Архив за Июль, 2016

Re: SDR# and RTLSDR WFM Stereo

I am a rookie at this SDR stuff, using HDSDR software, please someone enlighten me as to how to adjust the FM mode from wide/narrow and or mono/stereo. I cannot listen to any FM stations, All i get is noise in FM mode, waterfall shows strong signal and I have adjusted till I am tired of it. i get no speech or music in fm mode on local stations.

Re: Ultra-cheap SDR: HF with RTL2832 and transverter

It took me a week to get HDSDR to work with all the junk dlls ys have to import. It trashed the drivers for my wireless KB, so i had to revert to a usb KB. Now i wait for the HF-VHF SDR upverter to get here so I can monitor low band freqs with my PC.

Ребятушки, друзья подогнали такой вот полосовой фильтр.Нужна Ваша помощь в…

Ребятушки, друзья подогнали такой вот полосовой фильтр.
Нужна Ваша помощь в поиске какой либо информации по нему. Желательно техописание на него. Помогите найти.

Что это может быть?…

Что это может быть?

Airspy SDR as a Network Analyzer using for Antenna Characterization [00:18:54]

You can find more information on my web page: http://www.qsl.net/z33t/

The impedance of the Radio Station (transmitter or receiver) must be well matched to the antenna`s impedance if we want maximum available power to be delivered to antenna.
The return loss and SWR measurements show us the match of the system.

A poorly matched antenna will reflect costly RF energy which will not be available for transmission and will instead end up in the transmitter. This extra energy returned to the transmitter will not only distort the signal but it will also affect the efficiency of the transmitted power and the corresponding coverage area.

Return Loss and SWR both display the match of the system, but they show it in different ways.
The return loss displays the ratio of reflected power to reference power in dB.

The return loss view is usually preferred over the SWR linear scale, because is easier to compare a small and large number on a logarithmic scale.

More than 20 dB system return loss is considered very efficient as only less than 1% of the power is returned and more than 99% of the power is transmitted. In that case the SWR is around 1.2

For radio amateur usage, Return loss more than 14 dB is acceptable. This is adequate to SWR of 1.5 which means that 4% of the power is returned and 96% of the power is transmitted.

0 dB Return loss represent an open or a short antenna terminal, while 45 or more dB Return loss would be close to a perfect match.

Many different methods can be used to measure standing wave ratio.
Professionals usually use a vector network analyzer or frequency analyzer with sweep signal generator and directional coupler.
In this video I will show you very cheap and very good method for antenna characterizing which means measuring the Return loss versus frequency and usable antenna bandwidth like measuring with much, much more expensive, state of the art Network Analyzers and similar measuring equipment.

73 de Z33T


Декодируем пэйджинговые сообщения (POCSAG)

Декодируем пэйджинговые сообщения (POCSAG) (00:02:27)

VHF Repeater FM Communications in Macedonia [00:05:51]

VHF FM Repeater Communications in Macedonia.
Radio amateur FM conversation between radio amateurs from Macedonia (Z3)

Receiving with Airspy SDR on SDR# software and home made Vertical J-pole antenna.

SAQ VLF Receiving with Airspy+Spyverter and SDRplay [00:03:41]

"SAQ"- Radio Station at Grimeton is a VLF transmission facility at Grimeton, Sweden. It has the only working Alexanderson alternator
rotating armature radio transmitter in the world and is classified as a World Heritage Site.

The transmitter was built in 1922 to 1924 to operate at 17.2 kHz.
The antenna is a 1.9 km wire aerial consisting of eight horizontal wires suspended on six 127-metre high freestanding steel pylons in a line, that function as a capacitive top-load to feed energy to six grounded vertical wire radiating elements.

Until the 1950s, the Grimeton VLF transmitter was used for transatlantic radio telegraphy to Radio Central in Long Island, New York, USA. From the 1960s until 1996 it transmitted orders to submarines in the Swedish Navy.

The Alexanderson transmitter became obsolete in 1996 and went out of service. However, because it was still in good condition it was declared a national monument and can be visited during the summer.

On July 2, 2004, the Grimeton VLF transmitter was declared a World Cultural Heritage site by UNESCO. It continues to be used on special occasions such as Alexanderson Day to transmit Morse messages on 17.2 kHz. Its call sign is SAQ.

Recent transmissions from SAQ on 17.2 kHz with Alexaderson 200 kW alternator, was on Alexanderson day (Sunday, July 3rd 2016) at 09:00 UTC.

Distance between SAQ transmitter in Grimeton, Sweeden and Macedonia where the signal was received is about 1850 km.

Receiving with:
1. AIRSPY R2 - SDR + Spyverter and SDRsharp software.
2. SDRplay RSP1 and SDRuno software.

Both SDR receivers settings were previously set for maximum S/N ratio.

There are many thunderstorms in the summer. Those pulse noises are from thunderstorms and lightening. You can monitor the lightening in live on this link:


Antenna is Mini-Whip 10cm homemade active antenna on 6.5 meter plastic pole.

The homemade LPF filter (fc=535 kHz) is used also.

Mini Whip is excellent and cheap DIY active antenna.
Especially for lower frequencies! (VLF up to lower HF bands)

Some people who report poor performance of this antenna did not followed the rules of proper installation!
Grounding the outer conductor (shield) of the coaxial cable has to be done properly!
Coaxial cable is part of Mini-Whip antenna and collect a lot of RF noise.
You can treat Mini-Whip antenna as a vertical antenna feeding at the top where the impedance is very high. Outer conductor of the coaxial cable must be grounded at the bottom of antenna, where the coaxial cable touching the ground, and the second grounding have to be done at the point just before coaxial cable entering in the house.
The RF isolating transformer is recommend also.
In that way receiver ground is not physically connected to antenna ground but it is galvanic isolated from outer shield of coaxial cable.
All this measures is not difficult to implement and cost almost no money, but the benefit is clear, noiseless VLF and HF reception!

Mini-Whip antenna must be placed as far as possible from houses, buildings and power lines!

Here is the link of my Youtube video, with schematics of the Mini-Whip and Power supply (power inserter, or Bias-tee for powering the antenna thru the coaxial cable):


Mile Kokotov, Z33T

Звуки ОСНАЗа …

Звуки ОСНАЗа ★ Советский человек на Кубе
Звуки ОСНАЗа http://cubanos.ru/audio/audio03
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