Home Receivers

 

Belka-DSP

A shortwave receiver comes from Belarus which triggers the "must have" effect! The Belka DSP. Various videos have been circulating on YouTube from this device since autumn 2019. Once looked at, the above-mentioned effect occurs. The Belka-DSP is tiny! It is smaller than a credit card. Despite the very small dimensions, it is a full-fledged shortwave receiver with digital signal processing (DSP). This means that the operating modes and the filter bandwidths are software.

Its designer Alexander Buevsky (EU1ME) attached great importance to maximum portability during development. Therefore, no loudspeaker was installed in the Belka-DSP. Only a lithium polymer battery can be accommodated in the housing. The device must therefore be operated with stereo earphones, headphones or a small passive or active loudspeaker. He doesn't have a built-in antenna either. For this purpose, a 70cm long telescopic antenna with BNC connector is included. The Belka-DSP is very robust. The housing is made of high quality, black anodized aluminum. The voting button is on the right. On the left side you will find the BNC antenna socket, the 3.5mm stereo jack socket and a micro USB connection with an LED that shows the charging status. The large, white backlit LC display and four push buttons can be found on the front. The device lies comfortably in the hand and makes a high-quality impression.

.

 

The most important key data of the Belka DSP

- Frequency range: 3.5MHz-30MHz (tunable from 1.5MHz)
- AM, AMS, LSB, USB, NFM, CW
- MDS (smallest audible signal at): -135dBm
- Dynamic range: 80dB
- Bandwidths: 2.4 - 2.7 - 3.0 - 3.5 - 4.0 - 4.7Khz (audio bandwidth)
- High pass to bandwidths: 50 - 75 - 100 - 150 - 200 - 300Hz
- CW bandwidth: 300Hz
- CW pitch: 500 - 600 - 700 - 800 - 900 - 1000Hz
- Frequency stability: 0.5ppm (TCXO)
- Signal strength display in dBµV EMF
- 24bit ADC & DAC
- 32 memory locations
- 3.5mm stereo jack
- Operating voltage / charging voltage 5V (via micro USB socket)
- Built-in lithium polymer battery with 3.7V 2200mAh
- BNC antenna connector
- Dimensions: 84x50x20mm (WxHxD)
- Weight: 95g

Scope of delivery:
Belka DSP
telescopic antenna

Block diagram

 

The interior of the device is very neatly processed, which suggests that it is equipped with machines. The practiced eye does not miss the fact that the Belka-DSP reveals a little secret, if you take a closer look at the board. Bandpass filters can be seen on the upper left half of the red circuit board. This means that the small Belka DSP has a preselection in the antenna input. This also shows the block diagram above that the manufacturer provides. The large LiPo battery with 2200mAh has enough capacity for over 24h continuous operation of the device.

Working with the Belka-DSP

Although the Belka-DSP offers some functions and has only a few controls, it is still easy to use. Even inexperienced shortwave listeners will quickly get along with the little one. Experience has shown that similar developments by radio amateurs contained some shortcomings in operation. That is different with the Belka-DSP. Alexander Buevsky (EU1ME) built a device with logical and simple operation. As an example, the operating modes note the step size and the bandwidth that was last used. So you don't have to change the bandwidth every time you switch from AM to USB etc. The operating instructions are only available in Russian and English. I took some time and translated it into German. It can be downloaded from the following link.

Belka-DSP Bedienungsanleitung in Deutsch

 

 

 

The comparison on stationary antennas

Unfortunately I had no other portable receiver available in the test phase to make comparisons. That's why I let the Belka-DSP compete against a "big boy". His opponent was the Icom IC-R8600. Sure, it's like comparing a mosquito to an elephant. The Belka-DSP also had to demonstrate its ability on active station antennas.
So that you can get an idea of the reception performance of the Belka-DSP, I recorded a few audio comparisons.

Test conditions

Antennas: Datong AD370, Kreuzloop-Reuter RLA4 / E2, Sony AN-1
Comparison receiver: Icom IC-R8600
Both receivers are connected to the PC via an audio switch.
Recording software: Audacity - The audio files were not reworked. Cut to length only.

Audio comparisons

Differences between the receivers can best be determined with audio comparisons and not with the written word. Both receivers were set the same if possible. The station received was carefully selected so that it could be received as consistently as possible over the recording period so that the differences can also be assessed. A few audio comparisons are from stations on the sward, which means they are just above the noise floor. I therefore recommend using headphones.

Second 0 - 15: Belka-DSP
Seconds 15-30: Icom IC-R8600

3616khz-LSB
2.4khz
Hamradio
 3975khz-AM
6khz
Shortwaveradio
5025khz-USB
2.4khz
Rebelde.mp3
7850khz-USB
2.4khz
CHU-Canada
8776khz-USB
2.4khz
Olympia-Radio
9990khz-AM
6khz
Radio-Farda
10051khz-USB
2.4khz
Gander-Volmet
11815khz-AM
6khz
Brasil-Central
 
13264khz-USB
2.4khz
Shannon-Volmet

 
13870khz-AM
6khz
FEBC-Manila

 
14205khz-USB
2.4khz
Hamradio

 
15280khz-AM
6khz
Radio-Japan
17630khz-AM
6khz
Voice of Iran
28257khz-CW
0.3khz
Bake-DK0TEN
  

On the road with the Belka-DSP

I often had the Belka-DSP with me on long walks. One thing caught my eye. It is ultra portable! The Belka-DSP literally fits in the tight pocket of your jeans. I don't know of any other receiver that is so small. Of course, the telescopic antenna and the stereo- earphones must be taken along. The reception with the small Belka DSP is really fun. It is low-noise, selective and has a balanced audio reproduction. Battery capacity was not an issue. The battery easily lasts 25 hours. Two things weren't so good after all. If the outside temperature is cold, the response time of the LC display is very slow. During portable operation with a directly connected telescopic antenna, it was noticed that the Belka-DSP had a few more whistling points than with a remote antenna. This is actually normal, but sometimes it was a bit annoying when the whistle was exactly on the transmission frequency of a station.

.

Conclusion

The little Belka-DSP surprises and puts you in a good mood! No signs of overload were found during the test phase. And that on stationary active antennas. Despite its very small dimensions, the Belka-DSP has a preselection. The reception quality can be heard. Compared to the Icom IC-R8600, it does not have a particularly high-pitched audio reproduction, which reduces the intelligibility somewhat for weak transmitters, but makes listening more pleasant. The sensitivity is almost at the level of the IC-R8600 and is constant up to 30MHz. Portable operation is fun, except at low outside temperatures. Then the display reacts very slowly. When the telescopic antenna is directly connected, some whistling points are noticeable. For remote antennas, this was largely not a problem.
Top workmanship, very good reception at a very fair price.

Available from: http://www.belrig.by/

posted: 14.02.2020

 

Belka-DX

The Belka DSP quickly became a popular receiver on the go. What he was still missing, however, was a built-in loudspeaker so that the listening pleasure could take place without earphones. This has now been achieved with the "Belka-DX". As a further innovation, the reception area has been extended downwards. This now starts at 1.5MHz. It goes without saying that the reception area extension was equipped with an additional bandpass filter. And as the icing on the cake, the manufacturer gave it an I/Q output. This allows the mini receiver to be connected to the computer and, with the appropriate software, the signals can be demodulated and a spectrum can be conjured up on the screen. Everything else has stayed the same.

.

Block diagram of the Belka-DX

For the frequency range extension 1.5MHz - 3.5MHz a further band bass filter (BPF) was installed. In addition, a 3-pin jack socket was installed under the tuning controller for the I/Q signal output (IQ output).

 

On the go with the Belka-DX

Nothing has changed in terms of the mass of the device. The mobility and the pocket format have been retained as with the predecessor. A small thing that provides significantly more comfort is the miniature loudspeaker built into the rear! When going for a walk you no longer have to take earphones with you to listen to shortwave. In a quiet environment you can easily listen to the broadcasts with the Belka-DX in "loudspeaker mode". Of course, you shouldn't expect hi-fi sound from such a small speaker. But it is definitely enough for stronger stations. But there is a small damper! The white buttons produced in the 3D printer vibrate at high volume. This then creates a kind of rattle in the audio. If you hold it, the audio sounds clean (see video). By installing the mini speaker, the large battery with 2200mAh had to give way to a smaller one with 1250mAh. But this is still enough for a continuous operation of 15 hours, which is still long enough.
During a long walk I sat down on a wooden bench to enjoy the nice weather. Because the Belka-DX now has a built-in loudspeaker, I placed the device on the wooden bench. Placing the device down had a negative impact on reception! If you hold the device in your hand, the device has a "counterweight" because of its own body mass. Without this counterweight, strong noise from the display become noticeable! The Belka-DX absolutely needs a counterweight to the antenna. If you put it on a steel gate (see video), the counterweight is also given and the display disturbances disappear.
 

Operate the Belka-DX on the computer

The Belka-DX is the only miniature receiver to have built-in an I/Q interface which enables data to be sent to the PC in order to enable a spectrum/waterfall display. This is done by connecting the socket below the tuning button with a 3.5mm stereo jack plug to the sound card input of the computer. The I/Q output enables a spectrum bandwidth of approx. 40KHz. In addition to the spectrum/waterfall display, signals can also be demodulated, as can be seen in the video below. 

 

Conclusion:

The manufacturer has succeeded in giving the smallest DSP receiver in the world a small loudspeaker, an I/Q output and a frequency range extension with an associated band bass. The Belka-DX receives just as well as its predecessor, only with the new features. Nevertheless, there are two abnormalities to complain about. These loose keys that vibrate at high volume and impair the audio and the display interference when the device is placed on a non-conductive surface. Apart from that, the Belka-DX is an ingenious device that is second to none.

Price/performance: top!

posted: 02.04.2021

 

 

Belka-V3

Now there is the third version of the popular Belka DSP receiver. On the device it says only Belka, but I call it Belka-V3. So you can better distinguish the three versions.
The short overview:
-- Version 1: Belka-DSP (3.5MHz - 30MHz)
-- Version 2: Belka-DX (1.5MHz - 30MHz)
-- Version 3: Belka-V3 (0.1MHz - 30MHz)

.

 

Changes compared to the previous version Belka-DX

From the outside the changes are hardly visible. If you look closely, you can read "0.1 - 30MHz" under the Belka lettering. The little Belka has grown up now. Now it receives long, medium and short wave continuously. If you look even closer, you will notice that the hardware has also changed. The rattling buttons from the 3-D printer have been replaced by rubber buttons. These have a crisp pressure point and are much better than the previous ones. The rubber buttons no longer affect the audio playback. Now the audio sounds much better with the built-in speaker when the volume is turned up full. No more clanging or clunking to be heard! A small change was also made to the software. The 9KHz tuning step for the medium wave was added. Unfortunately the 10KHz tuning step was removed. This would have been interesting for the countries that have 10KHz transmitter spacing on medium wave.


 

Block diagram of the Belka V3

To be able to receive the long and medium wave range, some changes were made in the receiver circuit compared to the previous version. The preselection now consists of a low pass filter for the range 0.1-31MHz. All frequencies above this range are attenuated. If the Belka V3 is operated in the long or medium wave range (0.1-2MHz), an additional low pass filter is switched into the receive branch to attenuate the short wave above. The signal then passes through another 45MHz bandpass filter before it is digitized. The following circuitry remains largely the same.

The reception on long wave and medium wave

For LW & MW reception, a large antenna is actually needed. Because the Belka-V3 has a high impedance (HI-Z) antenna input, it copes amazingly well with the short telescopic antenna. In my area, BBC4 on 198KHz and Radio Gold on 1548KHz can be received quite passably during the day. If the signal strengths are low, some unsightly self-generated interference becomes noticeable! The display itself or the display control makes hefty disturbances in the LW & MW range. If you hold the device in your hand, this dampens the interference a bit, because the body mass is a counterweight to the antenna. In the evening or night hours, the Belka-V3 receives amazingly well in these low frequency ranges. Due to the excellent selectivity of the digital filters, the transmitters can be well separated from each other. Even if the transmitters are strongly incident, they can not mask the self-generated interference. Intermodulation of the ADC in portable operation at the telescopic antenna could not be determined.
The operation in the shack at an external antenna is almost interference-free. I operated the small one at an active dipole and the cross-loop with very good success. The decoding of DWD on 147.3KHz worked with the Belka-V3 without problems. The few remaining stations on longwave are received equally well by the Belka-V3 as with the comparison receiver "Arinst SDR Dreamkit V2D". Even with the antenna removed, the display interferences are still partially present. On medium wave, the same behavior can be observed, with one exception. In the evening hours with very strong sum signals, intermodulation is noticeable from time to time. Between the 9KHz transmitter intervals, undefinable stations or station mixtures can be heard. Turning down the sensitivity did not bring a clear improvement.
At the reception on shortwave everything remained the same. In direct comparison with the Belka DX no differences were noticeable.

The Belka-V3 outdoor on long and medium wave
During the day at 15:00 CET.

 

Conclusion:

The Belka-V3 is now a complete world receiver with continuous frequency range from 100KHz to 30MHz. The large signal compatibility also on the new frequency ranges is very good. Only a few intermodulations were noticeable in the evening on large antennas. Apart from the display interferences, which are much more noticeable on long and medium wave than on short wave. Welcome is the new 9KHz tuning step for medium wave, which makes tuning easier. Unfortunately, the 10KHz tuning step is no longer available, which is a shame.
The new rubber keypad is much nicer, more comfortable and no longer interferes with the audio.
An all around great device that every SWL should have.

posted: 26.03.2023

 

↑↑ Home Receivers