Differences in Sensitivity RTL2832U / E4000 Dongles
Are all RTL2832U / E4000 DVB-T dongles sensitivity about the same when being used for SDR radio use? If you read the previous post on this site about using the RTL2832U / E4000 as a SDR receiver, I was less than thrilled about the sensitivity of the generic white DVB-T stick I purchased. After reading some glowing comments on how well some of the dongles worked, I started to wonder if some DVB-T sticks performed better than others. Unfortunately, this area is so new, there is not a lot of info out there about performance differences between the various RTL2832u / E4000 sticks. Maybe eventually some of this information will gradually become available as more people experiment with this device. What info I could find based on user comments made me think that the answer to the above question was basically yes.
My guess is that most fo these dongles are based on a reference design which should mean that they all perform the same way. However, that is not always the case. Some manufacturers will often change the design to make it cheaper, change the form factor, enhance performance, or add features. For example, one user claimed that they had bought one of the tinier sticks and as it would heat up, the sensitivity would go down. Cooling it off brought the sensitivity back up. Some RTL2832U / E4000 dongles may have dead spots in certain frequency ranges where others may not. Also, these devices are mass produced in large quantities and quality control may not always be the best which can introduce more variables. Some users received non working sticks. Combine all of this with the fact you are asking the device to do something it was not designed to do.
The white generic unit I received worked reasonably well below 200MHz, but anything above that it was pretty much deaf. I even popped open the case and checked if the right chip set was in there, and it was. So, I figured it might be worth risking a few more bucks to see if another dongle. Again, there isn’t much info as to which dongles perform better than others, but I did see a few good comments about the EzCAP EzTV668 dongles, I thought it would be worth another try. I ordered a EzTV668 from NooElec a USA vendor and got it in a few days instead of a couple of weeks. This particular DVB-T dongle was slightly more expensive than the generic white one, but does include a remote (pretty much useless at this time, but who knows) which probably adds to the cost. You pretty much just get everything in a plastic bag, but thats okay.
The first thing I noticed was that the EzCAP is about twice the size of the generic white dongle. Not sure why, but it could be due to a slightly different circuit board design or due to the additional circuitry for the remote and power led. The build quality is much better also. The EzCAP stick feels a bit more durable than the white dongle. The PAL antenna connector is much better also. The included whip and my PAL adapter fit more securely in the antenna connector. Thats all well and good, but was it better than my original GWS (generic white stick)?
For some reason I could not get the EzCAP to work with HDSDR following the steps in the Setting Up Your RTL2832U / E4000 for SDR Use article on this sight. However, after installing the ExtIO driver mentioned in the article, SDR# worked fine with it. I then compared the two dongles using SDR#, the included whip, and an attic mounted discone antenna.
Here is how it went:
FM – Broadcast Band WFM
GWD Dongle – Picked up strong local signals easily.
EzCAP – The same.
GWD Dongle – Local signals and some distant signals (approx. 50 miles)
ExCAP – Local signals and a few more distant signals (encouraging!)
AM Aircraft Band – Local ASOS Station at 132.875 (very weak signal)
GWD Dongle – No Signal
EzCap – No Signal
GWD Dongle – Very low signal with some aircraft transmissions showing up in the passband
EzCap – Better reception (as good as my handheld scanner with a whip) and many aircraft coms showing up in the passband.
162.400 MHz NWS Station FM
GWD Dongle – Just over the noise level but intelligible.
EzCap – Full quieting
GWD Dongle – Full quieting
EzCAP – Full quieting
800 MHz Trunked System Control Channel FM
Included whip Antenna
GWD – No Signal
EzCAP – Full quieting (As good as or slightly better than desktop scanner with a whip)
GWD – No Signal
EzCAP – Slightly worse than the whip, but this normal for the discone at 800MHz due to lack of gain and some cable loss.
So you can see that the EzCAP performed dramatically better than the GWD dongle. Actually I would say that it performed on par with the Funcube dongle if not even a bit better. In the 800MHz band the EzCAP performed as well as my other 800MHz capable radio. So, needless to say I am much more impressed with the RT2832U / E4000 radio dongle SDR radio. This is a heck of an SDR deal for under $35 dollars.
I would highly recommend if you get a RTL2832U / E4000 dongle for SDR use. Set it up and try to pick some known strong frequencies that in the 70MHz – 1000MHz range. If you are getting weak or no signals in this range, you may have a not so good or defective dongle.