Category Archives: Reviews
As you know, SDR radio basically consists of two components, the radio hardware and the software used to process the signal. As SDR radio hobbyists we typically spend a lot of time looking into the specs of the hardware, but we don’t but as much consideration into the software side of things. The software can be just as important as the hardware we choose to get good performance from a SDR radio system. We often turn to some of the free software offerings to get started in SDR hobby. While there is absolutely nothing wrong with that and we greatly appreciate the work these authors has put into their efforts. However, you have to keep in mind that some of these programs use DSP (Digital Signal Processing) engines developed for SDR use that have been handed down for many years and have only been improved slightly over their original incarnations. With that in mind, the developers at SDR Applications set out to create a new high performance DSP engine for better SDR performance from your SDR hardware. That product is now called Studio1 and is distributed by Woodbox Radio. Studio1 is not a free application. However, this is a good thing because unlike the free offerings, this means that for this to be a viable product the developer will have to be committed to it’s continual improvement and provide support for its customers. In a nutshell Studio1 has gotten a good start on meeting those goals.
How would you like to have a very good HF SDR receiver with a wide spectrum display covering 2MHz or more for about $75? Well, you can when you combine the Ham it Up HF Up-converter with a RTL2832U stick. NooElec is selling an HF Up-Converter board based on an open hardware design in conjunction with Opendous Inc. for about $50 plus shipping. The Up-converter board basically converts HF signals to the FM band (specifically 100.5 MHz to 150 MHz) allowing your RTL2832U to tune in the HF signals. When used in conduction with SDR Sharp or HDSDR you are able to receive HF signals in AM, USB, LSB, CW, and other modes. HDSDR gives you roughly the same functions found on most better HF receivers like noise blanking, automatic gain control, variable filters widths, etc. These inexpensive HF up-converters are nothing new. There have been many designs floating around in either DIY form or completed boards. However, the Ham It UP converter looks like the first product produced in quantity and is available directly from NooElec in the US. I purchased the Ham it Up HF converter for testing from NooElec and it arrived very quickly.
The bad news is that the venerable RTL2832U / E4000 chipset DVB-T stick that has been the source of many SDR projects is getting a little harder find. The good news is that the new kid on the block the RTL2832U / R820T looks like a worthy replacement. The other advantage is the the RTL2832U / R820T is a bit cheaper. The RTL2832U / E4000 is typically selling from $25 – $35 while the RTL2832U / R820T sells for around $10 to $20. The frequency range of the RTL2832U / E4000 is generally around 64MHZ to 1700MHz with a gap around 1100MHz to 1250MHz. The RTL2832U / R820T frequency range is 24MHZ to roughly 1850MHz with no gaps (found yet), and no DC offset spike. RTL2832U / E4000 uses a Pal type antenna connector and adapters are easily found at your local Radio Shack for external antennas.
Since the introduction of the $25 to $35 Raspberry Pi mini pc was introduced earlier this year, there has a flurry of small inexpensive pcs that have followed. One of the most popular mini pcs has been the Mk802 pc on a stick. While the Raspberry Pi can still be hard to get ahold off, the MK802s are readily available from US vendors. The MK802 ships with Android 4.0 installed. The prices for the MK802 pc runs around $60 – $70 dollars shipped. Even though the MK802 seems to cost about twice as much as the Pi, you are getting a little more for your money. The MK802 comes with a case, built in wifi, power supply, HDMI adapter cable, usb adapter, and a mini usb cable. So in the end they are pretty equally priced considering shipping for Pi and adding the cost of the power supply and other cables. Plus running Android, the MK802 is pretty much ready to go out of the box. The MK802 also has more built in memory and a slightly more powerful processor. Like the Pi the MK802. the MK802 can run several Linux distributions using that can be installed on a micro SD card. Simply install the Linux distribution on an 8GB card, insert the into MK802s card reader and you are now running Linux. To go back to Android simply remove the micro SD card and reboot.
Having spent 3 weeks testing the MK802, it appears that this small computer is more useful as of this writing than the Rasberry Pi for Ham Radio applications due to it’s better performance with the built in Android OS and the Linux distributions are a bit faster. The one strength the Pi still has over the MK802 is with its GPIO interface which makes it easier to interface to external hardware devices. Like the Pi the Linux distributions are a little quirky and not as complete as a typical desktop Linux installation. Also since the MK802 and the Pi require ARM packages, some software is not going to work.