Building of a long wave JJY/WWVB software receiver



A long wave receiving system using FFT software Spectrum Lab of DL4YHF.       

If antenna connection is carried out to a sound card, it will become a long wave receiver to 96khz.

 jjy/wwvb,whistler, meteor sound and earthquake presage radio wave

1、 Spectrum Lab

  Download Spectrum Lab from the homepage of dl4yhf.


After installation of Spectrum Lab, audio output setting is performed.

Audio output setting
     Quick Settings
     Load & Create user-def'd entries
    Although it became an ELF/VLF receiver of 24khz, since the antenna is not connected,
only noise sound can be heard.
    If a signal is put into a sound card, it can use as a FFT analyzer.

Reception band enhancing
    Audio settings, I/O device selection
    Audio Processing Sample Rate (nominal)is set as 192000.
    It became the ELF/VLF/LF receiver of 96khz.


Setting preservation
     Quick Settings
     Load & Create user-def'd entries

2、Loop Antenna

     It's the antenna which can be made very easily, but it can be received well.
      Materials are only an insulated wire and an external speaker.
     @ Wound the wire around a carton box and it fixes with the packing tape.
     27cm×32.5cm  35turns 41.7m 0.9mm 32Ω
     Inductance and Q in 50khz became 915uh and Q=9 in the calculation with WEB.

     A Remove wiring of a speaker and connect with a loop antenna.

sp.jpg sploop.jpg      

3、Receiving Test

     JJI and JJY of 40KHZ and 60KHZ were received.
      40KHZ in Fukushima was heard clearly and 60KHZ in Saga was heard by a noise mixture.
     JJI 22.2KHZ in Miyazaki was also heard strong.
     Reception at the place where it's about 500 km away from Fukushima and Miyazaki.






4、Tuned Loop Antenna

     The resonance frequency of an antenna "is presumed" by Spectrum Lab.
      The calculation which calculates the value of F=, L=, and C= uses Excel.


     @ The capacitor such as 0.01uf(103,10000PF) is connected with the loop antenna.
      It searches for the frequency that the signal has strengthened.
     I measured in 6800pf of holdings. A resonance expectation frequency is ≒ 63.8KHZ.
     The color of 3 main lines per 60khz becomes red with capacitor and becomes blue without it.
     They seem to be resonating per 60khz.
     The inductance which resonates in 60khz in 6800pf is 1036uh.
     Completion of an antenna for 60KHZ JJY.

     A An antenna for 40KHZ JJY.
     The capacitor which makes 1036uh resonate in 40khz is 15297pf.
     But Q of an antenna is low, so it's substituted in 14700pf of holdings (103+472 and ≒ 40.8KHZ).
     The signal strength of 40khz is changing.
It becomes red with 14700pf and becomes blue without it.




5、VLF/LF Tuned Loop Antenna

(1)Inductance measurement.
@ Franklin oscillator was made for inductance measurement.
     fkosc2.jpg fkosc.jpg      
     A Loop Antenna 52cm×52cm、1mm Aluminum wire、 16turns、2turns pickup
       The loop antenna with the capacitor is oscillated in the Franklin oscillator.
coil.jpg lcosc.jpg
B It oscillates in 76.05khz with 10000pf, and an inductance is calculated with 438uh.
It oscillates in 24.05khz with 100000pf, and an inductance is calculated with 438uh.
It is an actual measurement although it seems that it is too accurate.

The result with 420uh had come out when measuring it in summer.

A line is tight and closed in cold time now.


76khz.jpg 24khz.jpg

(2)Reception band setting
     The combination of capacitors is chosen with DIP switch.
     When the value of inductance and the capacitor is input to a yellow cell of the Excel sheet,
      the resonance frequency is calculated.


It resonated from 19.3Khz to 100Khz
by combining 100000pf 33000pf 10000pf 6800pf 3300pf 1800pf 330pf.
The capacitor is not put up to msb.
Reserved for the future use.
That is for the medium wave, NDB, and SAQ 17.2khz, etc.

Antenna characteristic graph.



Frequency setting chart
Error compensation can be carried out if resonance frequency is measured using the Franklin oscillator.



 VLF/LF Loop Antenna