duminică, 18 noiembrie 2012

VLF

VLF receiver

Receiving the newcome VLF area is very easy now using computers with souncards. In general most of the amateurs use HF aerials or VLF loop antennas very easy to build but hard to use in portable field operation. The big radio electric noise caused by industry and other human activity in cityes make the necesity of portabile operation and easy transportabile antenna.


BBB-4 large band receiver

  1. Rezistors: R1-1Mohm; R2-10Mohm; R3-220ohm; R4-1Kohm; R5-10Kohm; R6-33Kohm; R7-4.7Kohm; R8-1.5Kohm.
  2. Capacitors: C1-100nF; C2-47pF; C3-100nF; C4-100nF; C5-100mF; C6-1mF; C7-100nF

The receiver above is the famous BBB-4 Rx with a small modification , eliminating the low pass filter between the two transistors increase to a large band capability depending on your soundcard. The antenna is a simple 1 to 3 m vertical wire.

The software used in this case is Linrad, a very good piece of work from SM5BSZ working on a P2 laptop with 64M of RAM.


Linrad in action

Linrad is one of the best software because its flexibility in configuration, you can use it from VLF to EME weak signals reception, and its working nice with ALSA audio server on Linux machines. There is others good programs like Spectrumlab, or Baudline very good for setup or put online a VLF receiver for everyone taste.

Software

Spectral analysis

VLF links