FlightAware Prostick vs FlightAware Prostick Plus: Review

Recently the FlightAware Prostick Plus was released. The Prostick is a modified RTL-SDR with a LNA built into the dongle. It is optimized for ADS-B reception and works very well due to the low noise figure of the SKY7150 LNA which is used as the first stage LNA. However, due to the increased gain from the LNA it can easily overload from strong out of band signals, such as broadcast FM, DAB, DVB-T and GSM. To eliminate this problem FlightAware recommend using their 1090 MHz filter in front of the dongle. 

The FlightAware Prostick Plus is the same as the Prostick, but the Plus also incorporates a 1090 MHz SAW filter into the dongle itself. The overall cost is about $15.95 USD cheaper than buying the Prostick + Filter combination. See below for a tabulated comparison between the two units.

  FlightAware Prostick + Filter FlightAware Prostick Plus
Price

USA: $16.95 + $19.95 = $36.9 (Buy Prostick) (Buy Filter)

Worldwide: $48.99 + $18 Shipping = $66.99
(Buy Prostick + Filter)

USA: $20.95
(Buy Prostick Plus)

Worldwide: $29.99 + $12 Shipping = $41.99
(Buy Prostick Plus)

LNA + Filter Arrangement Filter -> SKY7150 LNA SKY7150 LNA -> Filter
Filter Specs Type: Cavity? Ceramic?
Passband:
980 – 1150 MHz
Insertion Loss: 1.65 dB
Attenuation: 40 – 50 dB
Type: SAW
Passband:
1,075 MHz – 1,105 MHz
Insertion loss: 2.3 dB
Attenuation: 30 dB 
TCXO Old batches NO.
New batches YES.
YES
Current Draw 330 mA 300 mA
The new Pro Stick Plus RTL-SDR based ADS-B Receiver from FlightAware.
The new Pro Stick Plus RTL-SDR based ADS-B Receiver from FlightAware.

The first thing we notice is that the filter arrangement between the two units is reversed. On the Prostick the filter is external and must be placed before the LNA. This has the advantage of excellent rejection of out of band signals, but increases the noise figure (NF) of the system slightly. A higher noise figure means the ADS-B signal will end up being weaker, resulting in less range and reports. However, the FlightAware 1090 MHz filter has low insertion losses and should only increase the NF by 1-2 dB.

The Prostick Plus on the other hand uses a SAW filter positioned after the LNA. SAW filters at 1090 MHz typically have an insertion loss of anywhere between 2-3 dB’s. But since it is placed after the LNA the losses are almost completely eliminated by the gain from the LNA and thus the total NF remains low. The attenuation of the SAW filter is less, but it has a smaller pass band. The small pass band may be useful for people who live near an airport and suffer issues with interference from the 1030 MHz interrogation pulses or from GSM at 950 MHz.

In theory, the Prostick + Filter should operate better in environments with very strong out of band signals (any signal outside of 1090 MHz). And the Prostick Plus should operate better in environments with weaker out of band signals. The theory is that since the LNA is placed first in the signal chain on the Prostick Plus, it is more susceptible to overloading from the strong signals as it has no protection from a filter. The LNA used in both Prosticks is a SKY7150, which has a very high OIP3 rating. High OIP3 means that its performance in the presence of strong signals is excellent, and it will not overload so easily. However, even a very high OIP3 rated LNA cannot withstand the strong broadcast signals in some locations.

The Prostick Plus also has some other enhancements like a TCXO. ADS-B is very tolerant to frequency drift, so a TCXO won’t really improve decoding performance, but the cost of a 28.8 MHz TCXO purchased in bulk is under $1 USD, so they may have decided to add it anyway. They appear to also be using TCXO’s on the new production batches of the Prostick as well. The Plus also only draws 300 mA of current compared to the Prostick which draws 330mA. This may be due to the removal of the LED (Although the new batches of the Prostick might also have the LED removed as they advertise a power draw of 300 mA.) On the image of the PCBs below you can see the difference. The SAW filter is just underneath where the LED used to be.

Again, as we mentioned in our previous review of the Prostick it is a bit odd that the 39 dB OIP3 SKY7150 only appears to be drawing 60 mA, when it should be drawing 100 mA. The lower current usage is probably because they run it from 3.3V instead of 5V. The lower current use probably means that the OIP3 rating is reduced slightly by ~5 dBs.

The Prostick Plus and Prostick PCBs
The Prostick Plus and Prostick PCBs

Real World Testing

Here we test the Prostick and Prostick Plus in a signal environment with lots of strong interfering BCFM, DVB-T and GSM signals around. We’ve seen reports on the FlightAware forums that some users have seen improved performance with the Prostick Plus, whilst others have seen dismal or reduced performance. In these tests and review we are able to show when each stick will perform at its best. We do not test the Prostick without the filter, as without the filter we are unable to receive any ADS-B messages at all due to overloading.

Test 1: Flight Aware ADS-B Antenna

First we set up a test using the FlightAware ADS-B antenna, a 2-way signal splitter and the Prostick Plus and Prostick + Filter. We used Modesdeco2 as the ADS-B software, and ran the test for 45 minutes.

The results show that the Prostick Plus edges ahead of the Prostick + Filter by a small amount. It seems that the 1-2 dB loss in the external filter does not contribute to a huge reduction in ADS-B messaging, but the results do show that the Prostick Plus will give you better results in an environment with favorable reception conditions.

In this test we used the excellent FlightAware ADS-B antenna. This antenna is tuned specifically to 1090 MHz, and performs some rejection of the out of band signals. This rejection is enough to allow the Prostick Plus to work well in our test area without overloading.

In the image slider below we first checked ADS-B reception in SDR#, to see if there was any noticeable visual difference. The reception seemed identical. In the remaining images we checked to see how the reception was on out of band signals with the two units. In these tests we want the out of band signals to be low, so smaller signals are better. The Prostick Plus filters our out band signals significantly less, which can be a reason for increased overload. But the amount of filtering performed by the Plus was sufficient together with this 1090 MHz tuned antenna to not cause any overload at max gain.

http://ADS-BComparison

ADS-B Comparison

http://BCFM

BCFM

http://152MHz

152 MHz

http://858MHz

858 MHz

Test 2: Discone Antenna

In test 2 we show what can happen if the out of band signals going into the Prosticks are really strong. This could especially happen if you are using a wideband antenna that is not specifically tuned to 1090 MHz, or if the out of band signals in your area are exceptionally strong (living near a transmission tower for example). In this test we used the same setup as in test 1, but used a wideband discone as the antenna instead. This means that the natural out of band signal filtering from the FlightAware antenna is not present anymore, and thus out of band signals come into the dongle much stronger.

Here we found that the Prostick Plus produced dismal results. The out of band signals were too strong for the LNA to handle, thus causing overload and significant desensitization of the ADS-B signals. The messages received by the Prostick + Filter was significantly higher. 

In the SDR# screenshots below we can clearly see that the Prostick Plus has very poor ADS-B reception at 1090 MHz with this antenna. The noise floor is much higher due to desensitization and overload from broadcast FM and DVB-T signals. Reducing the gain on the RTL-SDR does not help a lot, since most of the overload occurs in the first stage SKY7150 LNA. This can also be seen in the amount of signal overload that is present when tuned to the broadcast FM and other bands in SDR#.

http://ADS-BComparison

ADS-B Comparison

http://1090MHzGainReduced

1090 MHz Gain Reduced

http://BCFM

BCFM

http://BCFMGainReduced

BCFM Gain Reduced

http://152MHz

152 MHz

http://415Mhz

415 Mhz

http://858MHz

858 MHz

Conclusions

The Prostick and Prostick Plus dongles are both excellent low cost ADS-B receivers. If you want to set up a permanent ADS-B monitoring station they are highly recommended. 

So what are the lessons learned from these tests?

  1. If you live in an environment with extremely strong out of band signals, use the Prostick + Filter combination.
  2. Otherwise use the Prostick Plus for slightly better performance and lower cost.
  3. To reduce the possibility of overload with the Prostick Plus use an antenna tuned to 1090 MHz.

The table below summarizes the recommendations again.

 

Antenna -> LNA -> Filter
(Prostick Plus)

Antenna -> Filter -> LNA
(Prostick + FA Filter)
Advantages

Noise figure (NF) is dominated by the LNA, thus this method gives minimum NF.

Losses in filter overcome by LNA gain.

LNA will not be susceptible to overloading from out of band signals.

Disadvantages

The LNA can overload from out of band signals since it is not protected by a filter.

The insertion loss (IL) of the filter directly adds to the noise figure (NF). For example a 2 dB IL filter will add 2 dB to the system NF. This may result in a few dB’s lower SNR.

When to use Use this method if you do not have strong out of band signals in your area and/or if you have an LNA with a high OIP3 rating, like with the SKY7150 LNA which is used on the Prostick’s. Use this method if you have very strong out of band signals in your area.

For most people the Prostick Plus should work fine and be the better choice. Also rest assured that if you purchase a Prostick Plus and find that it overloads in your environment, you still always have the option of placing an external filter in front of it. Then you’ll practically have the same performance as with the standard Prostick + Filter combination. A Prostick Plus + External Filter combination may even be more beneficial for users in very very strong signal environments.

Also remember that the Prostick’s are designed to be placed as close to the antenna as possible, without the use of coax cable. You can use USB extension cables, or run the Prostick on a remote Raspberry Pi computing unit to achieve this. If you want to run coax between the antenna and Prostick, you will see heavily reduced performance due to the losses in the coax cable. In this situation you should instead place an LNA like the LNA4ALL or Uputronics ADS-B LNA by the antenna, and use a bias tee to power it.

New RTL-SDR Drivers and SDR-Console ExtIO Available: Bias Tee Support, Direct Sampling, Tunable IF Filters and Improved Gain Profiles

Recently two branches of RTL-SDR drivers were updated. Over on GitHub racerxdl’s librtlsdr branch adds bias tee support for our V3 RTL-SDR.com dongles to rtl_adsb, rtl_fm, rtl_power and rtl_tcp.

For SDR-Console users jdow’s ExtIO and driver now has an option to enable the direct sampling mode, which is allows the HF mode on our V3 dongles to be activated. The ExtIO module can be downloaded from her Google drive.

To use Joannes drivers download the SDRconsole folder by right clicking it, and selecting download. Then copy files from the x86 (32-bit) or x64 (64 bit) folders into the SDRConsole folder, replacing any files that already exist. Run the RtlSdr Catalog.exe file, then open SDR-Console and from the definitions choose RTL-SDR(Full). Then in the Radio Configuration settings you can choose to use the Q-branch, which will automatically enable the direct sampling mode when tuned below 24 MHz.

SDRConsole with a V3 dongle and HF Direct Sampling.
SDRConsole with a V3 dongle and HF Direct Sampling.

We’ve also discovered that Joanne has been working on RTLSDR++, which is a driver upgrade that includes some pretty interesting enhancements. When running Joanne’s drivers in SDR-Console we also see options to change the IF filter bandwidths of the R820T2 tuner. This is very useful as this allows you to control the preselector on board the R820T2. You can use this to attenuate strong out of band signals. Her driver also has improved gain profiles. One gain profile is optimized to reduce IMD distortion (prevent overload and images), and the other is designed to optimize sensitivity.

RTLSDR++ Driver: New IF bandwidth settings for preselection.
RTLSDR++ Driver: New IF bandwidth settings for preselection.
RTLSDR++ Drivers: New Gain Options
RTLSDR++ Drivers: New Gain Options

In addition Joanne has also created RtlTool.exe which is a GUI replacement for rtl_test.exe and rtl_eeprom.exe. It can be used to test for lost samples on your RTL-SDR and to flash the EEPROM memory. Most RTL-SDR dongles on most PCs are stable up till 2.56 MSPS, but this tool can be used to check. It can also be used to set the dongle serial number, vendor ID and name by flashing the EEPROM which most RTL-SDRs contain.

There’s also the RtlSdr Catalog tool which also helps manage multiple dongles being connected to the PC at once. See the readme file for more information on using this tool.

All these programs can also be downloaded from Google drive. Her RTL++ driver is also open sourced and available on GitHub.

RTLTOOL
RTLTOOL

Reverse Engineering and Reading Data from a Wireless Temperature Meter: Tutorial + Code

On GitHub user spenmcgee has uploaded a write up and Python software that decodes data from a Lacross TX29 wireless temperature meter. Spenmcgee’s write up goes into excellent detail about how he actually wrote the program and reversed engineered the transmitter.

First he explains how he used Python to extract the data from the RTL-SDR I/Q samples. From those samples he calculates the amplitude data, and plots it on a graph which shows the digital signal. He then decimates the signal to reduce the number of samples and figures out how to detect the preamble, data bits and packet repetitions. Then to decode the signal he explains how he does clock recovery, convolution and thresholding, and also the importance and meaning of those steps.

If you’re new to reverse engineering signals and don’t have a DSP background, then spenmcgee’s write up is an excellent starting point. It’s written in a way that even a layman should be able to understand with a little effort. If you have a Lacross TX29 wireless temperature meter that you just want to decode, then his code will also be of use.

Bits detected from the RTL-SDR data.
Bits detected from the RTL-SDR data.

ThumbNet N3 Unboxing and Nongles.com: SDR Lego

A few days ago we received a production sample of the new ThumbNet N3 receiver. Our sample came with the works, which includes the green aluminum enclosure and shielding can soldered on over the PCB. This full set costs $33.50 USD + $4.50 USD international shipping, but there are cheaper options if you do not want the aluminum case or the RFI shield.

We’ve only had a brief time to play around with it so far, but it’s performance seems very similar to the prototype unit that they sent us earlier. We intend to give the N3 a longer review next week but our first impressions are favorable. In this post we’ll simply unbox the unit, show some photos and give it a quick turn on test.

The N3 comes in a protective cardboard box with the N3 and Thumbnet/Nongles logo on it. Inside sits the ThumbNet N3 unit itself, and there is a power plug terminal block adapter located on the bottom of the box. Excluding the F-type connector, the ThumbNet unit has dimensions of 6.2 cm x 4 cm x 2.1 cm, and weighs 58g. The green enclosure is strong and rugged.

Unlike the prototype they sent, this unit can run direct from USB power alone. We saw that it draws about 400 mA of power, and we had no trouble running it from our 1A capable USB ports. Of course one of the main advantages to the N3 is the ability to power it with a low noise external power supply, and we will be testing that in the next review.

Nongles SDR Lego

ThumbNet have also announced their new sister site, Nongles.com. On this site they intend to soon begin selling something called “Nongles” which is a mashup of “NOt a dONGLE”. Nongles are an idea that can be best described as a type of “SDR Lego”, and we think will be very interesting to people interested in experimenting with different SDR set ups and for use in education. Nongles will be based on the RTL-SDR design, but they are going to be split the RTL-SDR up into several discrete PCB modules/blocks such as:

  • R820T2 Module
  • RTL2832U Module
  • Experimenter Module
  • External Clock Module
  • LNA
  • Bias Tee
  • Signal Amplifier
  • 50 – 75 Ohm Transformer
  • Filter blocks such as SAW/FM Bandstop/High Pass/Low Pass and other DIY kits

Obviously you’ll at least need the R820T2 and RTL2832U blocks to have a working system. Then the other blocks can then be added in as needed. The Nongles are not ready for sale yet so keep an eye on their website for news of their release.

Radio For Everyone: An Easy Homemade Outernet Antenna, More FlightAware Pro Stick Plus Results

Akos from the radio for everyone blog (formerly known as the rtlsdr4everyone blog) has uploaded two new posts. On the first post he shows some further tests on the new FlightAware Prostick plus. The Prostick is an RTL-SDR that contains a built in LNA and the Prostick plus adds an additional SAW filter on the stick. For him the Prostick Plus works significantly better than the regular Protstick + external FA cavity filter and also gets about twice the ADS-B reception reports as our V3 which does not use an additional internal LNA. Next week we hope to release our own review of the Prostick Plus, and we’ll hopefully be able to show and explain why some people see better performance with the plus and why some instead see degraded performance.

In his second post Akos shows a tutorial on building an easy helical antenna for Outernet reception. The antenna is constructed from readily available household materials such as a soda bottle, coax cable, electrical tape and a cookie tin. With the cookie tin used he was able to get a SNR reading between 7 – 9 dB, which is pretty good considering that only 3 dB is required for Outernet decoding to work.

Outernet hardware plus the homemade helical antenna made by Akos.
Outernet hardware plus the homemade helical antenna made by Akos.

Some More Reviews of the SDRplay RSP2

Two days ago the RSP2 was released for sale as we released a review of a pre-production unit that they sent us. Since then there have been some more review that have come out from other users who had a review unit.

Hamradioscience.com have released a good review of the RSP2 along with a video. The author writes how he’s impressed with the additional shielding, the software switchable antennas and the bias tee. Like in our review he also tested the RSP2 bias tee with the Outernet LNA and found good results. He notes that the RSP1 and RSP2 are very similar in terms of RF performance, but writes that he noticed times when the RSP2 seemed to be more sensitive or exhibit a lower noise floor than the RSP1.

https://www.youtube.com/watch?v=fwshKQT1-7c

On YouTube user Laboenligne.ca reviews the RSP2 and also has a live Skype interview with Jon the head of marketing at SDRplay. Jon gives a good overview of the new features and some applications that they could be used for.

https://www.youtube.com/watch?v=a6aGy7_mQv0

Over on NN4F.com Paul Jones also reviewed his RSP2. He was very impressed with the performance of the Hi-Z port, the performance of the BCFM notch filters and the stability of the TCXO.

The author of swling.com has also released his review and he too was impressed by the improvements.

On a related note the RSP1 is now for sale for black friday at HamRadioOutlet for only $119.95 USD.

SDRPlay RSP2 Release Announcement and Review

Today SDRplay have just released their newest software defined radio – the Radio Spectrum Processor 2 (RSP2) which is the successor of the RSP1. The RSP2 costs $169.95 USD, and the older RSP1 is still for sale at $129.95 USD. There is also the “RSP2pro” model which is an RSP2 in a metal enclosure, and this sells for $192.95 USD.

The RSP2 has nearly the same base specifications as the RSP1 (12 bit ADC, 10 MHz bandwidth, 10 kHz – 2 GHz range), but now comes with additional features and enhancements such as a software switchable BCFM and BCAM notch filter, TCXO, multiple antenna ports, HF optimized Hi-Z antenna port, clock in and out ports, better shielding and can also now tune down to 1 kHz.

It is available for purchase at sdrplay.com/rsp2 (Worldwide), HamRadioOutlet.com (USA) and ML&S (UK).

The announcement reads:

SDRplay Limited has today announced the launch of a second Software Defined Radio product – the RSP2.

Building on the popularity of our first product, the RSP1, we have now launched the RSP2. The RSP2 delivers a significant number of additional features which result in a higher spec for specialist amateur radio users as well as benefits for additional scientific, educational and industrial SDR applications.

Here are the main additional features of the RSP2:

  • 10 built in front-end pre-selection filters, with substantially enhanced selectivity
  • Frequency coverage extended down to 1 KHz
  • Software selectable variable gain Low Noise Preamplifier
  • 2 x SMA Software Selectable 50Ω RF ports (1.5 MHz – 2 GHz)
  • 1 x High Impedance RF port (1 kHz – 30 MHz)
  • Built in software selectable MW /FM notch filters
  • Highly stable 0.5PPM TCXO trimmable to 0.01PPM
  • 24MHz Reference clock input / output connections
  • 4.7V Bias-T option (on one of the software selectable antenna inputs)
  • RF screening within a strong plastic case for the standard RSP2
  • A Rugged metal box version – the ‘RSP2pro’

When used together SDRplay’s own SDRuno software, the RSP2 becomes a high performance SDR platform. The benefits of using the RSP2 with SDRuno include:

  • Highly integrated native support for the RSP2 professional grade software based upon class leading ‘Studio 1’, free of charge
  • Calibrated S-Meter including support for IARU S-Meter Standard
  • Calibrated RF Power Meter with in excess of 100 dB of usable range
  • Best in class audio quality

Currently the RSP2 requires the use of SDRuno software, but in the coming weeks we plan to provide support for HDSDR, Gnu Radio, CubicSDR and we are working with Simon Brown to get support within SDR Console.

We believe that the RSP1 will continue to prove very popular as the lowest cost 12-bit SDR for general applications such as Short Wave Listening or for use as a panadapter and we pleased that we can now offer more choice to the growing community of RSP users.

The RSP2 is expected to retail at approximately £130 (excluding taxes) or $169 (excluding taxes)

For more information visit our website on www.sdrplay.com

The new RSP2
The new RSP2

The table below shows a comparison of the RSP1, RSP2 and RSP2pro. A datasheet can be found on SDRplay’s new RSP2 webpage.

Differences between the RSP1, RSP2 and RSP2pro.
Differences between the RSP1, RSP2 and RSP2pro.

http://www.youtube.com/watch?v=Irb7k1rOJ-M

SDRplay RSP2 Review

Two other reviews have already come out, one from swling.com and one from NN4F.com.

Thanks to the generosity of the SDRplay team we were fortunate enough to receive an early pre-production review model of the standard (not pro) RSP2 unit. The unit arrived a few days ago, and here we give it an initial review. In a previous review we did a comparison of the Airspy SDR, SDRplay RSP1 and HackRF. We found that the RSP1 and Airspy had similar overall performance, but that the Airspy would be better for those people who needed high dynamic range performance in strong signal environments, and that the SDRplay RSP1 would be best for people who wanted a low cost all-in-one unit with performance better than an RTL-SDR. 

The Inside

We decided to take a look inside and see how much the PCB has changed from the RSP1 to the RSP2. Judging from the two photos we can see that there is quite a significant increase in the number of components used. What was once a sparse PCB is now populated much more heavily with additional filter banks and several new switches. However, the core design of the RSP2 remains similar to the RSP1. The RSP2 uses the same Mirics MSi001 tuner chip and MSi2500 ADC chips.

The standard plastic enclosure is also now spray painted on the inside with conductive metal paint which helps by acting as a Faraday cage. This prevents interference from getting through and should be almost as good as a metal enclosure.

The conductive paint seems to be working well, as in our tests the RSP2 does not receive any signals with the antenna disconnected, whereas the RSP1 does weakly receive some very strong pager signals.

RSP1 & RSP2 PCBs
RSP1 & RSP2 PCBs
Conductive paint on the plastic case inside.
Conductive paint on the plastic case inside.

Continue reading for the rest of our review

Continue reading

The 2016 /r/rtlsdr Reddit Giveaway

The mods of the /r/RTL-SDR community on the Reddit discussion platform are currently hosting an RTL-SDR themed giveaway. The prizes up for grabs include units which have been donated from ThumbNet (Nongles.com) and us at RTL-SDR.com. The prizes also include several donated home brew projects including filters and downconverters. See the table at the end of this post for the full prize list.

To enter all you need to do is write a comment on the competition thread at reddit.com/r/rtlsdr and mention what you like about SDR and what you hope to do with a prize if you win. While you’re at it we strongly suggest subscribing to /r/rtlsdr if you haven’t already as that is one of the the largest and most active communities of rtlsdr users on the web.

The competition closes on December 3rd and only one entry per household is allowed.

Place Prizes Description
1st-2nd 2 ThumbNet – Nongles.com N3 SDR RECEIVER
3rd-5th 3 RTL-SDR Blog V3 Dongle + Antenna Kit
6th-7th 2 $25 ThumbNet – Nongles.com Gift Certificate
8th-11th 4 RTL-SDR.com Blog V3 Dongle Only
12th 1 PA0RDT Mini-Whip Antenna
13th-14th 2 RTL-SDR.com Blog Broadcast FM Filter
15th-16th 2 Up to ~4.5GHz Microwave Downconverter
17th 1 70cm HamSat / 433 Combline BPF
18th-20th 3 Choice of Custom Made 5 Pole HF BPF/LPF/HPF