VLF signal SAQ
24.12.2019 I received a weak signal in Kraków from TX Grimeton SAQ on 17,2 KHz.
SDR receiver fine work with Winrad software and other programs
My receiver contains three main blocks , I2S programmable synthesizer on Si5351 , digital demodulator , preamplifier on MOSFET.
Works on band 160m , 80m and 17m to 40m.
Several photos are below.
Pioneer A10 and Tube amplifier Warmar acoustic spectra
Measurements of spectra signal using a Fast Fourier Transform (FFT) in the domain of time are performed in a finite time. In other words, the portions of a waveform of the signal of the specified length are measured. Fragments are cyclically extracted and then subjected to the FFT. Fragments of the waveform on shores contain discontinuities, because they are collected at intervals. Discontinuities cause blurring to spectra. The spectra of the downloaded portions of the waveform are different from the spectra of the whole continuous signal subjected to measurement. To reduce blur spectra signal is passed through a time window. The Time window reduced spillage of energy in the domain of frequency. Measurements were made for spectra of acoustic signals Pioneer A10 amplifier and Tube amplifier Warmar. The signal was passed through a time window. The time window Blackman was used. The time window is a function shaping the signal measured undergone FFT. In the domain of time, signal is the function of time and was multiplied with the function describing by the time window. In the domain of frequency the convolution of these functions occurs. The result of the signal is subjected to FFT.
The results of the measurements of the acoustic signal spectra are following:
Picture above shows Pioneer A10 amplifier which carries sinusoidal signal about 1 kHz.
Picture above shows Tube amplifier which carries sinusoidal signal about 1 kHz.
Signal source supplied both apmlifiers in the same time. Next, there was measured how amplifiers carries a music.
Tube amplifier is playing music.
Pioneer A10 amplifier with on function loudness is playing music.
Pioneer A10 amplifier with on function loudness and Tube amplifier are playing music at the same time.
Pioneer A10 amplifier and Tube amplifier are playing music at the same time.
The acoustic spectrum of the test room background is shown below.
Acoustic monitors and amplifiers used to test.
Energia słoneczna gromadzona w cieczy
Tube amplifier made by Warmar
A tube amplifier consists of three tubes: one ECC83 and two ECL86. It has two audio analog high impedance inputs. In order to control sound you can use two potentiometers: treble and bass. Audio output power of this one is a few watts. Output impedance to monitors is 8 ohm.
The amplifier with three way monitors has excellent sound , perfectly deep bass tones and mature high registers. Sound is detailed with wide stereo base.
Some pictures are shown below.
Send yours music by AirPlay to music stereo system
We can transfer music from iPad to stereo music system by AirPlay. We need an only android phone and AirPlay software downloaded from Google Play. Below is showed a diagram that presents this technology. Android phone is connected by headphone connector to the stereo music system. Music from iPad to the Android phone and next to stereo music system is flowed by a WiFi connection. AirPlay Apple is fantastic technology by their you can send your favorite music to music stereo system.
