable. This means that also this rod needs around 900 - 1000 windings.Maybe I should repeat my first Rod conclusion: buy the longest and fattest rod you can get, do around 900 - windings and be happy! Maybe easier than looking for the holy grail.The Coil I connected to the preamplifier. This is not what I expected, as the mu = 350 or so. The results are: to get an L of 82mH, number of windings n = 1030. I will test them next week.The week is over and I have tested the 3B1 rod from box73.de.
Ro is the parallel set of 3 'resistors', ro of the fet itself, Rd (2k7-4k7) and Ri of the sound card (assumed 10k). This is basically : Av = -gm x Ro. That's not critical, and you can use this maximising and minimising to cancel out a disturbing carrier on a nearby frequency.The gain of this preamp is the gain of a common source configuration. Pointing the ferrite rod towards Sweden will give you minimum reception, it's a sharp null, the rod needs to be perpendicular to SAQ.
At the beginning I used a fet with a Crss of 6pF and it made the preamp oscillate. This is important as we have a resonant circuit at the input, and Crss gives feedback from the output back to the input. I chose a fet with relatively high gm at lower currents, and a small capacitance Crss between gate and drain. I chose Rd high enough not so have a lot of Id as it would draw the 9V battery empty. I chose Rd a few times smaller than Ri, so that the gain is determined mostly by the preamp and not by the sound card. Ri is something that can not be influenced, and Rd can be chosen.
With an L of 82mH, fres minimum = 15 kHz. I selected 330pF, so a total Cp = 1330pF. The fixed capacitor is chosen such that resonance occurs a bit below the SAQ frequency of 17 kHz. The 2 capacitance diodes have a total capacitance of about 1000pF or 1nF. Ci smaller than 30pF is also fine, this is not so critical.A small resistor is series with the gate (gatestopper) is used to avoid oscillation at VHF frequencies.The 4M7 resistor grounds the gate, so that the fet is set also when the coil is disconnected.The resonant circuit is made of the ferrite rod inductance together with 2 capacitance diodes and a fixed capacitor.
No big deal.FET 2SK241-GR, tested and preferred, 2SK161-GR Rd = 2k7 and Rs = 330 Ohm orFET 2SK161-Y, tested. If you want a higher fres max, remove the fixed capacitor and use 3 capacitance diodes in parallel.The diodes draw a little current, i measured 1V drop over the 1Mohm resistor, so both capacitance diodes draw 1 uA in total. This gives us a frequency range of 15-27 kHz and that is fine. Therefore fres max = 27 kHz. At 8 or 9V, the capacitance diodes only have a capacitance of 34pF max each, so Cp (8V) total is 68pF + 330pF = 400pF.
Rd=2k7, measure Ud and change Rs so that Ud = 4.5V +/-1V orFET BF987. Rd = 2k2 Ohm and Rs = 220 Ohm orFET 2N3819, Rd=2k7, measure Ud and change Rs so that Ud = 4.5V +/-1V orFET BF410b. Rd = 2k2 and Rs = 47 Ohm orFET 2SK522-d. Works fine.FET 2SK193-p or k.
Rechargable or not.LED Use a bright LED with bias resistor. Rd=2k7, measure Ud and change Rs so that Ud = 4.5V +/-1VFerrite Rod round, diameter 8-10mm, length 100-200mm, if you can choose: high muWire lacquered or enamelled copper wire, 0.25 - 0.3 mm, 30m lengthVaricap BB112 (EU) or 1SV149(Japan) 2x or one KV1270, KV1560 or BB212 (2 diodes in one)9V Use 9V monoblock. Rd=2k7, measure Ud and change Rs so that Ud = 4.5V +/-1VFET BFW10 or 11 or 2N4416. Pinning below near pictureFET 2N5485 or 86.
Saq Panoramic Vlf Receiver Windows 7 And Windows
Your audio recording devices look like this:Here you can see that the bottom input is disabled and the middle input shows that the cable is not plugged in. When you do not have any microphone or line input activated, this error occurs. SAQ48k, the following error occurs:This happens on both Windows 7 and Windows 10.This error is related to the program not seing any audio input.
I like the 300Hz setting as it fits nicely to the RTTY PSK and FSK transmissions to the submarines. When the program starts up, the CW bandwidth is set to 1 kHz.By accident I clicked on the CW button again and voila: the bandwidth changed! Please try this out for yourself. Only when you have the picture above it is useful to start SAQrx and then it will always start up properly.So make sure your audio input is activated and then start SAQrxSorry for the German language, but I guess that you will understand:The next topic is the CW bandwidth. Restarting the laptop always solves this issue and then you will get the picture above. This means that our famous microsoft product did hang itself up.
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