So far, SDRs have been developed and built in the USA, Russia and Germany. Now a country from the Far East has joined the club: China!
From the Middle Kingdom, there comes a SDR named "S9-C Rabbit SDR". Mr. Dale YU (BA4TB), a ham radio operator and the developer of the S9-C, sells this radio via his small "Venus Information Technology Co“. Here in Europe, the S9-C is absolutely unknown although it has been available since the middle of 2015. There is only scant information about the S9-C on the internet. Out of curiosity and with little hope, I asked Mr. Dale Yu if he would be willing to send me demo unit and after a couple of days I received a positive reply and was sent the S9-C Rabbit. I was very happy about that because I was probably the first person in Europe that could run tests with the S9-C Rabbit SDR.
The radio came neatly packed in a book-like box. A USB-cable, a pigtail from SMA to PL and N connectors, a switch power supply with adapters came along with the radio. The S9-C is a high-quality built SDR. The enclosure is completely made from milled aluminum and is actively cooled, i.e., there is a small fan under the cooling fins , which luckily is not too loud.
The S9-C sports good technical features. These are:
There are two SMA antenna connectors on the back of the S9-C: one for longwave, medium wave and shortwave (HF) and the other for VHF/UHF (U/V). To the right are the USB 2 connector and the DC connector for the 6V power supply. The combinable antenna connector "HF+U/V" is very convenient. With the controlling software (SDR') you can choose whether you want to use only one antenna for the complete frequency range or if you want to operate the radio with two antennas using "U/V" for VHF/UHF. At 54 MHz the antennas switch automatically when using two antennas.
Opening the S9-C, the trained eye will see that no effort was spared regarding the quality of the radio. All important components are additionally shielded. The workmanship and the parts leave nothing to be desired.
Controlling software for the S9-C
Considering the price range of this SDR, I had been hoping for independent controlling software. But, alas, that was not the case. Instead, the radio works with the tried and proven "HDSDR" and "SDR#" software. The necessary ExtIO.dlls and the USB driver have to be downloaded from the webpage of the manufacturer. There are two bandwidths: 1.2 MHz and 3 MHz which can be selected when starting the program. CW-Skimmer and RTTY-Skimmer are also supported, which I did not test, however.
I was pleasantly surprised when I found out that the ExtIO.dll for HDSDR also works with the "Studio 1" software, but not completely. There is no control of the pre-selector.
The installation of the programs went very fast and there were no difficulties installing the USB-drivers, either. You only had to copy the appropriate ExtIO.dlls into the correct program files. And then I could start!
How does it work?
You are always excited when you can test a new and unknown radio. I started with the HDSDR software. After some basic settings and program configurations, I could finally start. For reference I used the tried and tested Perseus SDR and NetSDR+, both of which are top notch receivers.
It says on the S9-C website that the S9-C's frequency range starts at 250 kHz which is not ideal for Europe because it means that longwave, which is still used here, cannot be received. Before Dale sent me the radio, I contacted him and he found a solution by optimizing the circuit so that the demo unit could receive longwave and even lower frequencies.
I started with the lowest frequency which the S9-C can handle. The radio received the French navel station HWU on 18.3 kHz with S 4. Using the same antenna, the Perseus rendered this signal withS9+10 dB, with more interference, however. So, this station is better readable with the S9-C and was more noticeable in the spectrum as well. The NetSDR+ received HWU with S 9 + 17dB. The time signal on 60 kHz was received with S8, the Perseus rendered it with S9 + 10dB, the NetSDR+ with S9 +20dB. The SNR was about the same for all three radios. BBC on 198 kHz was received with S9 + 10dB. The other two receivers had a signal which was about 10dB stronger with similar SNR.
Above longwave the differences were hardly noticeable and were so small that it was not worth the effort to make a video of each band.
Comparison between S9-C Rabbit SDR with HDSDR and NetSDR+ with SDR-Console V3 on Mediumwave.
Comparison between S9-C Rabbit SDR with HDSDR and Perseus SDR. Receiving Laser Hot Hits on 4029KHz.
Comparison between S9-C Rabbit SDR with HDSDR and Perseus SDR. Receiving on 6585KHz in LSB.
Comparison between S9-C Rabbit SDR with HDSDR and NetSDR+ with SDR-Console V3. Receiving on 11700KHz.
Comparison between S9-C Rabbit SDR with HDSDR and Perseus SDR. Receiving on 15580KHz.
Comparison between S9-C Rabbit SDR with HDSDR and Perseus SDR. Receiving on 17530KHz.
The S9-C is also compatible with the "Studio 1" software. The only feature that does not work is the activation of the pre-amplifier of the S9-C. Here you can see that the S9-C is also a good FM-receiver with a frequency range of up to 860MHz.
The S9-C Rabbit SDR is a top SDR which can compete with the best radios of this price range without any trouble. The hardware meets high quality demands. The only drawback is the reception of the lowest frequencies below longwave. In this regard, its competitors, the Perseus and the NetSDR+, were better when signals were weak. Reception of medium wave and shortwave was practically identical. The S9-C receives frequencies up to 860 MHz and clearly beats the Perseus in this respect.
Unfortunately, there was one feature which was not so good: the ExtIO.dll. At the time of testing, this interconnecting software between the S9-C and the actual control program had not been optimally programmed. The ExtIO.dll for HDSDR could only produce a 5kHz tuning step in the LO-frequency and the Center-tuning did not work correctly, either. If you use the "Tune" frequency feature, all steps can be tuned.
For the SDR# program, there is a ExtIO.dll with more functions. But there were also bugs in the programming which made it difficult to operate the radio with 'SDR#, and so I did not use it.
There was a surprise when I used the "Studio 1" program. This great software works with the HDSDR ExtIO.dll and the S9-C. The only feature which could not be activated was the S9-C's pre-amplifier, but that was no disaster.
It remains to be hoped that the manufacturer will correct the ExtIO.dll soon.