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SDRplay has been a well-known manufacturer and supplier of tuner-based SDR receivers for several years. The devices are all manufactured in England, where the company is also based. SDRplay receivers are becoming increasingly popular with SWLs, radio amateurs and even professional users. You can get devices with a huge frequency range, from 1KHz to 2GHz. With the right software, there are almost no limits. That is why I would like to introduce you to the newest member of the SDRplay family. The SDRplay RSP1B.
Strictly speaking, the RSP1B is the improved version of the RSP1A. It has received a few important hardware updates that should help it to achieve better reception. That made me curious. A good quality wideband SDR that costs well under 160€?
I contacted Jon Hudson, the owner of SDRplay, and asked if he could send me a test device. Would you believe it, less than 24 hours passed and the RSP1B was on my desk. My compliments to SDRplay for the speedy delivery!



The device comes in simple packaging, which also serves as the operating instructions. Unfortunately, the device does not come with a USB cable. This should be a type A to type B USB cable. You should definitely get a well-shielded cable to avoid interference.

The housing

The first thing you notice is the metal housing. It is designed to shield the sensitive electronics from interference. It leaves a good impression. It is very sturdy, has a precise fit and the paintwork is of good quality. The antenna connection in SMA standard is located on the left-hand side. The USB-B port is located on the right-hand side of the housing. I would have liked to have seen a newer USB standard here. Such as the current USB-C standard. The RSP1B stands on four rubber feet. The housing screws that hold the upper and lower housing shells together are hidden under these feet. I unscrewed the device to take a look inside. The circuit board is not screwed separately to the housing. It is clamped between the upper and lower housing shells by the screws. I noticed something here that is marked with red arrows in the picture below. The receiver board is clamped between eight support surfaces. Two of the four supports on the lower housing shell have been kept bare at the factory in order to establish an earth connection to the circuit board. Unfortunately, all the other supports, especially those on the upper housing shell, are not bare at the contact points. There are paint residues on them that prevent good ground contact. This can lead to the housing not shielding properly! The screw head contact surface was also painted over, which prevents ground contact. I removed the paint from all the supports before screwing them together to ensure clean ground contact. This way I can be sure that the metal housing really achieves its shielding effect.


The receiver board

Pictures say more than words! The circuit board is very cleanly constructed. Of course it was assembled by machine.
Sad but true... I had searched in vain for a block diagram on the SDRplay website to explain the signal path of the RSP1B here. After contacting Jon Hudson, I found out that SDRplay no longer provides block diagrams and detailed information on the components of the devices. The reason for this is product piracy! I fully understand SDRplay's approach.



The most important key data of the RSP1B

-- Frequency range: 1KHz - 2000MHz continuous
-- Low pass filter up to 2MHz
-- Bandpass filter for shortwave: 2-12, 12-30, 30-60MHz
-- Bandpass filter for VHF. UHF, SHF: 60-120, 120-250, 250-300, 300-380, 380-420, 420-1000MHz
-- High-pass filter from 1000-2000MHz
-- Switchable cut filters for MW, FM and DAB+
-- Built-in and switchable remote power supply with 4.7V/100mA
-- Sensitivity: approx. 0.15uV
-- ADC: 14bit max. (depending on the sampling rate)
-- Stabilized TCXO with 0.5ppm
-- SMA antenna connector for all frequency ranges
-- USB-B connection
-- Operating voltage 5V (via USB socket)
-- Operating modes: AM, SAM, LSB, USB, CW, FM, WFM, DRM, DAB+, Digital or software-dependent & depending on plugin
-- Spectrum bandwidths with SDRuno: up to max. 10MHz
-- Dimensions: 98x94x35mm (WxDxH)
-- Weight: 315g
-- Scope of delivery: RSP1B, short installation instructions on the box

The software

The software that SDRplay provides free of charge for its SDRs is called "SDRuno". For some time now there has also been "SDR Connect", which comes from the same company. This software is very promising, still "preview" but fully functional. Therefore, all tests were carried out with SDRuno & SDR Console-V3.
Here is an overview of the programs that can control the RSP1B.
-- SDRuno
-- SDR Connect
-- SDR Console V3
(ExtIO.dll download here)
-- SDR++
(not yet fully compatible at the time of testing)



Changes have been made to the hardware of the RSP1B which should significantly improve reception in the lower frequency range, i.e. in the VLF, long wave and medium wave range. Shortwave reception and the VHF range should also benefit from this. I got to the bottom of this and compared the RSP1B with the Elad FDM-S3.
The following antennas were used:
- Stampfl X-One (horizontal polarization)
- Datong AD370 / AD370-R (horizontal polarization)
- NTi Megadipol MD300DX (vertical polarization)

Reception on VLF

After many comparative tests at different times of day, a clear increase in the performance of the RSP1B in the VLF range is noticeable. Reception is usually as good as with the Elad-S3. The sensitivity of the RSP1B is practically on a par with the S3. There are hardly any audible differences. Only in the evening hours did the RSP1B occasionally exhibit signs of clipping. This manifested itself in a higher background noise level.

Audio comparisons

Second 0 - 10: SDRplay RSP1B
Second 10 - 20: Elad-S3

Some audio comparisons are intentionally close to the noise floor in order to test sensitivity and intelligibility under difficult conditions. Headphones should be used to hear the small differences in the audio comparisons.

During the day, reception on VLF frequencies is attenuated due to propagation conditions. That's why I made these comparisons during the day. At night, the signal strengths in this frequency range are much stronger and pose no challenge. The reception performance of the RSP1B is practically at the same level as that of the Elad-S3. I used the SDR Console-V3 for the visual comparison test on VLF and LW because the spectrum/waterfall can be set identically for both receivers. The active dipole Stampfl X-One and the MegaDipol MD300DX were used for these comparisons.

Alpha-Navigation-RUS - 14.9khz
Mode: CW
BW: 500Hz
Military-RUS - 18.1khz
Mode: CW
BW: 150Hz
Timesignal MSF-GBR - 60khz
Mode: CW
BW: 150Hz
Timesignal RBU-RUS - 66.66khz
Mode: CW
BW: 750Hz
Timesignal DCF77-DEU - 77.5khz
Mode: CW
BW: 150Hz

Just in time for Easter: reception of the Alpha navigation signals at 3pm in the afternoon. This could only be received with the MegaDipol MD300DX because it is vertically polarized.

Below: Reception of the time signal transmitter RBU from Moscow at 5pm in the afternoon. Can only be received with the MegaDipol MD300DX because it is vertically polarized.

VLF range 10KHz - 90KHz
Both competitors at the same time. The important SNR is slightly better with the S3!
Click on the diagram below to enlarge it.

Reception on longwave

Unfortunately, fewer and fewer stations are broadcasting on long wave. Where I live, only the usual stations can still be heard. Here, too, I made the recordings during the day. Antenna: Stampfl X-One & AD370-R

Antena Satelor - 153khz
Mode: SAM
BW: 8KHz
Medi 1-MRC - 171khz
Mode: SAM
BW: 8KHz
BBC 4-GBR - 198khz
Mode: SAM
BW: 8KHz

Longwave range 70KHz - 270KHz
Click on the diagram below to enlarge it.

Reception on medium wave

Listening on medium wave was a pleasant experience. During several test sessions, I was unable to detect any unwanted signals or clipping effects. The SDRuno offers direct access to predefined radio or amateur radio bands with the practical band buttons. This includes the medium wave. This function automatically sets the medium wave band to its full width with "LO Lock" tuning. This means that the local oscillator frequency is fixed. When tuning the frequency, the bandwidth bar is moved and not the spectrum/waterfall.

Radio Caroline - 648khz
Mode: SAM
BW: 8KHz
Danko Radio-HNG - 1116khz
Mode: SAM
BW: 9KHz
Radio Studio X-ITA - 1188khz
Mode: SAM
BW: 8KHz

Below: Full-width medium wave at 8pm on the Datong AD370 active dipole. Nice clean reception! As usual with multiple assignments that make listening difficult. Below is the 648Khz on which Radio Caroline broadcasts.

Reception on shortwave

A well-balanced receiver/antenna combination is the prerequisite for good reception! Of course, the location should be as free of interference as possible. The RSP1B performs well on shortwave! Not very well, because its inadequate preselection sets limits. The shortwave is not filtered well enough. The two built-in bandpass filters (2-12 & 12-30MHz) are simply not enough. Even if the sum signals are not excessively strong, you can hear and see intermodulation below 15MHz in the evening hours. The sensitivity on shortwave is sufficiently good and can keep up with the premium SDR Elad-S3. Very good to hear in the audio example "RAF Volmet". A signal at the limit of intelligibility.

Timesignal CHU-CAN - 3330khz
Mode: USB
Hamradio 80m-CHE - 3681KHz
Mode: LSB
BW: 2.8KHz
HCJB-DEU - 3995khz
Mode: SAM
BW: 6KHz
Shannon Volmet-IRL - 5505khz
Mode: USB
BW: 2.8KHz
Pirate Station-NLD - 6290khz
Mode: SAM
BW: 8KHz
Bangkok Volmet - 8743khz
Mode: USB
BW: 2.8KHz
RAF Volmet-GBR 11253khz
Mode: USB
BW: 2.8KHz
R. N. da Amazonia-BRA - 11780khz
Mode: SAM-U
BW: 4KHz
Timesignal CHU-CAN - 14670khz
Mode: USB
BW: 2.8KHz
Bake DK0TEN-DEU - 28257khz
Mode: CW
BW: 150Hz

Below: Maximum bandwidth of 10MHz for the first check before zooming into the detail. The resolution of the spectrum is up to 0.95Hz depending on the viewing width!

Reception on FM

I haven't done any detailed tests and comparisons above shortwave. This is not my hunting ground. In addition, there is hardly any radio traffic to be received above 135 MHz where I live.
In the VHF and lower VHF range, I only noticed minor irregularities. The RSP1B works best with the Stampfl X-One active dipole up to above the airbband. This antenna does not have too high a level and has little noise. This suits the RSP1B very well. It only produces a few intermodulation products. In direct comparison with the Elad-S3, the differences are small. Sometimes the SDRuno software performs slightly better than the Elad software. For example, the RDS decoder. This decodes much faster and the sound was sometimes more pleasant. The latter is of course a matter of taste.

SRF1-CHE - 94.4MHz
Mode: WFM
BW: 160KHz

FM range 90MHz - 100MHz
Click on the diagram below to enlarge it.

Reception in the airband

Civil aviation radio is still an interesting field of activity for many SWLs. The RSP1B is also suitable for this. The differences to the S3 with its downconverter are minor. The very good scanner function of SDRuno can be used particularly well here.

Volmet ZRH-CHE - 127.2MHz
Mode: AM
BW: 8KHz

Airband range 130MHz - 137MHz
Click on the diagram below to enlarge it.


DAB+ reception and other options

Thanks to the SDRuno software, the RSP1B can also receive and decode DAB+. This is possible with a free plug-in, which is included in the SDRuno package. DRM, Navtex, RTTY, Acars etc. can also be received with other free plug-ins. However, some plugins are not fully developed and cause a high CPU load or SDRuno hangs. What has worked well is DAB+.



SDRplay has not promised too much. The performance in the lower frequency ranges is impressive and is practically on a par with the Elad FDM-S3. The RSP1B is also largely convincing on shortwave. The sensitivity is not at the highest level, but at a good level. It is sufficient to keep up with the S3. The Achilles heel of the RSP1B is the lack of preselection on shortwave. Intermodulation is often a companion on an evening foray into shortwave. This is where the Stampfl X-One active dipole has proven to be the ideal antenna for the RSP1B. Due to its not too high level, it is very suitable up to 150MHz.
It would have been nice if SDRplay had paid more attention to the finish of the metal housing. Important contact points were painted over and could therefore impair the shielding effect of the metal housing.
The RSP1B works best with the SDRuno software and also offers the widest range of functions, leaving almost nothing to be desired.

For the reasonable price of less than 160€, the RSP1B can do almost everything and the hardware is good quality to boot”
Source of supply: SDRplay

postet: 13.04.2024



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